Running Rich ?????? (1 Viewer)

[Digger276]

On my 91 LC, 3FE, 154,038 miles. I was driving last week and noticed my MPG has dropped and I smell that the engine is running rich. I have also noticed my tail pipe is blacker. No codes have appeared or any running difference. I have replaced the plugs, wires, cap, rotor, cleaned the throttle body, ran a tank with a fair amount of injector cleaner. Still no difference. Any "normal" failures with this engine in this area. The only other thing I can think of is a leaking injector. I checked all the plugs as I pulled them out all appeared equally black.

All suggestions appreciated.

Thanks all.

 

[CJF]

O2 sensors come to mind; have you ever replaced them? They can be out of spec. without throwing a code, and are also (I believe) listed in the maintenance schedule for replacement at 100k or so.

 

[Digger276]

One was replaced about 20,000 miles ago, I was told the other was ok? Could be.

 

[semlin]

been trying to track down a similar problem on a 3FE with same mileage after the same steps taken plus replaced Fuel pressure regulator. Curious whether you have noticed any intermittent rough idle or loss of power at 50mph plus?

 

[landtoy80]

WHat injector cleaner did you use?
Toyota FI cleaner and BG44K both do a heck of a job cleaning.

 

[Koffer]

The Cruiser 92 fj80 started to run poor like this All the regular goodies were done first with a full blowen tuneup and FPR. After all was done I pulled the injectors as they needed a good cleaning .

Here is a link to a couple of svc companys in the post https://forum.ih8mud.com/showthread.php?t=30450&highlight=injector+service

 

[Digger276]

I have used the BG44k a couple times, I know the LC sat mostly for two years, the PO only put 3,000 miles in a dusty area in two years, and i don't think maintaning it was a priority for him.
I use STP injector cleaner every third to fourth tank. I know it isn't the greatest but hope it helps some without cooking the catalytic converter

So the concensous is injector cleaning huh

 

[landtoy80]

Injector cleaning, fuel presure regulator and new O2 sensors should help.

 

[Cruiser Jimmy]

I have experienced the same problem with my FJ80 when I was experimenting with adjustments of engine components to fix a difference problem. One thing I did was to adjust the TPS in order to rule out this as a problem. After I adjusted I noticed that the emissions after start up was very rich and I got a code 26.
That lead me to clean the throttle body and ohm out the TPS and to adjust the TPS per the FSM. Once I got the TPS was within spec the problem when away.

 

[Digger276]

Thanks i will check that