Volvo Penta 3.0L fuel starvation?

jucamvil

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Sep 28, 2024
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My 2007 Glastron MX175 was working perfectly. I was cruising 35-40kms/h then I decreased the speed and it died in the middle of the lake.

Now, it starts and then stops after the primed gas in the carburetors burns off.

It runs for 4-5 seconds, so I know it's not a spark issue. It's also not the mechanical fuel pump, as I have already tested it, and it’s pumping gas. The filter is fine as well.

The anti-siphon valve is not clogged, and the fuel bowl has gas. I can keep it running if I manually turn the butterfly or the throttle control but as soon as I stop, it dies.

Do you think this could be related to the carb? I don't want to open it yet, but at this point, I have no clue what else to check.
Appreciate your thoughts.
 

Fun Times

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What is the full model number of your Volvo 3.0? Example 3.0GSPLKD

First few thoughts that come to mind would be there ought to be a small fuel filter right at (in) the carb fuel line inlet connection that may have caught something, plugging up some of the flow, or possibly sticky needle and seat or an idle circuit flow problem both inside the Holley style carb.

filter is fine as well.
Just to clarify, the fuel inside was found to be clean with no water or debris found when dumped into a container? The O-ring is not doubled up or warped, etc.? Was a new one put on before or after the event?
 

jucamvil

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What is the full model number of your Volvo 3.0? Example 3.0GSPLKD

First few thoughts that come to mind would be there ought to be a small fuel filter right at (in) the carb fuel line inlet connection that may have caught something, plugging up some of the flow, or possibly sticky needle and seat or an idle circuit flow problem both inside the Holley style carb.


Just to clarify, the fuel inside was found to be clean with no water or debris found when dumped into a container? The O-ring is not doubled up or warped, etc.? Was a new one put on before or after the event?
It's the 3.0 GLP-E.

Gas was clean. And engine runs for 4-5 seconds or more if I prime more gas to the carb, so I dont think gas is bad.

I've also opened the fuel bowl to visually inspect but it all seems fine.

20240927_135243.jpg20240927_135230.jpg
 

jucamvil

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Mine doesn't have that part # 84. My carb have different parts to those shown in the diagram.
It just has the fuel line and the fitting. Nothing inside as the diagraman shows.

1000060161.jpg

Something is preventing the engine from continuing to run. Nothing but a mechanical issue should do this, as the only electrical/electronic thing that could stop it is the kill switch, but that is fine. This is not cutting it off.
 

Fun Times

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The filter should be in there, you'll need to remove the small brass line fitting then the bigger nut (where the red paint is but missing a small section already) with a 1-inch wrench I believe it to be,

Volvo penta part number 3854019, item number 6,


 

jucamvil

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Hi. I'll check that filter. Do you think it could be related to the issue?
The boat starts and runs for a few seconds, and there’s plenty of gas in the fuel bowl.

I don’t see how flow could be restricted before entering the fuel bowl.

I can manually empty the bowl by pushing the accelerator pump until I hear it pumping air. That’s the gas allowing the engine to run for a few seconds.

When I crank it, the fuel bowl is full of gas again. I can keep the boat running if I continue manually pumping gas.
It just stops when it’s supposed to be idling.

I'll give it a look but this is driving me crazy.
It's not an issue that started small and gradually got worse, nor was the carburetor acting up and then got worse. It just appeared all of a sudden after been running perfectly.
I think something very specific happened. 😭
 

kenny nunez

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Gasket #35 on Holleys will shrink and either open extra holes or block some. That is the only thing I can think of.
Be sure to to clean the air bleed holes in the throttle body and idle mixture ports.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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There are only 7 moving parts in the Holley 2300. Less than 30 parts total. Clean out the passages, make sure the accelerator pump circuit and idle circuit passages are clear
 

jucamvil

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Hi All.
This is an update as I haven't been able to put much time until this week.
I have reviewed all the suggested and have also discovered that it keeps running when choke is closed. As soon as I let it open, it dies.
I replaced it thinking it could be damaged but keeps doing the same.

At this point, I'm still confused what it could be the issue:

 

ESGWheel

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In the video it appears that it shuts down with the choke fully closed as if it was flooding out > seems like the opposite of the description.

Regardless, suggest this if not already done. Repeat the exercise in the video > ie run it until it stalls out. Since a mechanical fuel pump, the pump will stop pumping as well. Without turning over the motor anymore, disconnect the fuel line, etc., take the top of the carb off and look in the float bowl. Is it empty or full? I know you said you saw fuel in the bowl before, but was it after it stalled out like in the video?
The point is:
  • If no or little fuel in the bowl post stalling out there is an issue with the pump and/or the needle / seat / float of the carb.
  • If there is plenty of fuel in the bowl then there is an issue internal to the carb, like that gasket 35 that Kenny highlighted or something is clogging it up in the circuits and it needs to be cleaned / rebuilt.
 

jucamvil

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It keeps running when the choke is closed. In the video, it seems the opposite for a couple of seconds as I tried to prevent it from dying after I opened it.

Fuel bowl always has plenty of gas. I can manually pump the accelerator pump to keep it running when choke is fully open.

I don't thing is a passages or fuel issue as it keeps running when choke is manually closed, so there is flow of fuel to the carb while idling.

Also to note, pump is new, electric choke is new, gaskets are new, carb was cleaned and inspected, fuel filter is clean, anti-siphon valve is new.

It's odd. This is not a common issue, and I have no clue what's happening. It was working perfectly when it failed—there were no signs of a problem or rough behavior. I was cruising, then I decreased speed, and it just died. It never started again, and I had to get it towed.
 

ESGWheel

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Appreciate the broader picture and while frustrating keep at it as there is a solution. Here may be one:

Going off the logic that fuel delivery is not an issue (all good including the idle mixture screws properly set), and that this will only stay running with the choke almost fully closed, then there must be a massive air (vacuum) leak. And I assume you are not hearing one.

See if you can get the engine to stay running without out needing to fiddle about, some ideas:
  • Disconnect the electric wire on the choke and adjust the choke to be almost fully closed.
  • Kicking up the idle speed and going wide open on the idle mixture screws.
  • Using a piece of carboard with a slit cut into it for the choke to stick thru (wide open) but with some holes in the cardboard to 'choke off' the carb and keep it running.
The idea is to be able to get it to consistently run at idle or slightly higher without having to constantly play with the throttle or choke plate. Then using an UNLIT propane torch (so gas is coming out, but not lit) wave it around the intake manifold, base of the carb, etc. If the engine changes (increased or decreases in RPM) at a particular spot, there is where the vacuum leak is.

Normally vacuum leaks found via this method are small and the engine will run without the choke manipulation and thus when the propane gas intersects the vacuum leak, the RPM will pick up. In your case it may make the mixture over rich and thus why it may decrease in RPM.
 
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