Won't always start

[billy]

My sons 1994 Explorer does not always start. All will be well for a week or two, then one day it will not start. The engine turns over but the vehicle will not start. If he waits for 30 minutes to an hour it will suddenly start and he will not have that problem again for a few days or a few weeks. It happens 1-3 times per month. The fuel sensor has been replaced. I think it is an electricial problem but am unsure. Sometimes it will not start after driving it for awhile, such as in going to the store, and sometimes it will not start after sitting for awhile. It can happen any time of the day. We live in California where the weather is good. Once it does start the problem goes away and does not happen in the same day. ANY IDEAS???? Thanks so much

 

[marragtop]

When you turn the key to the ON position, (but don't crank) you should hear the fuel pump run for about 4 seconds. If you don't hear that, it could be either the fuel pump, fuel pump relay, or interia switch. I'd start with the fuel pump relay. Not sure what you are referring to as the 'fuel sensor'... do you mean the gas tank sending unit?

 

[engera]

Listening for the fuel pump would be the first thing to check. It will only run for a few seconds but if that doesn't happen it won't start. The fuel pump relay can cause the fuel pump to not kick on. I had the fuel pump relay intermittantly go out on my '94 and it had the same symtoms. I swapped it with one of the other relays that are the same and the problem went away.

 

[witchdoctor]

It could be the Crankshaft Position Sensor (if your 94 has one). My 98 started out like you are describing, and after awhile got progressively worse.

I would check it if the fuel system issues don't turn up anything; it's a $20 part and takes 10 minutes to change.

 

[XV17]

I'll bet $100 it is the IAC motor. It is $68 and has died on 2 of my previous EX's. Whack it with a screw driver handle and it will usually unstick and the truck will start right up.

 

[Eneurb]

I'll bet $100 it is the IAC motor. It is $68 and has died on 2 of my previous EX's. Whack it with a screw driver handle and it will usually unstick and the truck will start right up.

I'll take that bet.

 

[barnieman]

Had the same problem: sometimes, without any obvious reason, the engine cranks but no spark.
I unplugged / plugged my crankshaft-position-sensor connector (located in front-bottom of engine). No problems since then. I mean, no starting-problems since then...

 

[Josh]

With the first Gen trucks, there is a little gizmo on the front clip just in front of the battery called the ignision control module. Not to be confused with the coil pack or ECM. My truck would sometimes start OK and other times it would just turn over and nothing. I wrecked a starter trying to figure out the problem. I went to U Wrench It and got another one for about 10 bucks. If your truck just turns over and does'nt start, I would bet thats the problem. I would try the IAC motor first just to see since its the esiest. A brand new ICM costs about 85 bucks. The used one has been in my truck for over a year and no problems. Good luck

 

[Jules2001]

Where could I find the crankshaft-position-sensor connector? Where would it be located next to? My 01 XLT is doing the same. Sometimes it turns on then off right away. This morning it just cranks but doesn't start.

 

[Josh]

Well if your truck is equiped with said sensor, it would be located at the front of the motor next to the crankshaft pully almost up against it. try unplugging it and plug it back in. Make sure it seats all the way down and is secured by the retaining clips on the connector.

 

[Glacier991]

Obviosuly there are many things that can create a no-start condition. I guess it begs the question to say that the culprit will fall into one of two camps... fuel delivery, or spark.

You COULD have an intermittent problem in the fuel pump circuit (there is a relay that CAN go bad - doubtful it is the inertial switch but it IS possible I suppose). You could also have a problem in the ignition circuit. Of the ignition components, the one that frequently produces your symptoms is as Josh said the ICM (Ignition control module).

Before I started throwing parts at it though, I'd buy a fuel pressure gauge and when you get the no start condition see if you are getting good pressure (35-40 lbs) at the fuel pressure rail. If so, you saved yourself throwing good parts at a non-existent fuel problem. The ignition problem may not be so easy, but if you were inclined to start by replacing something in the ignition system, I'd advise to replace the ICM first.

Yes there are tests that can help rule it out, but you do not have the equipment to run those tests, and having a shop check it out may also not truly show the problem and still cost you more than replacement (I hate advising anyone to throw parts at a problem though). Anyway my 2 cents.

 

[Jules2001]

I replaced the crankshaft sensor, but still the sucker didn't turn on. I can hear the fuel pump hum and made sure the button didn't need to be reseted. And yes, there is fuel in the tank.

I was only able to check the current coming out of three of the spark plug wires and got shocked in the process. I couldn't reach the other three wires since it's so cramped. I used to have an 82 Bronco in high school and remember I could jump into it to work on that engine. Now I can barely fit my hands!

I originally had thought it might have something to do with the fuel pump since it would turn on then off within two seconds. I guess I'll have to check the pressure once I check the rest of the three wires when I have more time this weekend. It just pains me to see it parked like that.

Thanks for your feedback.

 

[taknitezX2]

i have started having this problem to. with my exhaust, i hear it turn over then it dies and just keeps cranking. i let it sit for a while and sometimes it works and sometimes it dont. not sure what it is. the other day i drove 30 miles home, parked for 10 min. then it wouldnt start. let me know if you find a problem. i think i may talk to the dealer since its under warrenty still but thats always such a hassle.

 

[Josh]

I originally had thought it might have something to do with the fuel pump since it would turn on then off within two seconds.

The fuel pump comes on long enough to presurize the fuel system and shuts off. Once the motor is running, the pump will run continuously to maintain the presure. It should be around 38 to 40 PSI, at least that what it is on the older trucks. If there is an ICM(Someone said there wasn't in newer trucks) I would definately look at that. If there is, I wonder what they would be interchangable with. Get one from a salvage yard, it will be a whole lot cheaper if you can find them. Don't forget parts interchange. Try to find out what trucks use those. Might be all OBD-II Explorers. If so, it shouldnt be to hard to find. I think mine was 20 or 30 bucks. This is the same problem I had. I actualy wore out a starter because of this problem. Look in your manuals. I traced the entire ignician system until I found this little unit wich on the first gens hides on the front clip between the headlight and the battery on the passenger side.

 

[Jules2001]

i have started having this problem to. with my exhaust, i hear it turn over then it dies and just keeps cranking.

The mechanic fixed it for me on Saturday. His wife has an 02 Explorer that was doing the same. He told me to first change the fuel filter, it could be keeping the fuel pressure from going through properly. If it still didn't start then he would lend me the pressure gauge to measure it. Problem was, it was too difficult for me to remove the filter. After a few hours, I gave up and gave him a call. He admitted to me that he also struggled with his wife's.

He changed the fuel filter and also cleaned out the idle control valve and now it starts. You might want to try these first since they are cheaper, but if the warranty covers it you might want to have someone else try it out. If you want to do it yourself, there's is this helpful link which I found how to take off the filter. If I hadn't looked at this link, I would have been looking at the thing puzzled for hours instead of struggling with it. Others found it easy to replace theirs, hopefully you have a better time than I did.

http://www.explorerforum.com/forums/showthread.php?t=102197

 

[steve2690]

I've got a starting problem too...

My '94 XLT has trouble starting after the engine has been running for a while. It starts fine in the cold, runs fine, but when you shut it off for like 5-10 minutes, it won't start up again. I can turn the key, and hear the pump go, and turn it further and will start to crank but it won't start up. I either stomp the gas pedal or get out and spray some starting fluid into the air intake. One of my friends said it might be vapor lock from the warm engine turning the gas in the line to vapor, but I really have no idea. I don't know what the problem with it is. Any help is appreciated. Thanks

 

[taknitezX2]

hopefully goin to the shop today. lately, the pump only comes on a handful of times when i go to start it. i might hear it charge before i crank it, but i think its not enough pressure cause it kinda bogs out but then it will make no sounds at all, i only hear a light click. turn the key and it just tries to crank and crank. im currently standed here at school. hopefully it will start after my next class.

 

[Glacier991]

You could have a plugged fuel filter, a bad fuel pump relay or a bad fuel pump.... lesser probability a faulty fuel pressure regulator. I'm betting on the relay.

 

[taknitezX2]

had to have it towed from school. My fuel pump is "dead". 50 buck deductible and a freshly running car, cant beat it. hopefully it will be done in a day or so.

 

[dogsNtrucks]

I'm with Glacier on this one. I had a '94 I got off our lot at work as a trade in. It had a nasty filter and the relay was toast. I cooked another relay before it occured to me to replace that fuel filter. Caused the same probs you are describing.