Rough Running at some startups

[bongo]

My son has a '98 GT with ~ 150k on it. It has been kept up and normally runs perfectly. Recently, however, it runs extremely rough after some starts. If he starts it a few more times, he says it will get back to normal. Is this an electrical problem, (bad switching). or could it be the starter motor gear is not disengaging? Other ideas? The car is in Alaska, so I can't troubleshoot it myself.

 

Thanks in advance, Greg

[Legacy777]

Welcome to the USMB.

 

Is the car an automatic or manual transmission?

 

 

When he starts the car up, and it runs badly, if he just lets the car still run, does it get better, or does it only get better if he turns it off and then back on again?

 

Has he tried to drive it when it has been running badly? If so, any other symptoms the car exhibits?

[bongo]

It is a manual transmission. He says it runs badly until he turns it off and restarts it, sometimes he has to restart it several times. I don't know if he has tried to drive it this way, I'll ask. He says it runs perfectly when it starts smoothly.

Edited April 29, 2010 by bongo
to completely answer the question

[rverdoold]

I have a similar effect on my 1.6 99 impreza manual. However mine is running on Propane, but starts on gasoline. So basically a full gasoline tank lasts for about 12000 km. I figured out that the problem is mostly there when the gasoline tank is getting empty.

It starts fine and jumps to 1500 rmp then drops to 1200 and then to sort of 300. When i apply some throttle it jumps to 1500 and stays there for a sec or 2 then back to 1100 and runs fine. (occasionally it jumps to 3000 after starting for some seconds).

I think it is because i run propane and when the engine is shut off (from propane) the fuel lines are low and it takes more time for the fuel pump to give gasoline just before the start. I tried to turn on/off the key before starting it. Just to get some more gasoline pressure on the fuel line. But i am not sure it it helped. You can try that perhaps.

After i have driven 5 meters it runs fine and switches to propane after approx 1 km without any hesitation or problems.

I have read it could be the temp sensor for the ECU, the throttle position sensor and some more things. good luck

[Legacy777]

That's a good point. He may want to put a fuel pressure gauge on or take it to a shop to check the fuel pressure.

 

The fuel pump will kick on for 3 seconds prior to starting. So even without starting the motor, fuel pressure should be around 30 psi or so.