'83 sc won't start...

springerman55 · 09-06-2010, 09:06 PM

My 911 has been sitting for about six months due to some serious medical issues that I had. Now that those issues have been resolved (thank God), I am trying to get the car back to running again but it will not start. The battery is fully charged and it has fuel that had Sta-Bil added prior to being inoperable. The engine spins very fast, it just has that sound like there is no fuel. I did some reading in my Bentley '78-'83 911SC service manual and I have not had a chance to troubleshoot the fuel pump relay, fuel pump fuse, fuel pump circuit, etc. I was wondering if there is something that SCs are notorious for that I am not aware that might be suspect. The car has been otherwise bulletproof in the past. The last time it was driven, it ran great. Any insight would be greatly appreciated...

ischmitz · ischmitz's Garage

It's impossible to tell from sound alone whether it is the fuel or the spark that's preventing it from starting. As an easy test you could spray some starter fluid into the intake. If it fires up you have confrmed that you have a "missing fuel" issue. Else it is a "missing spark" or God forbid both are missing.

Ingo

psalt · 09-07-2010, 03:06 AM

Remove the air filter, turn the key to "ON", manually lift the air flow sensor and listen for the pump for one or two seconds (no more). This will verify that the pump runs and prime the system. Try another start, then check for spark with a spare plug .

springerman55 · 09-07-2010, 08:49 PM

Update on some diagnostics performed this evening. There is voltage present at the fuel pump fuse as well as terminals 87a and 86 of the fuel pump relay socket with the ignition on. Removing the fuel pump relay and jumpering terminals 87a and 30 together bypasses the fuel pump relay and this exercise resulted in the fuel pump doing absolutely nothing with the ignition key on. Not a single sound comes out from underneath the fuel tank/front end. My next step is to get underneath the car, remove the stone guard and measure the voltage at the fuel pump terminals. One side question about the check valve on the fuel pump. The output side of the pump is the pressure side so I assume that the check valve prevents pressurized fuel from re-entering back into the fuel pump? Looks like I will be buying a new fuel pump soon.

sk6f3 · 01-22-2011, 01:27 PM

My 82SC would turn over but not start yesterday afternoon when I tried to leave work.

I left my car in our secure outdoor parking lot, and got a ride home from a co-worker.

Last night, I searched, found this thread, and considered the troubleshooting tips presented.

Armed with a few tools and few new ideas, my wife and I drove back to my workplace today.

I tried to start the car, no change, turns over but no start.

I sprayed starting fluid in the intake and turned the key. It started, but would not continue to run. Must be a fuel problem.

I checked fuses and switched relays, no start.

I removed the air filter, turned the key on and lifted the air flow plate. As I lifted the plate, I got a strange buzzing sound from behind the fuel distributor, but I could not hear the fuel pump run or hear fuel spraying from the injectors.

It seemed my fuel pump might be bad.

I laid on the ground, removed the rock cover and tapped on the fuel pump with a small hammer. I got up, dusted my self off, turn the key and the car started normally and continued to run.

My wife followed me home, just in case, but my SC ran great.

It is now in my garage, I intend to replace he fuel pump.

Thanks to this forum for helping me to get my car home under its own power!

fritzgator · fritzgator's Garage

When checking fuses, remove and replace at the least, not just visual check. Give them a spin or two or swap w/ another of same amperage.

psalt · 01-23-2011, 06:09 AM

sk6f3,

This is SOP on a British car with an SU fuel pump, maybe there's an E Type in your future....The buzzing you heard was the Frequency Valve for the lambda system.

mtndawg · 07:16 AM

I had the exact issue last week. I have good contact at the fuse, and voltage at the relay, when I jumped the relay and opened the sensor plate with the key on, there was no fuel at the injectors. I tapped on the pump a couple of times and the car started right up. I got an original pump (rebuilt) from Fuel Injection Corp in Livermore, Ca. Very affordable, with a warranty! With the new pump in, I primed it by jumping the relay with the key on. Once the pump was pushing fuel through the lines the car started on the first try.

Bob Kontak · Bob Kontak's Garage

Before springing for a fuel pump try psalt's suggestion of lifting the air sensor with the key on.