bronco shuts off after highway driving

[95BlueOne]

I'm a heavy equipment mechanic for the Navy so I have decent mechanical and technicalknowledge but I got my 95 bronco w/ a 351w back in february and the truck has one issue that i can't figure out, it's happened twice both times exiting the highway exact same circumstances. It will act like it's out of gas and you need to floor it to get it to stay running it will spark knock and eventually die then takes quite a while to get it back running. also it idle hunts quite frequently upon start up but doesn't seem to be at a specific time ie cold hot. . . . Ther are no trouble codes and I've replaced the plugs wires dist cap rotar button fuel and air filters fixed the clockspring and thermal fuse in the airbag control module still no cruise though installed a new iac and bought the spacer for the iac from ford and the problem still exists. Any help would be appreciated.

[SCRebel]

Thats weird. Have you put a fuel pressure gauge on it to see what the pressure was when it was acting up?

[Shadofax]

Originally Posted by SCRebel

Thats weird. Have you put a fuel pressure gauge on it to see what the pressure was when it was acting up?

That would be the next place I'd go. If it's never had the in tank pump replaced, it could very well be your problem.

[TheUnforgiven]

get the TFI module tested.

[JKossarides]

Do a quick fuel test at the rail using the "schrader valve" on the rail towards the front, it looks like a tire valve stem and just press the valve in the center and see if any fuel comes out indicating you have some fuel at the rail but a fuel pressure gauge testing the FPR = fuel pressure regulator on top of the rail towards the back drivers side will tell exactly what PSI and IIRC it should be 37-40 psi engine off cranking and running...look for cracks in the plastic vaccum lines and if so you can "bridge" it with a small rubber vaccum hose with tie -wraps at end end for a good seal.

The sending unit/fuel pump in the tank could also be an issue if it's the original one, old or dirty fuel filters may only "slow" fuel delivery at best but can't hurt to change if it's been a while....

In most instances when driving and the engine stalls, dies etc.....my first instinct would be the TFI = thick film integrated , ignition module located directly on the distributor or a "remote" located igntion module and have it tested "several" times with a passing grade otherwise replace it.

It seems odd there were no "fault" codes indicated initially so I would drive it around until it reaches normal operating temp and then perform KOEO = key on engine off and KOER = key on engine running and then see what elec/electronic fault codes show up....FYI there are no fault codes for FRP issues, it's vaccum only.

For IAC= idle air control and TPS = throttle position sensor AND ECT= engine cooling temp sensor all of which are "fuel managers" at cold start and normal operation ~ check the Haynes Manual for back probe tests if necessary to test for voltage/ohms resistance etc.

Check MAP or MAF sensor, culprits that affect performance as well.

Good Luck ~

[Kingfish999]

when i was haviung a problem of my truck driving fine for awhiel then after some time of driving either offroad or onroad at highway speeds, it would randomly do this and usually hit me soon as im at a stop or light and act like it outta gas. would take a while to get it to start back up. i ended up having to get new fuel pump(s) and this would cure it for about a week to a month. my main problem was alot of dirt in the tank making the fuel pumps quickly get ruined which cause me to have to buy 4 fuel pumps in a month and cary a spare. tho urs probably isnt from dirt in the tank like mine, ur pump might be going dead from age like mine was.

[BroncoJoe19]

A hunting surging idle is often a vacuum leak. I'd spend some time looking for one.

Even more likely in your scenario, especially as it relates to decelerating off of the highway; is a faulty IAC. I know that you stated that you replaced your's. It is possible that the one you got is malfunctioning. Follow this link to see if it may still be the culprit

http://www.fordforumsonline.com/foru...e-iac-iab.html

The next thing that I would do is pull diagnostic codes.
http://www.fordforumsonline.com/foru...996-fords.html

[95BlueOne]

I've checked fuel pressure it came out at the minimum 37 psi koer i replaced the fuel pump but since i live in an apartment i didn't purge it i haven't found any vaccum leaks so far i'll keep lookin i took it to ford and the guy working on it had over 20 years experience and couldn't find the problem. I'll get my dad to check out these problems i'm deployed for now. Who could test the tfi any shop?

[BRONCONUT]

Most of the auto parts stores can test it for you, just make sure they do it several times to make sure it gets up to normal operating temperature before stoping.

[95BlueOne]

great thanks guys

[Maverickkid]

okay i keep finding these threads and have read them all but I wanted to put my problem out there and get feedback...i'm thinking its the fuel pump

i have a '89 with 102,000 original miles. about a month ago i ran outta gas (or so i thought) came back about 15 minutes later with gas and then drove home so i thought that was the problem. next day same thing. seemed like after it would get hot i would have an issue and if i let it cool off 15-30 minutes it would be fine again. the last time however this was not the case.this time it wouldn't restart.

the bronco has a new tank, fuel filter, and relay. i tested the pressure on the rail and have nothing (and i mean nothing). i know there's the fuel pump/sending unit in tank and one on fuel rail. i can hear the one on the rail engage when you turn the key on.

is it the fuel pump? which one? is there a way to test before i go throwing money into it.

[Nite Rider]

I've got the same problem on my 92, 351W. Shuts off on the highway, i let it sit for a while and it starts again. This weekend it did it again, but would not re-start, had to take the "tow-of-shame" home.

I turned wrenches on helicopters in the Marines, so I'm fairly good with troubleshooting, but i can find nothing. I found an old mech who used to own a bronco and he says it's the ECM, or electronics control module, located on the inner side of the drivers fender wall. Says they just crap out after a while and it causes this to happen. I'm having that changed this week, so we'll see how that goes.

[Maverickkid]

let me know how that goes i'm still looking into things. i've heard ppl say everything from ecm, pumps, relays, and regulators. i've been trying them all and have had no luck. i'm just trying to self test before spending a good chunk of change replacing 2 pumps and a regulator the pumps are not tha bad to change (one in tank kinda annoying but installing an access panel this time thanks to suggestions by others) the regulator kinda a pain have to remove some things in the way.

[mnlabgeek]

Follow Bronconut's advise. Have the TFI tested. Or search TFI on here and your symptoms are described by many others with this problem.

Once the truck cools, the TFI will work until it warms back up. I had the same symptoms and replaced TFI and all is fixed.

Good luck. Respond back with your repair so others can learn in the future.

[TheUnforgiven]

Originally Posted by Maverickkid

okay i keep finding these threads and have read them all but I wanted to put my problem out there and get feedback...i'm thinking its the fuel pump

i have a '89 with 102,000 original miles. about a month ago i ran outta gas (or so i thought) came back about 15 minutes later with gas and then drove home so i thought that was the problem. next day same thing. seemed like after it would get hot i would have an issue and if i let it cool off 15-30 minutes it would be fine again. the last time however this was not the case.this time it wouldn't restart.

the bronco has a new tank, fuel filter, and relay. i tested the pressure on the rail and have nothing (and i mean nothing). i know there's the fuel pump/sending unit in tank and one on fuel rail. i can hear the one on the rail engage when you turn the key on.

is it the fuel pump? which one? is there a way to test before i go throwing money into it.

how 'bout you try pulling codes?

and start your own thread.

[95BlueOne]

It sounds to me his post was exactly the same as mine why would you want to post another thread. . anyway if ya'll figure this out let me know i'm deployed overseas now but my bet is on the tfi please keep me updated. Oh and by the way everytime i've diagnosed a computer issue there were no codes just my experience which is leading me to believe the tfi is the problem as i am showing no codes. i never go straight for the computer but i have tried every other thing mentioned on here.

[Maverickkid]

TFI does make sense but would it still cause me to not get any pressure when I test on the fuel rail? That is the only thing that keeps throwing me back to something with the fuel delivery itself.

[BroncoRex]

I had this problem but with codes showing a PIP problem. Replaced the dizz. no more codes and no more problems.
Good Luck
Sean

[Glayd]

I had the same exact problem with my 89 351W and after reading the many threads on this site about the Ignition Control Module, I moved it from the the heat of the distributor area and ended up mounting it on a bronze heat sink mounted to the AC compressor. Problem went away instantly and the module never overheats. From what I have read the module shuts down at 257 degrees F so the distributor area is definitely the wrong place for it to be. Also from what i've noticed the unit itself generates a great amount of heat on its own thus the need for a good heat sink.

[BroncoRex]

Originally Posted by Glayd

I had the same exact problem with my 89 351W and after reading the many threads on this site about the Ignition Control Module, I moved it from the the heat of the distributor area and ended up mounting it on a bronze heat sink mounted to the AC compressor. Problem went away instantly and the module never overheats. From what I have read the module shuts down at 257 degrees F so the distributor area is definitely the wrong place for it to be. Also from what i've noticed the unit itself generates a great amount of heat on its own thus the need for a good heat sink.

1995 had the Ignition Control Module remoted mounted from Ford. I do reapply heatsink grease (silicone based) every year or so. Hope this helps. Thermal compound improves thermal condctivity.
Good Luck
Sean