Gummed up fuel pump

930kitkar · 08:52 AM

My '83 928S doesn't want to start after not been started for several months - a year perhaps. I jumped the fuel pump relay terminals and nothing happened - no clicking from the fuel pump. I substituted a new relay and nothing happened either. There is spark. So I have to assume that the fuel pump is the problem. I am assuming that the old gasoline in the fuel pump has gummed up and locked up the pump. Assuming I am correct is there anything I can do to clean up the pump. Buying a new pump would be my last option and one I would have to put off for a while since this is a hobby car and money is tight.
Thanks

vdubr928 · 08-30-2009, 09:14 AM

I bought one on ebay for $100 new. It's working great. Quiet too.

Even if you get your old pump working it will be for a short period. Where will yuo be when it decides to give up the ghost? Tow truck probably cost you close to what I got my pump for.

930kitkar · 08-30-2009, 09:29 AM

I could do a hundred bucks for a pump but not 200-250!
I would call AAA, but if I could get my old pump going at least I could use it while I am sorting other things with the car and it is not going to be driven on public roads.

DPW928 · DPW928's Garage

Before replacing it, check the ground wire to make sure the connection to the body is clean. Also try hotwiring it in reverse (positive to the big post) and see if running it in reverse will clear it of the lacquer.

Mrmerlin · 08-31-2009, 08:20 AM

Are just trying to start the car OR do you want to put into service?
If your going to put it into service then I would suggest that you remove the fuel pump, drain the tank and remove the fuel sensor and inspect the tank for internal condition ( you might have to remove the tank for cleaning)
To got the pump freed up spray some carb cleaner into the inlet and let it sit ovenight in a little container.
Get a 12v power supply and touch the leads if the pump will run in either direction then fit a few hoses to the pump and fill the small container with some marvel mystery oil and run this through the pump, this should free it up and with a fresh fuel supply it should work, if the pump is old then a new pump should be installed after you clean out the tank and also install a new fuel filter.
Add some Marvel Mystery oil to the fuel as well as fuel stabilizer, if your not going to drive the car/run the engine, ( this only works with fresh gas in the tank)

930kitkar · 09-13-2009, 02:29 PM

Merlin,
Thank you for the suggestions. Today I finally was able to remove the pump bring it home and check it. I sprayed lots of carburetor cleaner into the pump - both ends - then I attached a 12v source to the pump and it ran quietly. I switched the polarity and it ran just as well. I then poured MMO and it dripped out the other end freely. I guess that whatever was gumming it up has been dissolved. I now need to check that the pump is getting voltage. I also cleaned the check valve with carb cleaner. The fuel pump part number starts with 550 I thought these pumps had a 928 for the first three digits of the part number.
Thanks

Mrmerlin · 09-13-2009, 04:28 PM

you might consider replacing the check valave prior to installing the pum also get new sealing washers and dont over tighten the cap nut, it damage the hard line and then it will leak, it will also leak if you use the old sealing rings