My Buddy has an 86 Bronco II 2.9 5-speed. His truck is not in the best shape so i have been helping him get it running like a champ again. I had done a major tune up on it, it was running good then all the sudden a week later one of his spark plugs was wet with fuel so I replaced it and it ran great for another week suspecting one faulty plug.

This week out of nowhere his truck started running really rough so I inspected the new spark plugs once again and they are all now black with soot and wet with fuel. I therefore went straight for the iginition system and checked it all out. He is getting spark to all cyclinders. so It seems he is just getting to much fuel. Since this carboning of all the spark plugs happened fairly fast and all at once I am suspecting the Fuel pressure regulator went out and is letting to much fuel pressure in. We are in the process of inspecting all of his injectors, but I doubt they all decided to go out at once.

There is another thought I had, that his timing chain slipped a few teeth and has thrown off his whole sequence of fuel and spark. It's a thought but I doubt it. Anyone have any Ideas??

 

Attach a fuel pressure guage to the sharader valve on the fuel rail and see what kind of pressure readings you get when the truck is running. Compare to those posted in a manual.

Good luck!

 

Check fuel pressure (30-40 psi), check your FPR for leakage into the vacuum line, check/set base timing with SPOUT connector removed/engine warm (10*BTDC), check primary/secondary on coil. If you absolutely have to check valvetrain/timing line-up, you can pull the valve covers (pain in the butt) and distributor cap and rotate the engine by hand and see if everything jives. My best guess is the FPR is going bad, the injectors are leaking by, the coil is getting weak, the spark plugs/wires/cap/rotor are junk. I can't remember what the resistance is supposed to be per linear foot on the spark plug wires, but you can probably look that up. Best bet on a lot of this is a Haynes or Chilton's manual or the Autozone Online Repair Guide. Hope this helps!

 

i'd have to agree with kernel..sounds like the fpr is going south...check the fuel pressure as mentioned..pull the hose off the fpr {the one leading to the fuel rail,and see if you have any sign of fuel in it..if you do,it's bad..if not,then could have an injector problem

 

I'm retired but I used to work on diesel equipment in the Oil Fields and that sounds like to me you have A CRACKED or LEAKING Fuel Injector Nozzle(tip).
Suggestion...take them all out and take them to a dealership and have them tested. Find out what the operating pressure is on the injectors and insist on observing when they go to test them. If they refuse then go somewhere else.
Once they are checked you will see whether the tips are cracked, leaking or are stopped up. Also, IF some of them are stopped up tell the mechanic to pressure up on them another 5-10lbs. Sometimes they will clear themselves and sometimes not. Either way; you'll know if you have to buy new injectors or not! Anyways, it's just an idea. Hoped this has helped!

THANKS,
Fenix2
Converse, LA

 

Injectors were already mentioned.... but it might be a good idea to pull 'em and test 'em. If only one is bad, though, I would replace them ALL and keep all the "good" used ones as spares.

 

Thanks guys, I just did a minor rebuild of all my buddies top end this weekend. The upper intake was caked with grime and oil, and the air charge temp sensor was covered in oil. We cleaned everything spick and span. I checked all the injectors and they seem to all be looking good. I was talking to a Mechanic at a strictly ford repair shop up here in Vancouver called job right, and he said hes 99% sure coolant temp sensor has gone bad, causing the computer to think it was freezing outside. this caused the computer to dump huge amounts of fuel into the engine. So I replaced that today as well along with the O2 sensor. I will keep you guys posted on how she runs today. Thank you for all the help.

 

Well the Truck fired up today but even after all that rebuilding it still running like crap, so we are going to bite the bullet and buy an FPR and see if this corrects everything. Its my last link that would cause this severe rich condition.

 

You may also want to check all the other sensors and pull codes to see what else could be wrong. You may also want to double-check your ignition, especially the coil. Could be that you're getting too weak of a spark. Another idea would be to (depending on what wires you have on there) set the spark plug gap for the maximum (.046, I believe), or as wide as .050 to see if it's just a spark issue. You should also think about checking all of your wiring and ensure that you don't have any odd faults caused by wiring. You could also be having issues with the MAP sensor and/or TPS. I would also go over all of the vacuum hoses, PCV valve, EVERYTHING really good. Could be a pinhole leak in the FPR diaphragm or the FPR is getting "weak" or some such. A vacuum leak would also affect the FPR as well. Basically, I would go over EVERYTHING with a fine-toothed comb testing and checking until every possibility is eliminated. Still sounds like somehow the O2 / ECT sensors are giving some false readings. What did the EGR look like? Yet another possibility of what could be going on. Hopefully, though, it's just a faulty FPR, but you never know. As far as the ignition, if the base timing is set correctly and the SPOUT is functioning properly as far as the timing control, and as long as you are getting a strong enough spark (I prefer Autolite plugs and wires, sometimes I also like more expensive stuff too), then that shouldn't be an issue with this. Could still be faulty injectors as well. You may want to run some of the fuel system/injector cleaner in it religiously for a few tanks just to see if that helps out. Anyhow... hope some of this helps and makes sense... and that you get 'er fixed soon.

 

Well with this problem, the truck runs so rich it doesn't run at all, just chugs like half the cylinders are not working. The plugs are black with soot. Before this the truck was running great then it was just turned off and on and this is when the truck began this problem. It seems to have happened across all cylinders at the same time. So Im still leaning towards the FPR, but I shall comb this motor and make sure its the only possible problem.

 

Well we put a new FPR on today and tried to fire her up and she ran exactly like when the problem first started, so i guessing I have an electrical Gremlin some where in there. Any ideas about what could cause this over rich condition? I know I am getting some form of spark, but it might not be enough.

-Thanks

 

i wonder if ... the coil is getting weak, the tfi module is not working right (those are known to go out when ever and however) the tps sensor is bad, or if there is a bad wire or loose ground.

 

has any one thought of carb might be time for a kit just thinking out loud..lol

 

A carb on a fuel-injected vehicle???? Uhhh.....

Anyhow, might be that the injectors are dirty or leaking, or like I've mentioned before I think and franken re-mentioned, could be bad ground or an ignition-related issue due to a weak coil, etc. Time to go through that truck with a fine-toothed comb and eliminated any possibilites! I am also wondering if the alternator is up-to-snuff and that both the positive and negative battery cables are good and that the battery isn't going bad (yes, if you have a weak battery, it will screw with the EEC/TFI-IV system, which is yet another thing I think is contributing to things on mine, although, mine's still running pretty darn good for it's age!).

 

ahhhhhhhhh wrong post lol