93 Yukon backfiring

[05goatls2]

Hey guys, as the title states my 93 Yukon is backfiring and losing power at high speeds. I was supposed to drive about 500 miles today to visit family for thanksgiving. I got about 40 miles down I-95 (average of 70MPH) and the truck started backfiring and losing power. I couldn't get her over 60MPH without doing the same thing. What could be wrong? I performed a tune up about 4 months ago (cap, rotor, spark plugs and wires, O2 Sensor). She would backfire a little back then, but no real issues. I also replaced the coil with an Accell, and I have a K&N airfilter. I just had a heavy duty transmission put in her about 2 weeks ago because it was going out. Any suggestions? Also note there are no engine codes.

 

[SunlitComet]

if you are backfiring out the intake then your mixture maybe to rich or your injection assembly is dumping fuel in the manifold.

 

[gpracer1]

Probably time to replace your fuel filter. Sounds like you are starving for fuel.
Are you talking backfiring (afterfire) out the tailpipe, or backfiring from the intake manifold/throttle body?
If it is running really lean, the mixture can burn so slow that it is still burning when the intake or exhaust valve is opened.
If it gets worse the faster you go (more load) then it is probably lean. If it was really rich, you would see black smoke out the tailpipe.

 

[AlanHurd54]

Fuel pump fuel filter had the same problem

 

[gpracer1]

05goat, did you ever figure it out?

 

[05goatls2]

05goat, did you ever figure it out?

Sorry for the poor follow up guys... Yes I did figure it out, it ended up being a failing distributor. The magnetic packing was loosening when the engine hit operating temperatures which caused the misfiring. Prior to that, I switched out the plugs a couple times, changed out the fuel injectors (which needed it anyways), and replacing the EGR/PCV valves.

Thank you guys for the help.