Extended start time hot or cold, doesn't matter. All new tuneup parts, injectors, runs perfect,,,I don't know much about the technical side of these cars but have heard if this sensor is weak(?!) it could cause this. Fuel pressure fine, no gas in FPR . It would be nice if it didn't turn over so much before firing. Changing timing doesn't help, either. Suggestions?

No air pockets in radiator, temps seem stable. I'm stumped!

 

I am having this problem only when cold. The suggestion on the board was to hook the computer to it when cold and see what temp readings the ECM is receiving. most likely one of them is way off.

I need to borrow my neighbors scanner.

 

ECT is like a choke. Mine recently pegged hot leading to hard cold starts. A scanner makes short work of it. You might also want to buy a new sensor and compare a scan with the old one. No need to install it. Just plug it into the harness on a cold engine and see what the scanner shows. Quick way to determine if it's the sensor or ECM (mine was the ECM).

 

The coolant sensor that reports to the ECM is located in the front of the intake manifold, pointing forward. If cold temps are reported to the ECM, the ECM will command a rich start up mixture like a choke on a carb, and a fast "cold idle". If warm temps are reported to the ECM, the start up mixture will be lean, and the ECM will command a slow idle. Even in warm weather it may not idle for a few minutes without playing with the throttle.

Exactly how are you determining that the fuel pressure is OK? Have you checked the pressure without otherwise touching the car? Depending on your pressure check methods, I have a thought or two.

RACE ON!!!

 

With the key in the "On" position, prssure shoots up to 44 lbs. When running its a steady 36 lbs, maybe 35.8. When i shut it off, pressure drops approximately 2 lbs. every 5 seconds.
Is there a check valce in the fuel pump that is supposed to keep the fuel there? It was replaced by the prior owner-Has less than 4000 miles on it. Don't know the brand. FPR was hooked up (vacuum lines)while taking readings. Pulled the line off when stopped, no trace of gas smell.
Am I supposed to take the reading with the vacuum line off?

Injectors are new. by the way. Idles smooth and runs great. FI is not my forte.

 

On my '89, the ECM was bad, causing the coolant temp sensor to report falsely high readings to it. I scan tool at the daig conn under the dash showed this falsely high reading, measuring the value directly from the sensor showed the correct reading. Car was alway to start when cold outside, fine when warmer. Replacing ECM solved the problem.

 

Turn the key on. Pump should run for 2 seconds and the pressure should be 38 to 42 psi and steady. It shouldn't drop - at least not for awhile - like 5 to 10 minutes. If it does, pinch the return line. You'll find the flex hoses on the lower right side of the block, just to the right of the Tensioner. If the pressure remains steady or builds (don't let it go over 60 psi) with the return hose pinched, the fuel pump check valve is faulty. If it continues to drop, either an injector is leaking or its a faulty regulator. Before you pushed the injectors back into the manifold, did you energize the rail and check for leaks? Does it appear to be to rich when it finally starts?

 

I take the above to indicate that the fuel pressure drops to zero, overnight, but in any case, the pressure recovers very quickly, when the key is turned on, but the engine not cranked. The pressure has three three places it can escape from; leaky injectors, leaky fuel pressure regulator, or the fuel pump check valve. If the fuel pressure jumps to 44# at the twist of the key, even with the leak, I don't see the fuel pressure being the problem. The leak should be fixed, but by the symptoms description, it shouldn't be part of the extended cranking.

The fuel pressure regulator can leak into the vacuum line or back through the fuel system return line. Disconnect the regulator vacuum line and crimp the return line flex hose. Power up the pump. If the pressure now holds, the pressure was escaping past the regulator into the fuel return fuel line. If the pressure drops, it is escaping, either through the injectors or the fuel pump check valve. Power up the pump and this time crimp the feed line after the pressure has built up. If the pressure holds, neither the regulator nor the injectors are leaking. By the process of elimination, it has to be the fuel pump check valve. If the pressure drops, it is the injectors, because we verified the regulator was OK in the previous step.

I tried to lay all that out as clearly as I could. I hope it makes sense and is easily followed. Good luck, and...

RACE ON!!!

 

Thanks for the input, guys! Dont know if I will have time tomorrow, possibly Sun I will check. I'll post the results!