hard starting question

mod · 04-14-2002, 01:53 PM

I have a strange starting problem that I haven~{!/~}t been able to pinpoint. If I let the car stand overnight in the garage, it starts superbly, like any Porsche ought to. It would go through the high idle for a minute or two then it would come down to about 850 or so. If I shut it off then, I could start it again, without any problem, again with the routine of slight high idling then down to normal. I could do that several times without fail. The drivability is excellent too, no lag, no fuel starvation, or anything. However, if I let the car sit for a few hours, after a normal driving, say 30 minutes or so, I would then have a heck of time starting it again – not at the moment of arrival, or even 30 minutes afterwards, but only after a few hours of sitting. The ~{!0~}sitting~{!1~} time could be anywhere from a few hours to 8 hours. After overnight sitting however, the starting would be fine again.

When the car couldn~{!/~}t start right away, I usually ended up cranking it about 10 times or more, with intermittent frantic gas pumping (I know I am not supposed to, but you would probably do the same under the circumstance!). Then somehow I could catch the engine, with very low and rough idle first. After the idle stabilizes, there is no problem driving it again, whatsoever.

My charging system is okay, the starter is probably okay, since it cranks. There shouldn~{!/~}t be any fuel pump problem, as once I get over the hurdle of hard starting it drives fine. I did have to adjust the air fuel mixture screw one time to pass the smog but I have since turned it back.

What could be my problem? Thanks for your help! ~{!/~}87 930, 40,000 miles

mod · 04-14-2002, 02:07 PM

Answering myself, fuel accumulator? Logical? If it is, where is it? Thanks

stlrj · 04-14-2002, 03:03 PM

Fuel pump check valve would be my guess.

Joe

makaio · 04-14-2002, 07:31 PM

First you need to determine if it is a fuel problem or an electrical problem.

I don't believe it is your acumulator or check valve. If it was your acumulator, it would have a hard time starting when hot.

Hladun · 04-14-2002, 07:53 PM

Just fixed same problem on my 78SC. Joe is right, fuel pump check valve. You can do a fuel rest pressure test if you want to confirm.

stlrj · 04-15-2002, 07:15 AM

Minimun residual pressure after 10 min. 1.6 bar, after 20 min. 1.4 bar. You probably don't have the right gages, (who does?) so all you need to do is remove your air cleaner, feel if there's any resistance when you push up on the sensor plate after 10 to 15 min. If it moves up freely soon after you turn off your engine, replace your check valve.

Cheers,

Joe