99 fuel pump/fuel gauge

duke350 · #1 06-11-2007, 11:35 AM

I have a friend whos older mom has a 99 windstar. A couple of weeks ago it wouldn't start. I went over and it started fine. A few more time it wouldn't start at first turn of the key, second turn its fine. As it turns out, you cannot hear the fuel pump when it won't start. I say, check the relay or replace the fuel pump, its probably going out. She then asks me if that would have anything to do with the gas gauge acting up, and says both issues started at the same time. Gas gauge is very slow to respond. You can fill it up and it may take 30 mins to read full. So, I get the pressue gauge on the fuel rail, turn the key to "start" and it builds maybe 10-15 lbs of pressure, and you cannot hear the pump. Turn the key off and back on and it will build pressure to 40 lbs with pump running, and will drop to 35-30 lbs when pump stops. It seems to hold pressure fine, no fast loss. The only thing I can think of is it may be a dirty ground on the tank electrics. I took a quick look and didn't see a ground close to the tank, but I also didn't spend much time looking for it. Does anyone have any ideas? Does the ground sound reasonable, and if so where does the tank ground? Could it be the pump, and if so, would that make the gauge act up? Any ideas are appriciated.

RickMN · #2 06-11-2007, 09:38 PM

Black wire from fuel pump/gauge sender unit goes into splice #S132 "dash to headlamp harness" left rear of engine compartment and then grounds to body at ground #G106 lower left front of engine compartment.

And yes, this sounds like a dirty grounding problem. That would be the first thing I would check. You can do a voltage drop check at the fuel pump with a digital meter or clean the splice and ground and go from there.

12Ounce · #3 06-12-2007, 07:23 AM

Lift the cover off of the relay/fuse box (near battery) and check all the voltages (there are two probe points on the top of each fuse for this purpose) in the box. If any voltage reading is less than the battery voltage, change out the associated relay. Of course, a circuit drawing makes this much easier to dope-out. But if you get low readings and can't determine which relay is the problem ... post here.

If you don't get low readings, the relays are probably OK.

12Ounce · #4 06-12-2007, 09:29 AM

Well, there are two relays that may still be suspect ... even if the fuse voltages check OK.

1. The PCM power relay
2. The fuel pump relay.

duke350 · #5 06-12-2007, 08:15 PM

Thanks for the advise/ideas. The car is gone for now, but I will have a chance to check it out again this weekend. I will let you know how it goes.
Thanks again.

catvents · #6 06-12-2007, 10:59 PM

Quote:

Originally Posted by duke350

Thanks for the advise/ideas. The car is gone for now, but I will have a chance to check it out again this weekend. I will let you know how it goes.
Thanks again.

If I would be you I would go to a Ford dealership part counter and get these 2 relays that 120unces recommand, Just don't take chance and change them, a big part of the problem you have mentionned is related with these relays, and soon or later has to be replaced. It is inexpensive, something like 20 dollars for both.

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