starting problems

[Chris17]

so im new to this fourm... i got a 94 9c1 and when i go to start the car it starts and then dies right away... i already changed the distributor and the ignition coil. what else could it be???

[silicon212]

Did you check the fuel pressure? It should be a minimum of 55 PSI.

[Chris17]

i don't think its that ... befor i changed the distributor and the coil the car would start one day and not start the next, it was to the point where it would start to get to that gas station and then wouldn't start to leave. and then i would go beack and it would start. after i changed them the car started for bout a day and a half. now it doin this

[silicon212]

Precisely what weak fuel pressure would cause.

Instead of dismissing someone's learned and experienced advice because you don't think it's the problem, try it and see. You might be surprised!

[j cAT]

Originally Posted by Chris17

so im new to this fourm... i got a 94 9c1 and when i go to start the car it starts and then dies right away... i already changed the distributor and the ignition coil. what else could it be???

this could be fuel problem. replace fuel filter. i replace mine every 30,000. cut open to see if the fiter is full of rust or dirt, your tank may need clean out or replacment. check fuel pressures also, but at the very least replace the filter. distributor usually causes backfire or missing.fuel pump voltages, fuel pump relay, I found that after 10 years the relay contacts need to be cleaned or replace relay. voltage drop to pump.

[PeteA216]

I have to agree with the probable cause of the fuel pump or related system. It provides just enough pressure to start the car, but not enough to keep it going. When you changed the distributor and coil it may have helped the engine just enough to keep it going longer than before, but also kept it going long enough for the fuel pump to get worse. All symptoms point to weak fuel pressure. Simply check it, and if the fuel pressure is good, then we're wrong, but if not then it's a reasonably good assumption your fuel pump is shot. Best case scenario, like j cAT said, is a dirty fuel filter.

[xXxHawkxXx]

Originally Posted by PeteA216

then it's a reasonably good assumption your fuel pump is shot. Best case scenario, like j cAT said, is a dirty fuel filter.

How do you go about checking your fuel filter/ pump? Ive never done that before, and my Dad can't recall if he has ever had it done.

[silicon212]

Originally Posted by xXxHawkxXx

How do you go about checking your fuel filter/ pump? Ive never done that before, and my Dad can't recall if he has ever had it done.

Filter, simple. You put a new one on. Before you do, you get a handheld fuel pressure gauge and screw it onto the diagnostic port in the fuel rail. Get before and after pressures - again it should be a minimum of 55 PSI. If it's running at 52 - this could be the problem. Yes, these systems are that sensitive. If the pressure is low and the filter doesn't do anything, check the fuel pressure regulator and then the fuel pump.

[PeteA216]

Now why is it that MPI needs so much more pressure than TBI?

[Chris17]

so it's not the fuel pressure... it was a pass. key fuse cause i have no idea what that is... but now its back to its old tricks of starting 1 day and not the next

[silicon212]

Originally Posted by PeteA216

Now why is it that MPI needs so much more pressure than TBI?

The TBI systems have two large injectors, that pulse back and forth with the needs of the dual plane intake. The turbulent air through the intake will take care of fuel atomization, so injection does not need to be 'precise'. The injectors each run at a 50% duty cycle, each one running for one complete revolution of the crankshaft.

SPI systems pulse small injectors for a much smaller duration - matching the time a cylinder is in the intake stroke. One half crank revolution. To deliver enough fuel at the atomization required, the fuel must be under high pressure.

Chris, is it throwing any MIL diagnostic trouble codes (check engine light)?

[Chris17]

the check engine light comes on after about 10 mins of driving, that when it starts...but when i don't start the light never comes on... i would of checked that but i dont have a code reader... im having a mechanic look at it tomorrow so he can tell me what the problem is and then i can go from there and fix it myself... i figure if it's something with the ignition system... thats just my wild guess

[PeteA216]

Since it's not fuel thats the issue, I'd say my next best guess would be the ignition module or pickup coil, both in the distributor if they still had either of those in '94. That or a faulty MAF sensor, again if they had those in '94. My buddie's Impala acted similar to how you describe the way your Caprice acts and his problem was a failing MAF sensor.

[silicon212]

Could be MAF.

The distributor used on these is the OptiSpark at the front, behind the water pump. The coil is external.

[Chris17]

so the mecahnic never came to look at the car, so i went to buy the code scanner but they one they had at autozone was compatible with a 91 caprice... what is a good code scanner? is believe its a obd1 but i jus seen that some of the 94's can be obd2 how do i tell?