truck running very rich

[swamprat]

I swapped a 5 sp into a 1994 4.0 ranger. It has been running very rich. I had a exhuast leak at the manifold Y pipe connection and fixed that. There was a bad seal at the air box and intake tube and I fixed that. Truck ran better for a few days then last night it started running poor again. Stopped and got gas and checked mileage and I got 8.8 mpg on that tank of gas. Truck runs fine as long as I am able to drive out of traffic. In traffic or drive thru it lobes like it has a big cam in it and you can smell the gas in the exhuast. Still have the auto PCM in it but havent had the trouble in other 5sp swaps. Was thinking about fuel pressure regulator. What y'all think? What can I do to check it? CEL is on and off when lobeing. That was first full tank since put back on road. Truck has sit for 5 years

 

[CarsonChris]

There is a ground wire on the harness that plugs into the fuel injectors. If you forgot to attach the ground wire to the back of the block it can cause your injectors to run rich. Just had a friend experience the same problem. Fixed when he attached the ground. His was in an 87 BII.

 

[swamprat]

didnt find a ground but did find a vacuum line that had gotten pulled off the fuel pressure regulator.

 

[RonD]

Remove vacuum line on fuel pressure regulator(FPR), if there is fuel in it then replace FPR, it is leaking fuel and it is being sucked into intake causing rich mix.
Higher vacuum and lower fuel use at low RPMs would cause your symptom, at high way speeds, it wouldn't be noticed as much, leaking FPR would fit that.

Sticking fuel injector could also cause similar symptoms.

 

[swamprat]

Truck ran better yesterday but this morning it was rough. Leaving a stop light it has no power and sputters then takes off like a scolded dog. If I rev it a little before in nuetral then take off it does better. Driveing down road it will be fine then just shake like it is cutting off. Will check vaccuum line after drive home to see if any fuel is in it.

 

[rathr-b-cruisin]

did you have to remove the O2 sensors at all for this? I had some bad problems with my 93 and the O2 sensors were crossed left to right. It was saying bank 1 lean, so it was trying to put more gas in it, when bank 2 was really lean. this caused bank 1 to actually be rich and made it run like total crap. bad mpg, sluggish.

 

[swamprat]

i did unplug the o2 sensors when I pulled the trans. Will look to see if I have them crossed.

no fuel in vacuum line. have run a half tank still getting 8 mpg