1990 Suburban 2500 2wd towing TH400 with 3:73 gears

[holcombehas6]

Hey everyone. So I had some work done on my TBI a few days ago and the next day I drove to pick up my camper and immediately hit the highway. The problem I had was that the transmission started acting all weird. Slipping, shifting funny, sometimes not even going out of first, other times starting in third, etc. the transmission was used. Regardless it was fine until the TBI gaskets were replaced. So I need to know: will the 2500 2wd TH400 with 3:73 gears in it able to tow a trailer that is 7000 pounds plus myself, my wife, and 4 kids. Thanks.

 

[yevgenievich]

It should be able to tow if everything is in working order. Check the vacuum line going to the transmission.

 

[holcombehas6]

Vac lines

Replaced the modulator on the side of the trans. I am having a hard time finding anyone I trust is the problem.

 

[HotRodPC]

Do check that vacuum modulator cuz it's the easiest thing to check. But, it does sound like a governor problem. If the governor is not acting right or the valve is stiff, then it may not upshift properly, then once the valve moves, if it hangs and doesn't come back down to allow downshift, then you might be taking off in 3rd gear when it's time to take off again. So, suspect the governor vavle to be hung up. You might be able to take it out, use some carb cleaner and get the valve to move freely in the bore once again. Or replace it. Next, were there any wires pinched? Maybe the kickdown solenoid has power some how and that's likely to cause delayed shifts, and MAYBE cause a 3rd gear hang, but I'd think it'll need help from the governor to hang in 3rd too.