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CaptnHk

'92 Euro F3 Sunsetter - Carb Issues

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CaptnHk

0D715122 Motor (5.7L 350 Chevy/Mercruiser) and Rochester Quadrajet carb 17085226

Purchased boat a few weeks ago, 1st time out, 36mph/3800 rpm, a bit rough running
2nd time out, added seafoam in fuel, replaced plugs, 39-40mph/4100-ish rpm
3rd time out, drained/replaced fuel, new plug-wires/cap.  39-40mph (same performance), but after about 45 minutes of just cruising around, it started starving for fuel above 1200rpm ish, bogs for a second then starts to recover and dies.
Replaced fuel/water seperator
Replaced fuel filter on carb
no change, still idled ok, increase rpm (on the lake or in driveway with fake-a-lake) to 1500 and held it there...after 10 seconds ish, it started to slightly bog down, then all of a sudden recovered rpm and immediately died.
purchased a basic rebuild kit
nasty gunk in one of the fuel wells before the float (bingo!  or so I thought), cleaned things up, re-assembled.
it starts really easy now and idles quite smooth...BUT same thing happens when I increase the rpm.
each time this happens I need to give it a slight pump then turn key and it starts pretty good (mostly just turns over without the pump, but it's a carburetor...), and then idles fine...for a long time too (seems like it'll run no problem at idle), without any issues.

I pulled one of the jets (bottom of float well) before I re-assembled and it looked fine. replaced the needle/etc with the kit, same float (float appears to be fine).  made sure all the copper air jet tubes were clean and open...

Thoughts?

I haven't checked timing yet (need to locate my light or find one to borrow for now) but it's idles really nice and it revs up fine, so I don't think timing is off (by much anyway), it just can't sustain a high idle...like it uses up fuel too fast in the carb and dies because it "ran out"....if I am quick enough to get a pump on the throttle (when I'm in gear on the lake) I can keep it from dying, but unless I slow back to idle it just repeats and mostly can't get it to keep going...then I need to pump it then start back up...

would this still be a carb problem?

1st two times out it ran, just was a dog from sitting for the off season...seems my adding seafoam loosened up the junk!  

I'm running out of ideas of what to check/clean/replace.

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Rednucleus

Are you still able to get 4000+ rpm wide open throttle or nothing above 1500; did kit include accelerator pump parts?

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Woodski

@CaptnHk:  Have you been burning ethanol fuel?  You might consider replacing the fuel lines and check to see if they have deteriorated, fuel lines of that era are not ethanol fuel compatible.  Same can be said of mechanical fuel pump diaphragm.

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tvano
11 hours ago, Woodski said:

@CaptnHk:  Have you been burning ethanol fuel?  You might consider replacing the fuel lines and check to see if they have deteriorated, fuel lines of that era are not ethanol fuel compatible.  Same can be said of mechanical fuel pump diaphragm.

i'm not positive it's the source of your problem but if those fuel lines are oem they are due for replacement.

 

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CaptnHk
15 hours ago, Rednucleus said:

Are you still able to get 4000+ rpm wide open throttle or nothing above 1500; did kit include accelerator pump parts?

I can get to higher RPM for a brief time before it does it's thing and dies.  And yes, the accelerator pump rubber ring (and the coil that hides under it) were replaced with the kit.

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CaptnHk
12 hours ago, Woodski said:

@CaptnHk:  Have you been burning ethanol fuel?  You might consider replacing the fuel lines and check to see if they have deteriorated, fuel lines of that era are not ethanol fuel compatible.  Same can be said of mechanical fuel pump diaphragm.

Like I said, I've only owned this for a couple weeks now.  It ran 'ok' first time out and then started this issue.  the fresh gas I put in it was 10% ethanol (hard to find non-ethanol around here).

Am I just that lucky to have this happen after I bought it?  :)  I added Seafoam...maybe that did something to break apart the inside of the main fuel line?

I was thinking about the fuel pump and if that's part of it... it can't pump fast enough due to destroyed diaphragm (old and never replaced)...what's involved with replacing/rebuilding the fuel pump?

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Woodski

@CaptnHk:  I suggest doing the troubleshooting steps to pinpoint the root of the problem rather than throwing parts at it to minimize your cost.  A fuel pressure test would be in order and check it across the RPM range.  Reading back over your first post, here are a couple of suggestions:  1.  I would check the in tank fuel inlet screen for debris,  2.  Check the fuel tank anti siphon valve to verify it is not corroded shut,  3.  Did you do a proper and complete carb rebuild (not just a quick clean), and if not that might be a good step.  Probably not an issue, you might want to check and clean the spark arrestor just to be sure no issues with that.  I am making the assumption that the throttle linkage is operating properly, you are getting full throttle, the secondaries are opening correctly and the choke is free and swings fully open, but worth going through that check, and there is no speed control system causing an issue.  Did you get a history on the boat, how it operated last year, what issues there might have been or the previous owner had with it?  Fuel pump replacement is a simple remove and replace, but as I mentioned, check it for performance before you simply swap it out as it may be just fine.  How many hours does this boat have on it?  It should run ~45 mph @ ~4500+/- RPM at WOT or in that ballpark.

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CaptnHk
11 minutes ago, Woodski said:

@CaptnHk:  I suggest doing the troubleshooting steps to pinpoint the root of the problem rather than throwing parts at it to minimize your cost.  A fuel pressure test would be in order and check it across the RPM range.  Reading back over your first post, here are a couple of suggestions:  1.  I would check the in tank fuel inlet screen for debris,  2.  Check the fuel tank anti siphon valve to verify it is not corroded shut,  3.  Did you do a proper and complete carb rebuild (not just a quick clean), and if not that might be a good step.  Probably not an issue, you might want to check and clean the spark arrestor just to be sure no issues with that.  I am making the assumption that the throttle linkage is operating properly, you are getting full throttle, the secondaries are opening correctly and the choke is free and swings fully open, but worth going through that check, and there is no speed control system causing an issue.  Did you get a history on the boat, how it operated last year, what issues there might have been or the previous owner had with it?  Fuel pump replacement is a simple remove and replace, but as I mentioned, check it for performance before you simply swap it out as it may be just fine.  How many hours does this boat have on it?  It should run ~45 mph @ ~4500+/- RPM at WOT or in that ballpark.

Thank you for the quick checklist...I'll look at the fuel tank items (assuming I need to pull the tank in order to get to these items...?  The screen would be at the bottom of the pickup tube inside the tank correct?)

Carb, I pulled it apart and cleaned it up (1st time, so I'm no expert) but removed all the gunk, checked/cleared all the air jets (copper tubes), lubed all moving parts with WD-40 as I reassembled.

No speed control, throttle linkage is moving good...throttle (and shift) cable looks like it was replaced at some point, but moves freely.

Not a very good history provided, hours meter is non-functional, but seller claimed it is about 300-400 hours as he barely used it over the 2 years he owned it, and original owner was in military and used it only occasionally.

I'll look at replacing the fuel line from the tank as long as I'm going to be messing with all that...

I'm hoping to get 45mph... I hang out with show skiers and barefooting is common, and my butt needs a good 42+mph to feel comfortable footin' :)

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Woodski

You might just have to slide part of the tank forward, pickup should be on one side, I don't recall the exact set up on the Euro F3.

You do know that you can foot right off the platform on that boat, step off step back on?  Kind of fun to do that.

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CaptnHk

ok, my 'greenhorn' status is showing... I looked for a fuel pressure test kit and I see they are for adding to fuel hose lines... but this has a metal line between the pump and carb... is there a trick to testing the pressure?  some fancy spot to connect to the carb?  one guy posted on a car site that he built a custom line between the pump and carb as a temporary solution to getting the pressure gauge connected...seems a bit overkill to me...  I was going to run for a basic pressure gauge today, but not sure how to even connect it.

I need to finish reinforcing the platform brackets...I seem to have a soft transom...the top bolts on one side pulled through slightly.  Added a fender washer for now, but having plates made for the bolts to go through on the inside so it can't pull through anymore.  But, that sounds like a face plant to the platform happening!  lol...

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Woodski

No fancy spot, use a brass T to connect a pressure gauge, available at any hardware store.  You should be able to borrow a kit from a good auto parts store, that is pretty common practice these days, and given the # of lakes in your area, the auto parts store probably has one capable of a marine application.  A custom rubber line for testing is also a pretty simple solution, auto parts store can help there also, 2 fittings, hose clamps and rubber fuel line is all you need.

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Michigan boarder

Just a thought, but make sure your fuel tank is venting properly too.  If the vent is plugged or partially plugged it will prevent air from flowing into the tank as the fuel is flowing out of the tank, and therefore restrict the fuel (create a vaccum).

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csleaver

Try running the boat using a small portable fuel tank.  If the problem is only with the fuel tank components or supply hose, the boat should run fine on the portable test tank.

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CaptnHk

zero fuel pressure, checked things before the pump and things seem ok... fuel pressure gauge had no movement, checked it with an air compressor and regulator and it tests good, pressed the "tire valve" center stem on the "T" connection and fuel just dribbled out in little spurts...had a rag up expecting to be more like mini fountain show.

So a new pump has been ordered and should be here Thursday, hopefully in time to install it and test again (hopefully successfully) and get out on the lake in the evening for a cruise! #fingerscrossed

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JasonK

I had an inline see-thru filter added to my 1990. At some point it started sucking in air at the hose connection and caused running problems. Check for air leaks in the fuel line system.

I replaced my mechanical fuel pump. Wasn't the problem.

The other prob with my 1990 was needing the carb rebuilt in it's 14th year of life (2004).

I also had a mechanic suggest and add an inline ballast resistor to the wiring harness.

I never got around to changing the fuel lines. Bought with 120 hours, sold the boat with 1,100 hours.

When we started surfing, I added the Racor fuel/air separator for the fuel tank vent line.

If you have a water separating fuel filter, make sure the old filter gasket came off when you replace it.

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CaptnHk

OK, been busy... installed a new fuel pump.  Started it up and DING DING...I had 8-9psi.  I could hold a high idle and it was working perfectly....until later, then the same problem came back.  I had removed the loop of hose I added for the pressure gauge, and then fired it up and it was still good, fixed the timing, then walked the timing light back to the neighboring auto shop I borrowed it from.  When I got back, I picked up the tools I was using, tossed some dirty paper towel pieces, then decided to fire it back up and take a little video to send to a friend... and...poof...it's dying again beyond idle.

Hooked my loop of hose and the fuel pressure gauge back up and ZERO psi.  I checked the new water separator filter, 2/3 full of fuel.  I hooked a temp tank up directly to the filter, bypassing the boat tank and line, still no pressure.  checked the filter housing and line from filter to pump, no blockage...as I was turning it over trying to get it the pump to move some gas, I noticed the pressure gauge start to move and hit like 1-1.5 psi, but as soon as the motor started it lowered back to zero.  It's a brand new pump!?

Any ideas?  this is becoming a total mystery now...

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CaptnHk

Ok, found what is going on...not sure why though.  The vacuum line from the carb to the fuel pump is killing the pressure.  I recall that I forgot to hook that up when I tested with the new pump when I had fuel pressure, when I was removing the fuel pressure gauge I realized it was not hooked up so I hooked it up after the gauge was removed...thus my repeat problem.  While it's running I can pull the hose off the pump, and the fuel pressure climbs to 5-6 psi and I can hold a high idle, when I hook it back up, the pressure quickly drops back to zero and I can't hold a high idle.

What's up with that?  When I put my finger on the end of the little hose, it's quite the suction!  I think it's hindering the function of the diaphragm with it connected keeping it from building fuel pressure.

What to do now....??

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MadMan
12 hours ago, CaptnHk said:

Ok, found what is going on...not sure why though.  The vacuum line from the carb to the fuel pump is killing the pressure.  I recall that I forgot to hook that up when I tested with the new pump when I had fuel pressure, when I was removing the fuel pressure gauge I realized it was not hooked up so I hooked it up after the gauge was removed...thus my repeat problem.  While it's running I can pull the hose off the pump, and the fuel pressure climbs to 5-6 psi and I can hold a high idle, when I hook it back up, the pressure quickly drops back to zero and I can't hold a high idle.

What's up with that?  When I put my finger on the end of the little hose, it's quite the suction!  I think it's hindering the function of the diaphragm with it connected keeping it from building fuel pressure.

What to do now....??

That hose should not be connected to a vacuum  source, it should be connected to a port that is above the throttle plates, near the flame arrester.  It's purpose is, if the fuel pump diaphragm ruptures, to dump the fuel in the carb instead of the hull.

It sounds like when it's connected to a vacuum source, the return spring in the fuel pump is unable to push the diaphragm back.

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CaptnHk
58 minutes ago, MadMan said:

@MadManThat hose should not be connected to a vacuum  source, it should be connected to a port that is above the throttle plates, near the flame arrester.  It's purpose is, if the fuel pump diaphragm ruptures, to dump the fuel in the carb instead of the hull.

It sounds like when it's connected to a vacuum source, the return spring in the fuel pump is unable to push the diaphragm back.

It's connected where it was prior...to a spot that's into the bottom/front of the carb.  Could something have happened to cause that to become a vacuum?  This particular issue (dying/starving outside of idle) pretty much happened all of a sudden while I was out running the boat.  I was WOT for a partial lap around the lake I was on seeing what kind of RPM/speed I could get without issues...about 45 minutes into riding around is when this started happening.

Edited by CaptnHk

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MadMan
25 minutes ago, CaptnHk said:

It's connected where it was prior...to a spot that's into the bottom/front of the carb.  Could something have happened to cause that to become a vacuum?  This particular issue (dying/starving outside of idle) pretty much happened all of a sudden while I was out running the boat.  I was WOT for a partial lap around the lake I was on seeing what kind of RPM/speed I could get without issues...about 45 minutes into riding around is when this started happening.

Maybe the original pump's spring was able to overcome the vacuum load on the diaphragm, then it weakened?  Or possibly the amount of vacuum increased?  Hard to say, but either way it shouldn't have vacuum on it.

By the way, your carbs bowl vent should have an up-side-down j-pipe on the bowl vent for the same reason, to dump fuel back into the engine.

Edited by MadMan

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Woodski

@CaptnHk:  The line you are referring to is a vent line, so it should simply see an ambient condition.  For marine, no fuel components should have the opportunity to vent or spill in to the bilge, thus the vent line runs to the carb air side inlet in case fuel is in that line as @MadMan noted.  Check it for any blockage that would build up pressure to offset the diaphragm action, a vacuum source could do exactly the same thing but in reverse.

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Michigan boarder

Is the line we are talking about attached where this yellow one is on my engine?  Or is it more on the front side of the carb?2016_engine_pic_6.thumb.jpg.d615761c6d30e27930e35aaac6107c30.jpg 

 

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CaptnHk

the old pump was working and then it seemed to stop while I was out running it... the new pump is doing the same thing with the hose connected.  somehow that turned into a vacuum line.

the little hose connects here on the carb (the small black host coming up from the bottom of the photo):

https://drive.google.com/open?id=1W1tsQ0YVTfdWgnWRoFYGXnroMWwfSlOgJw

 

Edited by CaptnHk

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CaptnHk
2 minutes ago, Michigan boarder said:

Is the line we are talking about attached where this yellow one is on my engine?  Or is it more on the front side of the carb?2016_engine_pic_6.thumb.jpg.d615761c6d30e27930e35aaac6107c30.jpg 

 

Yes, I see that goes to the fuel pump... but mine connected to the front of the carb... upper center (I said lower earlier by mistake)   I posted a link to a pic

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Michigan boarder

I think yours is connected to the wrong spot on the carb.  The plug on on my carb in the front was used to pull against the choke to keep the butterfly open (hence the vaccum), rather than the vent that should have no vaccum.  Here is a pic of my old carb:

 

Carburetor 003.jpg

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