Volvo Penta 3.0 GLP Stalling when reducing from high RPM.

[DPrang]

Good day all, I’m currently having an issue with my Volvo Penta 3.0 GLP engine. The Engine starts without any issues and is running fine when at High RPM on the plane. However, as I reduce the throttle to slow down the engine is wanting to stall. I’m able to keep the engine running if I throttle down very slowly and gradually. If the engine does stall then I’m able to start it again without issue. I was thinking that this may be a carburetor issue and I would be grateful of any suggestions as I start at looking to resolve the issue. All other indications, oil pressure, temperature, voltage etc are all normal, however the idle RPM does seem at little high, around 1000RPM.

 

[baker556]

Probably requires a carb rebuild kit - not a big job!

 

[baker556]

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[dubs283]

I was thinking that this may be a carburetor issue and I would be grateful of any suggestions as I start at looking to resolve the issue. All other indications, oil pressure, temperature, voltage etc are all normal, however the idle RPM does seem at little high, around 1000RPM.

Possible it's fuel related however you make no mention of recent tune up/fuel filter replacement

Not sure why but lately on this site when someone posts a runability issue the first response seems to be "rebuild the carb"

My suggestion is to start with routine maintenance items such as tune up and fuel filters. If the issue persists, check fuel pressure and vacuum. If those results are normal then you can start looking at carburetor rebuild kits. It takes more than just what you are describing to condemn a carburetor.....

 

[baker556]

dubs283 - reason I mentioned carb rebuild is that I've had this exact issue before on a 3.0 GSP-C VP engine, the rebuild worked.

 

[dubs283]

dubs283 - reason I mentioned carb rebuild is that I've had this exact issue before on a 3.0 GSP-C VP engine, the rebuild worked.

And that's perfectly fine, it worked for you and are happy to share insight. That's what this forum is about.

I'm just suggesting that OP needs to be pragmatic about their situation and a carb rebuild is not the first thing that comes to an experienced mind when looking at the given information

 

[DPrang]

And that's perfectly fine, it worked for you and are happy to share insight. That's what this forum is about.

I'm just suggesting that OP needs to be pragmatic about their situation and a carb rebuild is not the first thing that comes to an experienced mind when looking at the given information

Thanks for the reply, all of the normal service items have been replaced at the start of the season.

 

[DPrang]

dubs283 - reason I mentioned carb rebuild is that I've had this exact issue before on a 3.0 GSP-C VP engine, the rebuild worked.

Thanks for the reply, ill do some more investigation and if that doesnt work then look at a rebuild.

 

[alldodge]

Your idling high (about 1000) and needs to bring RPM's down slowly or it will stall. In most cases its the carb, but only if everything else is set correctly and no other issues.

Put a vacuum gauge on the intake and see if its low. If low it may have a intake leak.

Then checking timing, if good, check compression. If compression is 140 to 150 and within 10% of lowest to highest reading then your good. If its lower then that make sure your gauge is good, might be the issue

If it is low then the carb may help but may need more testing on what is causing the lower readings

 

[DPrang]

Your idling high (about 1000) and needs to bring RPM's down slowly or it will stall. In most cases its the carb, but only if everything else is set correctly and no other issues.

Put a vacuum gauge on the intake and see if its low. If low it may have a intake leak.

Then checking timing, if good, check compression. If compression is 140 to 150 and within 10% of lowest to highest reading then your good. If its lower then that make sure your gauge is good, might be the issue

If it is low then the carb may help but may need more testing on what is causing the lower readings

Thank you for the reply, and the step plan to investigation much appreciated.

 

[kenny nunez]

The only other thing that I have seen cause this problem is the rotor in the distributor. What happens is as the boat is coming off plane it puts a load on the ignition and the high tension spark goes through the rotor to the distributor shaft.