Volvo Penta 8.1 issue

[av8or98]

Source of the post 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.

When I changed the fuel filter and water separator, I didn't notice any water in the fuel. I was thinking about pulling the injectors and having them serviced as a next step.

[av8or98]

Source of the post 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.

When I changed the fuel filter and water separator I didn't see any water in the fuel. I haven't added any fuel since then. My generator can feed from either tank. I was thinking about swapping it to this tank to see if that has an effect. I was also thinking about having the fuel injectors flow checked as a next step.

[bud37]

Good idea to make sure the fuel is good.....also and I don't know for sure how Volvo does this,...but do you have a vacuum hose running from the intake to the fuel regulator ? If so check for raw fuel in that hose.

Wet plugs are usually from an overly rich mixture, or misfiring ( could be fuel ) causing the plugs to be wet. Do you have the laptop version of the Rinda where you can record a test run and review the info packets slowly to look at injector pulses etc ?

[av8or98]

Source of the post 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?

I also have a standard fuel filter and a Racor filter. Both were changed and they looked good with no water.

[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?

My generator can feed from either tank. I was thinking about swapping to this tank to see if it continued to run smoothly. Was also thinking about getting the fuel injectors flow checked as a next step.

[km1125]

Source of the post
My generator can feed from either tank. I was thinking about swapping to this tank to see if it continued to run smoothly. Was also thinking about getting the fuel injectors flow checked as a next step.

Yea, run it for a while under a good load and see what happens.

I'm surprised you can't do the same with the engines. That's one thing I really liked about my old boat. You could run either engine from either tank so if you had any kind of a fuel issue, vent issue or anti-siphon valve issue, just flipping over to the other tank would resolve it so you could get back to the dock. I was planning on adding a couple more filters in the mix so when switching tanks you'd also switch to an alternate set of filters.

[av8or98]

Source of the post 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?

I changed both filters on both engines, same issues before and after. I didn't notice any water in the filters when I changed them.

[buster53]

Source of the post

Source of the post 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?

I changed both filters on both engines, same issues before and after. I didn't notice any water in the filters when I changed them.

No water is good, but what did the fuel look like? Nice and clear is good...any cloudiness could mean phase separation and that is not good.

[av8or98]

I was able to run both engines today and record about three minutes of run time on each. Putting them side by side I noticed the following:
Sensor Port-Good Starboard-Bad
MAP 12.1 15.1
MAP Volts 1.65 2.25 Both were 4.65 prior to start
Injector Pulse 2.6 3.9 Port was steady, Stbd varied 3.3 to 4.0
IAP Position 125 157
Stall or Reset OFF ON Both were OFF prior to start. The Stbd took three tries to start. It remained on for the duration of the run.
Once the engine did start, I could hear the IAC open up to keep it from stalling. It stayed open for the entire run.
Enabling base timing seemed to smooth things out.
I ran the generator on the stbd tank for 30-40 minutes and it ran fine.
Any thoughts?

[bud37]

Clearly the STBD is not happy...what was your test rpm and were the engines completely warmed up ?....appears to be little higher fuel rate for one reason or another and the IAC seems like open too far for a warm engine at idle, but sometimes therde are other reasons.

First the easy stuff, were the flame arrestors off when you tested....are they both spotless clean, check the throttle plate and clean the throat and edges of the plate....check for gouges or sticking.

There used to be seals on the GM type map sensors that can go bad . Need to find out why it showed sensor bad but what I mentioned is good to do anyway, also if there is a vacuum hose from the manifold to the fuel regulator ,check it for fuel.