96 wagon starts but won't run

mishalah · 10-18-2006, 08:37 PM

'96 Sable wagon, duratec, 116K miles. Running perfectly until today. I can hear the fuel pump run, definitely puts presure into the rails/injectors. Cleaned the IAC, checked for spark when cranking (ok), checked two ground cables (ok), tested cam position sensor, replaced it with a new one but no change so put original one back in.

Engine cranks great, fires from fuel in rails (from initial powering of the pump), but dies as soon as it requires more fuel.

Had it running several times for a few minutes each to see if it would run above idle or hold at idle. Now, it won't keep running past initial startup.

What am I missing?

Cntrysthbst · 10-20-2006, 02:57 AM

I would check for codes first even if your check engine light is not on, this may tell you something.
How old is your fuel pump filter?
What is the psi reading before the engine is started, during cranking, and at idle?
You may hear your fuel pump but it doesn't mean it's doing its job. You may want to pull a plug and check that way.

mishalah · 10-20-2006, 05:12 AM

Quote:

Originally Posted by Cntrysthbst

I would check for codes first even if your check engine light is not on, this may tell you something.
How old is your fuel pump filter?
What is the psi reading before the engine is started, during cranking, and at idle?
You may hear your fuel pump but it doesn't mean it's doing its job. You may want to pull a plug and check that way.

The only code is the insistant P0401 (P1401?) that never goes away. Fuel filter is approx. 3 months old; ran a fuel pressure test at cranking and was ok; did a spark check and there's power to the plugs; injectors seem to be working ok until it tries to run and they seem to be told not to pump fuel.

Update: cleaned the idle/air components and emissions components. It didn't seem to help at first, but then re-cleaned the + battery cable and it fired up. We tried it several times and my wife ran some errands. I had my son pick up a new battery cable/terminal set which will go on tomorrow. I really suspect a low voltage and current problem due to corrosion inside the old cable. These systems are far more sensitive to voltage and current weakness than most people think.

Thanks for your reply.

Cntrysthbst · 10-20-2006, 01:29 PM

Goodness, I would have not even thought of the battery. Was it cranking fine when you where starting it when you where having the problems? After the engine starts doesn't the alt supply the engine voltage? I ask so in the future I can keep this in mine if I ever have this problem with wifes newer sable, 97. Please do let me know, Thanks

mishalah · 10-20-2006, 04:38 PM

Quote:

Originally Posted by Cntrysthbst

Goodness, I would have not even thought of the battery. Was it cranking fine when you where starting it when you where having the problems? After the engine starts doesn't the alt supply the engine voltage? I ask so in the future I can keep this in mine if I ever have this problem with wifes newer sable, 97. Please do let me know, Thanks

Everything seems to be working fine right now. The battery was ok until I had to crank it numerous times without getting it to run. That's a lot of drain with no charging. I've had similar problems with other computerized cars over recent years. Many systems will just not function if the initial voltage is low. Bad cables or corroded connections can cut the voltage and current flow drastically. I hope this will be the end of this problem.

mishalah · 10-20-2006, 08:06 PM

Well, the "fix" was short-lived. After a day of running just fine it's back to the same crap. Fuel pump primes fine, engine fires up, engine dies as soon as fuel in rails is used up. We played with the fuel pressure regulator, but no change. Sprayed carb cleaner into the and it ran while the solvent was going in.

SO....it's getting spark but no fuel (after initial priming). Since the pump primes every time I think the pump is ok. Something is shutting off the fuel between priming and running. Whatever it is, it was intermittent...but now may be permanent.

The question is: what circuit or component cuts off fuel flow after initial startup?

mishalah · 10-22-2006, 11:47 PM

Today it started and ran fine again. I tested the fuel pressure and it was 32-35 at idle, up to 40 at acceleration (pulling vacuum), 40 with just key "on", and varies directly with amount of throttle. When the vacuum line is removed from the FP regulator the pressure goes to 40 (max) and stays. So, the FPR and pump seem t be working normally.

What next?

mishalah · 10-23-2006, 02:34 PM

This morning it won't run again. Fuels into the rails, burns off, dies. Pump runs in "on", can't tell if it stops when trying to run. Same old, same old.

rogerlh · 10-23-2006, 03:41 PM

Shot in the dark!

Could it be an oil pressure sending unit /sensor. I had a bad one on another car and car would start but then die as computer would shut it down thinking oil pressure was low.

mishalah · 10-23-2006, 06:40 PM

Quote:

Originally Posted by rogerlh

Shot in the dark!

Could it be an oil pressure sending unit /sensor. I had a bad one on another car and car would start but then die as computer would shut it down thinking oil pressure was low.

Good thought. I'll check it. Thanks.

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