No fuel to injectors

[Red87]

My truck is an '87 R10 SWB 5.7L TBI (dual tanks) w/ ~160,000 miles on the clock, and off and on over the past few months, I've been experiencing misfires and lack of power, mainly on takeoff with a heavy foot.  Well, the truck will not start now and the injectors are not firing.  Up to this point, it was driveable, but then abruptly stopped last week (2/15) and had to be towed home.

Things done recently to the truck & what I've tried:

1. Replacing the fuel pump relay (didn't work, so returned it)
2. Banging on gas tank while my wife is cranking
3. Used a multimeter to check the electrical connections on the injectors and the connector to the right tank's fuel pump
4. New fuel filter (1/14/17)
5. New spark plugs and wires (8/9/16)
6. New EGR valve and MAP sensor, and new hoses for both components (2/2/17)
7. New battery (1/15/17)
8. New distributor cap & rotor (11/13/16)
9. New PCV valve hose (8/21/16)

I got voltage at the injectors' plugs but nothing on the plug to the fuel pump.  So I'm not sure if it's an electrical problem or a fuel pump issue at the moment.  I am going to try using the jumper wire to energize the fuel pump, just to make sure I didn't test the wiring wrong.  Also, I've read where the fuel tank selector valve could be causing problems, and I have had a heck of a time switching between the two tanks, but it could be that the left tank fuel pump is shot too.  I don't think the fuel pumps have ever been changed out, and because of the switching problem, we've been exclusively using the right tank.  Also, the fuel gauge isn't working accurately for the left tank, but it does for the right tank.

I would appreciate any feedback on what else I could try to be absolutely sure it's the fuel pump that is bad before I drop the tank and replace it.  Sorry for the ramblings...I'm an IT guy trying to be a mechanic.   

[VileZambonie]

If the tank switching valve isn't working it will prevent the pumps from energizing. I would encourage you to replace the tank switching valve since you know it needs to be replaced anyway.

[Red87]

If the tank switching valve isn't working it will prevent the pumps from energizing. I would encourage you to replace the tank switching valve since you know it needs to be replaced anyway.

That is the plan.  I put a jump wire on the fuel pump bypass lead and heard nothing, so it has to be either the selector valve and/or the fuel pump.

[Red87]

Just to be sure I was checking the fuel relay bypass correctly, there is a red wire on the relay connector that has a black spade connector on it.  From what I read, I used a jumper wire from the positive terminal of the battery over to that connector, and while my wife turned the key on, I was under the gas tanks to listen for the pump to energize within ~2 seconds (which they didn't...checked both tanks).  Is that the correct procedure?

[Irish_Alley]

if you jumped the red wire on the relay you dont need to turn the key. did you check both tanks that way?

[Red87]

if you jumped the red wire on the relay you dont need to turn the key. did you check both tanks that way?

Well the wire was hooked up before she turned the key on, but I wasn't down by the tank to listen within the ~2 seconds.

[Irish_Alley]

it will be constant power if you jump straight from the battery. your pump will be on as long as its getting constant 12v

[Red87]

Duh...that makes sense.  Well, I definitely didn't hear either pump energize, so they must be toast.  Time to get some new parts and get her up and running again...my rental is a Ford F-150. 

[Irish_Alley]

if both pumps dont pump then it could be the switch.

[Red87]

if both pumps dont pump then it could be the switch.

You mean the selector valve near the right tank?  That's where I'll start, but I think I have to drop the tank to get it off.  Not sure, but I'm about to find out.  I think I can get one locally, but it won't be ACDelco.  But if it works, I'll be happy.

[VileZambonie]

You do not need to drop the tank to replace the switching valve. There are 3 bolts holding the cover on over the switching valve and two bolts holding it to the frame. Get yourself a length of fuel injection rated rubber hose and good quality clamps too. Take a before picture before removing for reference. I've seen guys screw this up time and time again. You can also directly energize each pump at the connector with a fused jumper wire to quickly test your pumps.

[Irish_Alley]

what about the switch in the dash, vile?

[Red87]

You do not need to drop the tank to replace the switching valve. There are 3 bolts holding the cover on over the switching valve and two bolts holding it to the frame. Get yourself a length of fuel injection rated rubber hose and good quality clamps too. Take a before picture before removing for reference. I've seen guys screw this up time and time again. You can also directly energize each pump at the connector with a fused jumper wire to quickly test your pumps.

I got it off...didn't even need to use clamps.  Just a little gas came out.  So the fused jumper wire would go from the battery to the small, 2-wire pump connectors, correct?

[Red87]

what about the switch in the dash, vile?

I thought about changing it, too.  Does the dash need to come apart to get to it?

[Captkaos]

the valve in the dash come out by just pinching the ends in.  You have to be flexible to get to it though.