1988 B2 2.9L EFI Crank No Start after front end collision repair - already spent weeks debugging, HELP please...

[Ken_G]

Hello all, I have a 1988 Bronco II 2.9L EFI. It ran fine until I had a medium-bad front end accident this spring. I drove it away from the accident (so the engine ran after the accident), and then I have completely repaired the vehicle including replacing radiator support, driver fender, hood, grill, bumper, valence, and straightened out the driver frame horn (mashed about 6 inches). This took several months of part time work.
It all turned out great, all the electricals and mechanicals inside and out work Except: I never started it the whole time (about 5 months), and after fixing it, I tried to start it last month and it just cranked and cranked and never even fired a single time. When I spray starting fluid in, it immediately runs (so, not a spark or compression issue). So, some electrical gremlin with the injectors or fuel pump? Because, I also noticed the fuel pump stayed silent when the key was first turned on, I didn't hear any 2-second whir.
So I thought aha, fuel pump bad, but When I jumper the fuel pump on (meaning ground the fuel pump test port), the fuel pump runs and I have fuel pressure at the rail (schrader valve), but yet it still doesn't run (without starting fluid). I also confirmed the inertia switch works, and anyway jumper bypassed it for good measure, so that's not it. So, then I'm thinking electrical issue with the injectors, but why would the injectors not fire AND no fuel pump signal? I thought maybe ECU, but replacing that didn't help either.
So here's All the things I have done and still I have a 'crank no start' situation:
Inertia switch? No. I have jumpered the inertia switch (and have tested the inertia switch and it is fine, meaning it shows short circuit) so it isn't that.
WOT safety off issue? I'm not sure how to fully diagnose that, but I have removed the MAP sensor connector, and the TPS sensor connector, and still doesn't start (on the theory that there is a WOT safety kill on the injector solenoids and fuel pump that disconnecting those circuits would temporarily bypass).
I have detected 12V on the red wire of injectors when cranking (however, I've been told it is the ground that needs connecting to open the injectors and the red is always 12V when starting, so my test wasn't conclusive-- I haven't tested the injector ground circuits to see if they are working, but I'm confident the injector ground isn't being connected for some reason).
I did the RonD test of the fuel pump and EED relays from his April 25, 2015 post on this forum, and the relays all pass their tests (that is to say, yes there is 12V where there should be on the fuel pump relay with key off and key on, and 12V at the EEC relay).
Besides the brown (EEC) and green (fuel pump) relays on the passenger side under the hood, there is also a black relay nearby, which I've seen called the WOT wide open throttle relay in some places, but I'm not sure how to test that it works. Any suggestions?
Some final 'odd' things:
a. As mentioned the fuel pump doesn't come on at all when I turn the key on. Again, I know the pump works because when I jumper the test port it runs constantly, so what would prevent a working fuel pump from firing up at key on?
b. There is no check engine light (CEL) on, except when I briefly turn the key from ACC to ON (before starting). Interestingly, I just noticed yesterday that the Check Engine light DOES come on when I've jumpered the fuel pump to ground on the red service connector. So, why wouldn't the CEL come on with the key ON and turning to START? What is the normal behavior of the CEL?
c. I'm unable to get the CEL to flash in diagnostic mode, and I bought an OBD 1 tester, and it doesn't register anything either, it acts like the OBD1 port isn't working/has no signals at all. What would prevent the CEL from working, even though I know the CEL bulb is fine?
d. I have replaced the ignition switch (not the ignition key barrel, but the switch further down the column), still no change.
e. I have replaced the EEC (with the correct version, bought on-line remanufactured), and also still no change.

So what is going on? All electrical on the vehicle seem fine except no initial fuel pump cycle, no CEL, and no injectors. I feel like maybe there's some ground or WOT signal that is telling the ECU to not ground the fuel pump on, not cycle the CEL on, and not apply ground pulses to the injectors, for some reason I've been unable so far to ascertain.

Thanks for any help, this was long but I wanted to be thorough.
Regards,
Ken

 

[Brain75]

Ground connection on the fuel pump relay?

So what you describe is that it runs if you manually feed it fuel (starter fluid), and you don't hear the pump run.... I got to double check you said "I have fuel pressure at the rail (schrader valve)" - well what kind of pressure, 60 psi, 1-2psi?

Fuel, Air and Fire - these engines only need three things... if you get it to run on starter fluid then it is obviously a fuel issue, since spark and air are there enough for it to run. No sound out of the fuel pump I would say relay not closing - somewhere in the wiring between key<->relay<->pump.

Bypassing the normal wiring by jumpering the test port and getting a good pump means the pump is fine, again reinforcing the wiring gremlin theory.
I can't remember off the top of my head how the test port works - does that provide power to the normally open leg, or ....
Either way, another good thing to check is power at the arm of the fuel pump relay (key on).

Can you hear the relay click (my '90 2.9 is horrific in a quiet garage - I made a video for another guy and still have it handy : https://youtube.com/shorts/K5ZF4y2XjBo )

You got ignition cylinder (forward to on), relay closed (simultaneous with key), fuel pump, relay open, ignition cylinder (back to acc), 4 times and there is a lot of clickety clak I give ya.

 

[Brain75]

Well I just learned something - ground is not present continuously if I read this right - the control module closes ground for 1 second and during cranking and when the PIP signal tells it the engine is above 120rpm... might read up with me on the fuel system - I see TWO inertia switches... and I don't know what years Ford still did that...
Start with page 144:

https://www.therangerstation.com/tech_library/pdf_documents/Ford_Fuel_Injection_Book.pdf

schematic on 145.
Since you drove away, I tend to think the 2nd inertia switch is not an issue unless you had to hammer on the body pretty hard.

 

[Brain75]

Since you replaced the EEC, I got to ask, old one smashed in the wreck? Did it survive enough to use for diagnostics? If you new (reman) EEC is bad - looking at the schematic that would be a 2nd candidate if all the wiring is ok. (My hunch is still ground gremlin.)

 

[rusty ol ranger]

The black WOT relay just shuts the AC off if youre floored so you have some extra ass to get moving.

The ECM grounds the injectors to fire them. Its batch fire, so 3 on one bank at a time.

The ECM also grounds the fuel pump to run it.

IF im not mistaken i believe the ECM uses input from the TFI module to know the distributor is spinning to fire the injectors.

I would find a wiring diagram. Im not sure if the pump and injectors are on the same circuit (i dont think they are, but not sure)

Also....did you ground the new ECM properly? It sounds like the hit was mostly on the driverside and all the important electronics (ECM, battery cable, relays, etc) are on the passenger side, coupled with the fact it ran after the wreck tells me its probably something in any wiring you mighta played with, or possibly you got a faulty ECM.

 

[Ken_G]

Thanks for responding, i just returned from work and so I'm starting with some quick responses, and then Friday afternoon/this weekend I'll be able to invest more time debugging:
The old EEC (ECM) is probably fine, I got desperate and started swap-tronics (sadly), but I didn't replace it because I knew it had an issue, just got lazy and spent $130 (plus I rationalized to myself that those electrolytic caps are going to die someday, so let's get new stuff in there now while I've got her open), but no visible damage and no measured issues with old EEC or with new one. The old one wasn't smashed, I will go ohm out the grounds (easy to get to) at i think pins 20, 40, 60 if I recall from memory, but it is at the passenger side footwell, so nothing from the accident was disturbed over there:==> meaning, not likely to have developed an issue. But, ohming it out may tell me which wire could be broken if that wire snakes it way through the drivers side fender well somehow (which I've DEFINITELY messed around quite a bit with, getting the old removed and new piece bent to fit and primed and painted and reattached).
But in general the wiring looms have been pretty unmolested. I didn't have to replace any wires, fusible links or relays or connectors for example, all the old stuff looked good and seemed intact.
I'll double check the relays click-- there is 12V on the correct pins for both EEC relay and fuel pump relay (from a diagnostic tree) but that was from a month ago so I'll re-do it. yes I agree hearing relays click is an easy diagnostic, so stay tuned.
thanks again for the advice, I know it's hard to debug remotely! But its helping.
Regards,
Ken

 

[rusty ol ranger]

Thanks for responding, i just returned from work and so I'm starting with some quick responses, and then Friday afternoon/this weekend I'll be able to invest more time debugging:
The old EEC (ECM) is probably fine, I got desperate and started swap-tronics (sadly), but I didn't replace it because I knew it had an issue, just got lazy and spent $130 (plus I rationalized to myself that those electrolytic caps are going to die someday, so let's get new stuff in there now while I've got her open), but no visible damage and no measured issues with old EEC or with new one. The old one wasn't smashed, I will go ohm out the grounds (easy to get to) at i think pins 20, 40, 60 if I recall from memory, but it is at the passenger side footwell, so nothing from the accident was disturbed over there:==> meaning, not likely to have developed an issue. But, ohming it out may tell me which wire could be broken if that wire snakes it way through the drivers side fender well somehow (which I've DEFINITELY messed around quite a bit with, getting the old removed and new piece bent to fit and primed and painted and reattached).
But in general the wiring looms have been pretty unmolested. I didn't have to replace any wires, fusible links or relays or connectors for example, all the old stuff looked good and seemed intact.
I'll double check the relays click-- there is 12V on the correct pins for both EEC relay and fuel pump relay (from a diagnostic tree) but that was from a month ago so I'll re-do it. yes I agree hearing relays click is an easy diagnostic, so stay tuned.
thanks again for the advice, I know it's hard to debug remotely! But its helping.
Regards,
Ken

So did it run with the old ECM?

Or did you change the ECM cause it wasnt running?

Im not 100 sure what all the wires over on the drivers side do, but i know if you unplug one it wont even crank and will kill the truck if its running.

The other plug (the one with smaller wires) i i unplugged as an experiment and didnt notice anything.

 

[SenorNoob]

It sounds like the PCM doesn't have a ground. Have you checked those 3 pins yet?

 

[Ken_G]

Ok, I got it solved. Those of you guessing something to do with ground were on the right track (SenorNoob, RustyOleRanger, Brain), ... to make a long story short, there was one particular ground wire (that on my '88 Bronco II is a black with green trace) which was pulled out of the ground terminal battery cable.
I took a picture in case this helps anyone with associating a problem (symptom) with a cause. There is a connector (shown just in front of and below the Duralast label) that goes from a thick cable bundle up to one of only three wires to the negative terminal of the battery. This wire had a butt splice between the connector and battery, and during the collision repair, it seems the wire had been pulled from the butt splice (I'm guessing when the battery was rudely removed from the front end along with everything else: radiator, grill, headlights, hood latch etc etc).
So in summary, symptom: crank but no start, odd behavior with CEL, fuel pump and injectors.
Cause: broken ground in particular the one in the 2nd attachment (at red X).
Thanks all!
Ken

 

[Jazzer]

Good work-bet you’re relieved…