Relay is good. No power to fuel pump., Now what?? Options

[KaptKaos]

UPDATE: Self inflicted wounds are the worst. She's running.

So the other day when I was charging the battery, I knocked loose one of the 4 leads off of the positive terminal of the battery. I didn't know I had done it.

I am not sure what made me go check the battery, but as soon as I did, the wire dropped out.

Tom - I think that this is what your fuse box is for? Figures.

Thanks for all of your help.

Swapped in known good relay from headlight motor for fuel pump. No dice. No power to the fuel pump.

Fuses all look good. Going to replace the fuel pump one anyway.

Trans ground looks ok, but think I will double-check that.

Is there anything else I should be looking for?

Not sure if this is related, but a few weeks ago, my dash lights stopped lighting. The blinkers and idiot lights work, just not the illumination when the headlights are on.


I actually have some time this morning, and am going to try to diagnose my fuel pump issues.

Got a multi-meter, got some help to turn the key, and got a local VW store I can get a new pump or relay from.

So, which relay on the panel in the engine bay is for the fuel pump? I have a SirAndy Jumper in there (see his classic article).

Also, my multi-meter has ranges. Which setting should I use to test for power to the fuel pump?

Thanks in advance.

[Mike Bellis]

(IMG:style_emoticons/default/biggrin.gif)

[KaptKaos]

Thanks Mike!

[walterolin]

KG6DXN beat me to it. The Haynes manual shows the same configuration through 1973. I didn't see pictures for 74-76.

To check for voltage, set you multimeter to a scale that will read 12 volts DC, say 0-50 depending on the meter.

This also assumes that a PO didn't "improve" the wiring, my FP was jury rigged off another relay.

K4NVQ

[KaptKaos]

Update in first post.

[TravisNeff]

Try Brad anders DJET page, he has a fuel pump diagnostics routine you can do.

[markb]

You started from the beginning, and spun all the fuses in their holders before anything else, correct?

Grounds all cleaned?

Good ignition switch?

You can also spread the relay contacts just a little to make sure they're making good contact (the Cap'n had to do this on my relay board the other day).

Everything electrical on these cars is hooked together, so something seemingly unrelated can affect the strangest things. (IMG:style_emoticons/default/blink.gif)

[KaptKaos]

Try Brad anders DJET page, he has a fuel pump diagnostics routine you can do.

Link? I don't know Brad Anders. Thanks.

[KaptKaos]

You started from the beginning, and spun all the fuses in their holders before anything else, correct? Yes, will check again.

Grounds all cleaned? Other than the battery and trans strap, where else do I look?

Good ignition switch? Was working until last weekend. Still turns everything else on.

You can also spread the relay contacts just a little to make sure they're making good contact (the Cap'n had to do this on my relay board the other day). Will try that too.

Everything electrical on these cars is hooked together, so something seemingly unrelated can affect the strangest things. (IMG:style_emoticons/default/blink.gif)

Thanks!

[markb]

Do a quick search here for ground points. I'm not sure if I remember them all off the top of my head. One by the fuse panel, one below the relay board, one on top of the engine, one for each of the headlights, battery ground strap, tranny ground strap. I think that's all of them.

[TravisNeff]

http://members.rennlist.com/pbanders/FPChecklist_frame.htm

And more great DJET Stuff
http://members.rennlist.com/pbanders/

[Tom]

With your multimeter on 50 volt scale, check pin 30 on the fuel pump relay for 12 volts. Should be there all the time. If not, your fuse may be bad. Second one from front. If that is good, check for 12 volts at pin 85 of the fuel pump relay with the key to on. If no power, your power relay ( second from front) may be bad or connections bad. If you have that and the ground is good, the relay should operate and provide 12 volts to pin 87 of the fuel pump relay ( same electrically as pin 13 of the 14 pin connector. If you have power here, your fuel pump is bad or has bad connections between pin 13 and the fuel pump.
Tom

[KaptKaos]

With your multimeter on 50 volt scale, check pin 30 on the fuel pump relay for 12 volts. Should be there all the time.

Yes - have 12V there.

If not, your fuse may be bad. Second one from front. If that is good, check for 12 volts at pin 85 of the fuel pump relay with the key to on. If no power, your power relay ( second from front) may be bad or connections bad.

No power there. I swapped the power relay, with no change. So either I have a handful of bad relays (which I don't think that I do) or the problem is elsewhere.

Now where should I look?

Thanks again - this is very helpful.

[TravisNeff]

Do you have a spare relay board? yours could be bad - that flowchart will help you pinpoint it. You can take the tar off the bottom & resolder to fix (if that's what the root cause is).

Check for the 3 grounds at the rear, top of the engine, & ground point under the relay board.

[Tom]

I have had these relay problems before and found out the relays are OK but not making good contact with the female side on the relay board. Try taking a sharp knife and GENTLY pry the male prongs apart very slightly. This helps make good contact in the female sockets.
If you have no power at pin 85 with the key switch to on, your fuel pump relay will not work.
Tom

[KaptKaos]

I am thinking I need to focus on the power supply relay, yes??

[Mike Bellis]

Before you get too deep. have you verified the fuel pump works? Jumper power to it, or the relay terminal. Just make sure your not chasing a ghost.

[KaptKaos]

Not getting power to the pump at all. I ran my meter on it, no dice. I am also not getting power to the correct pin on the fuel pump relay.

So I am not sure where to go next. Ideas?

I spread the male pins on the relays to see if that helped, but no dice.

I was looking at SirAndy's fuel pump article, See here: http://www.914world.com/specs/SirAndyCarbFuelPumpRelay.php

If you look at his "Last Resort" method all the way at the end of the article, it says to run a jumper to that pin on T4b. I don't get power here with the key on either.

I am not sure that this is related, but it seems too odd.

Could there be an issue with my ignition switch or something by my fuse panel?

[TravisNeff]

Is this a DJET engine? the ECU controls power to the fuel pump. That's why the grounds on the block are important - the pump should run for a few seconds when you turn the key to the "on" position, then stop - until the engine is started.

[KaptKaos]

Updated. See the top. Thanks for all of your help.