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2002 mercury mountaineer starting problems

09-17-2009, 09:52 PM
I have a 2002 mercury mountaineer, v6, awd, automatic. We have been having trouble starting it. the engine just turns over but will not start or even try. we had it towed to a mercury dealer but it started for them and they couldnt find anything wrong. it has happened a few times since then and had a new fuel filter installed. this has been over the last three months. today it wouldnt start again, just turns over. had it towed to a shop and the tow man tried to start it also but nothing. the shop owner looked at it the next day and it started. he hooked it up to a computer and no codes were listed. what is the problem? when trying to start we smell gas so its getting fuel. can you help me locate the problem? want to take it out of state next month but afraid to. please help. thanks

09-18-2009, 06:25 AM
Welcome to the forum!

You can't necessarily decide that since you can smell gas it has enough of it. You really need to monitor the fuel rail fuel pressure when the Mountaineer won't start to decide if it has enough fuel pressure. For the time being we'll assume though that the fuel pressure is sufficient and the problem is not with the fuel delivery system, including fuel injectors and injector pulse.

The next thing to check is for spark. There have been quite a few folks with Mountaineers and their Explorer clones that have had random no start issues which appear to have been caused by the Crankshaft Position Sensor. They seem to start off as random no starts, or even random stalling. After putting up with that for several months, the sensors apparently fail completely and cause a no start condition. If you don't have spark, you should consider the CKP.

When the Mountaineer starts and runs, does it run fine with a smooth idle?


09-19-2009, 06:31 AM

Thanks for replying. The car sometimes seems to run just a little rough (I think) at the idle for a couple of minutes, but you cannot see it on the tachometer. I think im being too touchy about that. You know, once your car breaks down you get a little paranoid. Other then that it runs fine. I got the vehicle back from the shop yesterday and they couldnt find anything wrong. It started right up for them. No codes on the computer. He thinks it could be the anti theft? as of today over the past three months it has let us set four times. never nothing wrong. although we had the fuel filter replaced. The shop says to just drive it around until it does it again. going out of state in 1-1/2 months and dont want to be stranded there. can you help??????

09-19-2009, 09:13 AM
Unfortunately without being able to see the vehicle to make some measurements when it won't start, there's not a lot that can be done unless you want to shotgun out a bunch of possible suspects. For example, you could replace the fuel pump, crankshaft position sensor, camshaft position sensor, and Mass Air Flow sensor and hope that at least one of those items were the culprit and fixes it. But, if you aren't doing the labor yourself, this wouldn't be cheap.

If you were looking for one item I would consider most probable of those, it would be the Crankshaft Position Sensor (CKP) based on the information provided in your first post.

As for the shop's suggestion on the anti-theft system, if the key were the issue or the antenna ring at the ignition switch, when you're trying to start the vehicle you should see a rapidly flashing "Theft" or "Security" indicator on the dash. You could also try a different, previously programmed key to see if the vehicle then starts. If that's the case, you'll want to get another key programmed ASAP.


09-19-2009, 10:09 AM
Thanks Shorod, One more question. What would make it come back to starting after time? It seems like once it sets for an hour or so, it will start? Im thinking about taking it to another dealer, but without the problem actually happening at that time, is it useless to take? What direction would you sugguest for us to take? DOnt want this thing to leave us setting 600 miles away in two months. Anymore sugguestions would be a big help. Thanks...

09-20-2009, 09:09 PM
Both the fuel pump and CKP are electronic devices with windings of fine enamel wire. As the wire and connections cool (from sitting for some amount of time) connections can contract and again make contact. The fuel pump is an electric motor which uses brushes which also can be heat sensitive as they wear down.

As I mentioned in post #2 above, based on your comment that you are sure it is getting fuel, I went with the next most likely culprit in my mind. That being said, I would expect that a CKP would cause the engine to stall sometime while you're driving it rather than only act up when trying to start the engine. You really need to check the fuel pressure when it won't start to see what it reads. Spec fuel pressure is probably somewhere between 35-65 psi.


10-01-2009, 05:42 PM
Update: Had my mountaineer at the dealer for four days. He attached a computer to it and drove it around. No codes, started great. Couldnt find anything wrong. Brought it home and it started rough for a few times. Was told that if you have too many keys on your key chain that this can cause a problem for starting. Anybody heard of this? We took all our keys off and have been trying this for the last day. Any help would be appreciated.

10-01-2009, 06:37 PM
Yeah, if you have a lot of transponder keys on your key chain it can interfere with the anti-theft system. I would expect you to get a flashing Theft light if this were the case though. It won't hurt to try the single key for a few weeks though to see what happens.


12-04-2012, 07:36 PM
I have a similar issue with my 99. I was wondering what the fix was?? Thank you for your assistance.

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