1995 Pontiac Grand Prix Misfiring & Now Won't Start

Tiny
TEXASRAIDER
  • MEMBER
  • 1995 PONTIAC GRAND PRIX
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 200,000 MILES
1995 Grand Prix 3.1LV-6 was stored for 6 months with 1/2 tank of gas & ran great before. I started driving it again but it ran rough on start up, bucking a bit going up hills. I assumed water in the tank & used Berryman's B-12 thru 3 tanks of gas-no change. It was worse the faster I went - at 50mph or less, it ran a bit better.
One day driving to work it suddenly shuddered, ran very rough at all speeds & idle. It also had a throaty, rough exhaust sound (popping occasionally) that it did not have before. This happened just all of suddened, no warning.
I changed the plugs & plug wires & tested the ignition module at O'Reillys (tested OK) but problem persisted. I left O'Reilly's & it still ran rough but started shifting gears very hard. Suddenly it bucked hard once or twice & died. I had gauge lights & it cranked, but no restart. Not sure if coil packs got back in right order on the ign. Module. Plug wires are on correct coils electrodes. Car still won't start.
I then replaced the fuel filter and all 3 coil packs. Now when trying to start, it acts like it's out of gas. I put 4 gallons in, so I know it's not. It will crank & turn over, hesitate, & I hear an occasional muted pop from the tailpipe. It intermittently tries to catch and fire up, but never does. I can hear the fuel pump hum for a few seconds when I first put the key in and turn ignition to 'accessory' or 'on'. Any ideas? Help!
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Wednesday, June 25th, 2008 AT 6:48 PM

3 Replies

Tiny
RASMATAZ
  • MEMBER
Do you have a check engine light?

Try doing an Idle relearning if you have disconnected the battery

Idle Relearning process:

#1 set the parking brake and start the engine. You can put it in park or neutral. You need to let the engine run until the cooling fan comes on or it gets up to operating temperature.

#2 After step one you will need to let the engine idle in neutral for one minute. Then you will need to let the engine run in drive for one minute. Remember not to touch the accelerator in this step and #1.

#3 Remove the parking brake and drive the car at 20%-50% throttle until it reaches top gear.

#4 Cruise at light throttle for 5 minutes.

#5 Allow for the vehicle to come to a stop, you can use the brakes if needed.

Check the fuel pressure and also listen to the injectors whether they clicking meaning its pulsing opening and closing. Might also want to inspect and test the throttle position sensor/MAF/MAP sensors also the EGR valve if it has one-
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Wednesday, June 25th, 2008 AT 7:21 PM
Tiny
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Can't do that, as it won't start now. It cranks, and acts like it is out of gas, but isn't.
Also, no "Check Engine" light is on.
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Wednesday, June 25th, 2008 AT 7:25 PM
Tiny
RASMATAZ
  • MEMBER
If the engine's condition is in tip top shape-do below to determine if its fuel or spark problem that's if its cranking over and refuses to start

Get a carb cleaner and spray into the carb or the throttle body on an EFI. Did it start and die? If not disconnect a sparkplug wire or 2 and ground it to the engine -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel problem, check the fuel pressure to rule out the fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil, distributor pick-up coil, ignition control module, cam and crank sensors-

If both fuel and spark is present-check the valve and ignition timing, this will lead you to problems with compression and valves opening and closing at the wrong time
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Wednesday, June 25th, 2008 AT 7:30 PM

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