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Porsche 944 Fuel Pump Problem

I have a 1988 944 which has not been started for several years.
A recent attempt at starting was not successful due to lack of fuel (squirting gas in the air inlet will cause it to fire, but not continue to run). The fuel gage reads empty but there is at least 10 gallons of gas in the tank. I was told the fuel pump relay could be at fault, but could not find this relay in the fuse box. Where would it be located and what else could be at fault?

Thanks,
Old 07-03-2007, 12:38 PM
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It's the DME relay they are talking about. The fuel pump only runs when the car is being cranked or is running. Are you getting any fuel to the fuel rail? You can crack the fuel rail at the end, closest to the front of the car to see if you have fuel.

The fuel gauage is prob an electrical prooblem. Not a real big deal. At least it will start with gas added. So now you should expect it to be a fuel delivery problem. Either the pump is not working, there is a problem with the fuel pressure regulator, the fuel damper, the injectors, or something with the DME relay or the DME itself. Normally people find problems with the DME relay.

Did you drain all the old gas out and put fresh in? If not then that is a MUST do.

Try making a jumper as explained on this page:
http://www.clarks-garage.com/shop-manual/fuel-05.htm

Put the jumper in and try it. Let us know how it works out.
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Last edited by Icey1174; 07-03-2007 at 02:42 PM..
Old 07-03-2007, 02:25 PM
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This may go without saying....
But if it hasn't been started in years, have you replaced the timing and balance belts.

It would truly suck to get it started, just to crash the valves!

-Nick
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Old 07-03-2007, 07:02 PM
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Good point Nick! How the heck did we over look that?!?!?! Add the water pump too.
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Old 07-04-2007, 06:24 AM
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Continued 944 Fuel Problem

Thanks for the suggestions! I did replace the DME relay and now I have a reading on the fuel gauge. However, the car will still not start. I checked the fuel pressue at the fitting at the end of the fuel rail and there is "0" pressure. Sounds like a fuel pump, but can they fail while the car is being stored? Any other way to check the pump?

Thanks,
Old 07-16-2007, 10:32 AM
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they can fail due to storage: the old fuel gums it all up and they seize.
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Old 07-16-2007, 11:05 AM
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944 Fuel Pump Replacement

On checking a Haynes manual for replacing the fuel pump on 1983-1989 Porsche 944's, they show the fuel pump being located in the engine compartment, which is clearly not where it is located on my 944. Where would I find a procedure for replacing the in-tank pump?

Thanks,
Old 07-17-2007, 10:19 AM
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The fuel pump on my 86 n/a is right under the fuel tank. You have to take off the protective shroud under the tank by taking off the metal straps and then you can see the pump. Pretty easy from there.
Old 07-17-2007, 10:41 AM
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http://www.clarks-garage.com/shop-manual/fuel-10.htm

Have fun.
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Old 07-17-2007, 01:39 PM
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Since you have a spare DME relay, gently pry off the cover of the spare DME relay and replace your current DME with the spare. Use you finger to activate the top relay with the ignition key on. You should hear the fuel pump spinning when you activate the relay manually. If not, try the bottom relay (I've forgotten which relay actually runs the pump). If you hear the fuel pump spinning, it probable isn't the pump. If you don't hear the pump, try checking the fuel pump fuse to make sure it isn't blown.

When you crack open the front of the fuel rail, does gas spay out? If so, you at least have some kind of pressure, but maybe not enough to activate the injectors.

One more little trick, use a BIG screw driver, hold it like a pool que, and tap the bottom of each injector a couple of times. The injectors can get gummed/bound up after sitting a couple years and the tapping will often jar them loose. It worked for me.
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Old 07-22-2007, 09:13 AM
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While you're sorting out the fuel pressure problem, I have to ask...how old is that 10 gallons of gas in the tank anyway?
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Old 07-22-2007, 08:24 PM
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Before eliminating everything else I would use the 3 wire jumper and see if the pump runs. If it does I would drain the tank then fil with new and tap the injectors as I have seen this be the most common fuel no start after sitting for extended periods of time,

If you do get the injectors to pulse then I would
change belts and pump
drain fuel again
change filter
put some BG 44 in the first real tank of fuel
start chasing down and replacing old vacuum lines as I'm sure you'll be back on shortly wondering why it is running funny
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Old 07-22-2007, 11:20 PM
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does the 83 44 have a fuel pump fuse or just relay?
Old 10-17-2011, 05:43 PM
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Relay.
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Old 10-18-2011, 08:35 AM
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i heard the late model 44s the dmes can be tapped while someone turns key n they might crank over?there in the engine up near the windshied i think?
Old 10-19-2011, 10:36 AM
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Anyone know the best way to drain the old fuel out? (1987) 944 automatic. I have one that sat for along time. The fuel in it is probably completely dead... and probably all the way up to the fuel rails is bad. The person I bought it from said they ran fuel directly into the motor and it ran good... I have no idea how they performed this?
I need to clear out from the tank all the way up... I've never worked on a Porsche before, but I have dropped 96 mustang fuel tank, pump, filter, injector rail out once...
Old 09-13-2017, 07:36 PM
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PorscheChampion, I recently drained the fuel out of my '87 Turbo. It is actually quite easy.
Disconnect the battery, just to minimize the chance of a spark;
Raise the rear end of the car off the ground, at least high enough to position a 5 gallon bucket under the fuel tank;
Remove the cover that holds the fuel pump in place;
Now you will have access to the hose that connects the fuel tank "sock" filter and the pump. Disconnect the hose from the fuel pump side and that will allow you to drain the tank. You can pinch the fuel hose to control how much fuel flow you get from the tank.
Once empty, I would remove and inspect, and mostly likely replace the sock filter and the rubber seal that fits on the threaded side of the filter where it mounts to the tank. I always also replace the hose that connects the filter to the pump. It is cheap insurance while you are there.

Have fun.
Old 09-14-2017, 04:29 PM
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Thanks, I got the fuel changed out but still have a no start. Starting fluid kept it running however. I guess I'll try tapping injectors, then will check fuel pressure. I definitely am getting fuel up to the rail though, just not sure if it's enough pressure. Do these cars ever have electrical signal issues to the injectors themselves?
Old 09-22-2017, 10:08 AM
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Sure but it is also common that the injectors get plugged with old gas turned to sludge and varnish.
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Old 09-22-2017, 11:18 AM
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Also consider putting sea foam fuel cleaner/conditioner in at its strongest concentration. It will dissolve the gum/varnish and run it through. Of course you have to get it through the injectors and it sounds like you're going to tap and do that potentially. So don't jam more bad fuel through them - use fresh fuel/sea foam. I'm a champion of resurrecting old cars and this is my go to stuff. Also, pulling the injectors and bringing them to a professional cleaning service is a $12/inj service here so its worth it. You'll get them back balanced and graphs of before/after output levels if your guy is like mine. Mr. Injector in Coeur d'Alene, ID. Find someone local and its a one day turnaround because they do it for the trade (auto shops and dealers).
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Old 09-22-2017, 11:42 AM
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