arbeitm

In going through my latest problem, I discovered that my fuel pump runs all the time when it's not supposed to.

I know the first place to check is the connection behind the fuel distributor. Can anyone pinpoint exactly where this connection is. A photo would be great!

TroyN

Out of curiosity, when is the pump running when it shouldn't? I guess I'd suspect the fuel pump relay or ignition switch first. What is behind the fuel distributor?

arbeitm

It shouldn't run when the key is in the "on" position.

I'm starting to wonder if I'm wrong anyway.

The green connector behind the air meter is plugged in. Nothing is unplugged at the fuse box.

I checked for ground at pin 35 on the fuel pump relay and it is good.

Could I be mistaking the noise of the fuel pump. What should I hear when I turn the ignition on? I hear a faint buzzing from the front of the car as well as the hum in the engine compartment (which I know is normal).

justinsrx7

Is your engine stock? When I got my car, my fuel pump was running as soon as I turned the ignition one click. My '78 has an '86 engine, and it wasn't wired properly. It is fixed now. If yours was working fine before but now doesn't, I am sorry but I have no suggestions for you. Good luck!

TroyN

My pump runs in "run" too. In fact all of the SCs I've tried do the same thing.

Hladun1

When the ignition is on but the engine is not cranking or running the CIS flapper contact is closed and energizes a relay the turns the fuel pump OFF. The relay is on the front fuse panel. It's called the fuel pump relay but this is an erroneous description because it turns the pump OFF not ON. (To prevent arguments, the pump is actually energized through normally closed contacts on the relay; OK) The problem is that the pins lose contact and the fuel pump then runs whenever the ignition is ON. To fix it take out the relay and gently (and I mean gently) spread the pins with a knife blade. The fuel pump should then NOT run until flapper lifts.

Remember that this is a safety system that turns the fuel pump off when the ignition is on but there is no aiflow through the engine (engine not running). This is a situation that can occur in an accident. If your CIS is old it's probably actually better to pressurize the system before cranking starts. Just remember to turn off your ignition just prior to a major crash!

arbeitm

I just ordered the red relay to replace the black one that is in there. We'll see if that changes anything...I doubt it. I'm probably going to have to pull the full panel off so I can see if the wiring was changed.

Hladun1

Well certainly the change in color will be nice. New relay should solve the problem. When the new red relay eventually fails re-read my first post before you start tearing yor car appart....but then it's your car.

theiceman

okay slow down here a minute

the SC pump DOES NOT run with the ignition on , and should not
it should only run when the engine is cranking. Matt i have a pic i would be happy to post from my air box adventure.
The hum at the back as you suggest is normal. it is the ignition module. if you are not sure if the pump is running or not with ignition on do this test .
Take the air filter cover off, remove the air filter, each under and slightly lift the air plate with the ignition on , you should DEFINIELY here the pump run. if you all of a sudden here it you will know it.
Alternatively climb under and hook a voltmeter to the pump . when you turn on the ignition you should not have 12v to the pump , if you do then the pump is runing . turn off immediately.
if the pump IS running you are dumping gas into the intake plenum and cylinders without combustion. Can flood the engine and thin the oil .
As far as the relay goes it is suppose to be a red one yes, but it can be swapped with any other relay to test. I would do that before ordering another one.
I am not sure if you can remove the electrical connectors with the pump in place but if it were me. I would do that and do all the testing looking for 12v at the pump without the pump connected so i am not pumping fuel. you may find it is not your fuel pump at all but maybe some thing else like a fan or blower or something .

Anyway here is the pic.

Good luck

arbeitm

ICE - that picture is exactly what I was looking for. Thanks. It just confirms I was looking at the right plug and it is definitely connected back there.

I think your idea of checking for 12V at the pump with the ignition ON is a really good idea. That will defintely confirm if the pump is running or not. UGH...I have to take off that damn metal plate.

I tried swapping out different relays and there was no change. It's supposed to have the red one anyway, so I might as well put it in there regardless. And I did do the check on the air plate, but it's hard to hear the pump because of the buzzing and the high pitched sound it makes when you push that lever.

I don't think it's anything else, because when I pull the relay the noise stops. I think the next step is to check the voltage at the pump like you said. Thanks for the help.

Houpty GT

Pin 85 is the one that should have ground on it when the ignition is on or not and the pump is not running. This is the pin that is the fourth one towards the rear of the car of the 4 that are grouped together. You can insert the relay halfway so it will work and also give you access to check the pins while the pump is running.

Ice: If the pump is running and the airflow plate is closed, I don't think there is any fuel being injected into the engine. This is a typical test that is performed with the fuel pressure gauge anyway. The fuel is just recirculated back into the gas tank. I think the safety feature is more for the occurence of a fuel line rupture during an accident. Though, others have pointed out that if the car is upside down so will the flapper and you are going to burn.

GothingNC

Here is another thread from Pelican

http://forums.pelicanparts.com/showt...44#post3033344

John

theiceman

great point about the palye you are right. if the air plate isn't lifted the fuel distributor will not release fuel to the lines. Good catch. DIDm't even realize these cars had a return line to the tank.

Anyway i think we are on the right track. The meter will tell us for sure.

arbeitm

So today I pull off the protection plate beneath the car and confirmed that the fuel pump is running when I have the ignition in the ON position.

1. The fuel pump Relay is new.

2. I pulled off the relay/fuse panel to check out if anyone modified the wiring for a jumper...it does not look tampered with.

3. All plugs behind the mixture control unit are plugged in.

So my thinking is that maybe the problem is with the switch that tells the relay the air flow sensor plate is moving. I don't know where the switch is exactly and how to check it out.

theiceman

that is definitely what it sounds like. What happens if you just unplug it ? does the 12v to the pump stop ?

honestly I am not sure if it is normally open or mormaly closed, but i am sure someone would know. But if it were me i would monitor the 12v at the pump , then unplug it and see what happens, if it still stays on I would then short out the two poles of the harness and see what happens. That will tell ou a lot. if unplugging it or shorting it kills the 12 v then it is the switch. I can't remember exactly how it works though. And I had the whole thing of too grrrrrrr,,,Pete probably knows.