kclivie

hello everyone please give me some advice i have an 1988 chvey camaro with the tpi fuel injection it an 350 stock the only thing i have change is some new in jecter. my problem is when the car is cold or sitting for 20 mins it hard to start and the only way i can get it to start is spraying starting fuel in it. once it warms up it will run good. i look to see if this engine have an cold start valve but it do not. can anyone give me some advice or ideals on what to do am getting good pressure on the rail


thanks

Injuneer

Have you scanned it for codes?

Did you replace the injectors with the same flow rating injectors? If not, did you have a chip burned with the new injector flow rate?

While you indicate you have good pressure at the fuel rail, what is the pressure when you turn the key to "run" (not to "start") and let the fuel pump prime? After the pump shuts down, how fast does the pressure drop?

Check the coolant temp sensor for the ECM. The ECM has to know the engine is cold, in order to richen the A/F mixture for a cold start.

kclivie

there are no codes and the injectors was brought at advance so i am hoping that they was the same flow. stock computer nothing has been change i turn the key on the presure goes up to 47 i let it sit for 15-20 minutes it is back to zero. i am replaceing the coolant temp senor. is thereanything else i can do.

thanks for your help

Injuneer

Will it start faster if you cycle the key back and forth from off to "run" several times, to force the pump to prime multiple times?

kclivie

I try that turning the key still the same, is there anything that i could check.

Thanks for your help

Injuneer

If fuel pressure leaks down rapidly:

1 - Leaking check valve in the fuel pump. You have to find a way to clamp off or valve off the line between the pump and the rail hard line, so you can see if that stops the pressure from leaking down, confirming the leaking check valve. Easier to say than to actually do.

2 - Pull the vacuum line off the fuel pressure regulator and check it for wet fuel. That would indicate a torn diaphragm in the fuel pressure regulator.

3 - Clamp of valve off the return line, between the fuel pressure regulator and the tank, to see if that eliminates the pressure drop off. That would indicate the fuel pressure regulator is not closing.

4 - Pull the fuel rails up with injectors intact, turn key to "run" (not "start") to prime the pump, and look for drips from the inspectors.

5 - Check all the fuel lines for leaks.

This based on the fuel system arrangement of the 4th Gen engines. I'm assuming yours must be similar.