SHO has bad starts when warm...

[Silver Bullet]

My SHO starts up perfect when it is cold, or after it has sat for at least a couple hours after a drive. When I attempt to start it when warm at any other time, it engages, bucks like crazy, idles rough, and tries to stall out until I place my foot on the gas. It finally smooths out after 30secs to a minute. Once in a while it will start up ok when warm though... The car runs mint whether it has a good or bad start up....

Anyone have this happen to them, or know what the cause could be?

 

[93EmeraldMTX]

sometimes if i dont let the idle settle down before i turn it off, it will take longer to crank before it starts. it happens most when its been off from 30-60 minuts. i dunno why, i just try to let the idle settle.

 

[Rockledge]

A leaky fuel pressure regulator can cause hard starts after warm-up.

 

[SHOZ123]

Sounds like too much fuel. Try flooring it when starting. But you still need to figure out where the fuel is coming from.

Like Rockledge said check the FPR by pulling off the vacuum hose and sniffing for gas. Otherwise it is a FI sticking open.

 

[Silver Bullet]

Where's the fuel pressure regulator located? Also, is there a replacement porocedure for it anywhere?

 

[Mike Kopstain]

Where's the fuel pressure regulator located? Also, is there a replacement porocedure for it anywhere?

The fuel pressure regulator is located on the front fuel rail on the passenger side. Here is a post I made a couple days ago that might aid you:

As well as a failing fuel pump. To verify whether you are getting too much fuel or too little fuel, set up a scenario in which the problem will repeat and then push the gas pedal to the floor while cranking.

This shuts off the injectors and combined with the open throttle plate, should start a flooded car.

If the above works, then you are getting to much fuel on startup or your starter is spinning too slow. Hard starting was a common problem in the early SHOs and was a result of the old style 10 tooth starter not spinning the motor fast enough. A revised 12 tooth version remedied the problem.

To check if the engine is getting too little fuel, turn the key to the on, but don't start it. Repeat twice. This primes the fuel pump.

If the engine is not getting sufficient fuel, look for a failing fuel pump or a faulty check valve letting air into the system. The latter is more common when the vehicle is warm.

 

[fricker66]

My SHO starts up perfect when it is cold, or after it has sat for at least a couple hours after a drive. When I attempt to start it when warm at any other time, it engages, bucks like crazy, idles rough, and tries to stall out until I place my foot on the gas. It finally smooths out after 30secs to a minute. Once in a while it will start up ok when warm though... The car runs mint whether it has a good or bad start up....

Anyone have this happen to them, or know what the cause could be?

Experienced the same symptoms when my fuel pump started to fail. The original pump would show it's weakness only after it had been running for several minutes. A cold startup had no effects. A replacement pump cured it!