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Icing down the fuel pump


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Having a problem with my Bu (2006 Iride)! Love my Bu. I am a LOYAL Bu owner - never even considered another brand, but I'm starting to get a little frustrated. Boat will start, run , shut off, start again, and perform perfectly while out on the water and for the few minutes it's shut off in between boarders...until you shut it off and let it sit for 30-45 minutes. Then when you start it, it runs extremely rough. If you give it gas, or try and put it in gear and move forward, it hesitates really bad, won't respond, and you're forced to just shut it down. Here's the querky part...if I pull up the engine cover, place a bag of ice against the fuel pump for a minute or two, the boat will start right back up and run perfectly.

This is the third fuel pump on the boat. The first went bad with only a few hours on the boat and was replaced. Boat ran great for a couple summers - and then we started having this problem. Had an extremely intelligent mechanic (at the malibu dealer) spend countless hours on this - replaced fuel filter, a couple of other things of which are escaping me right now, and now the fuel pump and we are still having this problem (although the frequency of which has lessened, but the problem still remains). The mechanic called Indmar and spoke to them about the issue, and asked about known vapor-lock issues with this motor - they said none they were aware of. Being on my third fuel pump, I am starting to get concerned there is a larger problem at hand. Of course, as it goes, I am two months out of warranty now, and would really just like to get this problem fixed so I can not have to worry about my boat just not starting at all while we're out one day. Mechanic said he had one other boat that was doing this same thing - and never could figure out what was wrong with it and that guy spend serious $$ out-of-pocket (also out of warranty) to replace parts upon parts- and I would prefer this not come to that. Unfortunately, the dealer has since gone out of business, and I hesitate taking this to another dealer for them to start this whole discovery process over - because I feel like they're going to want to replace a lot of the parts that have already been replaced, and I honestly don't have the money for that.

Any suggestions or thoughts as to what might be the problem? I would greatly appreciate any suggestions or advice!!

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sounds like typical vapor lock situation. I have a 2005 with 340 Monsoon, and occasionally experience a similar situation. One thing I do to minimize this after running hard is to run the blower while sitting with the engine off. This draws out the heat that builds up in the motor box.

But if I forget, and vapor lock occurs, I get a towel wet, and hold it against the fuel pump for a few minutes. Presto....engine starts.

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BuFootin - thanks for the response. Yeah - I, as well as the mechanic, thought it was vapor-lock as well - and it might be. It just seems weird that I could go for a couple summers and never have this problem to having this problem almost every time we're out - and we haven't changed the way we do things at all. Our outings have the same format as previously and now we have the problem all the time.

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Damn Indmars! Making Malibu look bad.

Is your motorbox insulated? Have you tried running with it with the motorbox vented in some way?

If nothing in your routine changed, then it's probably filter probs. With all the maintenance you've done, how did the filters look?

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Never actually did any of the work myself, so I never saw the filters, but the mechanic replaced the fuel filter at one point (recently - like towards the end of last season). The motorbox is not insulated anymore than it is when it comes from the factory - I haven't added any kind of insulation to it. I have been running the blower at ALL times since this problem started - even when we're boarding - I keep it running and then run it for a couple of minutes before starting after it's been sitting for a while - still have the problem if it's been sitting for 30 min or an hour and a half. Nothing I do seems to aleviate the problem. What's strange is that when this problem started, it was in the middle of a boating season. No issues prior to that, and then one day - bam- it just started doing this and nobody's been able to figure out what's causing it. Same geographic location, same lake, same air and water temps - doesn't matter.

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I know it doesn't sound like a hugely inconvenient problem, but it seems that for the kind of money spent on these boats, I shouldn't have to ice down my fuel pump everytime I want the boat to start after it's been sitting, and additionally, I never had this problem before, and nobody else I know with a Malibu has this problem.

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It sounds more like the fuel pump is starving for fuel which is why it is overheating.

What is really weird is you say that it only happens after an outing where you let the boat sit for more than 30 minutes then try to start it. Fuel is rather cold and will cool the fuel pump. Even if you have no issues while driving and during short shutdowns, if the pump has been starving for fuel then when it is shutdown for a long period it really heats up from sitting longer. Shorter period of being turned off and it has less time to heat up after working so hard.

I would start by tracing the fuel line from the tank to the fuel pump and make use you have no kinks. It might not be a bad idea to blow the line out and make sure there is no debris in it. Sounds crazy, but you never know.

First, start by checking the screen on the bottom fitting of the fuel pump where the gas line leads in. It could be clogged. Do you have a regular inline filter or more than one filter, like a water separator filter?

There is also another small screen at the fuel rails where the fuel line leads from the fuel pump. You can get to it pretty easily by simply removing the fuel line by popping the little clip off that holds it on the fuel rails. Make sure you have plenty of rags to catch any residual gas that will spill out when checking these things.

EDIT:

Try making sure the vent for the gas tank is not plugged. I have heard of this causing this type of issue.

That is a good tip. That would cause a vacuum and the fuel pump would then be working it's tail off to pump fuel.

Edited by areamike
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Just some thoughts

- Did you switch gas, or did your filling station re-formulate?

- Just in front of the windshield are two vents. There are tubes underneath the dash that should lead from these vents into the Fibecs stringers. These end up venting the engine compartment when you are at any type of speed. Look under the dash on the driver and passenger side and make sure these tubes go into the hole in the floor (which lead into the stringers). Maybe your engine compartment is getting too hot because it's not getting any fresh air.

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I had vapor lock problems with my MC205 (Indmar/Chevy 350 with TBI). Similar symptoms, after running on a hot day, shut down, and it wouldn't restart for 30 or 40 min. Then it would run fine. Start it too soon & it would run rough, miss, etc.

The guys at Skidim.com suggested a fuel line insulation kit that they had for like $13. It really was nothing more than an insulation tube that I installed over the metal & rubber fuel lines that were near the engine. The theory was that the engine's heat soak would raise the temps of the gas in the lines, causing the gas to vaporize, which doesn't pump very well by these fuel pumps. Whatever black magic it was, it worked. :rockon:

Might be worth a try to insulate the fuel line, and maybe even the pump too.

As for why it just started, I have read in a number of places that the ethanol their adding to the gas vaporizes quicker & at lower temps. I guess the problem is more common now than ever.

All that said, I haven't had the issue at all on my Monsoon. I do tend to run the blower a lot. Hard to believe that is really helping that much though. :unsure:

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This is a known problem if your fuel pump is not in the gas tank. On Vrides 2005-2008 the pump is bolted to the engine block with a tiny piece of padding seperating it from the engine block. After you run hard for a while and then stop you basically have a hot engine that transfers its heat to the aluminum fuel pump. which vaporizes the ethanol in the fuel and creates either a vaccuum or a too low of octane fuel or a combo. of both. A condition sometimes called heat soak is causing the symptoms you are experiencing. Winter gas which usually has more ethanol or old gas which has attracted moisture will also exaserbate the problem. Helpful solutions are running the blower though this doesn't always work especially on hot humid days. Also, some have put more insulation between the fuel pump and the engine block, i.e. popsicle sticks, this does help. the most sure fired way to avoid heat soaking your fuel pump is to open the engine hatch and leave it open when you are just parking and floating. If you forget then as stated earlier ice/water on towel placed over fuel pump should do the trick. Sometimes it can also happen to your fuel rails, so check them too. The joys of ethanol. I believe all the newer Bu's and 2006 and up vlx's have the fuel pump in the gas tank now to avoid this problem. Easy to tell just follow the fuel line and see if it enters an aluminum canister just before traveling to the fuel rails. One note the problem usually occurs in Mch-Jun. here in Fl. depending on weather. By summer most gas station have stopped selling winter gas, and most boats have used up any old/winter gas that might have been in the boat's gas tank. Keep in mind though, more and more gas stations are using more ethanol and either putting 10% ethanol and some even flirting with 15%(E85).

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Surfin247, sounds like you have some familiarity with the symptoms... do you know anyone who has experience with this: http://www.skidim.com/prodinfo.asp?number=49-5137

No ask the skidim guys they are real good. The item you are showing is hard to tell if it would work on the 320LCR in a Bu. The skidim guys can tell you if this will help with heat soak which is slightly different than vapor lock, though they get used interchangeably on the forums.
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Keep in mind though, more and more gas stations are using more ethanol and either putting 10% ethanol and some even flirting with 15%(E85).

Just to clarify, E85 means 85% Ethanol, not 15% Ethanol.

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Do a compression check and make sure all cylinders are ok. Also you can take the bracket that the fuel pump is mounted on loose from the back of the engine block and place some pop cycle sticks between them this will help dissipate the heat that builds up and transfers from the engine to the pump

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If you keep having problems let me know. I know a guy that has the stuff to convert to an in tank fuel pump. Not sure of the cost right off hand but could find out. That would eliminate all problems. The fuel should be pushed and not pulled anyway.

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Keep it simple. I used to have exactly the same problem with my Lxi 2004, I replaced the metal piping connecting with the pump with a rubber hose for fuel and proper pressure rating, and also isolated the pump from the engine, which was normally running at a proper temp but once stopped heat accummulates and transfers to the pump with the typical symptoms you describe.

No more vapor lock after above mods.

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I have had the same problem with my DD wakesetter. just prop the engine cover up a bit while sitting and the extra air flow will keep the temps down enough that the vapor lock seems to go away. I say seems because I found a place that sells pure gas as well.

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Also check the vent hoses. I was running the blower alot and having similar issues, then found the vent hose was knocked off. Problem solved... cheap like!

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I have the same problem with my 06 VLX with Monsoon. Talked to Indmar tech myself and he was very knowledgeable to the problem. Gave me a part # that gets you another pump to put in line with your stock pump. When stock pump gets vaporized, secondary pump pushes liquid to stock pump and corrects issue. Pumps can't push vapor and ethanol fuels vaporize easier than straight fuel. Cost was over $100 and I did not want to put that much into it so I just use my blower after shutdown and open motor hatch more. The 1 or 2 times year I forget and get locked up, I just pour a bottle of cold water over pump and problem fixed. If I just wait for it to cool on it's own it takes about an hour to straighten out again. If any one wants the # for secondary pump kit, let me know and I can look it up. My boat never did this in the first 2 years (350 Hrs.) Started after we switched over to Ethanol.

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Thank you so much to all for your advice and suggestions. Some great stuff here to try. Sounds like I have some things to do this weekend!

Thanks again!

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One other thing to check. The vent on the engine cover on the back where the cup holders are. Cut the insulation back to help free up air flow.

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.... Keep in mind though, more and more gas stations are using more ethanol and either putting 10% ethanol and some even flirting with 15%(E85).

Don't ever put E85 in your Malibu.

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....

I believe all the newer Bu's and 2006 and up vlx's have the fuel pump in the gas tank now to avoid this problem.

...

It wasn't '06, I believe that it was '07 that they went to the in-tank pump on all models. And FWIW, the in-tank pumps have their own set of problems.

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  • 12 years later...
On 5/10/2010 at 3:54 PM, jesutton3 said:

Try making sure the vent for the gas tank is not plugged. I have heard of this causing this type of issue.

@jesutton3 how do you test this?  Having vapor lock issues and I’m trying to figure this one out. 

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