TheSamba.com :: View topic - Fuel pump wiring..Relay. (please take a look any help wba)

Tue Jul 01, 2008 6:44 pm

Ok looked under the dash of my 1970 squareback and found this mess... Could this be the reason that the fuel pump is not working? What should I use to clean the fuse contacts?

Tue Jul 01, 2008 7:06 pm

if you don't already have another source use this to make sure everything is wired correctly.
http://www.thesamba.com/vw/archives/info/wiring/type3_6870.jpg
disconeect the battery and some emory cloth or 400 -600 sandpaper should work well to clean all your contacts.I would also put the 8amp fuses where they should go instead of using all 16amp.check all your grounds and them check them again.

Tue Jul 01, 2008 7:23 pm

Thanks for the help. I traced a wire that was not connected in the fron to this part. I am assuming it should be connected somewhere?

Tue Jul 01, 2008 7:47 pm

Dramaguy wrote: Thanks for the help. I traced a wire that was not connected in the fron to this part. I am assuming it should be connected somewhere?

not sure exactly what on earth that wire could be, but I have seen one of my MAP sensors with a ground prong like that one. I dont think it should be connected to anything honestly, and it's definitely not factory.

Tue Jul 01, 2008 8:00 pm

Thanks man. I am wondering if when I replaced the fuel lines if reversed the fuel pump wire.... Shoul I try reversing it? I did unplug it.

Tue Jul 01, 2008 8:02 pm

Dramaguy wrote: Thanks man. I am wondering if when I replaced the fuel lines if reversed the fuel pump wire.... Shoul I try reversing it? I did unplug it.

the fuel pump should have a plastic plug on the end that only goes in one way.

Tue Jul 01, 2008 8:06 pm

OK.. So that eliminates that. How do I hotwire it to see if it pumps?

Tue Jul 01, 2008 8:12 pm

Dramaguy wrote: OK.. So that eliminates that. How do I hotwire it to see if it pumps?

I wouldn't hotwire it. Follow the wiring diagram and make sure everything is wired up correctly at the relay and the fuse box. then give it a whirl. if it doesn't work, test the relay for failure, as its more likely the culprit if the fuel pump is not pumping.

also, did you check the fuel pump wire in the engine compartment?

Tue Jul 01, 2008 8:26 pm

im gonna check the relay. I can't find that pump wire from the schematic.. what is it close to? sorry for being such a noob, but it's been a while since I worked on one of these.

Tue Jul 01, 2008 8:54 pm

I went to the parts store and they gave me a relay for the fuel pump, but it only has four prongs as opposed to five? thant can't be good right?

Tue Jul 01, 2008 9:39 pm

Dramaguy wrote: I went to the parts store and they gave me a relay for the fuel pump, but it only has four prongs as opposed to five? thant can't be good right?

they probably gave you the wrong relay. ask for the "rear defroster" relay for a t3, it is the same part number as the FI relays.

as for a wiring schematic, gimme till tomorrow to scan my manual with the diagram and then I'll post it up.

OR you can go to Russ's webpage, which escapes me right now, that he has the manual all scanned in.

Tue Jul 01, 2008 10:03 pm

Cool I will do. Thanks for all the help, I really appreciate it.

Tue Jul 01, 2008 10:40 pm

Dramaguy wrote: Thanks for the help. I traced a wire that was not connected in the fron to this part. I am assuming it should be connected somewhere?

That is an extra ground wire for the manifold pressure sensor pictured. I read somewhere it was sometimes retrofitted to ensure the case was grounded. Odd thing, it doesn't really need to be grounded to work. Might have acted as shielding so ignition noise didn't affect the sensor's coils.

Tue Jul 01, 2008 11:38 pm

If you do not have an automatic, then there should be an extra red wire coming from the front of the car near the fuel pump relay, and comes out in the harness that has the wire for the oil sender. It is a red wire, and is only used on the automatic tranmissioned cars.
When you turn your key one, the fuel pump will not run continuously. It will only run for about 1-2 sec and then shut off, unless your are cranking the engine or running the engine.
When you turn the key on, you should hear 2 clicks, about 2 seconds apart. The first is the power relay for the fuel injection, and the second is the pump shutting back off. If you do not hear this, then you need to find why the relays are not coming in. It could be that the power relay under the rear seat has lost its ground, or the power wire from the battery is corroded. The Computer for the fuel injection controls the pump, so the computer has to get power before the pump can run.

Wed Jul 02, 2008 2:51 pm

Easy way to test if your relay is the problem or something else:
(a variation on the "hotwiring" you requested)

Detach the two red wires from the relay, and (with the key in the on position) touch them to each other. This will cause the fuel pump to run continuously. If this works, then the problem is the relay; if this does not work, the problem lies elsewhere.

Wed Jul 02, 2008 3:10 pm

I got a new relay today, and I can't wait to get home hook it up, and see if I can get her started.

Wed Jul 02, 2008 3:12 pm

Russ Wolfe wrote: If you do not have an automatic, then there should be an extra red wire coming from the front of the car near the fuel pump relay, and comes out in the harness that has the wire for the oil sender. It is a red wire, and is only used on the automatic tranmissioned cars.
When you turn your key one, the fuel pump will not run continuously. It will only run for about 1-2 sec and then shut off, unless your are cranking the engine or running the engine.
When you turn the key on, you should hear 2 clicks, about 2 seconds apart. The first is the power relay for the fuel injection, and the second is the pump shutting back off. If you do not hear this, then you need to find why the relays are not coming in. It could be that the power relay under the rear seat has lost its ground, or the power wire from the battery is corroded. The Computer for the fuel injection controls the pump, so the computer has to get power before the pump can run.

Russ, I only hear one click as I turn the key on. It is coming from under the seat.

Wed Jul 02, 2008 5:31 pm

Chory! Where have you been? We thought you must have deserted us for a Honda! :D

Wed Jul 02, 2008 5:39 pm

Dramaguy wrote: Russ Wolfe wrote: If you do not have an automatic, then there should be an extra red wire coming from the front of the car near the fuel pump relay, and comes out in the harness that has the wire for the oil sender. It is a red wire, and is only used on the automatic tranmissioned cars.
When you turn your key one, the fuel pump will not run continuously. It will only run for about 1-2 sec and then shut off, unless your are cranking the engine or running the engine.
When you turn the key on, you should hear 2 clicks, about 2 seconds apart. The first is the power relay for the fuel injection, and the second is the pump shutting back off. If you do not hear this, then you need to find why the relays are not coming in. It could be that the power relay under the rear seat has lost its ground, or the power wire from the battery is corroded. The Computer for the fuel injection controls the pump, so the computer has to get power before the pump can run.

Russ, I only hear one click as I turn the key on. It is coming from under the seat.

So, the relay under the dash is the one at fault: check there.

Wed Jul 02, 2008 6:11 pm

architect_7 wrote: Dramaguy wrote: Russ Wolfe wrote: If you do not have an automatic, then there should be an extra red wire coming from the front of the car near the fuel pump relay, and comes out in the harness that has the wire for the oil sender. It is a red wire, and is only used on the automatic tranmissioned cars.
When you turn your key one, the fuel pump will not run continuously. It will only run for about 1-2 sec and then shut off, unless your are cranking the engine or running the engine.
When you turn the key on, you should hear 2 clicks, about 2 seconds apart. The first is the power relay for the fuel injection, and the second is the pump shutting back off. If you do not hear this, then you need to find why the relays are not coming in. It could be that the power relay under the rear seat has lost its ground, or the power wire from the battery is corroded. The Computer for the fuel injection controls the pump, so the computer has to get power before the pump can run.

Russ, I only hear one click as I turn the key on. It is coming from under the seat.

So, the relay under the dash is the one at fault: check there.

Ok so I just changed the relay and I still get just one click when I turn the key.. damn... what can I try next? Someone said someting about a fuel pump wire at the engine? where is it?