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1999 starts but wont stay running

M

markmopar

New member
I just got a 1999 GP with the 3.8l with 92k on the clock from a friend. His mechanic said he can't diagnose the problem because he doesn't have the equipment needed. That, and he just went into the hospital with lymphoma and probably will not leave there on his feet.
So my buddy got his wife a newer car and sold me this one for scrap price. The thing is immaculate inside and the body is very good. A/C doesn't blow cold but that's no big deal.

Anyway, the issue is the car will fire but not run. Sometimes it will start and run for 5-10 minutes then rev up and quit. Check engine light is not on.
I was able to drive it onto the trailer to get it home but it wouldn't run after that.
The mechanic told the PO that it probably needs one or both computer modules(ecm and bcm) but he wasn't sure. He told the PO that he had run the car on propane to eliminate the fuel system as a problem but it still dies.
I have a buddy at a local yard that gave me a used BCM with the same number as the one on the car. I put it in, started it up and it ran for 5 minutes, then died. Cranks, starts and won't run.

Any suggestions? Thanks!
 

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if the pcm was bad there would be a code. 99% of the time id think.

you need to get a fuel pressure tester on the fuel rail. see what you got, you want to see over 42 psi car at run not on, and the same running.

you can also get a spark plug test light thing, it plugs into the plug wire and flashes if its got spark. see if the spark stops then it stalls.

bad icm, coils, crank sensor crank sensor harness can get rubbed by the belt. bad grounds to the trans bell housing bolt. vac leaks as well.

ever notice if the tach drops to zero before it stalls? of if it dont work at all sometimes?

you got some searching to do on that engine.
 
Scottydogs- Unfortunately, no. I'm going to go see him Monday and ask. All I know now is that it started acting up and they took it to the mechanic and it's been there for months.
dsmuts- I will do that tomorrow.
 


hope your friends feeling better. and has some story to tell.

the maf trick, you unplug it car off, then start it. if it runs the maf is bad. you can try to tap the top of the maf too see if that makes it run longer. or not stall at all.
 
Thanks for tips on the maf. Dadblasted newfangled computer controlled cars-I'm used to working on antiques!
My buddy is fine, it's the mechanic he took it to that's sick.
 
oh lol ok then carry on...

yeah i miss the good old days of a timing light and tuning by ear. cant even think about that crap no more.
 
Looks like the MAF sensor. I went out and unplugged it and it started. I let it run for a half hour and then plugged in the MAF. Within 10 seconds it died. Unplugged it and repeated. Died almost immediately.
 
maf time then. also check the wires to its plug for damage, cracks or missing insulation as that will also make the maf seem to fail sometimes.

best to find a junk yard maf or a used one off ebay, search the # on the top of the maf, thats the part #. they run 40 ish used or less and work and last longer then aftermarket mafs.

im running a jy maf for the last 4 year years currently.
 


Update:
None of the local yards had a good MAF(would have been $40 if they did). I stopped at a u-pull-it down in VA while visiting my Mom last week. Got 2 for $13 each! At that price I figured I'd get 2 in case one didn't work.
They both work fine. The car seems to run well. I even got the A/C to run. Tomorrow, it gets an oil change, tire rotation and a brake check. Then we have to figure out something to do with the boring white appearance.
 
score!!

white cars look good when they are buffed and clean. tinted windows also make em look better. harbor freight buffer works great.
 
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