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Volvo penta 5.7 GLI missing some RPM and power

B

bssublime

New member
I have a 97 four winns speedboat with a 5.7
Volvo penta GLI. Last fall we did cap rotor plugs and wires and the boat ran amazing easily go to 5000 RPM. This summer so far been amazing as well, probably put 10 to 15 hours on it this year. This past weekend took my daughter tubing ran great. Stopped to swim and then after it wouldn’t go past 3000 RPM I added more fuel to it just in case the gauge was not accurate, I only use rec fuel. Boat still won’t accelerate past 3000 3500. Not sure what I should try to get the power and RPM back.
 
Could be a few things Carb needs cleaning, timing not advancing, blew a head gasket

Take the fuel filter off and dump the contents into a clear container to see if there is nothing but clean gas

Use a timing light to see if timing is advancing

Pull plugs and see if they all look good (cream color)

Do a compression test
 
OK, thank you I didn’t know that about the fuel underload. The engine is TBI not carbureted. I did run it with the cover off and it seemed like plenty of fuel of the spraying in, but that’s just with my eyes can’t really say for sure. Any suggestion on what to do with the TBI?
 
same idea...different device...RINDA makes the industry standards. they offer a stand alone box as well as software (and cables/adapters) for your PC. there are other products as well...
 
ok, TBI might be low fuel pressure
The GLi PLKDCE TBI shows in my listing as 11 psi, the GSi is 29 psi

Will need a Tee fitting to check it

VP TBI fuel 01800001320.jpg
 
I ran into the same issue with my 1995 Volvo Penta 4.3 GL. When started from cold, it would power up under load. Maybe a coincidence, but after running around the lake for a while and shutting off, I would not have power. Similar to you, it had no issue with rpm in neutral. First saw the issue last summer. I forgot about it over the winter. Winterized the boat. Ran it in the driveway it was fine. Launched it and it was fine. Then issue returned and jogged my memory.

I took off the fuel filter, dumped it out and all this gritty stuff came out. Seem to run fine afterward. Since the boat hadn't had a tuneup in over 10 years (we only put on maybe 25 hours in a summer now), I decided to change the oil, new plugs, wires, distributor, and the fuel filter. It runs great now.

So sorry it was not a mechanic's diagnosis, but this was my experience.
 
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