BAD hesitation

i have a 90 half ton chevy. its got a horrible hesitation. when i push in the gas to much or sometimes to fast it the engine will like completely stop sometimes a short period of time sometimes a long period of time then will kick back in but never shuts off, its horrible i hate it and have no clue why. i looked in the <a href="http://www.serverlogic3.com/lm/rtl3.asp?si=11&k=repair%20manual"; onmouseover="window.status='repair manual'; return true;" onmouseout="window.status=''; return true;">repair manual</a> and it said that i need new piston rings and the <a href="http://www.serverlogic3.com/lm/rtl3.asp?si=11&k=spark%20plugs"; onmouseover="window.status='spark plugs'; return true;" onmouseout="window.status=''; return true;">spark plugs</a> should have oil built up on them, well i checked a couple and they r fine, i also burn oil but i kno that i need new valve stem seals, but i still cant figure out this hesitation crap? anyone kno what it is?

i also got a pair of dynomax standard series headers the other day and have yet to put them on bc i need a new y pipe, i have an exhaust system hooked up already 3inch pipe to muffler to dual 2 1/2inch out and 3 in tips. i found a y connector for 2 2 1/2 inch inlet(size of teh collectors) to 3 in( size of pipe) from jegs. i thought about maybe making my own, well having my grandpa do it for me. he told me to buy two new mufflers and we could make true duals, well i dont have much money and the exhaust system is jus a few months old, i figure its alot cheaper to make the y pipe, any suggestions?

Carburated or fuel injected? If you hold the gas pedal on the floor, does the power come back eventually? Is there an exact point where it loses power? If so, does this point occur at a higher RPM if you're going faster? What is the vacuum at idle? If you can hook up a vacuum guage while you drive, what does the vacuum do when you lose power?

Carburated or fuel injected? If you hold the gas pedal on the floor, does the power come back eventually? Is there an exact point where it loses power? If so, does this point occur at a higher RPM if you're going faster? What is the vacuum at idle? If you can hook up a vacuum guage while you drive, what does the vacuum do when you lose power?

my truck is throttle body injected, ya if i hold the pedal to floor eventually the power does come back, theres no exact point sometimes it wont even do it but msot of the time it does, if im doing like 35 and floor it theres a small hesitation, but if im goin from a stop then there can be a much longer hesistation. im sure about the vacum at idle, and i dont have a vacuum gauge. i mean it seems like theres no fual when it hesistates or jus no compression im really not sure and i dont wanna spend alot of money and time on something not worth doing.

Has the EGR been replaced? If not, plug the vacuum line to the EGR valve and see if the hesitation goes away.

How does it idle? If the idle is high, you most likely have a vacuum leak. The TBI gasket is prone to leaking.

I have a 90 GMC K1500 and I also burn oil. At startup, I get some blue smoke. The valve seals are a common problem on our trucks.

//2000CAYukon

Start with the basics. When is the last time you did a tune up? Change the plugs/wires/cap/rotor/fuel filter. DO NOT IGNORE THE WIRES. I did and it cost me a ton of trouble , not to mention money trying to figure out what was wrong with my truck which eventually was found to be carbon arcing across the plugs because of bad boots on the plug wires. Also pour a bottle of injector cleaner into the tank. To me it really seems like a spark problem by the way you describe it. At lower RPM the spark is weaker and you get hesitation, RPM gets higher and the spark gets stronger and the truck smoothes out......... just a thought.

Start with the basics. When is the last time you did a tune up? Change the plugs/wires/cap/rotor/<a href="http://www.serverlogic3.com/lm/rtl3.asp?si=11&k=fuel%20filter"; onmouseover="window.status='fuel filter'; return true;" onmouseout="window.status=''; return true;">fuel filter</a>. DO NOT IGNORE THE WIRES. I did and it cost me a ton of trouble , not to mention money trying to figure out what was wrong with my truck which eventually was found to be carbon arcing across the plugs because of bad boots on the plug wires. Also pour a bottle of injector cleaner into the tank. To me it really seems like a spark problem by the way you describe it. At lower RPM the spark is weaker and you get hesitation, RPM gets higher and the spark gets stronger and the truck smoothes out......... just a thought.


i just did a tune up a few months ago replaced it all except the fuel filter, i have been thinking that maybe it was the fuel filter or pump but not sure, i have used 3 different types of fual injector cleaner still no help, i have also been running off of 89 octane gas for the last month still no difference, the spark plugs are almsot brand new like mybe 3500 miles on them at the most. i have headers i have yet to put on, when i get the chance to put them on then i will check it all out more and talk it over with my grandpa.

You may want to try replacing the MAP and O2 sensors. It's probably a sensor.... but there's just so many of them. MAP and O2 are what I would expect most, in that order.
If you think it may be the fuel delivery, look for a schrader(sp?) valve on the fuel line pretty close to the TB. Take the cap off and depress the valve with a small screw driver (make sure the fuel pump isn't running). Press it in with one hand, and hold you other hand between it and your eyes.... gas hurts pretty bad, plus it can't be good for you. There should be a fair amount of pressure in it (about 40 PSI). If there is NO pressure, you have a bad check valve. If there is LOW pressure, you may have a bad pump, but it could possibly be the check valve again. If I remember right, the pressure should be about 40 PSI. That is all assuming you don't have a fuel pressure guage either.

You said you've tried 3 different fuel injector cleaners? Have you tried "Sea Foam"? It works great. My uncle said he used it and it got so much varnish out of the tank it clogged the fuel filter. I used it in my truck (3 bottles in 40 gallons of gas, 1 bottle in crankcase, 1 bottle induced through the brake booster hose) My filter didn't get clogged at all, but just in case, you may want to have an extra on hand. It works great, but you pay for what you get (about $7 a bottle here).