86 2.9 running rough


Travlingman

15+ Year Member

Joined
Jan 15, 2009
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my 86 rangers 2.9 is running burn yur eyes out rich,idling super rough,and then it just dies, did the self tests, only pulled one code,67-neutral circuit fault, would this cause the condition im expeirencing,if so can i bypass this neutral switch,and what wires do i need to connect together in order to bypass it,its a A4LD auto.
 
Travlingman said:
my 86 rangers 2.9 is running burn yur eyes out rich,idling super rough,and then it just dies, did the self tests, only pulled one code,67-neutral circuit fault, would this cause the condition im expeirencing,if so can i bypass this neutral switch,and what wires do i need to connect together in order to bypass it,its a A4LD auto.
Click to expand...

You might start with checking out the fuel pressure, even checking the FPR vacuum line for raw gas. The diaphrams sometimes rupture and allow unregulated fuel to enter the engine. Also check the auto trans line and verify that it's not leaking trans fluid either. Also double check the circuit/wiring to the oxygen sensor. You might also take a peek at the MAP vacuum line, this is a critical piece for air fuel mixture, at low or no vacuum it thinks the engine is at WOT and run rich.

Just some thoughts.

Pete
 
86 ranger running rich/rough

Psychopete said:
You might start with checking out the fuel pressure, even checking the FPR vacuum line for raw gas. The diaphrams sometimes rupture and allow unregulated fuel to enter the engine. Also check the auto trans line and verify that it's not leaking trans fluid either. Also double check the circuit/wiring to the oxygen sensor. You might also take a peek at the MAP vacuum line, this is a critical piece for air fuel mixture, at low or no vacuum it thinks the engine is at WOT and run rich.

Just some thoughts.

Pete
Click to expand...
fuel pressure it at 40psi,no fuel in the FPR vaccuum line,FPR is new,all sensors are new,fusible links are all ok,trans line is fine no fluid, havent checked vaccuum to the MAP but it is a new MAP,checked the 02,no voltage in the plug,what sends voltage to the 02?could this be my problem?
 
The O2 sensor creates voltage, I don't think any is sent to the sensor from the comp, but the other way around. Could be a bad injector. One that is staying closed and flooding the cylinder. Check the plugs and see how they look.

Also, check the O2 sensor if it is bad, the comp could be thinking it is running lean and dumping more fuel into the engine. I had that problem on my dads truck, it ate through the cat in a few days.
Nick
 
Last edited:
the MAP sensor is on the passenger side inside fender. it has 1 black vacuum line goin to it. rectangle shaped
 
low vacuum

Psychopete said:
You might start with checking out the fuel pressure, even checking the FPR vacuum line for raw gas. The diaphrams sometimes rupture and allow unregulated fuel to enter the engine. Also check the auto trans line and verify that it's not leaking trans fluid either. Also double check the circuit/wiring to the oxygen sensor. You might also take a peek at the MAP vacuum line, this is a critical piece for air fuel mixture, at low or no vacuum it thinks the engine is at WOT and run rich.

Just some thoughts.

Pete
Click to expand...
What might cause a low vacuum condition,and thanks for all the info, has been very helpful!!
 
WOT or a vacuum leak will cause low vacuum.
Nick
 
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