Okay, I know this doesn't belong here, so hopefully before the Moderators yell at me and move this somebody with mechanical knowlege can help.

1998 Ford Explorer XLT
4.0L SOHC 198,000 miles
2WD Automatic

I have got the mysterious "sometimes it will crank over but not start for 30 minutes" disease that seems to be popular. My biggest problem is there is about a million threads on this website and others with people asking for help, somebody says "change the IAC" or "EEC Relay", but nobody follows up to say what actually works to fix the problem. Maybe there are just that many different solutions to this one problem, but I doubt it. And this is by far the most helpful forum I've been on.

Now for eliminating some areas:
I got this truck in 2003 from the original owner who is big into proper maintenance (dear ol' dad) and saw the problem once, though I didn't know until a year or so later. My girlfriend drove this truck while I was away in Iraq, and she couldn't get it to start one day to leave work. She had it towed to Ford who wanted $400.00 for a fuel pump. After a digital salute (I love angry redheads) she then had it towed to the oil change shop who scoped it, plugged something loose back in, and sent her on her way.

A few weeks later, it wouldn't start again so she got her dad to jump start it and it worked. Ahah! I came home a few weeks later and witnessed it myself. It didn't seem to cranking slow at all, but I swapped the battery out of my jeep (brand new bat.) and it started right up. A week or so later it did it again. I jumped started it, it worked. I asked a Ford mechanic at work and he too said it was the IAC valve. Cleaned it. Repeat prob. Bought a new one. Repeat prob. Did a tuneup. Plugs, wires, fuel filter, cleaned all the intake stuff (carefully). Repeat prob. Engine began to miss. Had the engine diagnosed; the check engine light came on at this point. Missfire. Bought a multimeter, tested everything I could think of, everything tested okay. Had the engine scoped again, mechanic said the coil pack was bad even though the resistance ohms showed good. Replaced the coil pack and fixed the miss. Repeat starting problem. Talked to another Ford mechanic who said change the EEC Power relay. Did that. Repeat problem again.

Okay. Now I've been searching the internet for a couple of days and nothing is making me feel any better. The only new stuff I have found says Fuel Inertia Switch, Coolant Temp Sensor, or Cam Position Sensor (I checked that one). Oh before anybody asks, I can hear the fuel pump priming prior to starting. I have tried letting it prime 2 or 3 times in a row; I have tried starting it in neutral (and drive); I have shut it off immediately after it finally starts to see if it will not start again, but then it starts. Nobody can check it because I cannot intentionally duplicate the problem. Maybe I should buy my own OBD II tester and just sit and wait. I don't even know if it will throw a code while not starting.

Any suggestions other than replacing the engine with the 351 out of my truck?

 

Not that I know anything about your motor or that problem, but...

I have a '94 buick that did something like that once. Turned out the 'fuel return valve' (dunno the official name of that thingy) on my fuel rail was bad. That caused zero fuel pressure at the injectors and it wouldn't start. Every now and then, if I turned the key on and off a few times, the fuel pump would "prime" the line with enough pressure that it would start for a second then die. I found out there was no pressure by putting a fuel pressure guage on the nipple at the fuel rail.

Just thought I'd throw that bone out there.

 

Yes, I agree, needs to be moved to the https://www.ford-trucks.com/forums/f...splay.php?f=59 2.6, 2.8, 2.9, 4.0 and SOHC 4.0 V6 forum.

How are the battery cables, and the grounding wires coming out of the cables near the battery? do the cables show signs of corrision?

Make sure all the grounds cable wires bolts for cables are snug and tight.

Isolate the problem, Does the engine have spark or fuel when the no start condition exist?

Does the engine run rich?

 

The cables all seem to be in good shape. Back when I replaced the battery I cleaned everything and gave it all good slathering of dielectric to keep it from coroding. About the fuel or spark, I would just guess the spark is what is missing. Like I said, I can here the pump prime, and sometimes I can smell fuel when the condition exists. I have not done any checking while the condition exists because I don't have a fuel pressure guage and only know enough about electricity to know it hurts. A lot. And there is nobody around to turn the switch while I look.

 

When the condition exist, pull the any spark plug wire off the spark plug. Place the spark plug wire about 1/4 inch away from the nearest grounding surface. Verify if the spark plug is getting spark by cranking the engine and looking or listening for the spark ?

The fuel rail on the intake manifold should have a fuel valve and cap. The fuel rail is what deliver fuel to the fuel injectors on intake manifold. When the engine does not start, depress the fuel valve on the fuel rail and check for fuel.
Be carefull if the fuel squirts out of valve. If you can borrow a fuel pressure tester, you can verify the fuel pressure when the engine does not start and when the engine is running. Post the fuel pressure results.

 

Quoted by Ncognito:
Back when I replaced the battery I cleaned everything and gave it all good slathering of dielectric to keep it from coroding.

~~~~~~~~~~~~~~~

Please explain "In Detail" exactly what you did.

This is too vague a comment and we need specifics.


On Ford's, a common problem through the years is the wire connectors under the hood and especially ignition system connections.

May I suggest a "complete" inspection of all the connectors and the wire ends for corrosion... being very careful not to twist or break any... as they are fragile.

THis will hopefully eliminate any intermittent problems that may happen from any
"on again - off again" connection.

also, visit your local "lend-a-part" store for a fuel pressure tester to get a pressure reading on the fuel rail.

 

By "everythig" I only meant the battery terminals and cable ends. They did not have a buildup of visible corrosion but I cleaned them anyway. I don't know if the battery has anything to do with it at all. All of the guages, lights and electric components inside the vehicle seem to be working fine, and the motor turns over plenty strong.
I'll try to get hold of a pressure tester and some help for the plug wire test this weekend (in b/t moving the mother-in law). In the meantime, if anybody else has an idea, I'm open minded to it. Thanks, fellas.

 

There is a ground cable terminal plug type which runs to the ECM from the battery cable near the battery. Will need to squeze one end to unplug.Verify the condition of this wire and terminals.

 

1975Ford is giving you some good diagnostic tips. An internal combustion engine needs 5 things to run properly; Fuel, Air, Spark, Compression, and Timing. As problems with Air, Compression, and Timing don't tend to self correct, the most likely candidate for intermittent problems are Fuel and Spark. One possible intermittent air problem could be the IAC, but if that is the issue the engine should start if you depress the gas pedal slightly. If you check for spark and have spark, it's probably fuel. Be careful when checking spark, the zap hurts like the devil. Another thing you should do when it is not able to run is to pull Key On Engine Off codes. You may find an idication of the problem from the codes. I'm suprised no one said anything regarding and ignition module. On my '92 I had an intermittent no start problem that took over 6 months to find. It turned out being a problem wire inside the connector to the ignition module. I could wiggle the wire and it would run. Which brings me to the wiggle test. After checking for Spark, Fuel, and Codes, try wiggling wires one at a time and see if that changes anything. If wiggling a wire seems to fix it, you may want to wait till next time and try the same wire. Often you'll move things you don't realize and one of the inadvertantly moved connections will be the problem one.

 

Well, so far so good. I crawled around and disconnected all the plugs and wires I could get to (one at a time). Cleaned the ones with corrosion on them, then I cleaned the ones that were clean. And now I'll wait some more and see if the problem comes back so I can try something else. Thanks for the help, I'll let you know what I find.

 

No need to get a fuel pressure tester, it was already done for you. Go back to your first post, how do you think the tech at the dealership diagnosed a bad fuel pump-he must of pressure tested it-only way i can think of to diagnose a fuel pump problem if the pump is getting 12 volts. It seems to be voltage related, because you said it started fine when jumped-it was getting 14 volts from running vehicle, and it started fine with your new/fresh battery. Check fuel pump relay and fuel pump wiring really good. Good luck!

 

I know this post is kind of cold already, but I like to follow up. FINALLY the old girl wouldn't start when I had somebody else handy. I pulled off a plug wire to check for spark and nothing. Ahah! Again.

I reached around behind the coil pack and wiggled the plug to the computer, and she fired right up. I had already inspected this plug when I changed out the coil pack before, but I failed to notice the retaining clip was missing until I looked for a picture of it in the repair manual. It didn't seem that loose, but I guess it wouldn't take much to ruin the connection.

I did the best I could to secure the plug and the problem was fine for a couple of days, then it took a couple of tries to get it started one day, but nothing as bad as it was before. I hope this will be the end of it, and thanks for all the help.

 

Thanks for posting results, hopefully that will take care of the problem.

 

Well, the I definately secured the coil pack plug with some "sensor safe" superglue and eventaully the problem got worse again. I did have help a few more times, and everytime it was a spark problem. I studied on the wiring diagrams for a couple of weeks and I don't remember how but I narrowed it down to the engine computer tells the coil to fire and the crank position sensor tells it when to fire.

AHAH

I took a gamble and replaced the CPS (it was the cheaper of the two) just before Christmas last year, and run like a champ ever since.

 

Thanks for posting the result, it might help if anyone experiences the same type of problem.