No injector pulse, no EEC-IV Diagnostics

[wolferaw]

95 Explorer, 4.0L Pushrod engine won't start. 12VDC measures good at the injector connector pins, but no ground signal from the PCM to the other pin on the injector connectors. The on-board EEC-IV KOEO test is totally inoperative (no signals and check engine light constantly on while running diagnostics). A third symptom is the fuel pump continually runs with the key in the run position (key on engine off).

All 12 Volt inputs and grounds to the PCM check good (12 VDC at pins 1, 57, 37, 22, 33, 21, and 8. Zero ohms to ground on pins 20, 40, 60, and 6).

I've swapped PCMs with one that tested good in the same vehicle a few weeks ago. Are there any sensors that would prevent the engine from starting while disabling on-board diagnostics, stopping injector pulses, and causing the fuel pump to continually run with the key in the run position?

Rich

 

[dogfriend]

Oof.

I'm not sure why you wouldn't get any diagnostic codes unless the PCM is fubar. But, I do remember that the PCM looks for the crankshaft sensor signal to determine cranking and therefore will start pulsing the injectors. So, you could check to see if the crankshaft sensor signal is present when cranking.

If the PCM relay is on and the Fuel Pump relay is on, then the fuel pump should be on, so I think this is normal. It will run to pressurize the fuel rail (pressure controlled by FP Regulator on the fuel rail) and will return excess fuel to the tank via the return line.

 

[MrShorty]

I assume the second computer gave the same result?

There shouldn't be any sensor that would cause the kind of behavior you're describing. if the computer itself isn't the problem, then I might expect it to be soemthing wrong in the wiring.

Are you certain you have continuity between the PCM and the self-test connector?
I wonder if there is a short to ground somewhere in the wiring harness -- grounding the fuel pump relay and possibly a bunch of other stuff.
Do you get spark from the spark plugs (indicating that the ICM is getting power and ground)?
All fuses/circuit breakers are good?
Will the fuel pump shut off if you unplug the fuel pump relay?

This one sounds like it could turn into a real mess. Good luck, and let us know how it goes.

 

[wolferaw]

Second computer did have same resulting symptoms. I'll check continuity between the PCM and self-test connector - hadn't done that yet. Plugs have spark so we can rule out the ICM. Fuel pump shuts off when fuel pump or PCM power relays are removed.

 

[Northwood777]

Quite the quandary isn't it.
I am in the same situation as yourself with my 95 X 4.0.About the only thing that hasn't been checked yet is the Cam position sensor.Have you checked your sensor ?
I started out cleaning the grounds on the fire wall.It ran again for about two weeks.Then I had the fuel pump relay changed.It worked for three days.I changed the PCM ,then the crank position sensor .Wiring was checked out, nothing.Then it would only start off and on for shorter periods of time until now nothing at all.Hope you have better luck than I am having.My X has been down now since March.Best of luck.

 

[knightpitt]

I'm very late to the party with this one, but this is the same *exact* issue as what I'm having with my '94 4.0 OHV. Injectors are not pulsing, spark plugs are... EEC-IV self test is inoperative with 2 different PCM's.

In my case, I do have good continuity between the test connector and the PCM.

Help! Has anyone figured out what the cause of this is? wolferaw?

 

[azmike12183]

Yuk, shades of my Ford... new to this blog, but as desperate to find solution to the problem. Not lucky enough to have an Explorer, just a Taurus, 94 with 3.8L. Same problem ... car just died, can't get any codes to read out, turns over great and when I shoot some starting fluid into the intake, it fires up immediately, then dies of course. Getting spark, fuel, wiring on the surface tests OK (haven't gone through entire harness). The Integrated Relay was removed an the new one acted the same.

Also, when the EEC is in place ... fuel pump runs continuously, but stops when plug is pulled ... also,
I checked the status of the "inertia sensor" (in trunk) and it appeared OK and pushed to reset, but nothing changed.

Old timer mentioned it could be in the harness, especially since I live in the "oven" of Phoenix. Started pulling wraps off around battery area, thinking that may battery acid got into play but aside from wires being real snug together, all appears OK.

I have had a lot of heat and oil residue issues and will look for the crank sensor pickup and see if its mucked up. I had another mechanic about a year ago face the same problem and he said that he just cleaned some ground wires and it started running again. This year same problem even though the grounds are cleaned and "lighting" up when the connectors were tested.

I was told at one time that "if the ground wires were shorting because of bad contact, they in turn could short the EEC (ECU).

Real problem, this one ......... Help .......... I'm Fordin' and there's a Chevy on my ass.

 

[btexpress]

Resistance checks are ok generally, but you may have to do voltage drop tests to make sure you don't have a poor ground. We had a lot of trouble with corrosion, especially at the battery and ground connections. Check the pins at the PCM carefully, one or more could be spread and not making good contact.

Even a bad sensor will not cause lack of self test, or the other problems mentioned. If you have voltage to the injectors but no pulse, could be the crank sensor, but that will not stop the testing. I think it is most likely a wiring or connection issue, but that's JMHO.

 

[cjones101812]

here's the voltage drop test...

 

[lennymu]

Does your check engine light come on when you turn the key to run?

If not, leave the key on and open your power distribution box (where all the relays are), and give the relays a wiggle. Check to see if the CE light comes on and try starting.

I have a problem with dieing and no starting sometimes. It turns out the terminals in the PDB suck and need to be replaced with wsomething that will maintain a connection.

ps. I don't have any codes showing up

 

[danken]

HI Guys, I just read this thread. Guess what, I too have a 94 explorer that has spark but no injecter pulse and the ecm doesn't grnd the fuel pump relay either.

Also no check engine lamp, and no connection to scan tool.

Its as if the emc has no power/grnd.

check that though and all is good.

All points to a dead ECm but I have a bad feeling about calling one.

Is there a definite test for ECM?



---Have any of you fixed yours Yet ????

 

[dogfriend]

Is there a definite test for ECM?

Substitute with a known good unit. :


In most of the troubleshooting charts, they have you go through all of the steps to rule out other possibilities, then once you exhaust the other possibilities they tell you to replace the PCM.

Its pretty rare to have a bad PCM.

 

[cjones101812]

when you connected the scanner...you did connect the 6-Pin and 1-Pin connectors, right?? i've seen people forget the 1-Pin connector before.

at the ECM connector, connector disconnected. check grounds Key in RUN, Pin16 O/R, Pin20 BK/LG, Pin40 BK/W, Pin60 BK/W. check for 12v power Pin57 R, Pin01 Y, Pin37 R.

if those check good then do the 'voltage drop ground test' i posted in #9

 

[cjones101812]

HI Guys, I just read this thread. Guess what, I too have a 94 explorer that has spark but no injecter pulse and the ecm doesn't grnd the fuel pump relay either.

i assume when you checked for ground at the F/P relay you checked it within 2 seconds of turning the key to RUN. as you know, the ECM turns on the fuel pump for 2 seconds when the key is turned on, to prime the fuel system.

 

[danken]

Found it.

It was the 5volt reference shorted to ground in a faulty DPFE sensor.

Thanks for the great advice, you folks are quite sharp...

 

[Ruggz]

Hi

 

[cardell]

im having to same trouble no injector pulse i cant get a code reading on my eec iv, the fuel pump runs continually with the key turned to on position. i used a timing light to check for spark at the spark plugs wires its getting spark turns over good. i checked for fuel an its getting fuel to the injectors. an my cooling fan runs continually also. so i was wondering could the DPFE SENSOR be the problem i even checked for bad wires an still no change please help anyone i been at it for two weeks an im lost here

 

[jcheinen]

I had this problem on a '89 ranger 2.9L V6 & it was the computer, cost me $40 at u-pull-it

 

[speedracerx0786]

hey every one i have a 1994 ford explorer 4wd v6 4.0 i was having the same problem with the fuel pump running constantly and no injector pulse i couldnt get the truck to give a code i changed the crankshaft position sensor i changed the ecu i followed all my wires with a voltmeter found nothing i cleaned up all my grounds on the truck still had no results i took my truck to 4 different shops including ford they couldn't find the problem i decided to go to my local junkyard and buy a used injector harness for $50 and swap it on my truck it started right up and has been running good for a while now so if you have this problem and have tried everything else i would say this is worth a shot good luck!

 

[Clinton131]

Same issue with 02 Mountaineer 4.6

Same issue and I need another set of eyes to troubleshoot. Long story short No start linked to no injector pulse.

I apologize for the long post but I wanted to supply everyone with as much info as I could.

History:

Approx. two years ago car would occassionaly stall due to a faulty idle air control valve. The vehicle would always start right back up after the stall. When I pulled the codes I found the 1504 code which is linked to the IAC. I cleaned the valve with carb cleaner and reinstalled.

Car ran great up to about two weeks ago. Wife complained of a similar situation along with a longer start (crank) times (on occassion) but was able to get it started after it stalled out. I again cleaned the IAC with carb cleaner and reassembled.

Last week I got a call from her advising she was stranded on the side of road and could not get it started at all. I left work to "rescue" her and could not get it started either. Car would crank but would not even think about firing.

A few hours later I returned to the vehicle and attempted to start it again. It started right up. I let it idle for a while and it seemed to run fine. Since I did not have another driver, I left it on the side of the road until after work. When I returned to get the car, it again started right up again. I made it about 100 yards down the road and the vehicle stalled out. It did not cough and gag at all, it stalled out as if someone had shut the ignition off. I was not able to get it restarted and ended up towing it home.

DTC CODES:

I pulled the codes using a scanner and found the following:

1401 which is EGR. This code has been there for a while and my check engine light has been on because of it for over a year.

1504 which is the IAC. I replaced the IAC. Vehicle still would not start (not suprised, I did not think that this would cause a no start)

B1601 My scan tool did not recognize this code so I googled it. Found that it is a PATS code: Unprogrammed Encoded Ignition Key. (more on this later)

SPARK:

Yes. Will run on starter fluid.

FUEL:

Checked the following

Fuse: Good

Fuel pump relay: Good (swapped out with like, known working relay)

Inertia switch: Good. Power in and out of switch. (It should be noted that when I was testing this switch I cranked the vehicle and it did start. Vehicle ran rough for about 5 seconds and then cut out)

Fuel pump: Good. Could hear pump priming when ignition turned on. (it should be noted that at one point the vehicle started up again. It ran rough for a few seconds and then ran like a v8 should. It may have run rough due to the computer aclimating itself to the new IAC that I installed earlier. Ran until I shut the ignition off. Could not restart and have not been able to restart it again since. Just cranks.)

Fuel Pressure at rail: 60 psi

DEALERSHIP INSPECTION:

Suspecting a possible PATS issue based on the code it threw, I brought the vehicle to my local dealership. They had to cut me a new key since I only had one and programmed the key. Still a no start. Most expensive key I ever bought at $209.43.

Their diagnosis: All eight fuel injectors were plugged due to possible vandalisim (contaminated fuel). I asked how this was possible if I was able to get it started after the issue began and it ran smooth. They had no answer for this.

Their exact diagnosis is as follows: "MULTI-POINT INSPECTION. CHECK SPARK-OK. HAS 60 PSI FUEL PRESSURE HAS PULSE TO INJECTORS. HAS RPM SIGNAL CHECKFUEL INJECTOR FLOW-VERY WEAK. TRIED GOOD FUEL-NO CHANGE. SUSPECT CONTAMINATED FUEL CAUSED INJECTORS TO GET PLUGGED. WILL NEED INJECTORS & FUEL TANK DROPPED & CLEANED AND NEW FUEL. MAY NEED FUEL PUMP IN FUTURE BUT WORKING OK NOW."

They wanted $1100.00 dollars to replace injectors and another $1100.00 to drop and clean the fuel tank. Since I found it very hard to believe that all eight injectors plugged at the exact same time, then unplugged, and then plugged again at the exact same time, I took the vehicle to another mechanic for a second opinion.

SECOND OPINION

The second mechanic advised that all eight injectors being plugged at the same time was not likely. He found with a Noid light that the injectors were NOT pulsing, contrary to what the dealership had told me. He checked the Noid light on a working vehicle to assure that the Noid light was functioning properly.

He checked all sensors, including the Crankshaft position sensor and camshaft position sensor. All appeared to be functioning. He even swapped the camshaft position sensor out with another known working vehicle. The other vehicle fired right up with the CPS sensor from my vehicle. All grounds were checked and appeared to be good. His diagnosis is that their is an issue with the PCM, that is no not signaling the injectors to fire, though he is not positive. I realize that these PCM's rarely go bad, and everything else seems to be functioning properly. The check engine light comes on when the ignition is turned on and I am able to pull codes from the PCM.

I have ordered a used PCM through my local Ford Dealership for $150.00. I am skeptical that this is going to work but I am getting desperate. I hate to throw parts at this car but I am running out of ideas.

Anyone with an idea please ad your $.02.