g16a 8v carb missfire! Help

[mike99]

hi i have a proble with m g16a 8v carbed engine! it runs fine under light acceleration but when i floor it it hessitates baddly from 2000-3500rpm then runs fine after that. it has 6month old electric fuel pump and bosh coil, new plugs, leads, i havent replaced the dizzy and rotor but they dont look that bad (seen far worse) has anyone had similar problems etc as its straring to get annoying as it does it on the open road quite bad!

[Swamped]

Could it just be a sticking needle and seat?
I've had a similar sounding problem with a couple 1300 8v zuk motors but I had to really floor it to pick up the revs.
Re-kitting and cleaning the carb fixed it.

[muduki]

What I found with mine was a faulty tps(throttle position sensor)

[lexulance]

Would start by cleaning the carb out,just incase its picked up a bit of crap,but before you do that take the top off the air cleaner and without the engine running give the accelerator linkage a quick little blip and check there is a jet of fuel being pumped into the primary throttle throat of the carb,if so the accelerator pump is ok if not replace the accelerator pump diaphragm. Otherwise the power valve in the bottom of the float bowl may be blocked or faulty,let us know what you find?

[mike99]

took the carb in for a recon. hopefully this will fix it!

[mike99]

ok so $200 later i still have the problem. ordering a new dizzy cap and rotor which will be here next week. sick of spending money on things that dont fix it. being a carbed engine theres not a whole lot it could be! any other ideas?

[Swamped]

Shit in the tank blocking or partially blocking the pickup?? I'd expect maybe it would be more intermittent though?
You tried running it at night with the bonnet open looking for sparks from the leads? Was the coil lead replaced when you did the others?
Really does sound fuel system related to me though.

Did it do it before you upgraded all those bits?

[Petemcc]

checked the timing? could be a free fix before buying more stuff

[mike99]

yea will do the dizzy cap and check the timing next. its allways had a slight problem on the open road and it was at random after driving for a while but now it seems to do it round town and all the time etc

[Swamped]

I'm not sure if these are the same but the 16v 1.6 engines flog out the front keyways on the crank where the bottom timing pulley goes creating a timing issue. It can get progressively worse over time. Check the timing to see if its out. If you have to adjust it and it gets better then goes back to being rubbish again that could be the cause.

[mike99]

ok so i chekd the crank keyway, cam and crank and ignition timing today and they were all fine! and new dizzy cap and rotor. so after all that ii had a thought and put the old 1300 carby on for a try. boom problem gone so the guy who done the carb done sweet #### all and its the carb causing the problem. only other problem it the 1300 carb is rather shagged to so ive got two useless carbs. will take it back to him tomorrow and wave my fists at him as for $200 you expect a decent job! has anyone used a old 4k 5k carb on one?

[BlakeJ]

some guys get an SU carb to work well on them, good for offroad aswell, othewise you can buy weber kits for them