Fuel Pump Runs Constantly with Key in On (but not started)
 

Per the title, I recently got my SC back from the shop and it is running great. However I noticed something odd. When I turn the key to On, but not yet to Start, the fuel pump runs. I expected this. But it keeps running and running.

If I recall properly, it is supposed to stop after a few seconds, probably when fuel pressure is achieved. Am I remembering correctly?

Isn't that normal to keep the pressure on until shut down? I think what you are hearing is the pump ready to go. My new PAG pump started to make noise after 2 years. :-( put old one back quite as a whisper.

Ok, I won't worry. It is just kind of weird to hear it running and running and running. I guess that means I should stop thinking about it and start her up!

I could be wrong but others will chime in I'm sure :-/

If the problem is on your '79SC then I had the same problem on my '79SC. The fuel pump is only supposed to run in the start position and, of course, when the engine is running. In my case it was a faulty URO fuel pump relay. It acted as any other black relay because the NC (Normally Closed) contact eventually did not work any more. Changed to a functioning "Wehrle" red fuel pump relay, single pole - double throw, fuel pump relay and the problem was solved.

If the sensor plate green plug is off, the pump runs.

Or the cold start injector and the air flow connectors are mixed up on the front of the fuel injection.
Bruce

I'll double check these. The shop had the fuel distributor out while they were hunting my engine issues two Fridays ago. I know those connections like the back of my... throttle body!

I have had my 3.2 for 5 years and when I turn the key to on I hear the fuel pump. Stays on, does not go off.

Sure enough, I reached back and the cold start injector connector had nothing on it, and the one on the distributor (pressure sensor?) had the injector's wire. The other wire was hanging loose.

Obviously if you don't know what you are feeling for and don't take off the spaceship boot, you can't see what's going on, and SCs are weird, so I forgive the shop. I switched 'em back with one hand in 2 minutes before I rolled out to work.

Now she starts more easily (amazing what the injector will do for you!) and has no constant FP running. I'll link a picture for Nick and anyone else who might come by.

Here is the view from the front. The throttle body and spaceship boot have been removed so you can see the two teal connectors.

The one on the upper right is the sensor from the fuel distributor. I believe it tells the FP when pressure is reached, to turn off the FP pre-start.
The one in the center is for the cold start injector. It sprays fuel into the airbox and to the cylinder heads to get extra gas for the initial start.
http://forums.pelicanparts.com/uploa...1440510398.jpg

Here is the view of the back, with the CIS system out of the car on my workbench. You can see the fuel distributor connection in the center, and the cold start injector down on the right. I believe the cold start injector connection is an "output" and the fuel distributor connection is an "input" as far as the systems are concerned. So swapping them results in neither having an effect. You'd have trouble starting when cold, and your FP would keep running.
http://forums.pelicanparts.com/uploa...1440510553.jpg

OsoMoore,

When I first got my SC I took it to a shop because of all the CIS issues. Same thing happened as you. I posted the same question and John Walker posted the same answer. I plugged the sensor plate wire back it and my CIS issues I paid the shop to fix came back.

I suspect this is a poor man's way of overcoming starting issues by causing the fuel pump to run and pre-pressurize the fuel lines before cranking. I'm not saying the shop did anything unscrupulous in your case -- it could've been an accident -- but I certainly believe it to be the case in my situation.

It is my understanding that in a rollover event, that connection also is designed to shut off the fuel pump so it is important to have it connected and fix the real problem.

Did some more reading - the sensor is actually called the fuel pump safety switch. And as you can see in my picture, it is actually on the air sensor plate assembly.

I think it was an accident. I recall the mechanic saying something about how he bypassed the fuel pump safety switch and the pressure (control pressure?) was too high and the injectors were leaking despite no sensor plate displacement. He must have put it back wrong when checking something else.

In any event, it is now quicker to start and doesn't idle the FP nonstop. Now if only the sun would come back out!

Glad you are enjoying you car again!

Outstanding!