924Board.org

Maybe924 · Joined: 14 Aug 2007 Posts: 412 Location: New London, CT

I tested Post #1 on the coil with the ignition in the on position and I get 12.39V

I then tested #15 on the relay board and I also get 12.35V

So the relay is definitely getting voltage.

I also tested Post #1 on the coil when running and as expected I get 13.49V

I wonder if the slightly low voltage output of my battery is causing the issue?
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1981 931 GT (CGT Intercooled)
1985 911 Targa Carrera (Sold)

Smoothie · Posted: Thu Aug 21, 2008 4:26 am Post subject:

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

Could a loose or corroded ground wire from the pump to the body cause this? Or a combination of a corroded wire connection and low battery voltage?

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

Maybe924 · Joined: 14 Aug 2007 Posts: 412 Location: New London, CT

I've cleaned the ground from the pump to the body, I've also cleaned the relay ground and the battery ground.
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1981 931 GT (CGT Intercooled)
1985 911 Targa Carrera (Sold)

462avi · Posted: Thu Aug 21, 2008 5:34 am Post subject:

I recently had some similar issues with my car. I checked timing, fuel pressures, frequency valve, etc. The only indications of an issue were like you, seat of the pants feel and two or more cranks to get her started. I finally got out the carb cleaner and started spraying vacuum lines. What I ultimately found was two cracks in the intake manifold. They we right at the mounting surface that attaches to the head on the intake runners for 3 and 4.

Just my two sense
Geoff
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2005 C230K
2002 grand cherokee with 4.7L

Maybe924 · Joined: 14 Aug 2007 Posts: 412 Location: New London, CT

Funny you say that because this afternoon with the voltage test showing no issues and 2 new fuel pump relays very unlikely to be the source of the problem I turned my attention toward vacuum leaks.

It turns out that my intercooler was not sealing very well at the throttle body and the whole charge tube assembly needed adjusting. So I tore apart the air box and fuel dizzy and re-adjusted the lower charge tube bracket. I got the intercooler to slip a bit more over the throttle body connection and I'm pretty sure she's sealed now. With that done it seems like I may have fixed the hard start and the "lean" feeling I described earlier. I'll know for sure in the morning.

Is this how people manage to get that "extra" fuel pump relay for the glove box that I always hear you guys talking about?
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1981 931 GT (CGT Intercooled)
1985 911 Targa Carrera (Sold)

462avi · Posted: Thu Aug 21, 2008 10:35 am Post subject:

Well I hope it does. I am in the process of reinstalling my intake as we speak. I bought a spare like 8 months ago, thinking I may need it. Dam CIS and it's sensitivity to vacuum leaks! The carb cleaner trick works wonders though. Good Luck

Geoff
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2005 C230K
2002 grand cherokee with 4.7L

Maybe924 · Joined: 14 Aug 2007 Posts: 412 Location: New London, CT

Update:

Although I still don't hear my fuel pump running when an assistant turns the key into the on position, the tightening up of the charge tube assembly has solved the problem of lean running and hesitation. It has also made the car a bit easier to start. I'd say its starting in 1 or 2 less turns. I'm gonna let this issue rest for a bit and I thank everyone for all the help... troubleshooting these problems teaches so much about these cars and the help and interaction is invaluable.

Thanks,
John
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1981 931 GT (CGT Intercooled)
1985 911 Targa Carrera (Sold)