My 99 grand prix cranks and backfires when letting off key from trying to starting. I have fuel pressure 45 psi. I have spark showing on ignition tester at the three coils i guess thats what they are called. My compression is all around 150 on all cylinders. Starting to wonder if it jumped time time. Is there an easy way to check since i cant start it? Not sure where timimng marks are.. :th_lipssealed2:
cranks wont start
- Thread starter Gboy
- Start date
Fivefingerdeathpunch
New member
You sure the spark plug wires are routed correctly?
BillBoost37
New member
What was done since it started last? Seems like some work was done or it happened randomly one day?
Scottydoggs
Killa Bee
what engine you got and whats the miles? the n/a engines like to clog cats for some reason.
could be a clogged cat if it slowly started to feel weaker and weaker as time went on, then misfire and sputter?
could be a clogged cat if it slowly started to feel weaker and weaker as time went on, then misfire and sputter?
BillBoost37
New member
He has an NA based on the sensor being on top of the pcv. 
BillBoost37
New member
Pull the front three spark plugs, are they went with coolant?
If so .. use the How to mod a LIM thread to plug the coolant ports.
If so .. use the How to mod a LIM thread to plug the coolant ports.
Z34Phoenix
Florida Tuner
possible crank sensor
mguzzo
New member
let's try to narrow it down:
air - unplug the MAF and try to start it.
if it starts the MAF sensor is dirty or failed.
fuel -- you say you have 45 psi at the rail? that's a little low for static fuel pressure / engine not running but it should be enough to start the engine.
Do this -- push down the pin on the schrader valve while someone turns the key to prime the pump. you should get a good stream of fuel.
spray some carb cleaner into the throttle body and crank it. if it starts then stalls then you may not be getting a good stream of fuel to the engine.
have you changed your fuel filter lately?
spark - you say you're getting spark on the front three plugs. so we know the ICM and crank sensor are working, otherwise you wouldn't get spark while cranking.
air - unplug the MAF and try to start it.
if it starts the MAF sensor is dirty or failed.
fuel -- you say you have 45 psi at the rail? that's a little low for static fuel pressure / engine not running but it should be enough to start the engine.
Do this -- push down the pin on the schrader valve while someone turns the key to prime the pump. you should get a good stream of fuel.
spray some carb cleaner into the throttle body and crank it. if it starts then stalls then you may not be getting a good stream of fuel to the engine.
have you changed your fuel filter lately?
spark - you say you're getting spark on the front three plugs. so we know the ICM and crank sensor are working, otherwise you wouldn't get spark while cranking.
Tried spraying starter fluid and tuning over still won't start. Checked plug wires on correct cylinder. Getting ready to replace plugs. Not sure why they would go bad. Motor has 208,000. On it Trying to see if I can put a timing light on it crank over and see if close to timing marks if it even has any.
Scottydoggs
Killa Bee
that timing light is nice strobe light these days, worthless on a 3800.
take a plug wire off the coil and prop the wire a inch over the coil. then crank the car, you want to see a blue spark jump to the wire.
you can do the same with a spark plug, take the plug out, put it back in the wire then rest the spark plugs threads on somthing metal, you should see a spark jumping the plugs gap.
or theres a spark tester, plug wire goes on the tester you crank the engine to see if it sparks.
take a plug wire off the coil and prop the wire a inch over the coil. then crank the car, you want to see a blue spark jump to the wire.
you can do the same with a spark plug, take the plug out, put it back in the wire then rest the spark plugs threads on somthing metal, you should see a spark jumping the plugs gap.
or theres a spark tester, plug wire goes on the tester you crank the engine to see if it sparks.