I have a 1987 5.7L TPI car with 120K that's had an interesting problem ever since I bought it. If the car was cold (more than 8 hours) you had to crank and crank and crank to get it started. If the car was hot, it started fine. We've replaced the fuel pump (twice!) the fuel pump relay, the Fuel-pressure-regulator and the Coolant temperature sensor so far. The FPR was definitely bad, the fuel pressure was leaking down significantly. However, once we replaced THAT the problem got worse! It now has a looooong crank when it's cold AND hot! The car has to be 24 hours cold and then it cranks over, boom! or, driven less than 10 minutes ago and cranks right over. Anything in between, and you actually have to step on the accelerator a bit to get it to crank over. This car is BONE stock, no engine mods at all. Once it's started, it runs like a scalded dog. The injectors aren't leaking down, the fuel pressure is fine, no problems that we can detect with the ignition, electrical or starter, no codes in the computer. Anyone got any ideas?!?!?

 

Co,

Your '87 TPI will have the cold start valve (injector) and control that enriches the starting mixture when teh engine is cold. If the injector or control are not working properly, cold starting will require a lot of cranking.

Your restart after heat soak is likely a different problem, however.

If the fuel rail pressure is rock steady after shutdown, that all but eliminates the possibilities of leaking injectors or pressure regulator. That may actually be an ignition problem, or something different. If you can test spark when you experience the hot no-start, you should be able to determine if the problem is ignition or fuel related.

Regarding the cold start system, there is a control unit located in the front coolant crossover of the intake base. This control will apply voltage to the cold start injector during cranking for an internally controlled time, and only when the coolant temperature is below 104°F.

It is the larger unit on the left side of the photo:



The circuit looks like this:

 

Hey Vader, NICE diagrams. Thanks! We checked the cold-start injector, it's working. And the car DOES start cold, it just has to be STONE cold. OR have been running less than 10 minutes ago. And it isn't that it DOESN"t start, but that takes quite a bit of cranking, or you step on the gas a bit. If the car has been sitting more than 10 minutes, or less than 24 hours, you turn the key and it cranks, and cranks, and cranks, and then starts. At least 5 seconds worth of crank. OR as you are cranking, you step on the gas. This will start it fine either cold or hot. It's almost like the computer has no idea of the temperature of the car is. 8 hours cold and 24 hours cold should be the same thing, right? The engine temp is gonna be at the ambient air temp, which is WELL below 104F in Colorado! Which is why we replaced the CTS. And BEFORE we replaced the FPR, the car ONLY had the problem 8 hours cold or more. Anything under 8 hours and the car would turn right over, no problem. So I KNOW the car WILL start under the right conditions. The fuel pressure is rock steady, the ignition systems tests out fine. We replaced the MAF also. IT's got 3 experienced mechanics at the local shop shaking their heads.

 

Just my $.02, but no where in the original posts did I see anything about changing the fuel filter. It doesn't seem like any type of obvious cause, but - stranger things have happened.

 

Have you checked your battery and starter...? I just got my 305tbi a couple weeks ago and it was having the problem you described. Took a couple cranks to finally turn over when cold. But when warmed up it would turn over immediately. I changed the battery and the problem was solved. If your having trouble turning over when your engine is hot or old then your starter might be messed up