Sputters when pushed...

[boiler]

i have an 85 4x4 720 king cab...runs great until you really tromp on it...it then sptters and hesitates...let off and it will run good again...

[pejsa s-13]

theres tons of things that can do this

read the sticky first please

but other than that im having the same problem but its because my original cat from 85 is clogged up

[breadbox]

Don't let your cat clog. It will kill the motor. zerothread/427942

Boiler, You might be flooding your motor when you gas it hard. You might need to put a fuel pressure reg on the fuel line if you think this is what is happening.

Other than that check all vacuum hoses for leaks. The z24 needs a great condition vacuum system to run like a champ.

[snakecbaker]

i have a 1985 720 st that does the same thing. when you floor it it floods it self. ive checked the vac lines, cleaned the carb with no luck. iam going to wate till summer and have the carb eather rebuilt to buy a weber becouse ive been told it could be the flout in the carb

[flinterman2000]

Closest problem I had to this with the Z engine is when you floored it it misfired a lot. The dizzy was my problem. With the J16 however, at stand still when you floor it it sputtered, backfired but wouldn't stall. The static timing was out three teeth.