Fuel pump in the tank issues

[jkufen]

My 86 b2 has been acting up here the past few weeks and I finally broke down and drop the tank. When I got the pump out I hooked the pump back up to the plug and turned the key. The pump under the door came on but the pump in the tank never made a sound. Should this pump come on and whine like the pump under the door or does it come on later?

 

[jkufen]

Well i have established the pump is good. My issue seems to be there is no power supply. I put a meter on it and volts are bouncing up and down. Any ideas?

 

[adsm08]

Wonky relay maybe. Jumper the relay and see if it stabilizes.

Postin' from teh Galaxy

 

[jkufen]

I tried the relay any idea which wire goes to the back pump? I tried the yellow wire and it turned on the front pump any idea which one would jump the rear pump? I tried jumping each one and I never got any response out of the rear pump.

 

[adsm08]

Both pumps should run off the same hot wire.

 

[jkufen]

Ok I got to figure out why I'm getting power to the front pump and not the rear if they are on the same hot wire. I will probably have to figure out where the four wires that connect to the top of the tank and make a new wiring harness to the tank. I'm not really sure how to go about that but I gotta find a way to get power back to the rear pump.

 

[adsm08]

It splits partway to the front pump.

 

[jkufen]

Ok I jumped the pumps at the relay and they both come on so my wiring throughout the truck is good. My issue is I believe the wiring I did at the new relay connector. I posted a prior thread about the Fuel Pump Relay and I asked which wire went to which part of the connector because the wires in the plug are all white. The plug that was in it was broken and I had to rig it and it worked for a year or so. I bought this plug and here is the diagram they gave me.

1-yellow
2-yellow
3-orange
4-red
5-tan

My issue is I only have one yellow wire and it is the hot wire. This diagram shows me needing 5 wires but there are only 4 wires present. Anyone have any suggestions. If I tie 1 and 2 to the one yellow wire both pumps come one but they come on without the key on so the yellow wire is the hot wire.

I have a haynes manual and have tried to decipher the wiring diagrams and it's just not clicking. I have been looking at it for the past few hours and i am drawing a blank! PLEASE HELP!

 

[adsm08]

You only need 4 wires for this relay.

One wire is always hot and goes to either pin one or two.

One wire will go to the interia switch, it will go to the other of the first two pins.

One wire will be hot in start and run and will probably go to pin 3.

The last one will have intermittent ground supplied by the computer and is probably pin 5 in this case.

I think that is all laid out correctly. A pic of your relay and/or instructions would be helpful.

 

[jkufen]

ok so I will use pins 1,2,3,5. Right now I have it wired to 2,3,4,5. I wish i had some instructions, the new connector didn't come with any that is why I am having these issues. If I would have had the original connector still wired to the truck I wouldn't have an issue but I didn't so I am having to piece all of it together. I have established that the yellow wire is the "all the time" hot wire. So I believe that if I turn the key and meter the other three then that will tell me which one comes on with the key. So that leaves the other two wires. Well I guess since there is not one that that is black the ground wire won't be as obvious. I guess Ill have to see if I can separate the other two from the cluster and try to see where they go from the relay. I guess i could check the inertia switch the in the floorboard and see what colored wires go into it maybe one can be eliminated that way. Thanks for all the help there ADSM08.

[/IMG]

This is the relay I am using it is a BWD or whatever the brand name is.

 

[jkufen]

ADSM08 I found this thread on the site from 3 years ago and it is exactly my problem. Apparently I have the wiring wrong. I thought the yellow was hot but maybe that is my problem I have the wiring wrong. I guess I will by a new relay pay day and try again.

Just looked at wiring diagram: the inertia switch is after the relay. So if you jump relay and fuel pump works, the inertia switch is good and so is the fusible link.

Go back to the relay. First off, ensure you plugged the replacement relay in the right way. I don't know if you can put it in up-side-down or not, but if you do it will not work. Most of the relays have a diagram on the side of them to show which pins are your control and which ones are your contact.

You could plug your fuel relay into another spot and see if you here it click when you apply power to it. Or use small jumper wires from your battery to the control pins and see if you hear it click. No clickie, no good.

On the relay socket the red wire should be hot (+12V) all the time, with key on. The other side, of the control circuit is a tan/lt grn wire. It comes from the ECU and is what controls when the relay is energized or not. If you place your test light inbetween thest two connections and turn you key on, it should light briefly and than go out. If you crank your engine over, I believe, it should stay lit.

Yellow wire on relay is your power going to the fuel pump, it should be hot all the time (key on or key off). The org/lt blu is on the other side of the relay, going to the fuel pump. These are your relay contacts, the ones you have been shorting together.

99.9% sure your problem is either a bad relay, or somewhere in you control circuit.

 

[jkufen]

Also the same thread the actual problem for the guy ended up being his computer in the passenger floorboard. He said he swapped the computer and everything worked fine. idk I guess ill start with the relays and then work my way up.