fuel pump relay

[Dklever48]

I am having an issue with a 1983 911 Targa. I need someone to tell me where to find the fuel pump relay switch. I have looked eveyrwhere and either I cannot identify or it is hiding. This is my first attempt at repairs so need help.

[Targalid]

I believe it is that round red thingy in your fuse box in the front of the car. If you read the labels on the fuse panel cover it names the components within.

[Oh Haha]

Front trunk, driver's side. Remove the plastic cover and read the layout. The fuel pump relay is almost always red. You CAN use a black one to test, like from the power windows.

[Dklever48]

Guess I am not as flakey as I thought. I have tried that. I reokaced the red relay switch with the one from the air conditioner and got the same results. Now I am back to square one. The car fires and starts when you turn on the key but will not stay running when the rwitch gors to the run position. I have replaced the switch already. This car was running just fine a week ago.

[Oh Haha]

It shuts off as soon as the key goes back to "run"?

Do you have an alarm?

[ossiblue]

I've noticed you have posted the same problem in a couple of different threads. For the best results, try and keep everything in one thread so we all can read the history and feedback of your efforts. I suggest you use this current thread as the only one until your problem is solved.

Now that you have identified the relay correctly, you still need to see if the fuel pump will run with the key in the "on" position. Remove the air cleaner, turn on the ignition and gently lift the plunger inside the air intake. Does the fuel pump start to run? Do you hear the injectors "squeal"? (Caution, if you hear the pump begin to run, do not hold up the plunger for more than 10 seconds.) Report your results.

Second test is to pull the relay and jump sockets 30 and 87a, turn on the ignition and see if the pump runs. Report your results.

If you get the pump to run during both the above tests, your problem is likely ignition related.

[Dklever48]

I took the air cleaner off and turned the ignition switch to the on position and location a flapper in the upper right corner of the air cleaner right under the injectors. I lifted this up and nothing happened and I could hear nothing running besides the fan. Do I have a bad fuel pump? the reason I did not think that was it is because the car does start when the starter is ingaged but cuts out when you release the key. Sorry for the dual thread.

[john walker's workshop]

lifting the sensor plate for 10 seconds could flood it. 2 seconds is enough time to feel the pump pressure and hear the injectors whine.

[ossiblue]

Originally Posted by Dklever48

I took the air cleaner off and turned the ignition switch to the on position and location a flapper in the upper right corner of the air cleaner right under the injectors. I lifted this up and nothing happened and I could hear nothing running besides the fan. Do I have a bad fuel pump? the reason I did not think that was it is because the car does start when the starter is ingaged but cuts out when you release the key. Sorry for the dual thread.

As long as there is some fuel pressure in the system, the cold start injector will shoot fuel into the intake during the "start" sequence. In a normal car, that will get the engine to fire immediately and when the key is released to the "run" position, the fuel pump will be running to feed the injectors and keep the engine going.

What you are probably experiencing is a bad fuel pump/pump circuit as you suspect, and the brief firing was from the cold start valve.

Try the jumper test at the relay as that will supply current directly to the pump with the ignition on. If the pump still doesn't run, you can check the voltage at the connectors to the pump with a voltmeter or test light (pump is under the steering rack, passenger side, behind the metal shield which has to be removed--4 bolts.) If you are getting power to the pump, then the circuit is good so your pump is likely gone. You may wish to give it a wack with a hammer to see if it begins to run. If it does, you still will need to replace it.

[Dklever48]

I am totally confused now. With the switch in the on position I ran a jumper wire from the battery to the fuel pump and the car started and ran as long as I had the jump wire on the fuel pump so somewhere along the line I am not getting power to the fuel pump. The pump does not run it the switch "ON" position. Again, I thought the relay ,ight be bad but I used the relay from the AC and still nothing. What next?

[fred cook]

Check the fp relay fuse. I believe it would be #16 from the front of the fuse panel. Check for corrosion on the fuse, correct spring tension on the brass tab that holds the fuse and for corrosion on the wires that are connected to the top and bottom of the #16 fuse holder. A .22 rimfire rifle bore brush is the right size to clean the holes where the wires are connected. You can put a #2 wood pencil in a drill with the eraser end out to use as a mild abrasive to clean the fuse holder ends. If the wires are badly corroded, you might need to cut them back about 1/4" to get to clean copper.

Another place to look would be at the safety switch mounted on the CIS intake that prevents the fuel pump from running if the engine is not running. You should be able to simply remove the plug attached to the switch and be able to hear the fuel pump run with the key in the run position but with the engine not started. If so, try starting the engine. If it starts, replace the safety switch.

Hope this helps!

[Dklever48]

I do not have an alarm system

[Dklever48]

I am sorry but I am new at this. Where is the safety switch I need to be checking and what is the CIS

[boyt911sc]

Originally Posted by Dklever48

I am totally confused now. With the switch in the on position I ran a jumper wire from the battery to the fuel pump and the car started and ran as long as I had the jump wire on the fuel pump so somewhere along the line I am not getting power to the fuel pump. The pump does not run it the switch "ON" position. Again, I thought the relay ,ight be bad but I used the relay from the AC and still nothing. What next?

DKlever,

You are doing it all wrong!!!! You need to isolate the problem (circuitry) and identify where the anomaly occurs. If I were in your shoes, I would do the following simple tests.

Here is the basic test for the FP and relay circuitry:
1). Pull out the FP relay and do the test (ignition switch @ OFF position) for the individual terminal at the socket: A simple 12-volt self-powered test light will work well for this test or a regular non-powered test light, or a volt meter.

87...........no power
87a.........no power
86...........no power (87a 86 are bridged)
85...........no power (should be grounded at this point)
30...........no power (has ground contact?)

2). Turn ignition switch @ ON position (not start):

87............no power
87a..........has power
86...........has power
85...........no power, presence of ground contact
30...........no power, presence of ground contact

3). Next, insert the FP relay into the socket and turn the ignition SW @ ON position (not start):

87...........has power
87a.........no power
86...........no power
85...........should have ground contact
30...........no power but exhibit ground contact.

4). To test terminals #30 and #85, follow test #3 and do the following:
a). Remove the air filter cover and filter.
b). Lift the AFS (air flow sensor) very briefly (no more than a few seconds) Three (3) seconds are too long for this test. The FP should run and deliver fuel to the injectors.

All the above is for a NORMAL operating FP and relay circuitry. Any deviation for these conditions will identify the culprit/s. The FP is good and out of the equation. If you have any question/s, just ask. Keep us posted.

Tony

[ossiblue]

Originally Posted by Dklever48

I am sorry but I am new at this. Where is the safety switch I need to be checking and what is the CIS

Follow Tony's steps in your diagnosis and don't worry about anything else at this point as you have established the pump is good. Read over his steps as many times as necessary to understand them and ask any questions if you are not sure. Remember, diagnosis is the first and most important step and that's what you are doing.

The "safety switch" is the air-flow sensor in the intake that provides a ground to the fuel pump relay (terminal 85) and is switched open by the intake plunger that you raised in an earlier test. Tony's tests will determine if the switch is operating properly.

CIS is the type of fuel injection system on your car--Continuous Injection System. It means all the injectors are continuously injecting fuel to all the cylinders at the same time (that's why you shouldn't lift the plunger for more than a couple of seconds when doing fuel pump tests as fuel is being shot into all ports which can rapidly lead to flooding or hydro-lock.)

[Dklever48]

You guys are great. Part of my problem is I do not have a diagram of the circut but I am assuming the when I pull the relay out the botton prong is the graound and the top left as you look at the box is the 87 then 87a then 86 and then 85. Is that correct?

[boyt911sc]

Originally Posted by Dklever48

You guys are great. Part of my problem is I do not have a diagram of the circut but I am assuming the when I pull the relay out the botton prong is the graound and the top left as you look at the box is the 87 then 87a then 86 and then 85. Is that correct?

DKlever,

We all started some where about this subject at one point in our lives. Some people are blessed with experience and others trying to learn. So you are not alone and this problem has been asked around so many times and will be asked again!!!! Getting a reference wiring diagram would make life more easier. To answer your question, NO!!! But there is a small probability it maybe. Why?

Take a good look at the back side of the red FP relay: The 5 terminals are #30, #86, #87, #87a, and #85 in clockwise order (orientation). The socket side would have the mirror image orientation. And depending how the FP socket is installed you might have a different terminal # at 6 o'clock position. But most of the FP sockets that I've seen have the FP terminal (#30) at 6 o'clock position.

Assuming you have the #30 terminal at the bottom (6 o'clock) for the socket and the rest would be:

#87a........between 10-11 o'clock position
#87..........around 1-2 o'clock
#86..........around 4-5 o'clock
#85..........around 7-8 o'clock
#30..........at 6 o'clock

When I jumper the FP (using my set-up), I simply use 6 and 11 o'clock terminals to do the test. So the critical setting is having the terminal #30 at the bottom (lowest position) for the socket and everything would easy to digest. If I may suggest, a good way to get a better understanding is draw or sketch the diagram until you could fully comprehend or remember it. All you need now is some practice. And keep us posted.

Tony

[Dklever48]

I have located the correct numbers and yes, 30 is at the bottom. The test 1 works out OK, test two works out OK as well but test three I get totally different results. 87 has no power, 87a has power and 86 has power

[Dklever48]

what should I try jumping accrools to get the fuel pump to run?

[Dklever48]

when I jump the 30 and 87a what should I expect to happen?