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Volvo Penta 3.0 GLP-E chokes when at high throttle

J

jannick

New member
Hi

I have a Glastron 175 with a Volvo Penta 3.0 GLP-E. We've been using it a fair bit in the early summer without any issue. Last weekend it developed an issue when we're trying to run it at 'high throttle':
  • Engine starts as usual
  • We can run at sub-planing speeds indefinitely
  • We can give it a bit more throttle and get on the plane. It also seems to be able to maintain this 'just enough for planing' speed - although I think it sounds a bit more 'loaded' than usual.
  • When increasing the throttle in small increments the engine will very briefly rev up, and then seem to return to the previous rev level

Increasing throttle even more will increase the revs (although less than usual) but after ~20s the engine will begin to sporadically drop in revs in a pulsing fashion, and after a while it will completely choke and stop. At this phase it is possible to prevent the engine from dying out by throttling back. The period-before-choke seems to become shorter the more throttle we apply.

We've also tried to do a 'waterski' start where throttle is moved to full from an almost standstill. The boat seems to get going as it usually would, and the engine does rev up (although perhaps a bit less than usual). After the same ~20s it starts displaying the rev drops leading to engine stop.

I've talked with their local dealer, and their initial thought was that there might be water in the gas. Today we tried mixing in some additive that was supposed to help, but it did not result in any changes in behavior. I've ordered a new fuel filter / membrane as a 'blind attempt', as it has never been changed while I've had the boat.

Any suggestions on what might be wrong would be much appreciated :D

Edit: Could not get forum image insert to work, so I've uploaded a picture of the engine here https://pasteboard.co/IlolQ9G.jpg
 
Last edited:
Ayuh,..... Sounds like it's runnin' Lean, from a lack of fuel flow,......

Start by checkin' the fuel filter for anything but clean fresh gasoline,.....
 
Thank you both for the suggestions. The new fuel filter part should hopefully arrive first thing next week - decided to wait with taking the filter apart until then.

To be sure I understand correctly: You mean I should try to see how the engine performs with the fuel gas cap off, as a way to verify if the problem might be a plugged vent? We did actually notice that it was impossible to unscrew the fuel cap for a few minutes after one of the engine stalls - but did not have a reference point if that was usual behavior. (Usually fill up before going out, this time we wanted to add more fuel with additives mixed in).
 
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jannick said:
Thank you both for the suggestions. The new fuel filter part should hopefully arrive first thing next week - decided to wait with taking the filter apart until then.

To be sure I understand correctly: You mean I should try to see how the engine performs with the fuel gas cap off, as a way to verify if the problem might be a plugged vent?
No need to run with the fuel fill cap off.
The suggestion was made as to eliminate any negative pressure in the tank that may be caused by a plugged vent.
If there is a Neg pressure build-up, you should hear a "hiss" when the cap is removed.

I no longer have the numbers........ but I once did some rather crude math to see how many gallons would need to be used in order to create X negative pressure within a fuel tank.
With a half tank, you'd need to consume a few gallons to create enough Neg pressure to affect the fuel pump's ability to supply the engine.
On a full tank, it would require less consumption.

Suggestion:
Clear the vent and vent line. This will eliminate that as the issue.


We did actually notice that it was impossible to unscrew the fuel cap for a few minutes after one of the engine stalls - but did not have a reference point if that was usual behavior. (Usually fill up before going out, this time we wanted to add more fuel with additives mixed in).
Click to expand...
 
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