1992 Pontiac Grand Prix
#1
1992 Pontiac Grand Prix
Can anyone give me an idea what'* the cause of my car that will not turn over. The car cranks, but will not fire up. The car have sparks, fuel, and power. I recently replaced the fuel filter and thought that was the cause of my problem. The fuel pump works fine. There is pressure in the line. I pulled the spark plugs to see if there was any fuel in the valve, but didn't see any. It'* Dry. I also cleaned the mass airflow sensor with mass airflow cleaner. And it still won't turn over. Can it be the crank sensor that'* causing my vehicle not to fire up? Any suggestions? Thanks
#2
Senior Member
True Car Nut
seems more like a lock of fuel, if the plugs are dry. did you check the actual pressure on the fuel rail? has to be within spec to start and when the pumps wear out it can still act and sound fine but not put out enough pressure to start the car
#3
Senior Member
If you have spark and good compression, try spraying carb cleaner into the intake while someone cranks the vehicle....
If it starts and runs as long as you spray, then you either have a fuel pressure problem(pump) or delivery problem(injectors)......need to check fuel pressure and also for injector pulse and injector resistance(since this is multiport, one bad injector can take out three on the driver circuit in the ECM)....
Is this a 3.1 or the dreaded DOHC 3.4?
Have you checked for codes by counting flashes in the dash when grounding the diagnostic pin in the ALDL connector?
If it starts and runs as long as you spray, then you either have a fuel pressure problem(pump) or delivery problem(injectors)......need to check fuel pressure and also for injector pulse and injector resistance(since this is multiport, one bad injector can take out three on the driver circuit in the ECM)....
Is this a 3.1 or the dreaded DOHC 3.4?
Have you checked for codes by counting flashes in the dash when grounding the diagnostic pin in the ALDL connector?
The following users liked this post:
WilliamE (07-15-2014)
#4
1992 Pontiac Grand Prix 3.1
Thanks for your help guys! It'* a 1992 Grand Prix 3.1 with 70,000 miles. I did spray carb cleaner while someone was cranking the car. It did starts, but will not staying running. It just crank and cranks. I will have to charge the battery over night. If it'* the fuel injectors, how do I go about it? Replace it or clean it with some kind of injection cleaners? Also, I was just curious if the fuel pump was working properly. I disconnected the fuel filter to see if fuel was coming from the tank and it did. Nice stream of fuel came out. So, I know it'* working. The code it gave out was a cam sensor, but this vehicle don't have one. I google on line and this particular vehicle only have a crank sensor. I bought the crank sensor to replace it just in case, but I rather not do it bc it behind the firewall. Could it be something much easier than the crank sensor? Any ideas? Thanks again for your expertise knowledge!
#5
Senior Member
True Car Nut
when the ckp goes its normally different symptoms. i wouldnt worry about the complicated issues until you see what the pressure is at the rail. you cant tell anything any other way than getting a gauge and seeing if its in spec. the parts stores rent them for free.
#6
Senior Member
A stream of fuel means nothing, it'* actual pressure that counts, so get a guage on it, like JW suggests......it'* not your crank sensor if you have spark.....
If fuel pressure is ok, you need to check for injector pulse, and injector resistance....
If your car does not have a cam sensor, then it is multiport....this means 1-3-5 injectors fire at the same time, and 2-4-6 fire at the same time....since theinjectors are wired in parallels of 3, if one injector is shorted, too much current will flow, and the injector driver in the ECM will shut all three down....
Injectors are 12 ohms each.....when three injectors are in parallel, their resistance equivalent is 4 ohms.....If it reads 12 ohms, two injectors are open...if it reads 6 ohms, one injector is open...if it reads near zero ohms, the harness is shorted(this is usually caused by rodents building a nest under the upper plenum....they like to eat injector harness insulation)......
You will disconnect the injector harness, and attach your ohm meter to the half going under the plenum....one lead to pnk/blk wire and the other to lt grn wire...then pnk/blk and lt blu......in both cases should read 4 ohms.....
If fuel pressure is ok, you need to check for injector pulse, and injector resistance....
If your car does not have a cam sensor, then it is multiport....this means 1-3-5 injectors fire at the same time, and 2-4-6 fire at the same time....since theinjectors are wired in parallels of 3, if one injector is shorted, too much current will flow, and the injector driver in the ECM will shut all three down....
Injectors are 12 ohms each.....when three injectors are in parallel, their resistance equivalent is 4 ohms.....If it reads 12 ohms, two injectors are open...if it reads 6 ohms, one injector is open...if it reads near zero ohms, the harness is shorted(this is usually caused by rodents building a nest under the upper plenum....they like to eat injector harness insulation)......
You will disconnect the injector harness, and attach your ohm meter to the half going under the plenum....one lead to pnk/blk wire and the other to lt grn wire...then pnk/blk and lt blu......in both cases should read 4 ohms.....
#8
Follow ups--------------I checked the fuel pressure from the fuel rail and I did not get a reading. It was at zero...I followed the instruction on how to attach the adapter and still no results. Instead, the car fired up, but then later died out. Could this be a sign that bad fuel pump? Also, tested the resistance and pulse. I did get a reading at 12....The key was in the on positon. What now?
Thanks in advance-
Thanks in advance-
#9
Senior Member
True Car Nut
after you put the gauge on you have to repressurize the system by turning the key to run, let it prime, turn key back off, repeat until reading stabilizes. has to be some if car starts.
The following users liked this post:
WilliamE (07-18-2014)
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