Thanks for looking, 87 XLT.

I shorted it at the self-test connector earlier, the fuel relay clicked in, I wiggled all the wires at the connectors on the drivers side and still no pump.

I did these tests also and no pump. Test #4 should have given the computer a passing grade.

Part 3 -Ford Fuel Pump Relay Test.

So I can't seem to get B+ to the drivers side wiring.

I traced the pink/black wire from the in-line pump up the firewall and it went to the largest white connector on the fender apron, then out of the connector to the harness going into the dash near the interior fuse box.

I confirmed it was the same wire by ohmmeter. I can't think why that wire would need to go into the dash, and I can't find it under the dash. Just for giggles I made sure all the fuses in the fusebox were good.

I found a wiring diagram for an '87 Bronco and it just shows the pink/black wire running from the inertia switch to the in-line pump.

One note of interest, when trying to trace the wire from the inertia switch to the drivers side, I got nothing by ohmmeter, so I hooked up a really light gauge jumper from B+ to it, hoping I could read voltage on the drivers side. I couldn't find anything, but I heard a whirring noise, suspected the pump, depressed the schrader valve and got a lil spurt of gas. That doesn't work again now, though.

Strangeder and strangeder.

 

If you got fuel in the rail once, back up and repeat whatever you did to make that happen. Then do it with the inertia switch jumpered out and attempt to start it.

 

Yes, thanks Old93junk, since my next to last post I've done both of those things. That's what I meant by "That doesn't work again now, though." Trying to recreate the pump-up by powering the wire coming out of the inertia switch didn't work with inertia switch in circuit or jumpered out. (w/key on)

I'll have to get back on it tomorrow after work. Maybe my brain will come up with something before then.

Thanks for the ideas.

 

Very stupid question, but one to ask.
Is this a 5spd truck?...........If so, did you jumper out the clutch interlock, so you can reach through the widow to try starting without having to sit in it and push the clutch in?

A friend chased a no start for a whole weekend before he remembered the rig would not start unless the clutch was depressed.

Things you forget about while concentrating on the problem.

 

I like to hear every question on the chance it'll shake something loose in my noggin.

But it's an auto.

That makes me wonder if there's a safety to kill the pumps unless it's in park?

 

The neutral safety switch only controls voltage to the starter relay. If it's not in park or neutral it wont crank.

If you cant find the break in the wire to the fuel pumps best bet is to run a new wire from the inertia switch to the white connector. That connector is 3 wires. One from the inertia switch & one to each fuel pump.

I have the factory wiring diagrams, but they dont show how the wires are physically routed or why that wire runs under the dash near the fuse box.

 

I'm going to try that, as I can't even locate the wire on the drivers side.

Do you know if that connector on the drivers side fenderwell or under in the frame rail? I don't see it up top.

And I realized why my latest power up the wire and wiggle test didn't work, it's because with the key on the pump will only run momentarily. It will only power up continuously when it receives a signal from the distributor or crankshaft position sensor that the engine is running. I don't know why it happened the first time.

 

The schematic shows connectors C160 & C161 "On the left hand fender apron". Exactly where that would be I dont know. Not sure why the 2 connectors either?

From inertia switch to C160 the wire is pink/black stripe. Could that be the wire that
you found near the fuse box?

From C160 to C161 the wire is black/pink stripe.

The 2 wires from C161 to the pumps are also black/pink stripe.

 

The pink/black wire coming from the in-line pump goes to the large connector on the drivers fenderwell,, then into the firewall.

I cut it between the connector and the firewall and wired in a jumper to battery positive. I then got B+ at the hot side of the two wire connector that feeds the in-line pump. I checked ground at that connector feed end- good.

I switched the jumper from battery positive to the inertia switch output and got B+ momentarily on key turn, at two wire in-line pump connector. Lookin' good so far. I plugged the two wire connector back in, turned key with hose leading from tank to my ear and heard nothing, and got no pressure at schrader valve after several key turns.

I pulled in-line tank and fuel flowed easily from tank side hose. I bench tested in-line pump and it pumped smoothly and quietly.

Next I left in-line pump loose but electrically connected, hooked up tank side hose , turned key and observed pump working. Reinstalled pump.

Turned key through pump up cycle 10 times- heard fuel pump relay click on and off. No pressure at fuel rail.

Removed jumper from inertia switch output (inertia switch is still jumped out) and hooked to battery positive. Fuel rail pressurized.

(Just read your post)

The wire returning from the inertia switch is pink/black. Near the relays it goes into a two wire connector and emerges orange, then goes into the harness crossing to the drivers side. Two orange wires emerge from that harness on the drivers side, but neither show momentary B+ on key turn when pink/black from inertia switch does show B+ on key turn on passenger side. One of those orange wires emerges from the medium size connector and becomes pink/black, and goes into firewall harness.

Two pink/black wires come from firewall harness and go to medium sized connector where they are simply joined- they don't continue. A black/pink wire emerges from the firewall harness and goes to big connector and emerges black/pink and is confirmed by ohmmeter to be the + feed for the in-line pump. At the pumps connector, however, it is pink/black.
I wish I knew why the heck those wires even go into the fiirewall, and why I can't spot momentary current on key on on the orange wire that becomes pink/black.

Thank you for your time, I hope I don't seem short (or have one, hehe.)

 

As 87 XLT suggested, I ran a new wire from the inertia switch output to connector 160. This is supposed to be pink/black but on my truck is orange. I now have momentary B+ every time key is turned to ON, at that connector.

The pink/black coming out the other side I originally thought went into the harness at the firewall. I stripped some tape and found out that wire goes into the harness three inches, u-turns, comes back out to connector 161 where it connects to another pink/black. It doesn't go through the connector, it's just joined to another pink/black in the female side of the connector.

The pink/black that joins to it goes into the firewall. I've got momentary B+ on key turn all the way to that wire before it enters the firewall.

There is a black/pink exiting the firewall that goes to connector 161 and on to the hot side of the in-line pump. (confirmed) I get no B+ on that black/pink on key turn.

The problem seems to be in the dash somewhere. Tomorrow I'll try to find it.

I want to thank you guys for your time and kind assistance.

I'm taking the night off.

-Alto

 

I took out the fuseholder, the instrument cluster, and the climate control panel. I located the pink/black wire and confirmed by ohmmeter that it's the one coming off connector C161. it goes over the steering column and ends under the cigarette lighter, in a six wire female connector that isn't plugged into anything, and nothing to plug into it anywhere. Probing its terminal, I get momentary B+ on key turn.

 

That behind the dash connector is only used if you had the dual fuel tank option with a front/rear tank switch near the cigarette lighter.

So your're good to the splice that feeds that switch- if you had it- & the in line fuel pump. Looks like you're closing in on the problem.

Now if I could just get this POS computer to work more than just once in a while, i'd be a happy camper. I'm about to put my foot in it.

 

Thanks for staying with me, 87 XLT, but I've been chasing whirlwinds.

I finally found the wire from the FPR and the connector where it splits to go to each fuel pump. I had rewired from the FPR output to C160 where the P/B is on the opposite side. That was wrong.

The truck is so old the P/B crossing the engine compartment has turned orange and lost its black stripe.

I ohm tested the correct wire and got no continuity, so I rewired and finally have momentary B+ on key turn at the correct connector, and the in-line pump comes on at key turn.

The truck still won't start for more than a few seconds without dying. The fuel rail pressurizes but not strongly.

The '87's have two fuel filters, a cannister type after the inline pump and a can type that takes a refill filter between the two pumps.

Tonight I'm going to change the refill type (the other is newish) and if that doesn't work I'll suspect the in-tank pump.

 

I got the cannister filter housing out. It wouldn't open but a blow through indicated that someone had previously taken the filter out and left it empty. I replaced the cannister.

I did a pressure test on the schrader valve and after 15 key turns got a max of 42 lb. 8 minutes later it was 33 lb. I started it up to relieve the pressure and the old girl ran!

I charged the battery overnight and it started fine this morning. Doesn't seem to be any fuel delivery problem now. Yesterday when it wouldn't run for more than a few seconds was because I'd unhooked the in-line pump connector to put dialectric grease in the connection and forgot to hook it back up.

The original problem was that the wire from the fuel pump relay to the pumps had gone bad somewhere in the cross-engine harness.

87 XLT, tonight I'm going to PM you a list of computer cleaning and security programs, all free and pretty simple to use. If your computer doesn't have hardware problems, there's a good chance these programs will help.

-Alto

 

Yep, same trouble with my 87 B2...........Wire harness.

Ford must use wire ins. that tastes real good to mice.