Trouble Starting & Temporary Rough Idle

[Black91SHO]

1991 SHO w/ 116k

Taking me a little while to start my car. I give it gas and eventually it starts. It's like it's flooded. But once it start, the idle fluctuates for a little bit. After a very short time, the idle becomes normal.

The only thing I can think of that could be related is that the fuel pump sounds a little strange sometimes. I can hear it sucking fuel from the tank sometimes when I first start the car. I haven't noticed that lately though.

Any ideas what might be causing this?

- Brian

 

[sperold]

Is the troublesome start the first start of the day (or after a long period of being off); or every time the car is shut off?

Try putting the gas petal on the floor when your try to start the car.
If the car is flooded due to a leaky injector or whatever, the foot on the floor stops any new fuel injection as the engine rolls over.

Your other assignment is to turn the key on and off about 3 times before you go for the start position on your ignition switch, which will give you a better shot of having a weak fuel pump deliver full pressure for your start-up.

Take your fuel pressure at the fuel rail schrader valve.

Of course, you have already checked your codes, current and stored, and found none.

If the fuel is ruled out as a cause, then you are on the the Cam Sensor and the Throttle Position Sensor quest for answers.

 

[luigisho]

If the fuel pump is making noises other than normal, and you've owned these cars for a while, then trust your experience and attack that first. Probably a bad pump or sending unit if the noise is from the back

 

[Black91SHO]

Thanks. I'll do a little troubleshooting and get back to you guys.

I'd change the fuel pump but it was changed last year because of that sound. Didn't fix it.

And I should've said I floored it, instead of have it has, for the reason you stated, Sperold. Didn't try the other stuff, though.

 

[Black91SHO]

Oh, and the car does it on first start and not starts, but not every time.

 

[rubydist]

these engines are really easy to flood in my experience, so if you try to start it and fail (stop cranking before it starts) with a warm engine, there is a good chance it will want to flood, so you need to push the gas pedal to the floor to get it to start a lot of times.