86 BII stumbles, stalls, black smoke, any new ideas ?

[cstill88@hotmail.com]

Here we go, I sure hope someone out there has a suggestion...I bought this 1986 plain Jane BII for 500.00, it needed stuff, sure... I tuned it and all. Now after tires, brakes etc, it still won't run right.

Symptoms : After starting right up, even at -20, it starts to stumble and run rich at about a two minute cycle. If I can keep my foot on the gas, it will run great, and a few minutes later, it starts over. It also backfires sometimes at start-up. It's thick black smoke. This engine uses no oil.

I replaced : Map sensor, new injectors, main brain, rail fuel pump, filters, o2 sensor, air temp sensor, coolant temp sensor, vacuum lines, what's left ? ( Of course I did cap and rotor, plugs and wires) (( And fuel press regulator ))

I can't read codes on this, the check engine light does not come on.

Some sensor somewhere is telling the computer to run rich about every 2-3 minutes. Any ideas ???? Please have mercy !!!!

 

[tw205]

You say this only happens at idle? Runs ok if you keep your foot on the throttle? Check the idle air control valve. It sound like it may not be allowing enough air into the engine at idle causing the rich burn( black smoke ). Im not sure of the ohms it should register but Im sure that info is available somewhere on line.

 

[cstill88@hotmail.com]

No, not just at idle, but it seems to be a two minute cycle. Someone suggested a fault in the coil, maybe it's not running rich, just not getting a spark. I'm about to give up.....

 

[xr75er]

black smoke

most times with this truck it is the o2 sensor. pull the codes at auto zone if you can. but it sounds like the o2. luck to ya.

 

[tw205]

Dont trust that check engine light unless you see it come on when the key is turned on. The bulb may be blown if you dont see it when you first turn on the key. If you can get the codes checked you will at least be able to cross that off your list.

 

[alwaysFlOoReD]

My '86 2.9 Ranger doesn't have a check engine light and doesn't come with one stock. I suspect your b-II is the same. It does have the wiring, passenger side close to the firewall, to attach a code reader or you can use an volt meter. Check the tech section for how to use a voltmeter.
Good luck,

Richard

 

[brinker88]

Sounds like it may be a bad valve or piston rings....

 

[bronco2billy]

check voltage going to O2(check tech section on how to do this).If voltage too high,your O2 sensor might not have a good enough ground.Same thing happened on my 87.