I have been having problems with my fuel pump on 81 S. At first I thought it was the relay so I replaced it and it still does not work right.
When I turn the key the pump will not come on for a second to pressurize the system. And if I try to start the engine it will not start and the pump will not run. When I connect the jumper wire between terminals 30 and 87 the pump runs and the car starts. When I connect the jumper wire between terminals 15 and 87 the pump runs when the key is switched to assesories and again it will start and run fine. Could I have bought a defective fuel pump relay or could my ignition switch be bad. Help, I'm going nuts over this- thanks for any ideas

 

I recently had problems with my '88 cutting out while under power. Turned out to be the fuel pump relay. Try replacing your fuel pump relay with the horn relay. If it's the relay, this should solve the problem. My understanding is that the switches rarely go bad, but you could try wiggling the back of the switch while idling. If it cuts out, that may indicate a bad switch. Also, if the idiot lights light up and/or the tach drops when it cuts out, that may also indicate electrical rather than fuel related.

Good luck!

Larry
88 S4 5sp

 

well if it's normal CIS (like vw and audi), his relay does't work the same as our LH cars. on CIS when you turn the key to ON, the fuel pump pressurizes the system. ours don't do that (ours only do it when cranking). his relay has an extra pin on it and isn't swappable with any other.

if the pump runs with the key ON and START then the ignition switch should be ok.

start by pulling your relay and check for ground on pin 31. if that's ok, i'd try another relay.

 

A somewhat related problem:
On my 83 US model, the fuel pump relay went bad.
No noise from the pump on any ignition switch position. I jumped terminals 87 and 30, and she started right up. I then replaced the relay, and the car again started right up and ran fine for a quick spin around the block.
I parked it for several days, and just now went to start it. It starts and runs fine, but the relay "buzzes" whenever the ignition is on.
We're talking VERY VERY loud......
The car runs fine, but this relay almost sounds like a warning buzzer.
Anybody seen this before??
What can I do to fix it??
Thanks!!
Barry

 

you are right David, it is CIS. The pump will only run when using a jumper wire on terminals 30 & 87 and also terminals 15 & 87 with the ignition on. I'll check for ground on terminal 31 tonight. I was just thinking it was something other than the relay because I just replaced it. Thanks for all your responses.

 

I just went home and checked for ground at terminal 31. I'm not sure if I did it right- I took my volt meter and connected positive with terminal 30 and negative to terminal 31 and it indicated 12 volts. So I assume this means I have ground at pin 31. Does this mean I have a bad relay?

 

Just to clarify - on CIS systems, the starter motor must be engaged to activate the fuel pump.

To test, turn the key just enough to engage the starter for a split second - you should then hear the fuel pump run on for an additional second or two.

 

Thanks for the clarification Randy. BUt even so, my pump will not come on even when cranking. THe only way I can get it on is to remove the relay and use the jumper wire.

I just got off the phone with 928 Intl. and he said being that it is a new relay it is doubtful the relay is bad. He said the relay needs to get power in the start mode but he did not know how to check for that. Anyone know how to check to see if the relay is getting power in start mode?

 

The relay is set up to provide about 2 seconds of power to the pump if it detects voltage at the #15 connector. This gives it time to pressurize the system and provides a safety to keep it from flooding. After the initial 2 seconds it must receive a signal (12 volts) from the ignition module to keep powering the pump. I haven't checked the manual but I believe the run/start signal is fed to the relay on the #15a connector. Try checking for voltage at the 15a connector while the engine is running with a jumper. If no voltage, check the connections at the ignition module on the right front fender well.

Dennis

 

[quote]Originally posted by Dennis Wilson:
<strong>The relay is set up to provide about 2 seconds of power to the pump if it detects voltage at the #15 connector. This gives it time to pressurize the system and provides a safety to keep it from flooding. After the initial 2 seconds it must receive a signal (12 volts) from the ignition module to keep powering the pump.</strong><hr></blockquote>

yep, standard CIS.

actually it's 31b (not 15a) on the relay goes to pin 16 in the ignition unit. but it also shows 2 pin 16 's, so it's the one with the green wire. (the other pin 16 goes to terminal 1 on the coil). so you want to check for voltage at 31b. like Dennis said, it should be there for a couple seconds right when you turn on the key and there when the engine is running.

the wire diagram is <a href="http://www.eskimo.com/~riffraff/images/01300.jpg" target="_blank">here</a> . it's big.

 

Dave,

Thanks for the correction. Guess I'm gonna have to get the manuals out of the garage. 8^)

Randy,

You must go through an awlful lot of starters keeping your shark running. LOL

Dennis

 

For what its worth, when the relay on my 82auto went bad I of course changed the expensive stuff first - fuel pump and filter. She started right up and ran just far enough for me to need a flatbed ride home. Fooling with it in the driveway, I could repeatedly get it to start/run fine for 4 to 5 minutes, then go dead regardless of rpm. New relay fixed the problem. Lesson might be that those little relays are more complicated than 'good' vs 'bad'. Carry the jumper wire, good luck.
RAS