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

[L\Bronco]

Thanks for the insight! The plan is coming together! I have always thought "We need to figure out why you are eating lp pumps." I know the present 5th Lpump (NOS fuel send unit) is working - it sounds good and smooth but of course that is only for about 2 minutes as i short pin#6 on the OB1 connector and climb underneath. I'm afraid to leave it running for longer i don't know if that will "blow up" because i do start to smell fumes when it runs a couple minutes.

I’m still thinking there may be something in your tank.
Just a hunch
Cheers

 

[Tpremru]

I’m still thinking there may be something in your tank.
Just a hunch
Cheers

There is something in the tank - the little metal flap in the filler neck fell in, but that was after we were already working on the issue. I have a replacement neck to swap out, if we have to pull the fuel send unit out we will fish out that metal plate.

 

[L\Bronco]

There is something in the tank - the little metal flap in the filler neck fell in, but that was after we were already working on the issue. I have a replacement neck to swap out, if we have to pull the fuel send unit out we will fish out that metal plate.

Sorry, I dont think that flap will cause your grief, I’d be looking for something a bit more substantial in there.

 

[johnnyreb]

Thank you Motech, L\Bronco, good01boydws & johnnyreb for all your idea's/experience/knowledge!

The one last thing i think about before making and divulging the actual plan is - when issue occurs I only have maybe 30 seconds or maybe 5 minutes most that it will run before it dies and only sputters while cranking. I think i have to jump and open the hood to see spark tester, but probably won't make it to the test leads on FP's. So wondering at that time can i just grnd pin#6 on the obd1 connector, key-on to get FP's running and go visit test leads to measure?

One way to be able to see the spark plug tester. Would be to go to a parts and get a long piece of spark plug wire. Cut into length to where you can place it to see it. You,ll also need the plug wire boots. So the tester would be snug. ,. but make you up some long wires for the spark plug tester and they might come in handy again. Another thing I noticed no on mentioning it the gas line for tightness and the age of the rubber on it. Old hose can have cracks and cause a air leak and you loose gas pressure.

 

[Tpremru]

Sorry, I dont think that flap will cause your grief, I’d be looking for something a bit more substantial in there.

Yeah i don't think we will find anything else as the first mech that worked on it 2.5 years ago said "it's really clean, the sock was pretty clean as well" Now we have had 5 new socks in there.

 

[goodO1boydws]

Thanks for the insight! The plan is coming together! I have always thought "We need to figure out why you are eating lp pumps." I know the present 5th Lpump (NOS fuel send unit) is working - it sounds good and smooth but of course that is only for about 2 minutes as i short pin#6 on the OB1 connector and climb underneath. I'm afraid to leave it running for longer i don't know if that will "blow up" because i do start to smell fumes when it runs a couple minutes.

A couple questions about the gas tank.

Have you ever drained that tank completely, and looked inside of it-with the pump off, to see if there is sediment and/or rust in it?

When you replaced the previous pumps, what did the in-tank, "sock" fuel filters look like? Were they by any chance STAINED brown or black, or distorted INWARDS?

When a vehicle is in motion, loose sediment and fine rust can easily get stirred up and suspended in the gas and then be sucked up against the "sock" filter. Then , after the engine dies from that being clogged, if there is enough gas in the tank to cover the sock it can gradually drop back off to await a new cycle.

About "sock" distortion.
If the filter sock goes through enough clogged-then-clean cycles it may stay in a semi-sucked-in state.
Also, If that filter EVER gets clogged, the pump will be straining to pull gas in through it, and if you have less gas in the tank than enough to cover the pump, (which is sometimes physically higher than the filter sock) the fuel won't be helping to cool the pump-and if its straining and overheating that might be what you're smelling.

ANOTHER THOUGHT:
If you (AND/or someone BEFORE you) added fuel conditioner or fuel injector, or fuel system cleaner (or a "home-made brew") to the gas in the gas tank, there's such a thing as having "too much of a good thing". Too high of a concentration of some solvents used for cleaning fuel systems can wreak havoc with certain plastic and other resilient parts-such as the material the filter "sock" is made of, as well as seals in the pumps and any rubber hoses it comes in contact with.

 

[Tpremru]

A couple questions about the gas tank.

Have you ever drained that tank completely, and looked inside of it-with the pump off, to see if there is sediment and/or rust in it?

When you replaced the previous pumps, what did the in-tank, "sock" fuel filters look like? Were they by any chance STAINED brown or black, or distorted INWARDS?

When a vehicle is in motion, loose sediment and fine rust can easily get stirred up and suspended in the gas and then be sucked up against the "sock" filter. Then , after the engine dies from that being clogged, if there is enough gas in the tank to cover the sock it can gradually drop back off to await a new cycle.

About "sock" distortion.
If the filter sock goes through enough clogged-then-clean cycles it may stay in a semi-sucked-in state.
Also, If that filter EVER gets clogged, the pump will be straining to pull gas in through it, and if you have less gas in the tank than enough to cover the pump, (which is sometimes physically higher than the filter sock) the fuel won't be helping to cool the pump-and if its straining and overheating that might be what you're smelling.

ANOTHER THOUGHT:
If you (AND/or someone BEFORE you) added fuel conditioner or fuel injector, or fuel system cleaner (or a "home-made brew") to the gas in the gas tank, there's such a thing as having "too much of a good thing". Too high of a concentration of some solvents used for cleaning fuel systems can wreak havoc with certain plastic and other resilient parts-such as the material the filter "sock" is made of, as well as seals in the pumps and any rubber hoses it comes in contact with.

The tank has never been drained although 2.5 years ago I ran it out of gas for the first time ever in preperation of installing new fuel send unit. I only have on hand or have seen the orginal fuel sock. i don't recall ever using any fuel additives but it's possible someone added some.

It seems this 1986-1988 was a bad idea using 2 fuel pumps. 1989-90 uses one. This makes me ask the question "If we determine inside of my fuel tank is rusty etc and need a new one....i wonder if i can fit a 1989 or 90 fuel tank that only uses 1 fuel pump?"

Thanks for all this info as it is now part of the master plan!!!!

 

[Tpremru]

Thank you Motech, L\Bronco, good01boydws & johnnyreb for all your idea's/experience/knowledge! I (think) I have enough data to make my plan to submit to mechanic. I want to do this in order because i am tired of peoples jumping around and throwing parts at it. Done as such and in this order:

1. Drop the tank.
2. Fully inspect the current fuel sock and the inside of tank for any debris and remove metal flapper if possible.
3. Prove that fuel line and return line and connectors have no problems.
4. if possible, run Lpump while submersed for flow check for 20 minutes (this length of time coincides with the Hpump sound-this would check the wire and the Lpump itself)
5. (Good time to do this)-> Inspect float because full tank registered not quite 7/8. Bend arm to adjust instrument fuel guage a.ccuracy
6. Inspect the fuel filter in the canister.
7. Add hot/grnd test lead to fuel send plug.
8. Reinstall fuel tank.
   
   
9. Add test leads to Hpump
   
   
10. Get voltage and amperage levels Lpump & Hpump while running good.
11. Get voltage and amperage levels when issue occurs (this will be the trick and crucial part if issue is not resolved in #1)

Any problems found at any step may provide the resolve and make remaining steps unnecessary.

Now i am wondering how many hours is this gonna take $$$$? Any idea?

 

[wyo58]

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.

I have seen this exact same problem on a 4.0 in a ranger. Nobody seemed to be able to zero in on what was happening. Would not start on warm engine but would always start on a cold engine. fuel pressures dropped as it warmed up, it turned out being leaky fuel injectors. when it was cold it could handle the fuel plus fuel pressure was up, as it ran longer getting warm it was just running fuel in not squirting it in. Replaced all injectors and it ran beautiful from then on. when it dies pull the plugs and see if they are wet.

 

[Motech]

Now i am wondering how many hours is this gonna take $$$$? Any idea?

Twice as much for all the reading and being bossed around he'll have to endure.

 

[Tiha]

Twice as much for all the reading and being bossed around he'll have to endure.

LOL truth.
Or at least he will want to charge a "owner helping" fee.

 

[Tiha]

Kind of skimming through this. So you are still not sure if you are losing spark or fuel at this point?

You can get a long hose and tape the fuel pressure tester to the outside of the windshield. That way you can watch it as it fails. Similar to the spark tester.

 

[johnnyreb]

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.

Have you tried a different gauge and see if it has the same or close to the first reading? I bought a Mr Gasket regulator and you couldn,t even set it one any setting.

 

[johnnyreb]

One way to be able to see the spark plug tester. Would be to go to a parts and get a long piece of spark plug wire. Cut into length to where you can place it to see it. You,ll also need the plug wire boots. So the tester would be snug. ,. but make you up some long wires for the spark plug tester and they might come in handy again. Another thing I noticed no on mentioning it the gas line for tightness and the age of the rubber on it. Old hose can have cracks and cause a air leak and you loose gas pressure.

Also alot of these mechanic,s don,t know asmuch as you do. Watch around for a bronco like your and try to ask the owner some questions. They might also answers for you. I took my Buick to a big garage up town. Raised the hood and about 4 guys started looking and their MAIN MECHNIC asked me where the map sensor was? He was leaning over it and I looked at him and told him it was between his hands. I knew then what kind of hired help they had. I told them to move so I could close the hood. He asked me if I didn,t want them to work on it? I told him **** no. I see right now what you know about cars and forget about charging me. Keep trying and remember you can get alot of bad parts these days.

 

[L\Bronco]

Kind of skimming through this. So you are still not sure if you are losing spark or fuel at this point?

You can get a long hose and tape the fuel pressure tester to the outside of the windshield. That way you can watch it as it fails. Similar to the spark tester.

I agree with Tiha on this one for sure. (I copied this from another thread with a similar issue)

Get a fuel pressure gauge on it, tape it to the windshield and drive it till it stumbles again, under load the fuel pressure should be about 9 psi higher than idle. (Mid 30’s at idle and mid 40’s at full load or with the vac line off)
If you are losing pressure under accel, check filters, and last the pump(s)
If your press stays high, look at spark.
Try and eliminate one thing at a time then move on to the next, it will help control the frustration, and the cost!
Hope that helps.
Cheers

 

[johnnyreb]

A couple questions about the gas tank.

Have you ever drained that tank completely, and looked inside of it-with the pump off, to see if there is sediment and/or rust in it?

When you replaced the previous pumps, what did the in-tank, "sock" fuel filters look like? Were they by any chance STAINED brown or black, or distorted INWARDS?

When a vehicle is in motion, loose sediment and fine rust can easily get stirred up and suspended in the gas and then be sucked up against the "sock" filter. Then , after the engine dies from that being clogged, if there is enough gas in the tank to cover the sock it can gradually drop back off to await a new cycle.

About "sock" distortion.
If the filter sock goes through enough clogged-then-clean cycles it may stay in a semi-sucked-in state.
Also, If that filter EVER gets clogged, the pump will be straining to pull gas in through it, and if you have less gas in the tank than enough to cover the pump, (which is sometimes physically higher than the filter sock) the fuel won't be helping to cool the pump-and if its straining and overheating that might be what you're smelling.

ANOTHER THOUGHT:
If you (AND/or someone BEFORE you) added fuel conditioner or fuel injector, or fuel system cleaner (or a "home-made brew") to the gas in the gas tank, there's such a thing as having "too much of a good thing". Too high of a concentration of some solvents used for cleaning fuel systems can wreak havoc with certain plastic and other resilient parts-such as the material the filter "sock" is made of, as well as seals in the pumps and any rubber hoses it comes in contact with.

Also ETHANOL GAS --WILL EAT the metal on the arm that holds the float. I know because it happened to me. Also when ETHANOL GAS sit for awhile it looks like tar.

 

[Tpremru]

Kind of skimming through this. So you are still not sure if you are losing spark or fuel at this point?

You can get a long hose and tape the fuel pressure tester to the outside of the windshield. That way you can watch it as it fails. Similar to the spark tester.

Thanks Tiha...i keep thinking about spark as well. So that will be first on the list. When it dies and i try to restart it will cough and sputter like it has spark but no fuel. Did ya see the video? Thanks

 

[Tpremru]

I agree with Tiha on this one for sure. (I copied this from another thread with a similar issue)

Get a fuel pressure gauge on it, tape it to the windshield and drive it till it stumbles again, under load the fuel pressure should be about 9 psi higher than idle. (Mid 30’s at idle and mid 40’s at full load or with the vac line off)
If you are losing pressure under accel, check filters, and last the pump(s)
If your press stays high, look at spark.
Try and eliminate one thing at a time then move on to the next, it will help control the frustration, and the cost!
Hope that helps.
Cheers

Last month the mech said he measured fuel pressure and gets 40 while running and watched it die all to less than 10 at issue time but also tested the pumps pinched off and they were capable of 90! I doubt that was at time of issue which is key here and it is getting harder to track because now it takes 80 minutes for issue to occur. The other shop keeps saying they don't trust Cardone reman ECM so we sent it to their FlagShip1 in Miami, same issue after FShip allegedly fixed something!

 

[L\Bronco]

Last month the mech said he measured fuel pressure and gets 40 while running and watched it die all to less than 10 at issue time but also tested the pumps pinched off and they were capable of 90! I doubt that was at time of issue which is key here and it is getting harder to track because now it takes 80 minutes for issue to occur. The other shop keeps saying they don't trust Cardone reman ECM so we sent it to their FlagShip1 in Miami, same issue after FShip allegedly fixed something!

First off, pinching off a file line isn’t a very good way to test the fuel delivery system because the volume demand is taken away and all you are testing is the hp pumps ability to produce pressure. That is not your issue.
Plus it will damage the plastic lines.
If it dropped to 10 as it was acting up, the fuel delivery is most certainly your issue.
I don’t want to be “that guy” as I’m not able to physically test your truck, but based on the ongoing story it sounds like your guy is throwing darts, “the parts till it starts” method of diagnosis.
I’m also not a fan of FS1, I tried dealing with them for the ecm for my 79 resto mod.
They want 3800 USD for a 2003 f150 lightning PCM (a non supercharged version is 135USD. The price was the same for a blank one that I could program myself! (Sorry for the rant, it’s a sore spot!)
I would continue down the path of an intermittent issue with the low pressure pump, either voltage loss in the wiring, or a blockage within the tank.
You might look for a tech with more experience in the older systems, or is at least willing to research first.
The most important thing to know is how it is supposed to work when trying to fix something.
Hope that helps.
Cheers

 

[Motech]

they don't trust Cardone reman ECM so we sent it to their FlagShip1 in Miami, same issue after FShip allegedly fixed something!

FS1 does not repair modules. All they do is source used ones and program for your calibration so they're plug -n-play. That's why they don't want your core and they have no tech support.