95 VP 5.0fi running rough

[jdblya]

I have a 95 Four Winns with a Volvo 5.0fi and SX drive. It is running a little rough when at idle, and if I have the engine in neutral running at say 1500rpm or 2000rpm it seems to run fine, but misses every once in a while. It also seems like the the rpm will drop 100-200 and then come back up, or even go up 100-200 rpm while the throttle is just sitting there. This is on the trailer with the muffs on. When it is just idling , it will idle, and then kinda hit a studder or something, and then correct it self, but it comes and goes. The cap,rotor, and wires are about 3 years old, and I just ordered a new set. The plugs are new also. So I'm not sure what effect that stuff will have on it. But with the efi, and two fuel pumps, tps, and isc, that this engine has all over it, I don't know if I should be looking for something else. I wish I knew someone who was big into mustangs or something and could prob look at this 302 and know right away what is going on.

I read some other post about surging and stuff, and I both my fuel pumps are making noise so I'm not convinced that it is either of those.

Any help would be awesome!

 

[Don S]

Re: 95 VP 5.0fi running rough

What is the full Model number or serial number of your engine?

 

[jdblya]

Re: 95 VP 5.0fi running rough

It is a volvo-penta 5.0Fi Sx Cobra Drive.

After reading about this other guys lower pressure pump, I decided to go out and pull that fuel filter, drain it , and start it up again. It was running, then running, rough, then it stalled. I kinda noticed that the hi-pressure pump was making alot of noise, like screaming. I'm wondering if the pump is dieing and causing my probs? I'm going to put a pressure gauge on it tomorrow but I'm still looking for opinions.

Thanks

 

[Don S]

Re: 95 VP 5.0fi running rough

I'm still looking for a full model number or serial number. Year of the boat doesn't mean that's the year of the engine. Depending on when you boat was manufactured, it could have an older or newer than 95 motor.

 

[jdblya]

Re: 95 VP 5.0fi running rough

Model number is 50fapncs serial number t01292959

 

[jdblya]

Re: 95 VP 5.0fi running rough

Ok, so I installed a fuel pressure gauge and was only getting like 10psi, on the rail, and can't get it to start now. I replaced the high pressure pump, and I disconnected the line from the low pressure pump to the fuel reservoir and turned the ignition on , and it seemed like it was flowing fuel fine. but I am still not getting any fuel pressure. I even removed the valve core on the fuel rain and tried cracking it and nothing it coming out. Now I am suspicious of thsi fuel reservoir and I don't know what it does or is supposed to do. My clymer manual only tells me how to r&i it. Help.

 

[Don S]

Re: 95 VP 5.0fi running rough

t01292959 is an OMC SN number, not Volvo. But the modle number had what is needed. the NC in the number indicates the year model of the engine.

I missed the part about both pumps making different noise. Might just try hooking a remote fuel tank (Outboard tank) directly to the engine and see if the problem goes away. Or try this. http://forums.iboats.com/showthread.php?t=283269

I have to upload the EFI manual for this engine. When uploaded, I will add a link to it.

OK, here is a link to the OEM service manual.
http://www.4shared.com/file/104993284/c34b9668/7788882_NC_Ford_MFI_Dia.html

 

[jdblya]

Re: 95 VP 5.0fi running rough

t01292959 is an OMC SN number, not Volvo. But the modle number had what is needed. the NC in the number indicates the year model of the engine.

From what I understand, this is technically and OMC engine, but it was built right around the time that Volvo bought out omc. The engine says Volvo Penta on it, and it has an SX Cobra drive, but a lot of parts say OMC on it also.

I missed the part about both pumps making different noise. Might just try hooking a remote fuel tank (Outboard tank) directly to the engine and see if the problem goes away. Or try this. http://forums.iboats.com/showthread.php?t=283269

The high pressure pump was making a lot of noise, much louder than normal. I don't know if it started making noise because it was starved for fuel? Not totally sure. I replaced that pump, same problem. And I am pretty sure that the low-pressure pump is working also. Like I said, fuel was coming out of the line. However, when I I don't think it is making it from the point where it enters the fuel reservoir, to the the point that it enters the high pressure pump. But again I'm not sure. I guess there could be air in there somehwere?