engine lacking power

[1972BackInBlackC10]

i know this is the wrong yr truck but i thught i might get some help here too,

i have a 1980 gmc, it has a 350 4 barrel it starts and runs fine in park but when you put the truck into gear it loses power and when the trans shifts the truck dies

my friend thinks theres something wrong with the trans but iv never heard of an engine doing that over a trans, i was thinking its possibly the carb or a vac line unhooked somewhere

when you flip the throttle wide open quick in park it tries to choke out and die

[sir_talk_alot]

sounds like a timing issue to me. sounds like your engines timing is wacked out. when your trans goes into gear it brings the rpms down farther, causing it to run really bad. check your timing and make sure its set correctly.

[VetteVet]

Do a compression check first . that will tell you if your mechanical stuff is OK. Look for 120 to 150 PSI on all 8 cylinders. Then check the accelerator pump on the carb. It will give all those symptoms if it isn't working. If you get a good strong spray down the intake then go to the engine forum stickies and look for engine timing . That will give you a step by step guide to timing the engine. It may be listed under engine FAQS. I looked it up for you.....http://67-72chevytrucks.com/vboard/s...d.php?t=290498

[1972BackInBlackC10]

the engine shuld be fine it only has 35,000 km but it sat for a long time

[Willys47]

check the cap and roter sounds like a tune up is needed check the vacume hoses as well.

[VetteVet]

Originally Posted by 1972BackInBlackC10

the engine shuld be fine it only has 35,000 km but it sat for a long time

Engines that sit for a long time can actually have the rings seize up on the pistons, result- Low compression. If it runs smoothly at mid range then that's
not the problem. I'd guess it's the accelerator pump and maybe the timing. As
stated a vacuum leak might cause it too.

[jhngardner367]

I'm going to assume that it doesn't have a lock-up converter,but to be certain,raise the hood,and look at the firewall,to the passenger side of the brake booster.Is there a vacuum line running to a small switch,with wires running to the trans,on the driver side,near the shift selector?Also,look at the brake light switch,and see if there are 2 wires(one orange/one white),OR 4 wires(1 orange,1 white,in one connector,and 1lavender/1 brown with white tracer,in the other).The 4 wire switch is for a lock-up torque converter.The converter can sometimes stick if one of the 3 switches sticks:brake sw./vacuum sw./or pressure sw.(inside trans).If it doesn't have the lock-up conv.,it may have a cable to the passenger side of the trans,thats stuck/frayed. If neither is used,chech the carb top for an electrical connector(choke side).That is the idle mixture solenoid.These were known trouble spots.I replaced my carb with an earlier model,because it was dumping so much fuel into the engine,that it took 1/4 tank of fuel to go 2 miles!After changing the carb,replacing the fouled plugs,and changing the oil,it was fine.

[motornut]

if it's got a vac line to the tranny from the carb area
check the vac module @ the tranny seen the rubber/steel line rot and make a vac leak
can even knocked that off in the bush