89 chevy k2500 shifting issues

[oreo61]

im new to this site i have a truck with the th400 that dosent shift out of 2nd recently rebuilt it shift out of first around 30-35 at what speed does it shift into 3rd? help would be greatly appreciated at 55 the motor screams and i get about 6 miles a gallon its got the 350 tbi

 

[1987 GMC Jimmy]

Are the modulator and governor new? I would first verify that my modulator vacuum line is intact and well connected at both sides. A cracked or brittle line is a no-no. I would pull the governor and make sure the springs in it are not broken and the weights move freely. Glance over the plastic pinion and make sure nothing chipped or cracked. Never know. Last thing I would suspect before tearing back into the transmission is the modulator itself. Also this is just a theory, but I feel like certain engine problems that adversely affect vacuum numbers that the modulator could affect shift points. I would check my intake for potential restrictions (i.e. bad air filter), and I'd make sure that you don't have exhaust restrictions (i.e. plugged catalytic converter).

 

[oreo61]

were is the govoner located?and at what speed should it shift at?

 

[1973c10]

Welcome to the site

 

[1987 GMC Jimmy]

were is the govoner located?and at what speed should it shift at?

Here's a picture. The governor is under the black cover on this one. I was scared that I'd show you the servo, but from what I can tell, the servo mounts in the valve body. This is just a guess, but I'd say the 2-3 shift point should be 300 plus or minus 100 RPM's higher than the 1-2. It's been a few months since I had a TH400, and I don't really remember nor did I ever really pay attention, but I can't give you an actual accurate vehicle speed because of differences in gearing, torque converters, governor adjustment, etc. Also found this... http://www.gmsquarebody.com/forum/showthread.php?t=1107