I am sure you have checked this out but just in case. 88 Bronco II has two fuel pumps. One high volume in the tank and a high pressure in the frame below the drivers door. Just ahead of it there is a large fuel filter mounted in the frame approximately in line with the fire wall. A partially plugged fuel filter will give you good pressure readings at idle or not under load. On the highway under load the fuel volume requirement goes up and will robb the power & almost act like a governor. Good luck!

 

Yup, i have already replaced the filter, which wasn't clogged. The gas tank is also new so it doesn't have junk in it.

 

hello,i had these same problems but what i found out was in neutral under no load i would get good fuel pressure of 30 to 45lbs but if i put it wide open it would briefly jump up to about 4500 to 5000 rpm and surge at around 3000 rpm and the my fuel pressur was only about 28 29lbs which a few pounds is all it takes to cause problems,so i changed the fuel pump and now it runs better than in a year and also note i had these problems also only when it got warm,but if it is a pump i wouldnt know which one i mine only has one in the tank....hope this helps d.

 

Someone please solve this problem! I have the same problem on an 87 Bronco II with the 2.9, and it is driving me insane. I have done all the stuff mentioned here, and more. It runs great for about 2 miles, then has the same symptoms.

I will continue to watch this thread for help!!!

 

My '89 B2 was having all kinds of troubles.......stalling, sputtering, weird shifting, backfiring, and no power at all. After pulling codes and taking care of everything I finally found the TPS to be the main problem.

 

I have swappped TPS, EGR, MAP, IAT, computer, you name I have swapped it. I am going to change the oil pump before I try anything else. I know the sending units were not to good on these engines, so I ignored the flickering oil lite, which was begining to stay on all the time. I changed the sender, only to find the lite still on, so I put a gauge on it, and it doesn't even lift the needle off zero. I started it with the line open and it does pump oil, but not enough to keep me from putting the line back on and starting the nut with one hand. In theory, I wonder if the pressure is so low the lifters won't pump up, and that is part of the problem. I have a steady backfire you can feel with your hand on the air filter box. With brand new heads I shouldn't get anything coming back past an intake valve into the intake manifold unless a valve is stuck open, but I am running 180 psi on all 6 cylinders when I check compression.
I hope I have not damaged the bearings with the low oil pressure. I had no valve clatter that would indicate I really had low pressure.

My book says you can remove the oil pan w/o pulling the motor, but with the engine jacked, and the tranny hitting the body, the pan will not clear the front diff. I put the pan back on with two bolts and plan to pull the engine soon.

 

Ok, i haven't been back for a bit, i was getting a good way to check the fuel pressure while driving and have determined that that the fuel pressure acts the same wether it is "acting up" or not. It seems to do just what it is supposed to.

 

14 is from the pickup in the distributor. at one time there was aproblem with that. they are a hall effect sensor and the magnet can crack. if after changing the TFI the 14 went away it is possible that the pip was bad and by tapping it by working on the distributor it wont give the code but is still bad. you have to pull the dist to replace it.

put and inductive tach on and if the rpm flutters driving at higher speed you are dropping spark could be low side or high side. put a coil tach on or dwell meter and in the same drop or flutter happens it is your low voltage side. wires could do this but usually it is more prevelant an low speed takeoff load.

 

my 88 ranger 2.9 is behaving exactly like yours

after 10-15 mins city driving it bogs right out and can't get it to pull over 3000 rpm's
i have changed the tps sensor, ignition module, o2 sensor and all have provided no results
its been doin this over a year now but i have only had the truck 3 months and with a very limited budget i can't do much
so any help would be greatly appreciated

 

change te ECU.. same thing happened to mine cold runs fine and then warmed up it bucks an jerks and idles bad