Teaching an old dog new tricks K1500 350

[jim_in_dorris]

I ran a 305 bin in my 87 4x4 for years wondering why it was so lean all the time. Finally determined that some PO had installed a 350 in place of the original 305. Put in an 350 bin and WOW I couldn't believe the difference. Yes it will run, but you will leave a ton on the table.

[Psycho_Daleic]

I ran a 305 bin in my 87 4x4 for years wondering why it was so lean all the time. Finally determined that some PO had installed a 350 in place of the original 305. Put in an 350 bin and WOW I couldn't believe the difference. Yes it will run, but you will leave a ton on the table.

Thanks so much for the heads up Jim! I'll check the fuel pump pressure, run another data log, then I'll be getting back to you. My truck is having the same issue you said you had, BLM 133 or higher constantly, afterfire coming off closed throttle downhill, stumble accelerating uphill under load, (seems the ECM detects a too lean condition and then tries to compensate by dumping more fuel to the engine.)

Moved this discussion to NEW POST HERE.