An effort to battle heat soak induced vapor lock...

[brad72]

Fingers crossed you have found a fix for your boat

On hot days I leave the blower running all day with the engine cover closed and have never had any vapor lock problems, touch wood. If going to lunch I just switch to battery #2 ensuring #1 stays fully charged. Whether this is coincidental or that we never run fuel containing ethanol I do not know. Might be like Greenman eluded to that our engines are facing the correct direction, .

[jackofsometrade]

I just had the vapor lock experience last week while on a week long vacation at the lake. Air temps were high 90's low 100's and boat would vapor lock after running 3-4 hours. Had to get pulled back by the ranger when the wind picked up. The $400 kit from Bakes seems steep, I would love to convert to a in the tank pump as that would fix the issue but I don't have the time to build that out right now. I am going to peice together a kit similar to the Bakes kit. https://www.summitracing.com/parts/crt-p4600hp  I have 1/2" line from the tank to the high pressure pump so I'm adding these as well https://www.summitracing.com/parts/trd-2272/overview/  I hope this helps, super annoying to hangout for 20-30 minutes trying to cool the pump down. I poured cold water on the pump but a few times I had to bleed the air out through the test port on the rail.

[formulaben]

You beat me to it...that's exactly the same pump I installed.  I may have saved a buck or two using eBay but was out the other day with relatively high temps and didn't open the engine cover and she started right up.  Usually I have the vapor lock issue.  Only issue I have with it is that I can hear it but for now it's not bad.  I'll probably relocate it deeper in the engine bay if it bugs me.

[bbelt]

So I finally bit the bullet and got the pump set up from bakes.  Yes I paid more than I should have but then I was hoping it would be all ready for install and have handy instructions.  All I got was the pump and fittings in a box with some wiring, no idiot proof instructions.  I am handy with dirtbike wrenching but not so much with automotive or marine in this case.  The two problems I am trying to figure out, where to physically mount the unit and how how to get power to it?

Curious, does it run constantly?  If not then how does it pressurize while boat is parked and we are swimming around?  Or or is it just enough extra kick to overcome the vapor lock when power is on?

The wiring harness I have has three ends, do I have to cut any wires and tap into something or just unplug the wires to the primary fuel pump and plug it right in there?

Oh, by the way I have an 03 Response.  Thanks.

[formulaben]

I wish I would have taken pictures with my install!  The harness will allow you to disconnect the power connect going to the pump and split the power to both pumps.  I mounted mine to the left of the v-drive using stainless screws going into the HDPE that holds the seats.

[bbelt]

Thanks, that helps with the harness.  I figured as much but wanted someone to confirm.

What does HPDE mean?

Anbody with a direct drive and mounting experience?  THinking about mounting between the front and rear motor mounts on the fiberglass, or left wall of the bilge area.  We do call that whole area below the motor the bilge area right? I expect the fiberglass is reinforced where big stuff is mounted to it and wonder if simply threading some wood screws in there will be innadequate.  Plus, I don't know what on the other side of that fiberglass wall for when I start drilling.

Edited June 17, 2016 by bbelt

[MalibuNation]

HDPE -High Density Polyethylene

[MadMan]

On ‎6‎/‎15‎/‎2016 at 10:17 AM, jackofsometrade said:

I just had the vapor lock experience last week while on a week long vacation at the lake. Air temps were high 90's low 100's and boat would vapor lock after running 3-4 hours. Had to get pulled back by the ranger when the wind picked up. The $400 kit from Bakes seems steep, I would love to convert to a in the tank pump as that would fix the issue but I don't have the time to build that out right now. I am going to peice together a kit similar to the Bakes kit. https://www.summitracing.com/parts/crt-p4600hp  I have 1/2" line from the tank to the high pressure pump so I'm adding these as well https://www.summitracing.com/parts/trd-2272/overview/  I hope this helps, super annoying to hangout for 20-30 minutes trying to cool the pump down. I poured cold water on the pump but a few times I had to bleed the air out through the test port on the rail.

That exact plan cured my vapor lock issue on a previous boat.

[blk93jeepzj]

10 hours ago, bbelt said:

So I finally bit the bullet and got the pump set up from bakes.  Yes I paid more than I should have but then I was hoping it would be all ready for install and have handy instructions.  All I got was the pump and fittings in a box with some wiring, no idiot proof instructions.  I am handy with dirtbike wrenching but not so much with automotive or marine in this case.  The two problems I am trying to figure out, where to physically mount the unit and how how to get power to it?

Curious, does it run constantly?  If not then how does it pressurize while boat is parked and we are swimming around?  Or or is it just enough extra kick to overcome the vapor lock when power is on?

The wiring harness I have has three ends, do I have to cut any wires and tap into something or just unplug the wires to the primary fuel pump and plug it right in there?

Oh, by the way I have an 03 Response.  Thanks.

It only runs when the key is on just like the High pressure fuel pump.  My understanding is that it provides that extra bit of oomph to push more fuel into the system to push the vapor lock experience past the injectors.  I added the low pressure pump 4 years ago, no vapor lock issues since.

[bbelt]

Thanks for all the responses.

Who has placed it in a direct drive?  Where to mount the unit?

[bbelt]

Ok then so I fabricated a bracket to mount the fuel pump just infront of the primary fuel pump.  Took hours but secures nicely.  I go to the local auto store to get some 1/2 I/O fuel line and when I go to instal I notice that it is more narrow outer diameter than the "marine 1/2 I/O" fuel line.   

So is I look around town and no one caries the right fuel line.  Do I need to order the proper marine grade fuel line online or is the 35PSI/2.4 bar stuff from autozone good enough?  After all it is will be upstream from the primary fuel pump where the pressure is low.

[Woodski]

@bbelt:  For fuel injected engines you want a fuel line that meets SAE 30R9 specifications which are more stringent than the SAE 30R7 spec of the fuel line you noted.  Easy to find on line from any of several distributors (SkiDim, Michigan Motorz, Overtons, GLS etc.).

http://www.gates.com/oreilly/tech_tips/PermeationResistantFuelLineHose.pdf

[ibelonginprison]

Just saw that this one was bumped. Not that it would have mattered much, I have no experience with a DD boat. :/

You should also be able to swing past a race shop or hydraulic shop in town and pick up some stainless steel braided lines and fittings if you don't have time to order it online then wait for it to be delivered. More expensive, yes, but it's an instant solution.  The marine environment shouldn't affect ss braided hose/lines any different than when I used it on my truck when doing an LS swap in it.  In fact, I guarantee my boat leads a MUCH easier life in a MUCH more friendly environment than my truck does. LOL

Hope you get it figured out soon!

 

btw.. HPDE also stands for High Performance Driving Event.

But in this case it is referring to the plastic they make cutting boards out of.

[bbelt]

THanks guys, all helpful info.  Boat comes out this week.  Gonna seriously cut into my whitewater kayaking, and mnt biking, and dirt biking. . . the sacrifices we make to water ski.

[ibelonginprison]

I've had a couple of people ask me about this over the last year, so I wanted to update this thread.

While I can't promise that this fix will work for every instance, it HAS worked for me. I haven't had a single issue with vapor lock (with ethanol or ethanol free fuel) since I did this last August. And it's been plenty hot this year. The reflective insulation seems to have done the trick for me. She starts up with zero hesitation, every time. 

 

I'll try to remember to take some pictures the next time I'm in the engine compartment. But it's not complicated. I just wrapped anything that was metal. ha

[echie]

 

Gasoline Engine Vapor Locking

Models

All Mercury MerCruiser 4 Cylinder, V6 and V8 engines.

 

Situation

Under certain conditions, engines may experience a ‘vapor lock’ condition. The three most common complaints that vapor locking cause are:

The engine starts. When the throttle is advanced, the engine quits running and will not restart.

If the engine does restart, it quits when advancing the throttle to get the boat up on plane or to pull up a water skier.

After running the boat and shutting the engine off for 1 to 3 hours, the engine does not want to restart.

Conditions That Affect Vapor Locking

Fuels containing alcohol and ‘winter grade’ fuels will cause vapor locking complaints to increase.

NOTE: The new ‘Reformulated’ fuels have the RVP (Reid Vapor Pressure) very carefully controlled.

It will normally take several following conditions to make an engine ‘vapor lock’. These conditions include but are not limited to:

Type, formulation and RVP of the gasoline in the boat’s fuel tank or sold in the area. ‘Winter grade’ fuels sold from October through March in most areas have the highest RVP.

Engine compartment air temperature and its ventilation system.

Temperature and vacuum on the fuel that is being delivered to the engine.

The location of the fuel tank.

The boat’s fuel supply system. This includes Inside Diameter (ID) of fuel line and fittings, fuel line length, routing, bends or kinks and the clamps that secure it. Extra fuel filters, fuel manifolds, anti-siphon valves, shut off valves, tank selector valves and the number of 90 degree fittings used.

Engine coolant temperature.

How quickly the engine is shut off after running at cruising or higher rpms and how long the engine and engine compartment are allowed to cool off after use.

The outside air temperature on the day the boat is being operated.

Corrections That Can Be Done To Help Minimize Vapor Locking

Before looking at the customer’s problem as a vapor locking condition, make sure something else is not causing the running problem.

Air leak in the engine or boat fuel system. Check the tightness of all fuel fittings and clamps. Check for a cracked housing where a brass fuel fitting is threaded in it.

IMPORTANT: Do not pressurize the boat’s fuel tank(s) in this test.

Disconnect the fuel line from fuel tank(s). Pressurize the fuel system that goes to the engine to 8 psi (55 kPa) with a hand pump to see if it holds this pressure. Often systems will leak air but not fuel. Always use a wrench to hold a brass fitting that is threaded into an aluminum casting when tightening another fitting threaded into it to prevent the casting from cracking.

Check the complete fuel supply system of the boat for a fuel restriction. Include the brass fitting threaded into the engine’s inlet in this test. Use a portable outboard fuel tank connected directly to the engine’s fuel inlet fitting as a quick way to test the system.

If these more common problems are not causing the complaint, then continue.

Follow instructions below:

a. Find out what type of fuel is in the boat’s fuel tank. Fuels containing alcohol are more likely to vapor lock on hot days.

b. Find out what the RVP of the fuel in the boat’s fuel tank is. 11 to 15 RVP (cool to cold weather) fuel will change from liquid to a vapor at lower fuel temperature than 8 to 10 RVP (warm to hot weather) fuel will. Refilling the boat’s fuel tank with lower RVP fuel will decrease the chance of vapor locking. Fuels purchased in most areas of the USA from late September through early April will cause most of the problems.

Follow instructions below:

 

a. Over the last several years, engine compartments have been designed to be quieter. This is done by using an insulation material and by making ‘engine covers’ tighter. This can cause high air temperature inside the engine compartment while the engine is operating and for a period of time after it is shut off. This period of time is called the ‘heat soak’ time. The air temperature inside the engine compartment during a ‘heat soak’ will rise higher than during the engine’s ‘running time’. This is because there is no air movement inside the compartment and no coolant flow through the engine. Normally, the quieter the engine compartment is, the hotter the air temperature will be on the inside during the ‘heat soak’. The highest air temperatures during a ‘heat soak’ will occur 30-40 minutes after the engine is shut off and can stay at that peak for up to 1-1/2 hours. This greatly increases the chances of vapor locking.

b. Mercury MerCruiser engine compartment air temperature specification that became effective January 1, 1996 is:

Under the hottest outside air temperature condition that the boat will be operated in, the maximum air temperature inside the engine compartment, measured at the flame arrestor, shall not exceed 176o F (80o C).

c. Increasing engine compartment ventilation to move the hot air out of it during a ‘heat soak’ will decrease vapor locking. Other items that can help reduce vapor locking are:

Letting an engine idle for 3-5 minutes before shutting it off.

Open the engine cover to let the hot air escape.

Operate the bilge blower to remove the hot air.

3. Follow instructions below:

a. Fuel temperature (at the engine’s fuel inlet fitting) and the amount of vacuum required by the fuel pump to draw the fuel from the boat’s fuel tank can contribute to vapor locking.

Mercury MerCruiser’s maximum engine fuel temperature specification that became effective January 1, 1996 is:

Under the hottest outside air temperature condition that the boat will be operated in, the temperature of the fuel being supplied to the engine shall not exceed 110o F (43o C) at any location between the fuel tank and the engine’s fuel pump.

Mercury MerCruiser’s specification for the maximum vacuum measured at the fuel inlet of any MerCruiser engine is:

2 in. Hg (7 kPa) maximum at idle rpm, 3000, full throttle and back at idle rpm.

Use an accurate digital vacuum gauge that reads in either in. Hg (inches of mercury) or (kPa) to check this specification. Common vacuum gauges to check an engine intake manifold vacuum are not accurate enough to make this type of measurement.

b. Reducing the temperature and maximum vacuum of the fuel being supplied to the engine will help reduce vapor locking problems.

NOTE: Carbureted and EFI/MPI with VST models only: The Water Separating Fuel Filter can be removed from the engine to a lower, cooler location. Use a Coast Guard approved fuel line between the filter and the fuel pump. 

4. Check to see if the fuel tank is in an area where engine compartment heat or sun can preheat the fuel that is in the fuel tank. Putting insulation between the fuel tank and the heat source can help keep the fuel cooler.

5. Follow instructions below:

a.

The fuel supply system can be a major cause of vapor locking. Remove all kinks in any of the fuel lines. Move the fuel line to be as close to the bottom of the boat as possible to keep it in the coolest area of the engine compartment. Replace clamps used to support the fuel line with larger clamps if the fuel line is being pinched or constricted with the current clamp.

b.

Reduce the total length of the fuel line to be as short as possible. Eliminate or reduce the number of 90 degree fittings used in the system to no more than 2.

c.

Any anti-siphon valve or restriction that causes a higher than specified vacuum reading can contribute to vapor locking and other driveability problems. If the vacuum reading is too high, try a less restrictive anti-siphon valve or the Electric Anti-Siphon Valve Kit. 

NOTE: An engine that has a vapor locking condition may show a very low vacuum reading. This could be a false reading because vapor can give a very low vacuum reading. Check the inlet fuel line to ensure that a good solid flow of fuel is in the line instead of a mixture of fuel and vapors. As a test only, use a clear plastic hose between the engine and the supply line to look at the fuel flow visually.

d. Going to the next larger Inside Diameter (ID) fuel line and fittings can help lower the vacuum and help correct vapor locking conditions. An example is shown below.

5/16 in. (8 mm) fuel line and fittings ID5.5 in. Hg (17.8 kPa), too high.

3/8 in. (9.5 mm) fuel line and fittings ID2.5 in. Hg (8.2 kPa), too high.

in. (12.5 mm) fuel line and fittings ID0.8 in. Hg (2.7 kPa), good.

NOTE: Engines with 3/8 in. (9.5 mm) ID fuel line and 15 ft (4.5 m) total length or less: Going to a in. (12.5 mm) ID fuel line will not give much improvement. Fuel systems longer than 15 ft (4.5 m) may see an improvement by going to in. (12.5 mm) fuel line and fittings.

e. Mount fuel manifolds as low as possible in the engine compartment to lower the fuel temperature or remove them if possible.

6. Follow instructions below:

     a. Make sure that the engine has the correct degree thermostat in it. Replace with the correct one.

b. Keep fuel lines as far away from engine cooling hoses as possible.

c. EFI and MPI engines with the ‘Cool Fuel’ system should have the fuel cooler temperature measured after the engine is shut off. The coolant hose going to the ‘fuel cooler’ should not get much hotter to the touch after the engine is shut off for 10-20 minutes than what it is with the engine running. If it gets hot after the engine is shut off, hot water from the cylinder block might be siphoning back. Installing the Check Valve Kit will stop this backward water flow. 

NOTE: On inboard engines with water cooled prop shaft seals, make sure the water tap for this seal is not causing the siphoning. The only approved location from Mercury MerCruiser for this water supply is the raw water hose that goes to the 90-degree fitting (with Blue drain plug) in the bottom of the port exhaust manifold.

How quickly the engine is shut off after running at cruising or higher rpms and how long the engine and engine compartment are allowed to cool off after use can greatly affect vapor locking. To help the boat owner reduce their chances of vapor locking, suggest that they do the items listed under 2c.

Nothing can be done about the air temperature the boat is being operated in. By following suggestions outlined in 1 through 7, the causes for most vapor locking complaints can be greatly reduced.

If all suggestions 1 through 7 have been done and engine still does not restart after it is shut off, the Fuel Pump Kit can be used. This kit will help a vapor locked engine to restart. IT DOES NOT CURE VAPOR LOCKING! The engine may still bog on acceleration. Kit contains a low pressure electric fuel pump, Check Valve Kit and installation instructions. This low pressure fuel pump helps feed fuel to the pump in the cool fuel system.

NOTE: If the items in this Service Bulletin are not checked and corrected before putting the Fuel Pump Kit on, the kit might not correct the restarting of the vapor locked engine.

Kit Part Numbers

P/N 21-862271A 1 Check Valve Kit.

P/N 862733A 1 Electric Anti–Siphon Valve Kit.

P/N 862264A 3 Fuel Pump Kit, (contains Check Valve Kit).

Test Equipment

Following is a list of equipment that can be used to testing.

Testing Fuel RVP:

SPX OTC sells a test kit, Gasoline Quality Testing Kit – P/N 7670.

 

Testing Fuel Temperature or Vacuum:

Fittings required to make connections between engine fuel inlet and the boat’s fuel line and fitting.

(1) Pipe Fitting -in. pipe thread at both ends, 1-1/2 in. (38 mm) long.

(1) Tee Fitting – in. female pipe thread.

(1) Schrader Valve – P/N 22-805408.

(1) Cap, Schrader Valve – P/N 22-805515. Tools required to measure fuel vacuum at fuel inlet of the engine.

(1) Digital Compound Gauge, that has an accuracy of within 2% of the reading. Cole-Parmer P/N P-68950-00. (Note 1)

(1) Gauge Guard (30 in. Hg to 15 psi). Cole-Parmer P/N U-07359-02. (Note 1)

(1) Gauge Guard Liquid (4 fl oz). Cole-Parmer P/N U-07359-50. (Note 2)

Tools required to measure fuel temperature at fuel inlet of the engine.

(1) Hose connected to digital gauge with adaptor to connect to the Schrader valve. Can use hose and Schrader valve connector from Fuel Pressure Kit, P/N 91-881833A 2.
(1) DMT 2000 Meter – P/N 91-854009A 3.
(1) Reducer Bushing -in. male to 1/8 in. female pipe thread – P/N 22-48556.
(1) Temp Probe Compression Fitting – 1/8 in. pipe thread. Cole-Parmer P/N H-08539-04.
(1) Temp Probe – 4 in. long with K connector. Cole-Parmer P/N P-08117-45.
(1) Temp Probe Extension Cable – 10 ft long with K connector. Cole-Parmer P/N H-08516-30.

 

[Jive]

I'm having the same issues lately. Got the kit and new filters to install today.

Can anyone tell me if the secondary pump goes before the twist on fuel/water separator or after?

I know it goes before the filter but that's near the pump so no option there.

Thanks in advance

     

 

[formulaben]

You want the secondary pump downstream of the fuel filter/water separator.  I re-located/re-installed the entire setup recently (and yes, last pic the full install is incomplete...)

 

 

[Kmfish87]

Just now, formulaben said:

You want the secondary pump downstream of the fuel filter/water separator.  I re-located/re-installed the entire setup recently (and yes, last pic the full install is incomplete...)

 

 

Is that a remote mount oil filter set up to the left of the fuel transfer pump?

[formulaben]

Yup!  The double was only $10 more than the single...

 

[Jive]

Thanks for the response! That is one clean install!  

I went ahead with install and luckily that's the way i did it. 

Another quick question if I may... I noticed my boat is reading empty and will not start...tried jacking the trailer way up to get fuel to the back..  Ok I'm out of gas you would think.

Went to fill it up and it only took 23 gallons in a 30 gallon tank to fill... I guess my question would be has anyone ever had pickup issues in the tank? Say maybe a cracked hose or something to that effect?

   

 

[formulaben]

Can't comment on it reading empty, but if you didn't "key up" several times and also didn't fill the fuel filter with fuel you will have a LOT of air in the fuel system.  I filled the filter as best I could then did several key ups, listening for the fuel migration a few seconds afterwards.  I probably did a couple dozen and she fired right up...

[Jive]

Yeah I keyed it up about a dozen or so times and nothing. But once i topped the tank it fired right up...  Just would like to think it would get enough fuel with seven gallons in it.

Oh well I'm about to go enjoy some near 90 April weather and see if vapor lock has become a thing of the past.

Wish me luck!    

   

[williemon]

I just installed the carter marine pump. May be the same one. I installed it with a 40 micron filter between it and the tank. Then i had custom fuel hose built to replace the crossovers, added a section to the top of the high pressure pump, connected it to an10 micron filter from summitt racing, then to another custom hose  and into the fuel rail. I also had the injectors cleaned and tested.  So far it runs real good. The new carter is not too loud . The existing high pressure pump is a little loud. I custom wired the nwe pump myself.  i used a seperate ground  onnected to the engine, then spliced the power onto the high pressure pump power wire.  

 

[Malibuguru0515]

On July 27, 2015 at 4:13 PM, ibelonginprison said:

This thread is to document my efforts to help reduce and/or eliminate heat soak induced vapor lock, and hopefully help anyone with the same issue in the future. This is pretty much for any boat with an external fuel pump, in my case a 2006 Wakesetter 23LSV with a 5.7 340hp Monsoon that has the fuel pump on the starboard side of the engine block, inside the engine compartment. (In 2007 Malibu started using in tank fuel pumps, which are submersed in liquid, therefore keeping them cool and avoiding vapor lock. I'm not sure if they did that for ALL boats, so you would have to research the location of your fuel pump before continuing.)

Issue:

Vapor lock happens when any related fuel delivery item (fuel pump, fuel filter, fuel line or fuel rail etc.) becomes hot enough from radiant heat that the fuel inside turns to vapor. Your fuel system is designed to pump and flow fuel as a liquid, and when it turns to vapor it cannot pressurize or pump/flow enough fuel to fun the engine efficiently, or even run it at all. Hence "vapor lock."

Symptoms:

In my case it's pretty straight forward. The boat is hard to start, and in many cases won't start at all, until the fuel system has cooled down enough for vapor to return to liquid and able to be pumped through correctly. If the engine does start, many times it will idle very poorly, and in most cases will eventually shut off - at which point it is usually very difficult to get back started. Sometimes this will be accompanied by whining or squealing from the fuel pump as it struggles to suck and pump vapor rather than liquid. In some instances (but not mine) you may experience issues while driving, even. Power loss, hesitation, and even stuttering can be symptoms.

On the Water fixes to get you back to the dock:

If you have an external fuel pump that you can get to (in my case, it's easy to see by lifting the rear center cushion above the transmission/vdrive unit and looking backwards on the starboard side of the motor, OR looking down from the top if you pop the engine hatch - it's usually a silver cylinder, and it's easy enough to find if you follow the fuel line from the fuel filter to the pump itself) then you can do a couple of things to help get going.
First, pop the hatch and let it breathe. I've run the blower as well to help, but since heat rises it's questionable how much this truly helps in the grand scheme of things.

Second, you can use a cup and pick up some cool lake water to pour on the side of the fuel pump. Several cup-fulls will help bring the heat way down, and may be enough to get you going. Keep in mind this isn't a permanent fix we're going for here, we're just trying to get your boat started and back to the dock.

Third, try priming the pump several times. (Turning the key to the "on" position, without turning the motor over, or trying to start it.) This can help build pressure inside the fuel system, and sometimes will be enough to get the boat started. However, if the fuel pump is vaporlocked, then it may still run poorly and eventually shut off. You should be able to hear the pump "prime" itself when you do this. Normally you'll hear a soft whirring sound. If it's making loud noises (such as squealing or whining) then at least you know that it's working - even if it is struggling.

Conditions when I experience vaporlock:

For me, it's always a very specific condition. It's later in the day after the boat has been running off and on, and most notably after I've run it for about an hour or more recently, and then let it sit with the hatch closed for about an hour. That 45-75 minute range where it bakes seems to be the magic number for my boat. My theory is the engine stays nice and cool while water is running through it, but if it sits for that hour period then the engine compartment turns into an oven, and the fuel pump becomes hot enough for the fuel inside of it to turn to vapor. In my instance it usually STARTS, but idles poorly, then shuts off and won't start again. My quick fix the 3-4 times this has happened is to poor cool water down the side of the fuel pump (about 6-7 cup-fulls) then prime the fuel pump 3-4 times, and it usually starts and runs effortlessly after that.

Known off the shelf fixes:

Bakes sells a kit to help combat vapor lock here: http://bakesonline.com/detail.aspx?ID=2903

This is a pre-fuel pump fuel pump, essentially, and pressurizes the fuel system with fresh liquid fuel so that the pump isn't struggling to pull vapor. However, it's almost $400.

My first attempt:

The first thing I'm doing is insulating the fuel pump and fuel line from the fuel filter. That's coming this weekend.

Thermotec insulation for the fuel pump: http://www.amazon.com/gp/product/B00029KC2K/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

Heat resistant fuel line sleeve for the fuel line coming from the fuel filter: http://www.amazon.com/gp/product/B004GNLGTQ/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

The theory is if I can insulate the pump and line leading to it enough, then the radiant heat from the block and manifolds won't affect it to the point that the fuel turns to vapor - thus solving my issue.

I'll be doing this on Saturday and taking pictures - then I'll run it through the paces that afternoon and try to set up the perfect condition where my boat usually says "nope" after lounging for a little while in the water, and update this thread Saturday night, or Sunday morning. If it works, I'll do several more weekends of testing and trying to get it to falter and update the thread. If it doesn't work - then on to plan B.... which I'll figure out if plan A fails. lol

GREAT write up, i hope i did not mis this. but id like to point it out to help other understand,

boat with fuel pumps mounted on motor have to pull fuel from the fuel tank. Now lets go back to junior high school... what happens to the boiling point of most fluids when the pressure drops? the reverse of a "pressure cooker" this is how i remember it.  pressure cookers are used to raise the cooking temperature above boiling point without boiling water via raising the internal pressure. raising pressure raises boiling point!

So lowering the pressure inside your fuel lines will greatly decrease boiling point of fuel! Pressure is lowered by the motor mounted fuel pump trying to "SUCK" hence turing to vapor.  then add in crappy fuel aka ethanol and additives.. now your problem is worse!  good news is adding a fuel pump as close to the fuel tank will GREATLY help these issues.

hope this helps, and that i did not over look this info elsewhere. 

I tell people to park with your motor hatch open, to vent and prevent heat soak!