potent951turbo

This is a dumb post, but I wanted all the second opinions I can get before I order a new pump. My 88' 951 project car would not run the fuel pump when cranking the car. So yesterday I hooked a volt meter to the connections at the pump and had someone turn the car over, and sure enough I had power going to the pump, but no pumping. I could feel the pump give a split second kick when the power first got to it, but it feels like it just jams inside. So to double check I got some wire and alligator clips and ran a wire from the positive side of the battery to the pump and it still would not spin. I tried switching the pump with a spare pump that I had and still got the same result, a slight jerk from inside and then nothing. The car has sat for at least two years, and the spare pump I had was a freebie that has just been sitting on my shelf for at least 6 months or more. I also bench tested both pumps(yes I know its bad to run them dry) using the battery and wiring both the the positive and negative sides, and they will give a small jolt but just stop immediately.
So are both the pumps I have bad and I just need to go ahead and order a new one? It just seems strange that both pumps do the same thing, considering the spare I had was said to be in good working order when I got it.

sillbeer

it's unlikely you have two bad pumps. Id suspect a clog in the feed line. Check the tank for debris and also check the line going from the pump to the tank. I'm betting on fuel sitting for 2 years has gummed up the works in there.

potent951turbo

Both pumps were tested off the car however and still would not pump.

Legoland951

Yes time to replace. These pumps go bad from sitting. I had a batch of 6 used pumps I had sitting off a car and they all went bad by the time I needed one. I even took one apart and couldn't see much rust or junk inside it. I guess it doesn't take a lot to get them jammed.

sillbeer

ah, well if they tested bad off the car then yes, you have two bad pumps. Thats 100% more bad pumps than I have seen in my whole life lol

Chris_924s

Yep. bad pump.


Ever bought a bad water pump off the shelf? I have.

potent951turbo

What do you guys think about the slight jolt/kick both pumps do when first connected to power? Just a normal characteristic of a dead pump?

Legoland951

The pump spins momentarily before it gets stuck on rust or crud causes the jolt/kick. I have never gotten the pumps to work properly when it quits working like that.

PorscheDoc

Yes sometimes a bad pump will jolt if you hook it up to power, but will not spin. That pump is shot.

potent951turbo

Alright guys, well I ordered a brand new bosch fuel pump and a new fuel filter. Hopefully that does the trick.

potent951turbo

Update- The new fuel pump did the trick and the car is now running and driving for the first time in over two years. The PO said the car shut off while he was driving it and it would never start again. When I opened the DME up it looked like part of the circuit board exploded and was burned black, but after switching the computers the car still didn't want to start. So the original problem must have been the DME going bad and then the fuel pump must have frozen up after sitting for so long. Now the real ordering can begin with new vacuum lines, front seals, water pump, timing belts etc.