720 hesitates

[hauntingurcoma]

10 of 85 720 z24 carbed starts right up idles good when i let out clutch it stumbles wants to die put the clutch in and idles fine again.hesitates through out all gears but clears up at about 3500 rpm.Ran great until a week ago.changed plugs,fuel filter.any ideas??

[Rev_D21]

EGR possibly could be causing this. Timing could also be causing this. How old is the chain if you know?

[hauntingurcoma]

original as far as i know,only got the truck a month ago.

[seang]

I dought the timing chain is stretched at all. z24 engines have duplex (double row) chains. They are way overkill. My old z24i had 165,000 miles on it, and the timing chain was never at fault. My ka24e timing chain is more of an issue and thats a newer motor. But I don't care because I know the 96-97 ka24e's had metal backed timing chain guides that can be loud at start up, but not wear out. There are never any metal shavings in my drained oil. I just don't want you to go and do this tedious job just to have your truck run the exact same.

[Rev_D21]

I've seen GA16DEs jump timing so I am open to ideas. A faulty tensioner can shift timing a little bit and who knows, combined with other faults can cause things like this to happen. The other thing I can think of is bad vacuum leak somewhere.

[hauntingurcoma]

ive done cap and rotor and changed some vac lines and is better but just has rough idle like a miss.plugs are new fuel filter new,waiting for dealer to get fuel pump filter in.can i loosen dist on turn to adjust like old chevys?

[seang]

Yes, you should probably do that. I have my ka24e's timing turned all the way to the right and I run 89 octane. I didn't use a timing light, but I test drove it and listened carefully, its all good. You might be able to pick up 2-3 horsepowers with timing advanced for premium gas. Why not? It might even work on 89 like mine. You do have the vacuum advance right?

[hauntingurcoma]

yes it is.i run 89 as well

[hauntingurcoma]

changed fuel pump filter,think i got all vac lines,noticed the butterfly on carb is always open hot,cold am,pm shouldnt that be closed at some point?

[Rev_D21]

Step on the gas pedal before a cold start to see if it closes.