I have an '89 W150 W/318 that runs like crap. I got this truck on trade and soon after I put it on the road it would just turn off at random times while driving(never the same conditions). I replaced the Hall Effect Sensor in the distributor and the issue went away. The truck seemed to be running rich all the time and was sluggish(more than an average tbi 318). I found that the previous owner unhooked the coolant temp sensor for the computer and plugged an aftermarket gauge into that port and left the sensor for the computer hooked up, but just laying on top of the engine. I put it back the way it should be and the rich exhaust smell went away and it ran fine for a while. Now when the truck is warm and I'm accelerating from a dead stop or nearly stopped, it will bog down and start backfiring through the throttle body. The truck has a new TPS and MAP sensor, good fuel pressure and injectors, so then I started thinking about the O2 sensor. To my surprise, there isn't one. Just exhaust manifolds, a y-pipe, no 02 sensors, and no catalytic converter.

Being that my truck is a former Federal Government vehicle for a national park, does anyone know if it's set up different than a civilian vehicle and doesn't have any 02 sensors, or it's because the previous owners hackery? The smog equipment has been removed as well but there's evidence it was once there. Could someone show me a picture of where the plug is for the 02 sensor?

 

Found the O2 sensor, boy that little thing is hidden well. Does anyone think It'd be a good idea to replace it based on the trucks symptoms?

 

O2 sensor should be replaced at 100,000 miles but I’ve burned them out sooner. If it’s bad it should go into a closed loop and set off a light on the dash I believe.

 

Plug wires or carbon tracks in side the distributor cap?

 

I put a new distributor cap on it when I did the Hall Effect sensor. Plugs and wires are new as well. Thanks for the reply.

 

When it Boggs? it the transmission coming back to first gear when its trying to go..... Or is it staying and bogging in 3 gear or Overdrive?
It should come all the way back to first gear or at least kick down when you full throttle it going that slow?

 

It will only bog down off the line and will backfire in second gear.

 

I'm going to take a shot in the dark here..... I'm think the engine may be out of time... Could need a Timing gear set and chain...
Other than that... I'm currently out of ideas for you to check... Maybe some else has something to add?

 

I have the timing gears and the chain is soaking. I'm just going to pull the engine and freshen it up while I'm at it. Thank you for your help.

 

Auhhhhh, I see.. lol
You was kind of headed in that direction anyways... Cool
Hope you find whats pestering your engine... Cheers

 

Sorry for the delay to anyone that was interested in the outcome of my situation. The previous owner adjusted the timing to compensate for the worn out chain instead of replacing it. I replaced the chain and gears and set the timing to 12 degress BTDC and it's been running just fine for months and not a single backfire.

 

Good news… Thanks for the up date!!