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

[Tpremru]

It could be an electrical issue, but back in the day they told us that a fuel pump would get hot and stop, cool down and start.
Or get hot and stick.

So a car would die, no fuel pressure, get towed home, start to test it, car starts right up as if nothing is wrong.

Thank you....so this could still be a bad Lpump...but it would be the 5th one to go bad so 1st week in february will be when we can drop tank check wires, rewire, replace pump, etc.

 

[Tiha]

Thank you....so this could still be a bad Lpump...but it would be the 5th one to go bad so 1st week in february will be when we can drop tank check wires, rewire, replace pump, etc.

There was a deal and I don't remember all the details because the constant LP pump replacement is why we went to a single pump system.

But there was something about the LP replacement pumps. Ford used a certain style and most of the aftermarkets were a different style.
Like one was a progressive cavity type pump and the others were a positive displacement type pump.
Anyway, made sense at the time, but I didn't care because I was done with the 2 pump systems.

But it was like you had to have the proper style low pressure pump for it to work for very long in the 2 pump system. Sure most parts stores sold pumps with lifetime warranty but when you are going through them like candy you get tired of swapping them.

When I was going through it I had read where a guy was having the same problems with constant LP pump failures, he went to the junk yard and got an OEM ford LP pump, old used one even. That fixed his problem, no more LP pump failures, or at least less than what he was having because threads like that kind of die out and no reason to update.

 

[Tpremru]

There was a deal and I don't remember all the details because the constant LP pump replacement is why we went to a single pump system.

But there was something about the LP replacement pumps. Ford used a certain style and most of the aftermarkets were a different style.
Like one was a progressive cavity type pump and the others were a positive displacement type pump.
Anyway, made sense at the time, but I didn't care because I was done with the 2 pump systems.

But it was like you had to have the proper style low pressure pump for it to work for very long in the 2 pump system. Sure most parts stores sold pumps with lifetime warranty but when you are going through them like candy you get tired of swapping them.

When I was going through it I had read where a guy was having the same problems with constant LP pump failures, he went to the junk yard and got an OEM ford LP pump, old used one even. That fixed his problem, no more LP pump failures, or at least less than what he was having because threads like that kind of die out and no reason to update.

That's why after 1 Precision and 1 other brand, then 2 Napa's, (complete fuel send unit, which i don't think any of them really had the correct impedence range for an accurate reading 70-0) then i said I will get a NOS OEM which is in there now. I still have my original OEM as well which the pump still turns on, wondering if it was a flow problem orginally - but if it turns out that this 5th Lpump is bad and the wires are OK then i plan to install an alleged direct replacement Lpump only which is a "Carter". Still looking into if a 89 Lpump fits my tank.

 

[Tpremru]

You are not going to believe this because i still don't believe it.....today Monday i hooked up the Lpump only, did not hear it prime so i grnd pin#6 and still nothing. I decided to redo my "guitar cord test" and moved wires around in reverse from the other day started at the relays, then under master cyclinder, Hpump, harness on the rail, then i decided to reach in from drivers side rear wheel with a 3ft wooden dowel and barely touched the wires exactly on the top of the pigtail plug....bzzzzzzzzzzzzz the Lpump turns on! I'm really hoping this is it but is way way way too simple. @$!#%&*(^ Have you ever been so happy and so ^%#&$^# ****** at the same time?

So i have a special tool i made 40 years ago for my trolling motor - a childs broom stick that i laquered 36" x 3/4" with a bent brass hook. I was able to reach in from driver side rear wheel well and slip the hook under the pigtail lock tab and twist the dowel so up popped the plug, uh oh can i get it back on? It took about an hour or more to get it back on...so i could try the Lpump again because i don't know how good was it plugged in to begin with. Lpump still not coming on so tomorrow i will pop plug and be able to test wires with multimeter.

Today Tuesday: I popped the plug out again and snaked it back as far as possible to the driverside rear wheel. When i first saw that plug i immediately said eureka that's it, but that's too simple but makes sense from yesterday's test and especially that time about a year ago i left the driveway and i when i hit the dip it stalled. So i pulled that wire and the ground all the way out, hooked up my multimeter and turned key on with ODB1 pin#6 grounded. Moved the wires everywhere and no meter fluctuations. Then i plugged in my old pump and banged it around making sure no intermittant running. It took 3 hours to unplugg it, test it and replug (not easy part). I idled it for 30 minutes, drove it for 50 minutes about 20 miles and idled it in the driveway for 35 minutes. No issues and when driving it and step on it, it got the fuel it was needing and took off. I'm going to drive it further than 5 miles and longer tomorrow and will report back here with "the rest of the story".

 

[Tiha]

That is awesome. Always feels good when you find something.

 

[goodO1boydws]

So was the connector simply a loose fit, corroded terminals , or what?

 

[Motech]

In the next couple of days i'm going to be trying to find G200, S303, S304 and C118.

If you can do some volt+drop testing between pump power and ground and battery positive and negative while running, good readings will eliminate all those points the very first test.

 

[goodO1boydws]

Oh I see it now.
I've never seen a threaded-in wire connector like that come apart.

 

[Tpremru]

Oh I see it now.
I've never seen a *****-in wire connector like that come apart.

I think it's the only replacement you can get. see pic. LMC and Amazon and everywhere else. What i can't believe is the first guy must have made a mistake and i was going to ask him to drop the tank June 2020 and check the wires and i did not...but damn took it to Palm Harbor Auto (the pros) told owner twice in 6 months "Please check that plug and wires, the mechanic does great wire work but check it" Then 6 months later i say "Did you check the wires, that plug?" They always say yes nothing wrong there. They changed the Lpump 3 times so how can that &*^%$ be?

 

[Tpremru]

If you can do some volt+drop testing between pump power and ground and battery positive and negative while running, good readings will eliminate all those points the very first test.

Thanks - The plug comes off somewhat easy but getting it back on is damn tough. I may have to take it off again based on what you said. I know it will start and run without Lpump soi think it's doable. I did get Lpump wire readings but not while running or any other loads. The Lpump wire readings maybe troublesome according to my electronics buddy.

Otherwise I don't what's good/bad or where to go next other than clean the new Engine block grnd connection and get a new engine to body flat web cable which i cleaned up and soaked in vinegar and baking soda.

Reading 1 = Batt posts 12.12 V
Reading 2 = Lpump Hot & Lpump Grnd 11.84 V
Reading 3 = Lpump Hot and Frame 8.7 V
Reading 4 = Batt Neg and Engine block .2 mV
Reading 5 = Batt Neg and Engine block headlights on 12.8 mV
Reading 6 = Batt Neg and Frame .1 mV
Reading 7 = Batt Neg and Frame headights on 8.3 mV
Reading 8 = Batt Neg and Body .1 mV
Reading 9 = Batt Neg and Body headlights on 46,2 mV


Otherwise i drove it 42 miles today about 2.5hrs and after the first hour i shut down for 15 and restarted it made a bunch of air bubble sounds in the fuel tank on restart...so i promptly got it home and disconnected Hpump and grnd pin6 to check the Lpump-it's still working. Hpump does not sound bad but don't sound that good. I connected both pumps with pin6 still grnd and there's that air bubble sound again. Is the Hpump tired of 18 months of doing most of the work and maybe it's a lower quality Napa they put in????

 

[Tiha]

Air bubble sound, interesting, can't say I have ever heard it or listened for it.

So to have air bubbles air has to be getting in someplace.

The only other thing I can think of is if the fuel is boiling in the rail, maybe that would make that sound when it clears and the vapors reach the tank again?

I honestly have no idea.

 

[Tpremru]

Air bubble sound, interesting, can't say I have ever heard it or listened for it.

So to have air bubbles air has to be getting in someplace.

The only other thing I can think of is if the fuel is boiling in the rail, maybe that would make that sound when it clears and the vapors reach the tank again?

I honestly have no idea.

Definitely wierd sound, i noticed it about 4 times now. Only when hot, not when just the Lpump, but does it with either both or just Hpump, just on the initial start after hot and rest short period. I was already to record it yesterday but did not do it again yet.

 

[goodO1boydws]

Otherwise i drove it 42 miles today about 2.5hrs and after the first hour i shut down for 15 and restarted it made a bunch of air bubble sounds in the fuel tank on restart...so i promptly got it home and disconnected Hpump and grnd pin6 to check the Lpump-it's still working. Hpump does not sound bad but don't sound that good. I connected both pumps with pin6 still grnd and there's that air bubble sound again. Is the Hpump tired of 18 months of doing most of the work and maybe it's a lower quality Napa they put in????

Hmmmm.

There are a few ways that air could be getting into the fuel delivery/return path, (without fuel leaking out) such that it could make an air-bubbling sound OR a sound similar to air bubbling in the tank at startup. But it would tend to be there any time that the vehicle had been sitting for some time.

There could be a rusted area with a pinhole somewhere on the fuel return line (a rust-perforated area, likely on the top surface or at a supporting clip) or the hose connection(s) to it could be a tiny bit loose.
In that line the pressure is low so when the engine is shut off and the pressure drops even lower, air could be infiltrating there.

Another way would be if the end of the outlet pipe for the return line is out of position and high enough for it to be above the level of the fuel in the tank. The fuel SPLASHING might sound like air bubbling, because normally it would be making a gurgling sound from being released under liquid. That rubber/silicone one-way valve on the very tip of the outlet pipe could be compromised (maybe having a piece of rust or other crud stuck in it) and not sealing completely when the low pressure drops, allowing any section of pipe that is above it to drain.

Another way would be if there is a small hole/crack on the fuel INTAKE pipe inside the tank high enough to be above the fuel level. That could allow air to enter at that point. As could any very slightly loose hose connection that seals better when its under pressure-or when it heats up.

Another way would be if one of the clamps on the short section of hose on the outlet pipe INSIDE the tank is loose-AND above the fuel level sometimes. OR if that piece of hose itself is compromised, OR if the point at which fuel enters the pump's intake is sometimes above the level of the fuel) These could be checked by seeing if the noise is there or if it changes, with a neck-full tank-and when parking at different angles. (fore and aft and sideways too)

I don't know if you've said whether you've been getting complete pump assemblies or only replacing the LP pumps themselves, but the fact is you've had several LP pumps in and out. You've needed to disconnect and reconnect the exterior hoses, and to manipulate the pump and float assembly parts to do that, so if its actually air entering the system, I'm leaning towards it being a problem with air getting into the system INSIDE OF or AT the tank.

 

[L\Bronco]

Not 100% sure, but it sounds like fuel returning to the tank through the return line, there are often bubbles of vaporized fuel in the return line as the pressure is nearly zero there.
If that’s what it is, it’s completely normal
Hope that helps
Cheers

 

[Tpremru]

Thanks again to L\Bronco and good01boydws these are more reasons to drop the tank and things for mechanic to check even with my latest probable fix. I'm hoping and going with L\Bronco as this happened with 4 gals and 22 gals in the tank.

Another thing to note auto shop says "Oh yeah we cleaned up all those grounds" I now call BS as i can only find the New neg that goes to block (that was a bitch to get back on today after cleaning, yeah it's new but what the heck) and the old braid strap goes from wierd mount on exaust pipe to a clip on the body right front fender and 2 little wires that go as pigtail on the Neg batt post to the body in front of battery.

 

[goodO1boydws]

If its there full or empty, I'd go with L\Bronco too.

(I'd still check the condition of the return line though.)

 

[Old&Cranky]

I had a 1986 Bronco ii, 2.9L 4x4 5 speep manual. I sold it in 2005. This truck had the same problem for about a year until I finally told a mechanic to drive it till it happened again. It happened to him and he figured it out right away. It was a loose distributor...that was it. He fixed it and I never had another problem with stopping for 2 or 30 ninutes.

This past Saturday, Feb 18th, 2023, I bought another 1986 Bronco ii, 2.9L, 4x4, 5 speed manual Eddie Bauer with 78000 original miles. It is beautiful. Yesterday it got new pipes. Today it got new tires and shocks.

 

[goodO1boydws]

I had a 1986 Bronco ii, 2.9L 4x4 5 speep manual. I sold it in 2005. This truck had the same problem for about a year until I finally told a mechanic to drive it till it happened again. It happened to him and he figured it out right away. It was a loose distributor...that was it. He fixed it and I never had another problem with stopping for 2 or 30 ninutes.

This past Saturday, Feb 18th, 2023, I bought another 1986 Bronco ii, 2.9L, 4x4, 5 speed manual Eddie Bauer with 78000 original miles. It is beautiful. Yesterday it got new pipes. Today it got new tires and shocks.

GREAT catch on finding that low of a mileage B2.

 

[johnnyreb]

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.

Maybe that is why it had the low miles on it. I,d (if I could) talk to her about it and see if she had trouble with it? Maybe she did and could tell you her mechanic? Good luck and welcome to the club.

 

[Tpremru]

Congratulations on the B2 find! There's a few around, but, ya don't see 'em! The other day i just saw one for sale in Oldsmar...maybe 8 miles from here. I just finished all the weather stripping on 2 doors and hatch and hatch window and the wipers and felts and repaired and reweb driver seatbelt. Going on Tuesday to get axle pivot bushings and radius arm bushings and new Hpump. Contemplating 5 Cooper AT3 4S p225/70r15 near future. Will it end?