'86 5.0 EFI Manual No-Start Issue

[Gary Lewis]

I need to see if I can find a gauge locally to go onto the fuel rail schrader valve, but the last time it happened, I had pressure, just not sure how much. That and the sound of the fuel pumps running lead me to believe the issue is ignition/computer related, not fuel system related.

The easiest thing to do is to check for spark. If you have spark and if you have some pressure at that valve I'd see if there's power to the injectors. If power to the injectors then see if you can detect the injectors opening, and to do that you could put a trouble light across an injector. If the injector is firing you should be able to see the light glow dimly. Or put your DVM across there and you should see the voltage go bonkers.

[fords4life]

The easiest thing to do is to check for spark. If you have spark and if you have some pressure at that valve I'd see if there's power to the injectors. If power to the injectors then see if you can detect the injectors opening, and to do that you could put a trouble light across an injector. If the injector is firing you should be able to see the light glow dimly. Or put your DVM across there and you should see the voltage go bonkers.

So.... I picked up an inline spark tester light and cheapo distributor cap on the way home. Plugged in the tester, turned the key and she fired right up.... So frustrating. I almost wish she hadn't so I could start working on discussing the issue. The cap definitely had some rough spots on some of the terminals so I'm going to replace it, but I'm no further along in diagnosing than I was.

[Gary Lewis]

So.... I picked up an inline spark tester light and cheapo distributor cap on the way home. Plugged in the tester, turned the key and she fired right up.... So frustrating. I almost wish she hadn't so I could start working on discussing the issue. The cap definitely had some rough spots on some of the terminals so I'm going to replace it, but I'm no further along in diagnosing than I was.

Intermittent problems are the worst. Technically you don't ever know for sure that you fixed them, although usually you can tell in a few drives that you have. But until then you worry about it.

Anyway, keep us posted.....

[fords4life]

Intermittent problems are the worst. Technically you don't ever know for sure that you fixed them, although usually you can tell in a few drives that you have. But until then you worry about it.

Anyway, keep us posted.....

So after some rain yesterday and last night, the problem is back..... I had a few minutes before I had to leave for work so i got a couple things checked. Confirmed I have spark via inline test light on cylinder #1. Also looked at the throttle VREF which is second on the list for the EEC IV No Start Pinpoint Tests. I just wasn't sure which wires I needed to confirm voltage on. There are 3 in the connector. I have 3.8v between Orange/Green, and 5.0v between Black/Orange. If someone can confirm which wires are correct, it will at least tell me which way to go in the testing next.

I'll have to see how far I can get going through the Pin point test without a breakout box.

Thanks for all the help and guidance.

Nathan

[Gary Lewis]

So after some rain yesterday and last night, the problem is back..... I had a few minutes before I had to leave for work so i got a couple things checked. Confirmed I have spark via inline test light on cylinder #1. Also looked at the throttle VREF which is second on the list for the EEC IV No Start Pinpoint Tests. I just wasn't sure which wires I needed to confirm voltage on. There are 3 in the connector. I have 3.8v between Orange/Green, and 5.0v between Black/Orange. If someone can confirm which wires are correct, it will at least tell me which way to go in the testing next.

I'll have to see how far I can get going through the Pin point test without a breakout box.

Thanks for all the help and guidance.

Nathan

Are you checking the voltage to ground? I'll see if I can find the correct procedure.

[85lebaront2]

Are you checking the voltage to ground? I'll see if I can find the correct procedure.

Voltage is checked to the Signal Return wire for the sensors. 1985.5-1986, check the EFI system ground near the battery, it is an open style with 2 1/4" wide flat pins and is attached to the negative batter post clamp with the bolt. If it has high resistance the whole system goes FUBAR on you.

TPS wiring, 5.0V VREF circuit 351, O/W; Signal return SIG. RTN, circuit 359, BR/W; TPS signal, TPS, circuit 355 DG/LG. I have a voltage chart, Gary has it also for the testing. Sweep check should be done with a analog meter as digital doesn't update fast enough to accurately measure the response.

[fords4life]

Are you checking the voltage to ground? I'll see if I can find the correct procedure.

No, checking between pins on the plug.

Voltage is checked to the Signal Return wire for the sensors. 1985.5-1986, check the EFI system ground near the battery, it is an open style with 2 1/4" wide flat pins and is attached to the negative batter post clamp with the bolt. If it has high resistance the whole system goes FUBAR on you.

TPS wiring, 5.0V VREF circuit 351, O/W; Signal return SIG. RTN, circuit 359, BR/W; TPS signal, TPS, circuit 355 DG/LG. I have a voltage chart, Gary has it also for the testing. Sweep check should be done with a analog meter as digital doesn't update fast enough to accurately measure the response.

I will have to see if I have an old analog meter, I might, but will have to dig.

Just to confirm, Circuit 359 should be BK/W, not BR/W? That's what my diagram shows and the wire color in the truck is BK/W.

If I put my meter on the pins for C351 and C359, I get 5.0v(with the digi meter) which is in spec per A2 on the pinpoint test. Next is A3 which is spark and I confirmed that this morning. That leads to A13 which is the Spout Signal verification. This is where it gets tricky because I don't have a breakout box. Can I pierce the wire for C324 that attaches to Pin 36 on the connector and verify voltage to ground that way? If I can do that, what about the timing switch portion at the bottom?

 

[85lebaront2]

Are you checking the voltage to ground? I'll see if I can find the correct procedure.

No, checking between pins on the plug.

Voltage is checked to the Signal Return wire for the sensors. 1985.5-1986, check the EFI system ground near the battery, it is an open style with 2 1/4" wide flat pins and is attached to the negative batter post clamp with the bolt. If it has high resistance the whole system goes FUBAR on you.

TPS wiring, 5.0V VREF circuit 351, O/W; Signal return SIG. RTN, circuit 359, BR/W; TPS signal, TPS, circuit 355 DG/LG. I have a voltage chart, Gary has it also for the testing. Sweep check should be done with a analog meter as digital doesn't update fast enough to accurately measure the response.

I will have to see if I have an old analog meter, I might, but will have to dig.

Just to confirm, Circuit 359 should be BK/W, not BR/W? That's what my diagram shows and the wire color in the truck is BK/W.

If I put my meter on the pins for C351 and C359, I get 5.0v(with the digi meter) which is in spec per A2 on the pinpoint test. Next is A3 which is spark and I confirmed that this morning. That leads to A13 which is the Spout Signal verification. This is where it gets tricky because I don't have a breakout box. Can I pierce the wire for C324 that attaches to Pin 36 on the connector and verify voltage to ground that way? If I can do that, what about the timing switch portion at the bottom?

Where are you located? I have an EEC-IV breakout box (was real handy when my Taurus started acting wonky). Chris Tubutis has my EEC monitor and recorder. Either way something could probably be arranged. My son drove his 1986 F150 5.0L for several months with the breakout box on the floor hump and a little pair of LEDs to show injector pulses plugged into it.

[fords4life]

Where are you located? I have an EEC-IV breakout box (was real handy when my Taurus started acting wonky). Chris Tubutis has my EEC monitor and recorder. Either way something could probably be arranged. My son drove his 1986 F150 5.0L for several months with the breakout box on the floor hump and a little pair of LEDs to show injector pulses plugged into it.

I'm in Greeley, CO.

Any thoughts on piercing a wire to check the voltage? I have the power probe with the probes that clamp on to the wire.

[85lebaront2]

I'm in Greeley, CO.

Any thoughts on piercing a wire to check the voltage? I have the power probe with the probes that clamp on to the wire.

Piercing the wire will lead to moisture intrusion and eventually corrosion. If you slide a paperclip alongside the lead you wish to check at the EEC connector plug (easiest way on yours, pull the EEC out of it's mount so you can reach it better). The pins you want SPOUT 36, PIP 56, these are the ignition distributor to EEC and return. If you need more let me know.