98 Malibu 3.1 - Stalls on warm restart

[locovaca]

Foreword- I haven't done any digging in yet but wanted to get an idea of what to look at.

We have a 98 Malibu 3.1 with 165k on it. All maintenance has been kept up to date. It's had an issue for a while where it has issues restarting warm. Cold startup is fine, idle is fine, no codes at all. After I've driven it to the store and come back out I have to let the fuel pump prime 2 or 3 seconds and it restarts fine. If I don't I have to goose the throttle a bit before it will idle.

My first thought was the fuel pump. I unfortunately don't have a fuel pressure gauge that'll hook to the intake so I never got to testing that theory, but then I started thinking about it more and am thinking maybe the IAC might be slow or clogged? I plan on pulling that off when I get a moment in a couple of weeks and cleaning it, just wondered if there was anything else that'd be good to check?

Thanks

[caffeine]

Possibly the fuel pressure regulator?

[unchained01]

When was fuel filter changed ?

[locovaca]

When was fuel filter changed ?

About a year and a half / 15k miles ago.

[TGP37]

I know a plugged up fuel filter can cause hard/no warm start. Seems fine when cool as well.

Try unplugging the FPR vac line (block it so it isnt a vac leak). If the car starts easier you may have a fuel pressure issue.

When warm, you can hit the schrader valve on the fuel rail and see if you get vapors or just liquid.


I had a lumina do this before. The fuel filter was the problem followed by a weakened pump. The engine was running lean, really hot. She started fine cool, ran well until 30 minutes into driving. Then it starts to sputter if idling at a stand still. Restarts were near impossible until the engine sat 2+ hours.

An idea......check fuel pressure.