1991 Ex cranks but doesnt start...HELP 911

[L.A.X]

My explorer cranks and cranks but doesnt start. If for some miracle it does start, it runs good but after idling for awhile completely shuts down like if someone just flipped a switch. The problem started after using seafoam. It might just be a coincidence.

Heres the 411,
When I get in my truck and turn the key to start, if the CHECK ENGINE light illuminates, then truck starts. If CHECK ENGINE light doesnt illuminate, then truck does not start. When truck cranks and cranks, there is no spark. Starting system is all new. Ignition system has new plugs, wires, Crankshaft position sensor and coil pack.

The fuel system consists of 91 octane, new working fuel pump, filter, fuel pressure at the rails.

Not getting power to the injectors. When truck is cranking and not starting, no power to the injectors.

When the truck does run, I have spark, power to the injectors etc. What component could be malfunctioning?

 

[L.A.X]

I have a cool $50 bucks to the person that gives the right diagnosis to my problem. If no one comes thru, I may or may not up it to $100. To collect, Ill deliver locally or mail out in the U.S

 

[arco777]

The CHECK ENGINE light not lighting is an indication your PCM is not getting power. With no PCM power, you'll get no spark and no fuel.

Check the main EEC relay and fuses. Try swapping the relay with a known good one such as an ABS relay. You probably have a faulty relay not switching. Also check for wiring shorts; on some models the main wiring loom can fall down on the exhaust manifold and melt through.

 

[L.A.X]

Where's the location of the EEC Relay?

 

[arco777]

Power distribution box, under the hood, passenger side near the fender.

 

[L.A.X]

Heading to Pick A Part to get a used ICM and relays to test before I purchase new

 

[L.A.X]

All new relays and still no start.

 

[L.A.X]

A cool $100 dollar bill to whoever diagnoses my problem

 

[Turdle]

The check engine light symptom is the root of the problem. PCM power is dropping out.

Try leaving the key turned on, engine off. Now start jiggling the relays to see if you hear clicking while you move the relays. It could very well be something as simple as a bad connection in the tabs where the relays plug in. Even the ECM relay fuse could have this issue, so move it --push on it, jiggle the wiring behind it.

If this doesn't work, play with the PCM (ECM) cable where it plugs into the ECM.

hHile in there, take the ECM cover off and look for broken solder. Your symptoms sound like a bad connection-broken wire somewhere int he truck. Moving things around may help you find it easily.

 

[FR-425]

I see you started a new thread, Good plan.

I also noticed the bounty went up.

So here's my final answer: The ignition switch is bad.

No more guesses I'm sticking with IGNITION SWITCH.

 

[colintrax]

If the radio comes on when you turn the ignition then ignition can be ruled out. Wouldn't hurt to try replacing the whole computer. But I have a feeling it's a loose wire like others have said. Make sure the computer is getting power. Look for wiring diagrams to find the power wire

 

[Turdle]

I see you started a new thread, Good plan.

I also noticed the bounty went up.

So here's my final answer: The ignition switch is bad.

No more guesses I'm sticking with IGNITION SWITCH.

If I agree with you do I get 50.00?


I'm kidding. I just want this thing fixed. That is a good suggestion.

 

[FR-425]

I'm not taking the kids money either after all this brain squeezing!

 

[arco777]

If I had the right answer I wouldn't take the money, this site is all about helping people and not about profit... Profit is for repair shops, lol

 

[larrydd999]

I have an '86 F150 that had an intermittent engine computer a few years ago that did the same thing. It also died sometimes when driving. Replacing it was the only solution. I don't recall whether or not the check engine light came on.

 

[L.A.X]

Changed the ignition switch and still no luck. Radio does turn on when ignition is turned on. I've worked on hundreds of cars, never been this stumped. The price is now $125, I need this truck running yesterday. By the way, in the process, I came across two good used ICMs. ICMs run 100 plus at autoparts stores. Since you guys have been trying to help, I'll give them out free to whoever decides to pick them up from my house. Message me

 

[L.A.X]

Whoever comes up with the right diagnosis can pick up the cash, I'll send thru paypal, deposit in their bank or mail them a visa gift card. It would be my way of saying thanks. You could donate it if you like

 

[L.A.X]

How much will a computer set me back, where is it located and what is its official name....ecm? Pcm?

 

[Stic-o]

So it doesn't start at all? or some times it does?

I had a '88 B2 that would run, then once it was warm it would die, and would not start again till it cooled down. It was totally random. Some times it did it, sometimes it didn't. Wasn't getting spark. Drove me nuts.

Found out it was a module on the back of the motor. Once I replaced it, no more issues.

 

[arco777]

How much will a computer set me back, where is it located and what is its official name....ecm? Pcm?

Ford calls it a Powertain Control Module, PCM. ECM is just a common street name. EEC (electronic engine control) is Ford's name for the fuel injection system which the PCM is a major central part of. The EEC relay switches power to the PCM and without it the PCM cannot wake up to command spark or fuel delivery. Junkyard is a good bet for best price, just try to swap one with the same catch code (4 digit i.e. UMP1) if you go that route. PCMs don't typically fail that way though. Generally they are consistent in a failure mode, not intermittent. Check if the PCM is getting power when you have a no-start. Some research or wiring diagrams should net you a pinout of the PCM connector you can use to probe the power supply wires. If the PCM gets no power during a no-start then look at the relay and fuse and see if they're switching. The relay should be clicking on when you turn the key ON, you can pull the relay and check if the relay is getting power from the ignition switch at the terminals that fire it. You can check for voltage across the EEC fuse as well. You can if you're careful manually supply power to the PCM for testing purposes but you should know basic electronics theory first and be careful to avoid shorts and back feeding. It is the same basic procedure that you would use for fuel pump testing, check that the target device's relay is activating and supplying power, and check that the device responds to power as it should.

Right now I would focus all my efforts on checking the PCM is supplied with power at key on. The intermittent nature could indicate a loose connection, bad ground, or bad solder joint somewhere. Turn the key on and wiggle various things to try to get the check engine light to come on or EEC relay to click.