Why is she dying?

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Well, I found my pressure gauge, and finally found the schraeder valve, but now all I need is the adapter to make the GM size gauge fitting fit a Ford. I've looked everywhere, but no joy yet.



It just died, with no warning. I coasted to the shoulder each time.
 
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Is it just shutting off or losing power then dying? If it is just shutting off chances are that it isn't a fuel pump, now if it is losing power and then dying it could be a a fuel pump.
 
It's a little hard to say. It's like I suddenly can't get power anymore, then it dies completely. I'm not sure that's all that different from dying suddenly. The effect on the driver is basically the same!
 
Hmm. Not sure it's a fuel problem then if it dies that suddenly. I had a similar problem with my old Expedition. After the shop tested my fuel pump, changed the fuel filter, cleaned my injectors, and did a complete tune-up it still died. After all that it turned out to be a faulty computer.
 
Well, as soon as I can find that stupid adapter I'll test the fuel pressure, and then I'll know!
 
I had the same issue with a Crown Vic several years back. My car showed these symptoms during one summer. My issue turned out to be the computer as well. Each time the engine died, I had to just sit on the side of the road and wait till it cooled off a bit.



While Ford had it, the engine was cool and they couldn't find what the deal was until they let it sit running and after it warmed up, it would die on them and they were able to troubleshoot the issue and said a chip in the computer was getting hot causing the engine to die.
 
My father-in-law picked me up with his 5th wheel car hauler, and she fired right up to load and unload. She died in the driveway after unloading, though. That was after 90 minutes waiting to be picked up, a 10 second run up the ramps into the hauler, and 35 minutes to get home. I'd say she was cold enough. She'll only run about 30 seconds now.



And wouldn't a computer problem throw a code? Although I would think a fuel pump problem would throw a code as well.
 
Usually problems that happen quick like this don't ever throw a code. When it doesn't start have you tried pushing the schrader valve on the fuel rail to see if you get a nice shot of fuel out of it, you should.
 
WHY WOULD IT BE THE..uh, why are we yelling? Why would it be the alternator? The battery spins the engine just fine, even for several starts in a row. I'll check it just in case. Can't get to it to fix it until this weekend, though. I have end-of-month paperwork to finish, and we're switching traffic from one road to another today. I left last night at about 9:00PM, after getting here at 7AM! And then drove the 65 miles home!
 
My Expi never threw a code. That's why they did over $500 worth of repairs before figuring out the computer was to blame.
 
OK, NEW INFO!!!



I found the adapter to my pressure gauge and tested the fuel pressure. (it was in a drawer in the master bathroom. Don't ask me how it got there or why I thought to look there!) The fuel pressure reads right at 64 psi at startup and idle. After running for 15 or 20 seconds, though, the fuel pressure starts to drop and the engine starts to stumble, dying totally within 5 seconds.



Is this the fuel pump (probably) or is it a fuel relay problem, or something like that?
 
It is possible that the fuel pump is losing power and thus causing the drop off in pressure, the only way you can make sure is to tap into the f/p power wire with a dvom and monitor the voltage as the incident occurs. With the mileage that is on your ST I wouldn't be surprised by a bad fuel pump... but you know if you replace it without checking the voltage then it will be an electrical issue. An easy place to check voltage to the pump(this assumes that the wire adn connection to the pump is good) is at the inertia switch in the kick panel, you can probe the pink/black wire(the power wire to the pump) and monitor the voltage there, if voltage stays above 10 volts and you lose pressure change the pump. If you want to eliminate the relay and the computer control of the relay pull the fuel pump relay out of the underhood fuse box and jump pins 30 and 87 together, as soon as you do this the pump should start to run as it is basically hotwired to battery voltage.
 
It's been a difficult week, and I've just now been able to get back to the Trac for electrical testing.



Which pins are #30 and #87?
 
Ok, now the saga continues...



I went to test the relays and computer like l1tech suggested, and fired it up to see what voltage she has when she dies. But she hasn't died! She's been running out there for a good half hour when before she would only run for 15 or 20 seconds! Is it possible the inertia switch is bad? I pressed it once or twice to verify I had the right component.



Also, it's hard to find one of these pumps! No one stocks them!
 
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by dreman,7/6/2008 14:53 MT



Ok, now the saga continues...



I went to test the relays and computer like l1tech suggested, and fired it up to see what voltage she has when she dies. But she hasn't died! She's been running out there for a good half hour when before she would only run for 15 or 20 seconds! Is it possible the inertia switch is bad? I pressed it once or twice to verify I had the right component.



Also, it's hard to find one of these pumps! No one stocks them!

dreman
Click to expand...



Unfortunately that's the way these things usually go that's why when I suspect a failing fuel pump and pressure and volume is ok I break out my scope and amp probe and check the amp wave form of the pump...that's a bit much for your average diyer though.

 
Ok, I went ahead and dropped the tank. Took pictures, too, so maybe you'll see a writeup soon.



Now, how do you get the hoses loose from the pump? They seem to be different from the fuel filter fittings.



And no, I don't have the equipment to take the waveform of the pump!:blink:
 
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