Whats wrong with my bronco.

[Bubba]

I just bought a 89 bronco and its using way to much gas. It will blow black smoke if I rev it. I think the problem is that i dont think when the person before me swapped from a 351w to the 302 that they didnt swap the computer (eec). If anybody else has any suggestions or knows anything else it might be I would apperciate it. Thanks.

 

[Broncobill78]

I just bought a 89 bronco and its using way to much gas. It will blow black smoke if I rev it. I think the problem is that i dont think when the person before me swapped from a 351w to the 302 that they didnt swap the computer (eec). If anybody else has any suggestions or knows anything else it might be I would apperciate it. Thanks.

Well, start at the top and work the problem one step at a time. If it's blowing black smoke then it's probably running rich. Cheeck the EEC and see (it's behind the passenger side kick panel). It's also possible the engine was swapped for something from a junkyard or another truck and has a lot of miles on it and you just plain need some rings. But if it's blowing black smoke then it's either running rich or burning oil, eliminate the suspects one at a time.

 

[19Bronco93]

i had the same exact problem with my 93.

-I bought the truck knowing of the problem.

-Check Engine Light went on and off a lot.

-Got new complete exhaust system, headers, duals, nice. (FAILED to replace 02 Sensor)

-Check engine light failed to come on for a while and my truck started to bog down at a stop and sometimes stall.

-black smoke would blow at idle and when i rev, oil burning was a little on the high side, a quart every thousand miles

-got tired of the horrible gas mileage, so took it to my mechanic

-check engine light came on seldom

-mechanic thought he had the problem fixed, test drove it, only to realize he didn't.

-the culprit= 02 sensor. it was old, and stuck, so the computer always read it as too lean, always pumping more gas in, bogging the engine down, blowing black smoke.

-due to frequent oil burning and a slight knock, i switched from 10w-30 to 20w-50, and have had no smoke problems since

 

[Dizfunkshunul]

i found a 1984 bronco for sale it has a 351 with a brand new edlebrock carb on top but it blows out black smoke alil but u really cant see it unless u smell for it or if u r lookin cllose but u can see the build up on the tail pipe, ther is so much buildup that the eaust will blow it off the tip on to the ground but once it warms up there is no smoke at all what so ever and it runs good but when i drove it i can tell its missin some power like passin gear barely kicks in when u punch it but its still pretty quick (maybe just the type of trnny) but if some one cld help me with this i would be thankful cuz this bronco is in great shape for the price!!! thankz

 

[BroncoJoe19]

i found a 1984 bronco for sale it has a 351 with a brand new edlebrock carb on top but it blows out black smoke alil but u really cant see it unless u smell for it or if u r lookin cllose but u can see the build up on the tail pipe, ther is so much buildup that the eaust will blow it off the tip on to the ground but once it warms up there is no smoke at all what so ever and it runs good but when i drove it i can tell its missin some power like passin gear barely kicks in when u punch it but its still pretty quick (maybe just the type of trnny) but if some one cld help me with this i would be thankful cuz this bronco is in great shape for the price!!! thankz

It is probably due for a tune up.

Black smoke is incomplete combustion, running rich.

the repair may be as simple as replacing a dirty air filter.

It may be more, but if you buy it and need help, let us know.

joe

 

[crazyhorse85]

HEY BRONCOJOE19 YOU MIGHT LOOK AT THE ADJUSTMENT ON THE CARB...WHEN I FIRST REBUILT MY 351W I TRIED TO USE THE 4180 HOLLEY THAT CAME ON IT...BUT THE PREVIOUS OWNER HAD IT SO FAR OUT OF ADJUSTMENT THAT IT WOULDN'T IDLE RIGHT...I REPLACED IT WITH A HOLLEY 750 DUAL LINE...NOT DOUBLE PUMPER...THAT WOULD'VE GIVEN THE SAME PROBLEM TOO MUCH FUEL...WITH A LITTLE TWIKING IT RUNS GREAT NOW AND NO BLACK SMOKE.. HOPE THIS HELPS YOU OUT... >-

 

[barrett86]

FYI all caps is considered yelling.