George2002

Grand Prix Cranks but wont Start

My 1988 Pontiac Grand Prix 2.8 V6cranks but wont start. I checked for spark at the spark plug wire and dont have any. It sounds like the fuel pump kicks in fine when the key is turned to ON and there is gasoline spewing out from the "fuel injector service port" when the needle is pressed in.

Whats the best way to troubleshoot a no-spark condition on these cars? Is it most likely the coil (there are 3), the module or the crankshaft position sensor? Thanks!!

bejay

most likely cause would be crank position sensor, but you should check and make sure you are getting power to your ignition module first this is the 2 wire connector on the drivers side of the module you should have power at one terminal with the key on and ground at the other terminal.
the coils realy isnt even a possibility cause there is no way all 3 coils would of went bad at once.

George2002

I cant even find the crank sensor... I guess I have to keep looking. The manual says its pretty easy to replace though. Any ideas?

I pulled one of the coils already cause i wanted to test the module... 2 more to go; its real tight getting to the bottom screws though so i might have to drop the starter?? this is ridiculous!!

I might just replace the crank sensor for $20 and see what happens... ahhhhh.

any comments or ideas would be appreciated!!

bejay

the crank sensor is on the other side of the block you kinda have to reach between the engine and transmission from underneath the car to get to it just one bolt holds it in just be carefull and try not to break the old one off removing it.

Joe_F

Original poster: Whoa nelley.

STOP! Don't change parts. You must TEST them first to damn them as being bad first.

If autolibrary doesn't have the test specs you need, then Alldata will for $25 annually.

George2002

Any ideas on how you would check the crank sensor?

Joe_F

Ya, again, using autolibrary or Alldata, follow their procedure. Usually it involves the part being within a certain resistance value range.

davo

Joes link to autolibrary has the testing info for the crank sensor.Check for spark on all 3 coils not just one.Also borrow or buy a noid light for your car and see if you have a flashing light during cranking.

bejay

there probably is a resistance for the crank sensor but i didnt see it listed on auto library, a shop would use a lab scope to check for a signal but this is an expensive piece of equipment, another thing you might check is for oil inside the connector of the crank sensor which would mean the sensor is junk and should be replaced, also if you remove the sensor any cracking in the plastic casing and it should get a new one, cracks will allow oil into the sensor.
you might also check the wiring running from the crank sensor to the module for rubbed through spots that would ground out the signal causing a no start all though not a common problem ive seen a few.

Joe_F

Davo is correct. AL has the procedure, I checked yesterday before the power went out .

George2002

Thanks, guys... i put in a new crank sensor and it fired right up!

While I was at it, I replaced the spark plugs, wires and air filter. I just have to dress the plug wires neatly now and replace the fuel filter too.

Joe_F

Good job.

Curious, did you check it or just change it?

bigguy05641

It would have been useful to know if the injectors where being pulsed, if they were or weren't it woulda whittled down the possabilities..