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1999 Grand Prix gt won't start

Yamahakid88

Yamahakid88

New member
Drove it this morning it was fine, when to go out for work a couple hours later, it wouldn't start. I hear fuel pump go on it turns over but will not start, I tried giving it gas. That helped a little, but not enough to start it. Please help ASAP guys. Thanks
 


Well if giving it gas helps, it's probably not the crank sensor. I haven't known a bad MAF sensor to make it impossible to start, but you could try unplugging it and see what happens. If that doesn't work, I'd check fuel pressure. It may turn on but not have enough pressure.
 
It's possible. Check the fuel pressure, could be the regulator as well. Pull the vacuum line off of it and see if it has gas in it.
 
Pretty sure yes. I unplugged the battery for giggles, checked the intake. Neither worked. T dark to try anything big. However, I push down on the gas pedal about half way and tryed starting it, it came to life as long as I kept pushing on the gas, it sounded like hell forte few seconds it ran, backfiring, sputtering, sounds awful.
 


Try a MAF. mine was doing the exact same thing and a MAF fixed it. I borrowed one from a friend to try, then bought one when his fixed mine.
 
Ok, finnaly found some time to poke around and try some things. This is what I found. Hooked up a code reader to it, all sensors are working properly and how they should. There is about 45 psi at the fuel rail which should be adequate, Tryed spraying starting fluid in the intake, and nothing. I also found that every single cylinder is misfiring. More than 30 times on each one O_O So if it was a coil pack, then just 2 cylinders would be misfiring, Any ideas?
 


Sigh, Im leaning toward Icm, crankshaft sensor, or where the coil packs plug in. I already have the crankshaft sensor, so i will try this first. What do you think about the coil pack theory?
 
If it were the MAF, you could unplug it and it would work.

I'd start pulling the easy access parts and cleaning them with brake/electronics cleaner.

ICM, that would DEFINITELY throw a code.

Cam position /knock sensor is relatively cheap.
 
well the crank sensor and cam sensors tell the icm to fire the coils as needed. so something in that area is a problem if its got all 6 cylinders misfiring.

maybe a bad harness to the crank and cam sensors, check that for damage.
.
 


I retaped and loomed mine yesterday before I put it back on. The coolant temp sensor and Wiring harness near the radiator cap were looking pretty ragged too...

Could be a silly short somewhere too.
 
Where is the cam sensor located? I highly doubt it would be anything along the lines of the maf sensor, iac etc. Otherwise it would still run even if it didnt work.
 
19 is cam. 23 is knock.

That Harness is your engine Wiring harness. It plugs into your icm, runs along the belt, and over the top of your lim.

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