When the ign. is in the on position does the fuel pump get constant power or is it only when it primes for some reason I've lost my fuel pump again but this time I'm not showing any power to the pump My fuse is good and so is my relay

 

Here, I have a book in front of me. It says on the 85 thru 88 models there are two pumps. The high pressure pump is frame mounted and is accessible from under the vehicle. The low pressure pump is located within the fuel tank and requires removal of the fuel tank for replacement. On 89 and later models, there is only one fuel pump located in the fuel tank. As far as with the ignition on, says you should hear a brief whirring as the pump comes on and pressurized the system. Have someone turn the engine on and you should hear a constant whirring sound from the pump.
Steps if the fuse is good:
With the ignition off, unplug the fuel pump electrical connector. Using a jumper wire, ground the negative termianl of the fuel pump. Using a fused jumper wire, apply 12 volts to the other termianl. If the fuel pump doesn't rune, replace it. If it does run, the problem lies somewhere in the electrical circuit to the fuel pump. Next step on next section.

 

This is straight out of book:
Pressure Check:
1. relieve the fuel pressure
2. Connect a fuel pressure gauge to the Schrader valve on the fuel rail.
3. Turn the ignition switch to on. The fuel pump should run for about 2 seconds, then the pressure should hold steady. (says on a 65 the fuel pressure is 4.5 to 6.5 psi. On fuel injected models it should be 40 psi on or off)
4. Start the engine and allow it to idle. The pressure should be lower by 3 to 10 psi. If all the pressure readings are withing specs, the system is operating properly.
5. If the pressure did not drop by 3 to 10 psi after starting the engine, apply 10 inches Hg of vacuum to the pressure regualtor. If the pressure doesnt drop, replace the regulator.
6. If the pressure is higher than specified, check for a faulty regulator or a pinched or clogged fuel return hose or pipe.
7. If the pressure is lower than specified:
a) inspect the fuel filter
b) look for a pinched or clogged fuel hose or line between the fuel tank and the fuel rail
c) check the pressure regulator for a malfunction. With the engine running, pinch the fuel return line. If the pressure rises, replace the fuel pressure regulator.
d) Look for leaks in the fuel feed line.
e) check for leaking injectors.
8. After the test is done, relieve the fuel system pressure and remove the fuel pressure gauge.
Hope this helps, just typed word for word.

 

No power is not at fuel pump all the time. It is cycled via the computer. Have you jumped the relay to get power to the pump? Also have you checked the crash switch to see if it has not tripped? Let us know . good luck.

 

ok on the relay there are 3 small tabs and 1 larger tab the 3 are horizontal and the 1 is vertical which do I jump. I have a haynes manual but it doesnt spscify which wires to jump. I've put a test light on the pink wire going into the high press. fuel pump and didn't get a light. I'm also not showing pwr. going into the tank. My fuses are good . There are 3 relays exactly the same on the firewall which one is it and what are the other two?

 

ARe you on the drivers side right under the drivers seat???? It's on the frame rail below the drivers side or in the fuel tank. Are you sure you're not on a fuel filter???? We did that the first time.

 

No The relays I'm looking at are on the Pass. side fender well under the hood. There are 3 relays here I was told 1 of them is the fuel pump relay

 

sorry cant help you anymore, no idea of what those are.

 

The FP relay should be green. My 1989 manual lists power from the ECU relay as y/pk, tn/lg as the other side of that circuit, bk/y as power for the pump and o/lb as the wire running to the inertia switch. The 1988 manual (two pump) lists power from the ECU relay as r, o as the other side of that circuit, bk/y as power for the pump and r/br as the wire running to the inertia switch.

 

I have an 87 B2 with the 2.9. i also have the 3 relays. after looking time and time again at the wiring diagrams I found my fuel pump relay. I don't know if it will help you but the relay for my fuel pump was green abd the other two were black. I am still not 100% sure what the other two are for yet but i think one is for the puter under the dash and the other is still a mystery.

I think, if I remember correctly, I looked at the repair section on the autozone web site and got the wiring diagram. I will have to check on that. But once I found it I disconnected the battery and jumped the lone vertical slot with the horiz. one under it. then I just touched the battery cablr to the terminal and there was no doubt that the pump was working.

Hope this helps.

 

Yeah.. listen to Ken00.. he knows what he is talking about

 

long story short chcek your neg post on batt. you should see some black things ......with key in run,,,,,,,shake them,,,,,,,,,,,,,,,, with a jumoer , if nothing jump past them with a jumper wire and ground them ,,,u cant hurt anything since they already groud to the neg post try this if u find u have power going to the fuel pump and its not working took me a tow and 3 days to figure this out a few years ago

 

ok I do have 2 blk relays and 1 green relay. Unfortunatly I've got to go to El Paso for 2 wks. for a job so I'm parked in the garage until then.I'm going to try jumping the wires when I get back. But in the mean time I'm going to study this manual and wiring diagrams until I know them inside out. So I will give you an update then hopefully I can figure out what the other 2 go to.Thanks again guys as always this club has been VERY HELPFUL