1991 PCM 351 Fuel Pump Problem

[Cougar Zeke]

Hi all!

I purchased a 1991 Comp last year and it ran great. I winterized it for the cold, rainy Seattle weather last November.

I pulled it out of storage on Friday to get it ready for the summer and haven't been able to get gas to the cylinders.

It will run when I pour gas down the carb until the gas runs out. When I pump the throttle, no/or very little (drops) gas is dumped into the intake from the carb.

I suspected a stuck float in the carb, but first checked to see if fuel was pumping to the carb. I disconnected the fuel line to the carb, but no fuel came out when I cranked the engine. I cranked the engine over quite a few times to see if a could get any gas to come out and nada. I could pull fuel through the line from the fuel pump with a "jack rabbit" hand pump, but even after pulling 2 pints of fuel through it the fuel pump wouldn't pump fuel.

I did confirm that there is gas in the fuel filter and the fuel line is unclogged. There was some water in the fuel that I pumped out of the fuel line.

The fuel pump appears to be original as it is also painted black like the engine so it is ~23 years old.

My obvious hunch is that the fuel pump has died, but I'm not sure if I'm missing something or if there's something more I should check.

Many thanks!
Andy

[CJD]

It sounds like a good diagnoses to me!

[Cougar Zeke]

Thanks CJD! It seems obvious, but with boats there always seems to be something else to consider!

[wotan2525]

Mechanical fuel pump? I'd pull it, install a block off plate and add an electric fuel pump. Cheap and reliable and works better to "prime" the carb if you ever run out of gas.

[lively]

Mechanical fuel pump? I'd pull it, install a block off plate and add an electric fuel pump. Cheap and reliable and works better to "prime" the carb if you ever run out of gas.

Hey do you have electric on yours ? If so how do did you wire it to shut off when engine dies to prevent fuel overflow ? And is it a external mount , inline ?


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[wotan2525]

Yes. Mine runs off of my ignition switch. The carb prevents it from overfueling -- once the floats shut the gas off, it can't pump any more. It's a little, low-ressure in-line electric pump. I've had several mechanics surprised that it provides enough fuel to my engine but I've never had a problem and why fix it if it's not broken?

It looks like this model.

http://www.ebay.com/itm/NEW-AIRTEX-E8251-Fuel-Pump-Electric-Universal-low-pressure-marine-application-/111356064047?pt=Motors_Car_Truck_Parts_Accessories&hash=item19ed56b12f

I just did the calculations and 30gph should be good up to 385hp. I know mine doesn't make that much.

[lively]

So as long as the ignition is on the pump is on ? I was thinking of doing this and hooking it off my ignition too . But need 6-9 psi . That one you showed me is like 4-5


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[CJD]

Your mechanical lasted 23 years...that says a lot. I've yet to have an electric pump last that long!

[ssa]

If you want to wire an electric with a kill switch mine uses this one. http://www.skidim.com/prodinfo.asp?number=49-6007 Its plumbed into the oil pressure gallery. You can also run a leg from the I terminal on the starter to the terminal the pump connects to so that it will energize the pump while cranking before theres sufficient oil pressure to close the circuit in the switch.

[Cougar Zeke]

Your mechanical lasted 23 years...that says a lot. I've yet to have an electric pump last that long!

Good point CJD!

[michael hunter]

You guys are so quick to change things? Test the fuel pump if bad replace it with the same pump and enjoy it for another 23 years.

[CJD]

From what I read in the inital post...no fuel pumping from a mechanical pump, but fuel can be sucked through the pump from the tank. That sounds tested to me. The pump isn't pumping.

[Cougar Zeke]

I wanted to circle back with everyone who had suggestions on my lack of fuel problem to report that I replaced the fuel pump yesterday and the old girl cranked right up!

Replacing the fuel pump was easy. The hardest part was lining up the metal fuel line between the fuel pump and carb. It just didn't want to thread.

I did want to add that I read in a couple of places that if the fuel pump was bad, there would be fuel in the clear tubing going from the fuel pump to the carburetor. That wasn't the case with mine. There was no fuel in mine.

[michael hunter]

Connect a vacuum gauge to the inlet side of the fuel pump . Crank the engine it should go to 15 in min.