Fuel Pressure regulator??

[Peter E]

Hello folks

My vehicle has recently been hard to start on occasion. I have to keep my foot on the gas for it to start and keep running, otherwise it stalls. This only happens intermittently (3.4L V6).

It has no codes. The IAC seems to be working fine according to a snap-on diagnostic scan. Plugs, fuel filter, PCV, etc are recent, and the car runs smoothly when it is running, so I doubt there are vacuum leaks. Under throttle, it runs fine and doesn't stumble, so I think the TPS is OK.

Maybe a fuel pressure regulator?? any advice would be appreciated.

p.s. this is my wife's Chev venture van, but I like this Forum better

[xeroinfinity]

How many miles ?

Even though the IAC on the scan is working within perameters , that doesnt mean that the passage it sets in is clear and non obstructed to incoming air.

I would pull it out and check it, clean it and the TB with TB cleaner. Carbon builds on the back of the TB butterfly and up in the IAC port, this can effect idle.

Another possibility is the injectors are dirty.
Might try some fuel system cleaners, I've been having great luck with Seafoam injector cleaner.
I use it once a month, it keeps my misfires at bay.
My SE used to get at least 1 misfire a week(even with new injectors and wire harness) now I havnt had one for a couple years.

... I'm still on my factory fuel pump @ 189,000 miles.

Have you pulled the vacum line from the pressure regulator ?
Check your fuel pressure, should be 41-47 psi.
If fuel comes out of the regulator when you remove the hose its bad.

hope that helps.

[Peter E]

Thanks for the advice. The throttle body has been cleaned recently, and the fuel pressure regulator vacuum line has no gas in it. Throttle response and driveability are fine, the car just simply stalls at idle. No vacuum leaks, no smells, no codes.......

I presume if it was a bad MAF sensor or crank sensor, I would be getting codes?

I appreciate the help

Pete

[xeroinfinity]

I would try and check your fuel pressure.
Has your fuel filter been replaced recently ?
Do you use any type of injector cleaners ?

Dirty injectors will give you problems off and on with these newr grand ams, cheap injectors that clog easily.

Yes you are correct, if your MAF or crank sensor were bad you would know either by the SES light or by driveability issues.

Intermitant problems are a pita sometimes.

Also when was the last plug & wire change ?

[Peter E]

I decided to take a gamble and replace the IAC. ($65). It fixed the problem right away. It is interesting to note that the IAC turned out to be defective, but did not give off any codes.

thanks for the advice

Pete