will not shift

[itsunday25]

k first off its a cucv i was driving it and it just started pulling out slow like it was in 2nd gear it was i manuley down shifted it and it went to first it would not shift up it would just stay in first but if i would sift it my self it will shift the thing on the side of the ip it has vacum lines running to it it has vacum on one side when i rev it up but not the other can eney one tell me the part number i no its a ac delco part the trans dos not slep can u guys help thanks

 

[cucv1833]

you say you put it manually in first gear in that case i dont think it will up shift to 2nd.
I had this problem also first i would check all the vaccum lines for damage. I had a rubber line that was was dry rotted . then do a search on this topic. the part you are looking for is the vaccum valve heres one in the classifieds. i changed mine for $150 and it turned out to only be a .50 cent piece of rubber vaccumline
New CUCV Transmission Vacuum Valve - Steel Soldiers::Military Vehicles Supersite

 

[lavarok]

Check your vacuum lines. You have:

1. Leak
2. Clogged line
3. Bad tran modulator
4. Bad vac pump
5. Bad vac modulator

My bet is leaky vac lines or a clogged line. Been there....and fixed all 5 at one time or another.

 

[HAWKMAN]

been there...done that......

 

[rnd-motorsports]

If your checking vac on the ip bye unpluging 1 vac line at a time then you will only have vac. on one line . 1 is from the vac pump on back of engine and the other goes to the modulater on the trans, only the one coming from vac pump will have vac when running. check lines and then unplug vac line on modulater with truck shut off do you see any transfluid? is there any fluid in the line? if so change the modulater . the vac pump should have about 20 inchs of vac with a gauge check that as well will not need to rev to get it vac pump may have took crap!