1986 Bronco II EB 4wd 2.9 gas - warmed up dies no run for 20+ minutes

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Tpremru

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I've been chasing the "heat up and won't run" demon aka curse of the 2.9 since March 2020 on my 1986 EB 4wd B2 2.9 gas I'm the 2nd owner and we know this problem never existed until 3/2020. All these have been replaced as a result -> Plugs, Wires, Alternator, Battery & Cables, Coil, Condenser, Ignition switch, IAC, 2 new TPS, 5 new in tank pumps, in-tank pump plug, 2 new hp rail pumps, distributor, relays, 9 ECM's, 3 or 4 harness plugs, inertia switch, inertia plug, fuel filter, fuel regulator, MAP sensor, (o2, air temp, engine temp sensors). allegedly all ground connections cleaned up and passed voltage drop tests (no details received)

The problem first was that I watched a mechanic hook up a pressure gauge to the fuel line and while vehicle was running fine it was close to 40psi. In 18 minutes as predicted it coughed and sputtered, died and won’t restart as expected, as it coughed the fuel psi was 5-10 and he said there’s the issue a new rail pump needed. That was not the cure as 2 more fuel pumps later it still does this same thing – idle for 20-40 minutes sputters and dies won’t start and run properly for 30+ minutes. Sometimes you can just drive it for 60+ minutes and notice it might buck when you step on the gas or it may die at a red light and I will be stuck for 30 minutes. The other day i idled it in the driveway for 60 minutes and it was fine, next day drove it for 70 minutes idled in the driveway for 15 and it died.

Lots of talk always about the issue of the TFI overheating on the distributor, but I look at my records and I have never had anything near this issue before. I see the 1st TFI was replaced at 9 years 34k miles, the second lasted 12 years 94k more miles, the 3rd lasted 11 years 77k miles. Reinstalled a new one each time no issue. I don’t see why a TFI should be relocated.

FYI - I'm not a mechanic, i'm the researcher and yes i can change the plug wires and coil and simple things - but i have paid 3 shops one is a supposedly classic auto shop and after 1 year they said they give up. Another classic auto shop said no i won't work on that issue. This is a family heirloom that i drove from 96-2016, i got it with 34k and it now has 208k. All along trying to fix this running issue i have lots of other new parts and plan to rebuild motor/tran and possibly repaint. Who in Tampa Bay area can fix this? Any direction appreciated. Thank you. Completly frustrated and about heartbroke and wallet broke.
 

Motech

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Hello @Tpremru and welcome to the forum.

I can usually offer decent input and helpful coaching on issues like this, but most components I'd point to have been replaced.

The one component that typically causes your symptom is the PIP sensor, but that's inside the distributor that you've replaced. When they fail, you may get low cranking fuel psi, but it should still achieve full psi on initial key-on prime. And the Check Engine light can tell you that story too.

Since replacement distributors have been known to fail out of the box sometimes, it's worth rechecking real quick. Observe the check engine light next time it will not start. When you turn the key on, it should come on. Then crank it while watching. If it stays on while cranking, then your PIP sensor is bad and you should warranty your distributor.

If it does not come on at all with key on during your symptom, it is definitely an electrical problem.

I'd reckon you have a ground problem affecting multiple systems, and I can emphasize with your struggle to find a mechanic with the skills, experience and equipment to track this down easily.

My approach would be to first install an EEC IV Breakout Box to test all PCM circuits, especially grounds, both cold and hot.

And there's where you might have success finding someone who can. Ask your mechanics if they know of any others in the area real sharp with old Ford tech. (Hint: you probably won't find any at a dealership) Start cold-calling around if you need to. Try to talk with shop owners. Ask if they or any of their techs are good with older Ford EEC IV systems, and if yes, ask them if they own a breakout box. If they do, and they're good with it, they will be quick to acknowledge it and be pleased you're aware of it too. If they don't, or tell you that's outdated tech they don't need, move along cuz they're B.ull sitters.

Good luck to you. Wish we were closer.
 
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Tpremru

Tpremru

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Thank you so much Motech for your professional advice! I can check out the PIP sometime this week! I was thinking the same on the idea that somehow all those wires at the ecm need to be checked most importantly when the issue is occuring especially the grounds. 2 out of 3 places said they "ohmed out" the pins, i think that means they just checked continuity. 1 place said they checked for voltage drops at the tank pump but i'm sure that's not checked at time of issue but they said the pump is dead. I'm going to ask the latest guy about the breakout box - i am thinking of a couple other places i can call about that. Thing is the latest guy did work at Ford years ago, the last place the owner went to Ford school for eec iv way back then which makes me think they need to keep moving things along with bigger fish to fry so they threw a lot of parts at me $$$$ and rather work on easier big name baseball players toy classic cars that are an easy buck. (rant over)

I don't want to buy a breakout box myself and learn how to use it, but, i might. Meanwhile is this idea a waste? -> Because the lift pump asmbly has been replaced 5 times, and now has a NOS OEM, I want to run 2 wires out my cab and splice into the grnd and hot very close to the lift pump and connect a 12v lite bulb so i can see it in the cab lit and tell if there is a drop during the issue which maybe causes bad amps destroying the pump sooner rather than later. In my mind if the bulb flickers etc then there could be a bad ecm, wire, icm, sensor or other electronic component but not a bad lift pump. I learned how to grnd pin 6 on the OBD1 and i can obviously hear the HP pump, but i really can't tell about the lift pump because of the even hum the HP pump is sending throughout the vehicle. I put my hand on the top of the lift pump and can't feel any vibration either. KOEO just code 11 meaning all is good.
 

Motech

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they "ohmed out" the pins

Remember the Borg: " RESISTANCE IS FUTILE"

I don't want to buy a breakout box myself and learn how to use it, but, i might.

I wouldn't if I were you. You'd have to know what and how to test, which will require a high-end DVOM at best, then a book to explain it all.

(But if you do, get Doc Norman Nall's training manual)

20899488015.jpg

Comprehensive volt drop testing is an enigma. The tests are very simple, yet they require a pretty deep understanding of the electrical circuits. Also, to get a good volt drop test on either power or ground requires testing between the battery and the connector at the component, which can really stretch you out going between your hood and fuel pumps underneath.
 

Motech

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That all said, the main ground for PCM and all things it controls is at pin 60, and it starts at the pigtail ground connector between battery negative terminal and body. In factory form, they would age, develop a bad case of the "greenies" inside terminals and wreak all sorts of maddening issues. I would think with everybody who's looked at it that it would have to have been addressed by now, but check it nonetheless.
 

Tiha

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I would agree, TFI, PIP, but you never really followed up.

Is it still losing fuel pressure after 30 minutes? Or is it losing spark now?

I suppose could be a bad fuel pump relay? Bad safety switch? Lose electrical connections get hot, heat raises resistance.

Just some more thoughts for ya.
 
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Tpremru

Tpremru

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Tiha,

The TFI changed 3 times in a couple of months Master Pro and Motorcraft but that changed nothing. I'm going to do the PIP test later this week, even though that is a new distrib that still had the same result. I personally checked the inertia switch, took it out in my hands, looked great, continuity test in hand tripped or not - worked as designed. End plug connector for inertia switch is new - no change. Fuel pump relay changed several times, changed the pigtail for that relay also - no change. Forgot to mention they switched out FPR 3 times no change. The 2 plugs under the master cylinder and the HP pump and lift pump have been eliminated due to their green connection - no change.
I would agree, TFI, PIP, but you never really followed up.

Is it still losing fuel pressure after 30 minutes? Or is it losing spark now?

I suppose could be a bad fuel pump relay? Bad safety switch? Lose electrical connections get hot, heat raises resistance.

Just some more thoughts for ya.
 

Tiha

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Tpremru

Tpremru

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Thank you so much Tiha & Motech - because it can take upward of 90 minutes for the test, i have to get time this week to try the:
  1. PIP test "check engine light while cranking during the no run condition".
  2. I'm then onboard for testing FP and Spark - so i will have to get my mech to do that with his gauge and spark tester next after PIP.
I can't get mech to work on it until after January 1st so....If the first item does not help i can get mech to do #2 after Jan 1st and if still no path to resolve then the mech's plan is:
  1. temporarily hook toggle switch to front pump and another to rear pump with their own power source, when condition happens throw each switch independantly - if condition is eliminated when either or both pumps forced on then add a new wire for the affected FP.
My next post should be about the PIP test result hopefully later this week.

Thanks again!
 
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Tpremru

Tpremru

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Add battery pigtail ground inspect as your number 1
What is "pigtail ground"...I know we have new cables pos and neg on the batt all they way to starter and all the way to ground. I don't know if this is any help but in just speaking with mech #1 that worked it 2 years ago, he said he hooked up a light bulb at 3 key places = fuel relay, inertia switch and just before fuel pumps - he watched the light bulbs never flickered at time of the issue. I was also saying how i am going to do the PIP test but because ambient temp may keep the issue from happening as when i get the time to do the test is when we are going to have record low temps in few days.
 

L\Bronco

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All these have been replaced as a result -> Plugs, Wires, Alternator, Battery & Cables, Coil, Condenser, Ignition switch, IAC, 2 new TPS, 5 new in tank pumps, in-tank pump, 2 new hp rail pumps, distributor, relays, 9 ECM's, 3 or 4 harness plugs, inertia switch, inertia plug, fuel filter, fuel regulator, MAP sensor, (o2, air temp, engine temp sensors).
And a partridge in a pear tree!
(Sorry, I couldn't resist given the season)
Welcome to the zone!
As Motech said, all of the common issues have been addressed (along with many others)
Based on your extremely detailed description, (Kudos there), Every logical possibility has been ruled out. All that remains is the illogical.
Has anyone physically looked in the fuel tank for debris? (I found a plastic bag in one once that would cover the pickup sock and stop the fuel flow randomly. Yours seems more "time sensitive" but we are way past following the rules here)
It must be incredibly frustrating fighting with it that long to no avail. If you keep the info coming and the data all adds up, this forum is your best chance of success.
Motech is correct, its hard to find very many people who are fluent in OBD1 Ford.
(There are a few in here, I assure you!)
Hope that helps
Looking for the next few bits of info.
Cheers
 
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Tpremru

Tpremru

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Thank you L\Bronco for your support and "Pun"! Every single day i think this over and over (since 3/2020), again i'm not a mech at all but very much inclined, a researcher, i'm the person kicking the horse over and over to make sure. I'm laughing at myself today considering calling the 3 local Ford dShips and ask "do you have a EEC IV breakout box" thanks to Motech, but the dShip? I pondered the debris question a few times, i know the little metal flap in the filler spout broke and fell in, but that was after already trying to address the time/temp sensitive problem. Next time the tank is dropped, i'm getting that out still!

I have sold a few guitars that i think about sometimes and several cars i don't even care about - but this B2 is special - Wife and i just moved back to FL from Dallas TX in Christmas 1986, It was easter when our family was going to drive about an hour north to uncles farm in Brooksville, first time to see my aunt since we moved back, who lived on the beach was like the second mom that spoiled us 3 kids. We all met at my parents to drive a few cars and my aunt said would i like to drive her new "horse" as she called it. I looked it over and could not believe she bought this! I drove an hour there and back loving it...she said "you can have it when i'm done with it" 10 years later should bought a stang and turned this over to me with 34k miles. I put 174k on it myself driving it everywhere and retired it to the garage in Jan 2016 with full intent to completely restore begining in Jan of 2020 with replacing everything on the brakes except the steel lines on the frame. Then i noticed the gas guage was not moving and that's when all this started.
 

L\Bronco

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Thank you L\Bronco for your support and "Pun"! Every single day i think this over and over (since 3/2020), again i'm not a mech at all but very much inclined, a researcher, i'm the person kicking the horse over and over to make sure. I'm laughing at myself today considering calling the 3 local Ford dShips and ask "do you have a EEC IV breakout box" thanks to Motech, but the dShip? I pondered the debris question a few times, i know the little metal flap in the filler spout broke and fell in, but that was after already trying to address the time/temp sensitive problem. Next time the tank is dropped, i'm getting that out still!

I have sold a few guitars that i think about sometimes and several cars i don't even care about - but this B2 is special - Wife and i just moved back to FL from Dallas TX in Christmas 1986, It was easter when our family was going to drive about an hour north to uncles farm in Brooksville, first time to see my aunt since we moved back, who lived on the beach was like the second mom that spoiled us 3 kids. We all met at my parents to drive a few cars and my aunt said would i like to drive her new "horse" as she called it. I looked it over and could not believe she bought this! I drove an hour there and back loving it...she said "you can have it when i'm done with it" 10 years later should bought a stang and turned this over to me with 34k miles. I put 174k on it myself driving it everywhere and retired it to the garage in Jan 2016 with full intent to completely restore begining in Jan of 2020 with replacing everything on the brakes except the steel lines on the frame. Then i noticed the gas guage was not moving and that's when all this started.
Trust me, I fully understand, I have many Rides that I keep because of the emotional attachment. The 67 Cougar that we last drove when my wife was pregnant with our first son (he's 35 now) , My 69 mustang convertible that I chased down for 30yrs (started in high school/83) and my 2nd son used as his wedding car. Plus many others all the way down to my 79 Bronco project that my 3 boys bought together for me because they knew I sold my 79 years ago to buy "the minivan"
(It's a restomod now, I have a build thread in here.)
Thank goodness I have 10 acres, I cherish them all!
So I totally get it, don't worry, we will get you through this one.
Cheers
 

L\Bronco

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Wow great cars! Just so happens my same aunt had this exact 67 cougar! before the B2.

That is so cool! Mine is the same color scheme!(External) Black leather inside, its a 390 GT XR7.
That is really awesome! AGBK6624.JPGDSCF0287.JPG
 
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Tpremru

Tpremru

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I really did get to do the PIP test a couple minutes ago. Here are lots more details:
I am wondering why throughout the 3 years consistantly run a little longer every few months. It first would mostly be 18 minutes then a year later up to 30 minutes. This past 2 weeks, 2 times it now runs for 80 minutes before the issue. The last mod increased it from 30 minutes to 80 minutes. Here are lots of details:

In July I idled it for 30 minutes until it died then I went to remove the ECM and it was so hot you could not touch it without getting burned. I let it cool and left it alone was not able to work with it until a couple weeks ago when the mech reproduced the problem at his shop he found the 2 grnd wires next to the ECM, 1 insulated 1 not insulated (he knew what they are for) was hanging by 3 strands, surprised I did not catch that as many times I removed ECM, but he fixed that connection up really good. I had not previously told him about the heated up ECM. Now we run 80 minutes and when it dies the ECM is only as expected "very warm". I had also noticed in July after 20 minutes there is a sound in the dash that could be the sound of the HP pump but only after 20 minutes. At time of issue the sound changes from a hum to a rougher hum. I still wonder if the LP pump burns out because of bad amperage from bad wire and the HP pump can actually run the 2.9 although it's not supposed to, for as long as it can. The other day I did the pin 6 ground to turn on the fuel pumps. I can easily hear the HP pump but I can not tell at all if the LP pump is on. I even climbed underneath and put my hand ontop of the send unit and could not feel the slightiest vibe. The issue just happened for my second time in 2 weeks after idling for 80 minutes.

I now have a video of dash as it looks when cranking after the die out. I can hear the HP pump prime but no start. I am also puzzled a litte more about the lights. Why does the parking brake light come on during crank? The P brake light comes on as supposed to when park brake is on. Also, the Check Engine bulb is not present, i have some photos of last year when i had the dash apart for umteenth time for various reasons, but i was changing over to LEDs and there is a photo documenting what bulbs are present and only the ones i replaced. I am going to have to upload the PIP test video to an external link. B2 dashview lights for heatup and won't run issue-->
 

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Tpremru

Tpremru

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OK now i see that the pbrake lite coming on during cranking is normal as it did today and that there are no CEL's installed previous 1988 as owners in CA had to find out to pass smog tests.
 

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