Volvo Penta 8.1 issue

[av8or98]

Hello all. I purchased my first Carver, a 396 with Volvo Penta 8.1 GiL-E engines, about six months ago. Since then I've been having issues with the starboard engine.
Hard start-turns over, starts then quits. Does this 3-4 times then will idle.
Rough idle-not terrible but you can tell that it's not hitting on all cylinders.
Won't produce rated power - 3200 RPM is about all I can get out of it.
I typically do all the maintenance on the boat so I'm fairly mechanically inclined. Initially I though maybe one of the plugs was bad. Replaced them all, nothing looked odd. Swapped out all 8 coils & wires port to starboard. Compression test was 145-150 on all 8 cylinders. New fuel filter and water separator. Checked the anti-syphon valve - good. Fuel vent is good. Fuel pressure is 40 PSI at idle and 42 PSI under a load. I have the Rinda program and I'm not seeing any issues, no codes. All the systems that are monitored look very similar to the port engine. I had about 2-3 hours on the plugs before I pulled them for the compression check. They all seemed a bit wet so I was thinking something was causing the engine to run rich. I'm at a loss as to what to check next. Any ideas?

[Viper]

Congrats and welcome aboard.

This could be a number of things anywhere from ignition to fuel/air related such as IAC, dirty injectors, a sensor, an adjustment, etc. There was also a campaign on the fuse/relay box due to intermittent starts and runability issues. The replacement kit changes the way the unit gets mounted to minimize vibration. Don't know if yours falls in that range of serial numbers.

[km1125]

Source of the post ....
Fuel pressure is 40 PSI at idle and 42 PSI under a load.
...

Is that the actual spec for the engine?? I don't know on this particular motor, but most port fuel injected engines regulate the pressure relative to manifold vacuum, so the pressure should drop significantly when you're at idle. But this also depends on if you're measuring pressure on the fuel rail where the injectors are at or before the regulator.

However, most of your symptoms are very typical with bad fuel. Have you tried running on a separate tank (with known good fuel) to isolate that issue?

Is the rough idle and 'not making power' consistent or intermittent issues?

[buster53]

Agree it could be a fuel issue. Try draining your fuel filter into a clear glass container so you can get a good look at the fuel. Any water will be immediately noticed and any cloudiness seen will not be good. Also, you may need to have your injectors serviced.

A while back, I had bad problems with one of my engines. Turned out to be bad fuel with a lot of water. Took care of the fuel issue, but not before my injectors got messed up.

[thatchh]

Just in case this helps.... I have a 396 with Crusader 8.1 mpi. My fuel supply system is the returnless type with a small gold Racor filter can. I was having idle stalling and difficulty at higher throttle settings. It turned out to be a kink in the short fuel line from the low pressure pump to the filter. It gets bent in a U. If you have a similar setup, it's easy to check.
I am considering the Rinda diagnostic program you mentioned also. It seems expensive, but it might more than pay for itself when I'm on the way to from Seattle to Alaska. Is it straightforward to use? Can you monitor parameters underway?
Regards,
Thatchh

[buster53]

Something else I haven’t seen mentioned...
Not sure about Volvos since I have 8.1 Crusaders, but my engines both have 2 fuel filters. I have standard 10 micron Racors and each engine has a small engine mounted 2 micron Racor. Any chance your engines also have these and yours is clogged up?

[Viper]

Not as standard equipment, but a previous owner may have installed something.

[Viper]

Source of the post..... I am considering the Rinda diagnostic program.... Is it straightforward to use? Can you monitor parameters underway?....

Pretty straight forward window based program, the trick is interpreting the data. The numbers won't do anything for you if you don't understand what they mean. Some fault coeds though will be easy to interpret but a lot of running conditions don't trigger fault codes.

[av8or98]

Source of the post Congrats and welcome aboard.

This could be a number of things anywhere from ignition to fuel/air related such as IAC, dirty injectors, a sensor, an adjustment, etc. There was also a campaign on the fuse/relay box due to intermittent starts and runability issues. The replacement kit changes the way the unit gets mounted to minimize vibration. Don't know if yours falls in that range of serial numbers.

I've though all along that it was an ignition issue but I've either swapped or replaced about everything in the system. I hadn't heard about the fuse/relay box issue, my S/N is 4012135018.

[av8or98]

Source of the post

Source of the post ....
Fuel pressure is 40 PSI at idle and 42 PSI under a load.
...

Is that the actual spec for the engine?? I don't know on this particular motor, but most port fuel injected engines regulate the pressure relative to manifold vacuum, so the pressure should drop significantly when you're at idle. But this also depends on if you're measuring pressure on the fuel rail where the injectors are at or before the regulator.

However, most of your symptoms are very typical with bad fuel. Have you tried running on a separate tank (with known good fuel) to isolate that issue?

Is the rough idle and 'not making power' consistent or intermittent issues?

40 PSI is the spec for the engine and I checked the pressure on the fuel rail. Port engine had the same numbers. When I bought the boat, the starboard tank was almost empty and I filled it with fuel from the local marina, then from the same hose, filled the port tank. It may be the fuel and I have the option of feeding the generator with either tank so I might try that.
The rough idle and not making power is consistent.