83 ignition left on... fuel pump running for hour ..no start ... ideas

[uksailmaker]

I moved my 83 911 out of my drive to get another car and left the key in the on position with fuel pump running.

Plumber working next door goes ... hey buddy your car is making a humming noise

I smell fuel and did not start. Turned over but battery starting to drain a bit.
i pushed back into drive let it sit overnight with battery charger on trickle and next day tried again. Put charger on start mode and Will not start and smells like fuel again

My Indy is great guy but 100% German so when I called he was leaving for Octoberfest in Bavaria and will not be home for 3 weeks.

Like to drive my car but now afraid to start it if it will start. He told me to AAA to him when he returns that plugs have been soaked with fuel and may also have gas in oil.

Sound right to you guys. Should I try to start, remove plugs or AAA.

Only other possible problem is I added one bottle oil and checked still low added a 2nd bottle putting it between marks on dip stick and just above half on gauge. It was hot and sitting level but maybe I put too much oil

thanks as always

[john walker's workshop]

hold throttle to the floor and crank until it starts is the generally accepted way to start a flooded engine. a long crank, not short little blips. or pull the plugs and clean, dry or replace them.

[psalt]

The fuel pump should not run on an 83 911SC with the key ON and the engine not running. You have another problem. If the injectors and CSV are to spec, no fuel should enter the engine with the FP ON at rest. I would check the air flow meter safety switch, fuel pump wiring circuit and check the injectors and CSV for leaks.

[prschmn]

If you have an SC leaving the ignition on without running for that long may have damaged your CDI box. If you can't hear a high pitched while from it it may well be dead.

[911scnorm]

Uksailmaker..

About 6 month ago I noticed the same problem with my car, the fuel pump would run with the ignition on and the motor not running. After some investigating I discovered that the issue was at the fuel pump relay switch. The fuel pump relay was removed and replaced with a setup jumping the relay. I removed the jump setup and replaced replace it with a relay switch, much to my surprise the fuel pump would not work...I think the wiring at the fuel pump switch were rewired. Because I'm not familiar with electrical issues I just replaced the jumper wire and have been living with the knowledge that the fuel pump will run went the ignition is on.

As a side note, I purchased the car about 3 years ago from a friend. He had the car sitting for about 15 years before I started reviving it. Prior to the car sitting for 15 years my friend always had the car serviced at the dealer, I'm inclined to believe that this was done at the dealer, but I have no proof. Can anyone shed some light as the possible reason for this setup and potential issues. Thanks

Norm

[psalt]

Can anyone shed some light as the possible reason for this setup and potential issues. Thanks

Norm

The reason the fuel pump should not run with the engine at rest and the key ON is crash safety. The air flow meter contacts kill the fuel pump power so that in the event of a crash where the engine stalls, the pump does not keep pumping fuel. Modern cars with EFI use inertia switches for this purpose. Usually the problem of the FP running with the Key ON is an unplugged air flow meter switch or mis adjusted contact. You need to review the wiring diagram for your model, the alarm system and the rev limiter are in the same circuit, depending on year. The FP is powered when the key is in START, then a different path powers it after the engine fires and lifts the air flow sensor plate, which can be killed by the air flow meter switch, the alarm or the rev limiter on an 83 911SC.

[uksailmaker]

Thanks guys

Sidenote I am saying the FP is running with key on but maybe it is somthing else.

When key is turned on there is a humming noise in front. Is that the FP

Also when I bought this car 18 months ago, I had an issue with not starting when hot. My mechanic told me that if you turn the key on for 10 seconds before starting it would start and has started in this manner. However if you try to start without waiting it will not start unless you hold up the arm inside air box (what is this arm)??

Indy said I need fuel accumulator and it is about $300-400 installed

Does any of that make sense to you guys.

Would any of the above related to my current issue

[uksailmaker]

[Flat6pac]

I have to go with Psalt on this problem. Sounds like the airflow sensor and cold start injector wire is mixed up in the front of the fuel injection. the cold start injector is suposed to ohm with the temp sensor on the chain cover left rear.
Bruce

[boyt911sc]

Originally Posted by uksailmaker

Thanks guys

Sidenote I am saying the FP is running with key on but maybe it is somthing else.

When key is turned on there is a humming noise in front. Is that the FP

Also when I bought this car 18 months ago, I had an issue with not starting when hot. My mechanic told me that if you turn the key on for 10 seconds before starting it would start and has started in this manner. However if you try to start without waiting it will not start unless you hold up the arm inside air box (what is this arm)??

Indy said I need fuel accumulator and it is about $300-400 installed

Does any of that make sense to you guys.

Would any of the above related to my current issue

uksailmaker,

There is a very simple technique to determine if the AFS (air flow switch/sensor) is causing the problem. Remove the FP relay and turn the ignition switch to ON/Run (not start). Use a test lamp/lite to test terminal #85 (FP relay socket). There should be ground @#85 at this point. Or the AFS plug is not connected or an open line.

Another scenario is that the FP relay could be bad. The Normally closed (NC) #87a-#30 could be stuck closed causing the FP to run once you turn the ignition switch @ ON. Or there is wiring connection anomaly in the circuit. You don't have to wait 10 seconds to make it run. If the car does not start immediately on the first crank there, is something wrong within the system. Either fuel pressure or unmetered air or something else. You could check these problems without guessing. Test and verify.

Your mechanic probably discovered that waiting 10 seconds makes the car start better with the FP running. In the first place he should know that the FP should not be running and it is building fuel pressure to compensate for the low residual pressure. A new fuel accumulator is about $120 from our host and it is a 5-10 minute job to install it. Keep us posted.

Tony