Fourth Fuel Pump

[Jack2048]

Hey all,

I have had repeated Low Pressure fuel pump failures. All with minimal hours, less than 20.

I replaced my LP fuel pump last October. Used the boat several times, last trip was for 70 miles. Worked great.

Winterized the boat, fuel stabilizer, fog engine, etc.

Started the boat in the spring quit after a few minutes. After some diagnosis, I determined the LP pump was failing. I got a replacement pump, put it in, ran for fifteen minutes, fine. Busy w/family, etc., could not get out. Went to start it today, ran great for ten minutes, then quit. No fuel coming out of pump.

The LP Pumps are all Volvo Penta OEM. New Fuel filter with last pump.

I am now getting ready to put in the fourth pump.

What is going on?

I really need a recommendation in the Maryland / DC / Annapolis area for a top notch Volvo Penta mechanic.

Here is my engine:

Engine: 1994 Volvo Penta 5.0 Fi PMDA

Here is what I have done: Within the last three years here is what I have done to the engine:

Fuel tank drained and cleaned.
New Fuel filter
New fuel hose.
Fuel injectors cleaned.
Fuel reservoir cleaned.
Fuel rail cleaned.
New pistons / rings.
Heads machined.
New belts.
New headers and risers.
Oil changed (end of last season).
Probably more, but don't remember.

 

[JustJason]

Check your fuel system for excessive restriction, air leaks, and check the voltage at the pump to make sure it's not low. Those 3 items will all cause premature fuel pump failures.

 

[Assassin3F]

I don't know a lot about how the fuel injection system is set up but I would absolutely do a vac/pressure gauge test on that pump's intake before replacing it again. If you are burning out a pump over and over then the problem isn't the pumps it is the intake or flow lines being blocked. If the pump is truly shot then have the mechanic replace it and put a vac/pressure gauge on the intake line and then have them do a vac/pressure gauge run on the out flow line. High vacume on the intake indicates something is blocking the line on the fuel storage side of the system, high pressure on the outflow indicates a blockage on the engine side downstream

Also a normal intake vaccum reading on the intake side may indicate an air leak in the intake line/path, which could cause a burn out of the pump by making it work harder than it should to provide fuel flow..

It might be possible to burn out one replacement pump due to a manufacturers defect...it is not possible to burn out 4 in a row without there being something wrong causing them to burn out. Speaking of which, have you checked to ensure the vent lines are clear? A blocked vent or return line will place drag on the system by pulling the tank into vacum. There are also a number of issues currently with the new fuel mixtures (out west) causing vapor locked fuel lines on some carburated engines but that shouldn't be effecting your FI system (I don't think).

 

[ericga]

You may have a fuel pump relay giving you intermittent problems and/or low voltage.

 

[Jack2048]

Check your fuel system for excessive restriction,

air leaks,

Not sure where this could happen. Fuel goes from tank into NEW fuel line, into filter, into pump. It would have to leak at the barbed fuel line connections or where the filter or pump seals.

and check the voltage at the pump to make sure it's not low.

12.5V

I don't know a lot about how the fuel injection system is set up but I would absolutely do a vac/pressure gauge test on that pump's intake before replacing it again.

Any equipment recommendations?

If you are burning out a pump over and over then the problem isn't the pumps

Odd since I ran fine one day then after the winter it quit after five minutes.

If the pump is truly shot then have

I pulled it off the boat today and hooked it up to a power supply, it would not turn. Seems jammed up.

the mechanic replace it and put a vac/pressure gauge on the intake line and then have them do a vac/pressure gauge run on the out flow line. High vacume on the intake indicates something is blocking the line on the fuel storage side of the system, high pressure on the outflow indicates a blockage on the engine side downstream

Ok thanks, I'll do that.

I feel it must be on the intake side. I have cleaned everything on the output side. Fuel rails, reservoir, injectors.

It might be possible to burn out one replacement pump due to a manufacturers defect...it is not possible to burn out 4 in a row without there being something wrong causing them to burn out.

Totally agree, that is why I am here.

A blocked vent or return line will place

Doesn't work like that, the fuel return line goes straight to a reservoir which is picked up by the HP pump. The reservoir is just like the float bowl of a lawn mower.

 

[Jack2048]

Here is the part about this that really gets me, which I have not mentioned.

The original pump stopped working, I bought a pump to replace it. It constantly whined while running, but always worked great. But the whining bothered me and I finally figured the whine was because I bought the wrong pump. This pump was for a GM carbureted engine, larger than mine. I then bought the correct pump and there begins my story.

Every time I plug in the other pump, it runs fine, I can go out and run all day works great, where as the "correct" pumps are giving me problems.

I just don't like running with this pump because it whines, and runs hot, since it is not pump enough fuel through it to keep it cool.

 

[gm280]

I would most certainly test the voltage with the pump running to see if it is a low voltage issue like previously stated. Because a low voltage will work the pump harder then it was designed to run and prematurely burn out. JMHO

 

[Assassin3F]

I am not a fuel system expert...but in other posts regarding fuel pump issues a whining noise indicates that the pump is working too hard and has been linked to line obstructions...

Just a thought...try hooking that model up to a short length of intake hose and a short length of outflow hose and run it between two gas cans. That would tell you if the problem is with the boat fuel system or if it just a noisy pump.

Also those barbed fuel lines can go bad if they are bent or stressed while removal or reinstallation...I just had to put a barbed connector on my carb cause I bent one slightly and couldn't get it to reseat flush...that is a low pressure line not sure if it would work for your system

 

[Jack2048]

GM280:

I would most certainly test the voltage with the pump running to see if it is a low voltage issue like previously stated. Because a low voltage will work the pump harder then it was designed to run and prematurely burn out. JMHO

EricGA
Using the backup pump, this is the one that I ordered, meant for a larger GM carbureted engine.

When running, I measured 14.5V at 5.5A.

Assassin3F

try hooking that model up to a short length of intake hose and a short length of outflow hose and run it between two gas cans

Yeah did that, the "new pump" wouldn't even turn.