I have a 1988 Pontiac Formula with a 305 TPI setup. A little while ago it started to get harder to start. When I go to start it, whether hot or cold, it cranks and after 10-15 seconds it starts to catch and usually starts. Sometimes I have to crank it a second time. I checked fuel pressure and when you turn the key on it goes to 20 psi and then zero, as you start cranking it goes to 30 psi and that's when the car starts. I've also taken the vacuum line off of the fuel pressure regulator and there's no real change in pressure. I have since changed the distributor cap/rotor, spark plugs and wires, TPS sensor, fuel pressure regulator, fuel pump, fuel filter, and fuel pump relay. I did an ohm check on the injectors and they all fall between 16.7 - 16.9 ohms. I set the TPS at .540 volts. On the fuel pump relay I get 12+ volts on the orange wire. Any ideas?


Thanks
Ted

 

I forgot to add, When it is running it idles and drives fine.


Thanks
Ted

 

Something you could try is removing the throttle body and IAC and giving it a good cleaning to remove and carbon build up. Then perform the IAC calibration procedure.

Also check the coolant temp sensor connector, they are notorious for getting corrosion on the contacts and giving the ECM false readings causing hard starts and rich conditions.

 

Thanks, I didn't think about he IAC, will check and post what I find.


Ted

 

There's your problem. It should hold pressure. You have an internal fuel leak some place. Also, your fuel pressure is about 15 psi too low (this is probably due to the leakage).

Read and follow the attached flow chart to isolate the problem to either the regulator, injectors, in-tank check valve/leaking hose at the fuel pump.

 

Thanks, I thought so to. I've replaced and checked about everything on the flowchart and was hoping it wasn't the injectors. I'm going to replace them next, there 28 years old and are probably due.


Thanks
Ted

 

It was a defective (new) fuel pump. Replaced the fuel pump with a new one and when you turned the key on it did the initial prime and then still started hard. Finally got it running and was able to check fuel pressure and it was between 25-30 psi. Replaced fuel pump and was around 40 psi and it started fine. Thanks for everyone's help.


Ted