Pirate 4x4 banner

1 - 3 of 3 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
My 1991 Bronco, 5.0 Full size, 4wd has a problem that stumps the local mechanics. Any help with this is most appreciated.

Under normal condidtions the fuel pump should cycle for about two seconds when the key is turned on and then cut off. After my Bronco runs for about 30 minutes and warms up it starts to sputter and blow black carbon smoke like it is burning rich. When I try to start it again the fuel pump continues to cycle instead of the short burst and will not start. It does not help to disconnct and reconnect the battery. If I come back to it after a week it will cycle correctly, start up, and run untill it gets warm. I know it is not going to start back up when the tell tale sign of the fuel pump is cycling continualy instead of that short burst when the ignition key is turned to On. Before I repalce the computer has anyone ever had this from a bad sensor, alternor, or actuator. I hooked up a code reader and it said it could not read computer. I replaced the relays to no avail.
Help! - She is my Ranch Mule team!!
 

·
Registered
Joined
·
2,088 Posts
its probably the computer in your case. the drivers are retarded from an over voltage somewhere or something. but when it stalls do you still have good spark?

check and make sure you got spark.

but if its not coding at all its probably going into los mode(not fmem) cause its got something inside thats cracked that is not even visible. if you know someone with the same setup as you pop your puter in thier truck and see if it dies in that truck too. then make sure you got no shorts anywhere and replace it if it dies in the other truck.
 

·
Registered
Joined
·
2 Posts
Discussion Starter #3
Thanks for your reply. The engine does have a spark when this occurs. If I spray a little Carb. Cleaner up the air intake it will even try to start yet does not, indicating to me that it is not getting fuel to the cylinders. Two things are happening: Fuel pump is cycling when it should not be and vehicle will no longer start, yet it is getting a spark. (??)
Last week I was inspecting all the wires and relays for any shorts and breaks by moving them around. (Lots of mice in the country) I noticed the wires that come off the altenator and run to the solonoid are very very hot. The connections look good (?) and the starter turns over good. This weekend when I get back out to the property I am going to check the voltage output on the alternator and check PSI on fuel rail. Any other ideas? I do not know of anybody else with a Bronco but I like the idea of swapping out the computer. Is it the silver tin box located over the gas pedal on the firewall?
I am at such a loss with my bronco down. Lke I said it is my mule team. I have a JD crawler Loader and a massey furgesson tractor but neither one of them compare for skidding tress and the ranch work I do with my bronco in Low - Low 4wd.
 
1 - 3 of 3 Posts
Top