94Explorer:Fuel Pump runs runs run& cranks -no start

First off.. stop swapping relays. Ford has a habit of "piggybacking" relays - i.e., one relay will control a device PLUS the control circuit of another relay. Swapping relays can have one trsavelling in circles.

Second, the PCM does not look at fuel pressure to turn the fuel pump on your car on or off - when the key is first turned on, the PCM commands the fuel pump on briefly to ensure that the fuel rail is charged but it has no way of checking to see if, indeed, there is no pressure there. (This strategy didn't appear until the last few years).

Are there no Continuous Memory codes displayed in the KOEO test? Also, it is essential that you complete the KOER test.... the PCM uses the dynamic response to test many sensors. I don't know which tool you are using nor what cues it gives for when to perform the switch test and dynamic response test but the switch test comes first....

HTH

All well & good. Q: Does the ECM tell all the injectors to close when first turning on key? Thus allowing fuel rail pressuraztion. if a couple aint closed due to ECM mis control, bingo no pressure. Then after crankshaft revolution (crank sensor) start pulsing?? Could this posibly be the culprit? On & off with the key will get the pump to stop running! & will then start with fuel rail pressureized.

Maybe?? $90 from Autozone + $90 core.

Rather than close the injectors, the PCM opens them (they are normally closed). Depending on the program strategy, the PCM *may* pulse all the injectors once when the key is turned to run or start to purge air or vapours from the fuel rail and/or richen the mixture in the intake port. Again, depending on program stategy, the PCM may bank fire sequential injectors until the PCM sees the motor is running or until a predetermined time period or temperature is reached.

Whether the fuel rail pressurizes or not, the fuel pump should only run (KOEO) for 1.5 to 2 seconds (gasoline engines) and wont turn on again until the PCM sees an rpm signal. If your pump is running continuously KOEO, then there is a problem with relay, wiring or PCM (the relay control circuit is ground side switched by the PCM). You'll need to do some circuit testing while the problem is happening. It makes no sense to throw parts at this thing willy-nilly without some kind of diagnostic proof of a problem.

Ya I know about throwing money at car problems. But at this point, it does seem like the ECM or PCM (the one that controls the injector pulses) is mal-functioning. I can get it to stop just by waiting, or by switching the key on - off (no engine cranking) Or after its running & has gone into a "check engine light" condition & poor throttle response, turn the engine off & restart - no check engine light & great throttle respose - for about 1-5 minutes! Evertime. PCM or ECM?? the one behind the passenger side headlight. Carquest says there were 4 or 5 to choose from, depending on which one I had. great! $140.

I think I'm just gonna do it this weekend.

Gil

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Well..... you keep saying that the CEL has come on when the problem occurs..... is there some reason you arren't aving the code(s) read? This is offering what could be a very important clue to solving your problem. I would think (at the very least) that you would have a memory code stored in the PCM.

The module you are referring to, behind the right side headlight, would be the ignition control module..... not the PCM.

Which one ICM or PCM gives the injectors a pulse when turning on the key? Is that the culprit not releasing that pulse until I cycle the key on-off a bunch of times? I will try again to get the codes this weekend. Maybe between my son & I we can get it to go into the second part of KOER test. All I come up with in the first part is "insufficant EGR voltage/opening" That anit it.

Thanks again.

The PCM controls the injectors. The ICM controls spark at the behest of the PCM. The ICM also provides rpm signal to the PCM.

What test are you using to prove that the PCM isn't pulsing the injectors?

Rather than giving some aftermarket code description, I am better served with the exact code retrieved. This way I can refer to the factoy service manuals.

Here are the last set of codes I got from my Actron code scanner:

327 332 327 332

The 327 and 332 are EGR related codes. The DPFE sensor on these motors is notorious for failing and I think it would be a safe bet to change the sensor. Be sure the two rubber hoses going to the sensor are in good condition and that the metal tubes aren't plugged off.

The 538 and 536 simply indicated that the dynamic response test and BOO switch tests were either not performed or the PCM didn't see a change of state.

However, this still doesn't address your fuel pump concern. The only way you can be sure of having adequate fuel pressure is to use a guage. As for the pump running when it shouldn't, you still need to do some basic electrical diagnosis.

I hooked up the scanner again last night & got these codes:

11/19/04

412

326 538 412 326 538 (these same codes sent again)

It does not seem I'm getting the dynamic response test required by doing a WOT? What am I doing wrong? I see the engine code flash, the single light blips, I turn the steering wheel, stomp on the brake, & then floor the bitch! codes 412&538 = insufficent rpm change during DRT I'm at a loose.

Thanks Gil

Scanning through the PC/ED, 538 wants to be sure that the rpm did go past

2000 during the dynamic response test - if it did, they are indicating a bad PCM as the likely cause ( I always hesitate to suggest the module as the culprit because it is to easy to shortcut a pin point test and all roads lead - eventually - to replacing the module). 412 indicates that the PCM can't control rpm to it's satisfaction.... any things can influence this including having someone monkey with the base idle screw....

No monkey business with it. I am thinking about buying a PCM off E-Bay, but I don't know if it will interchange. Mine is a F47F-12A650-NB UMP1

the one on Ebay is a F47F-12A650-MB VET1 ???

Gil

Update - 3/22/2005

The last thing I did in November 04 was to swap out the ECM (inside by passenger kick panel) I bought it off E-Bay - big risk. but it worked & did the same as my original, for about a week. Fuel pump runs, runs, engine cranks, finally pump shuts off(pressurized)engine starts. F....!!1!.. Same shit different ECM. could I have 2 identically bad ones? Same scanner codes also! about a week later this FP run / no start problem went away. Its now Feb. 05 & no problems with that. CEL still comes on after a short time. 1min - 5min. & poor throttle response from idle(smooth) to around 2000rpm. Not noticeable when on the road. It passed emmision test last week( weeew!)

So its one of "those" problems. The only thing I did was to run a few cans of sea-foam injector cleaner in gas last Oct 04. Hmmmmmmm I've never had much faith in cleaner additives correcting an injector problem. But I could see using it as preventive maintance regularly during the year. I never did that. Ok that's that for now. Time will tell

94 Explorer limited (yes very limited) 4L v6 4WD 160K (bought new in 95) Have used Amzoil 2X / year its intire life. No oil leaks/no oil burning. I think that says somthing.

Thanks again to all out in usnet land!

Gil

Jim Warman wrote:

indicating a bad

better

factoy

code(s) read?

headlight,