UPDATE 10/24/10-Need Help With 98 Mercury Mountaineer 5.0 Has Starting Issues

[mobbdeep]

First off i wanted to say HI because I'm pretty new to this forum!


Vehicle: 1998 Mercury Mountaineer 5.0 V8 144,000 Miles!


Things i did was swap out the PCM Power & Fuel Pump Relays with the Blower & Horn Relays and the problem is still there.



It all started after i changed out the alternator & battery. My battery level gauge was starting to get low one day and then the next day my head lights & interior lights started to dim out so i knew it was either a bad battery or an alternator. I got a new battery and a new alternator installed those parts and the truck came back to life the gauge was where it was suppose to be and my lights were bright and everything was running properly. Now the strange part. A few hours later on that same day and this starting problem started to happen. Sometimes it starts right up no problem and then sometimes it won't. It turns over the battery has full power and the starter is turning over it sounds like it's not getting gas. Sometimes when it tries to start it will sound like an old carburetor car when it stumbles and backfires and then dies out. However when it starts it runs beautifully no problems doesn't stall out the idling is accurate it runs fine it just this weird starting issue. It does it when it wants to it does not do it all the time. When it doesn't want to start i notice the CEL is on when i turn the key and i hear some noise like a whizzing/click noise from under the dash. Lately I've been listening every time i start it and when it starts i don't even hear the fuel pump turn on. Is it loud enough to hear and where would this sound come from?. So I'm thinking the fuel pump is not getting power at start up sometimes. Whenever it won't start if i let it sit for a few minutes like 5 minutes and try it again it will start. It's weird can anyone tell me what it could be?? Like i said if it starts it runs fines no stalling and no rough idling. Wouldn't this rule out the fuel pump? I'm confused on this and when i did the battery and alternator replacement i did it right i disconnected the battery installed everything making sure i did not hit the battery terminals with anything to cause a short. Everything went in smooth. I think this starting issue is just a coincidence that happened to start on the day that i replaced the the new parts. Never did this prior to replacing these parts. Any help would be greatly appreciated!


Also this problem has been going on for a few weeks now!

 

[drothgeb]

Sometimes mine stumbles a little also...I think I'm going to clean the MAF and IAC again. Have they been cleaned on yours? It may be a start. Hopefully someone with more knowledge will chime in.

 

[mobbdeep]

Sometimes mine stumbles a little also...I think I'm going to clean the MAF and IAC again. Have they been cleaned on yours? It may be a start. Hopefully someone with more knowledge will chime in.

I didn't spray anything inside but i wiped it down inside a little before the butterfly with a clean rag since i had to remove the air intake when i did the alternator change. I checked the truck today it started up i drove it to Dunkin Donuts like 4 miles this morning came back shut it down tried to start it 5 minutes later and it wouldn't start. I smoked a cigarette came back another 5 minutes later and it started up WTF is going on i have a good feeling I'll end up getting stranded one day and my luck winter is coming and it will be probably be on a wintry day I'll be pissed.....

 

[swetrid]

Probably fuel pump crapping out.

 

[drothgeb]

How do you check if it is the fuel pump?

 

[TestPoint]

Might want to check out the connections on the alternator and battery since that was the significant change prior to the problems. Low or interment power to the systems could produce such issues.

 

[mobbdeep]

I should add something i do hear the fuel pump turning in the back when the key is in the on position. Could it be a sensor or something? Any wires connected to the alternator are in tact and the battery terminals are tight.


Also when you change out the PCM relay does it take the computer a little bit to relearn everything or no? Cause i did the relay swaps first thing this morning and i took if for a ride until the engine got up to normal temperature went back home and shut it off for a few minutes and then tried to re start it and it did the starting issue turning over but not starting. Waited a few minutes tried it a few times and it started up like nothing happened. The thing is it started up every time since then as of today.

 

[mobbdeep]

I got these codes today

p0308
p0302
p0354

I'm assuming this is the culprit to my starting issues. Today it started to shake when i started and then the CEL come on i ran my scanner and got the above codes. I drove today earlier no problem but when i went to use it later on this is when i got the CEL.

What should i do now to fix the problem?


Also when i did my Alternator and Battery change could this have cause this problem with the CEL. I started to have the starting issues after i replaced the above parts. Thanks

 

[mobbdeep]

I checked today and both #2 and #8 are on the same coil on the left side. So I'm going to replace that coil pack and I'm pretty sure this was the culprit to my starting issues that started to happen here and there.Thanks for the answers guys!

 

[2000StreetRod]

plugs & wires

I suggest that you check the #2 and #8 spark plugs and wires before replacing the coil pack. With your waste spark system both plugs fire at the same time - one on the compression stroke while the other on the exhaust stroke. One bad plug or wire can affect both cylinders.

 

[Kiliona]

Your truck should be able to start and run on the 6 cylinders that were working, I don't see why that would cause the no start issue.

My explorer had similar issues and it turned out to be that the fuel pump was fine, but the sock (filter on the pump) was totally full of rust. Don't rule the fuel pump out completely. Easy to check if it's fuel related, push a pin in the schrader valve on the fuel rail see if it squirts fuel at you (have a fire extinguisher nearby JUST IN CASE).

Coincidences are few and far between, I'd check all of your cables on the battery and alternator, make sure the connections arent loose or that this issue isn't still related to yoru battery or alternator somehow.

Again, don't rule out fuel until you make sure there isn't fuel at the rail. Likewise don't rule out spark until you check for spark at the plugs. and check these few things first (after an inspection of your work after the battery and alternator replacement).