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95 Jimmy won't go faster than 20 mph, help!

mitch16mitch16 Member Posts: 11
edited March 2014 in GMC
I have a Jimmy that won't go any faster than 20 mph. I have cleaned out the TB, as it was gummmed up. The engine rev's freely. It just won't go any faster. Any ideas?


  • wljlds2wljlds2 Member Posts: 14
    Air filter ok? Runs ok up to 20mph? Not stalling or dies? Have the converters and muffler checked for being blocked or restricted. Consider this if the truck has been losing power over a period of time.
  • mitch16mitch16 Member Posts: 11
    the Air filter is good and it has a new CAT and a new Muffler. I'm thinking its the transmission. Any thoughts?
  • wljlds2wljlds2 Member Posts: 14
    Are the brakes hanging up or the emergency brake on? Jack the vehicle up off of all four wheels, place on jack stands for safety and make sure the wheels rotate freely. If the wheels turn freely, start the engine and place in drive and see what happens. Be sure you don't get happy with the gas pedal and be sure to use the brake to stop the wheels before placing back into park or simply shut the engine off. You could also have a starving fuel system while under a load. Bad fuel pump, clogged filter, clogged injector(s), low voltage at the fuel pump. Get a repair manual at your local auto parts store for reference
  • jrvb89jrvb89 Member Posts: 1
    Having problems with acceleration when the vehicle is hot. Runs better cold. Will not take the gas. Have 50 psi fuel pressure at intake. Backfires on hard acceleration. No codes or lights with GM tech 2 scanner. New converter. The vehicle has been gradually getting worse. Any ideas or where I should look next?
  • jlflemmonsjlflemmons Member Posts: 2,242
    Does the engine rev up okay when in park? Is it racing up when you are driving?
  • jlflemmonsjlflemmons Member Posts: 2,242
    Coil pack can put out weak spark when hot. I know this sounds crazy, but next time it happens, lay a bag of ice up there on the coil and see if it changes anything.
  • mitch16mitch16 Member Posts: 11
    Yes, the engine revs fine. I drove it yesterday and I noticed that starting out it is fine. It goes through the 1-2 shift (automatic) with no problem. It just doesn't shift from 2-3. I'm not sure if overdrive works or not. Do you think it's a solenoid? The trans fluid looks fine and it's not leaking. I know that the trans is electronically controlled but I'm not sure if that has anything to do with the problem or not. It runs fine, if I could just get it to shift properly I'd be all set to use it as a extra vehicle. Any thoughts?
  • jlflemmonsjlflemmons Member Posts: 2,242
    Well, the fluid could look good and still have a dirty filter. Don't know the history of the vehicle, but some quicky lube places will suction out the fluid and replace without dropping the pan and changing the filter. Not too difficult to do, and the filter/gasket kit is not expensive. Might not be a bad idea anyway to see if anything is collecting in the pan.
  • mitch16mitch16 Member Posts: 11
    OK, I'll give it a try and see what happens.

  • mitch16mitch16 Member Posts: 11
    Thanks for the tips. However, I do have one more question. I decided to swap out the filter and fluid and could only get so far. I unbolted the pay but could not wiggle the pay out from between the frame crossmember and the exhaust coming down from the manifolds. Any clue how to remove the pan? I worked on this for a couple hours and gave up yesterday. Do I have to unbolt the trans from the mount (crossmember)? Please advise.


  • thesweetrosslgthesweetrosslg Member Posts: 28
    had a simaliar problem could be the 2-3 downshift silanoid
    that needs to be replace check that out if you cant do it yourself becouse you have to drop the entire tranny pand to get to it take it to a shop and tell them all you want is the 2-3 salanoid dont let them tell you you need a whole rebuild
    it should be about 200 for parts and labor not more .

This discussion has been closed.