Idle - not carby problem

[Wesley]

92 suzuki g13b- will never idle in the same spot (idles fine just between 800rpm to 2000 rpm) ive had 3 different carbys on it and it now has a recon carby that runs fine on my other 1.3 ive put a new dizzy on it and checked the timing thats all good i had to do the head gasket so i did the intake manifold gasket, timing belt and got the head skimed still run the same before and after ive replaced all the hose's to the carby and cant find any vacuum leaks any idea's im thinking it might be electrical?

[CairnsZook]

Fuel pump?

[Wesley]

Fuel pump?

Dont think so as it hasnt lost any power and dosnt seem to be running lean though i do have a spare i might put it on and see if it makes any diff

[Farmz]

I had a similar problem, but it ended up being my manual choke.
The choke cable had slipped and was actually stopping the carb from closing properly. But as you have changed your carb, I doubt that would be it.

[Wesley]

Still cant work it out, Its lost a bit of power up high in the revs . I can get it to run good when its parked i can give it a big rev and it still idles mint, but as soon as i go for a drive its back to the shit. I cant work it out ill have to take it to the shop if no one else has any ideas. Also when i drive it at low revs the engine keeps missing (at 1/4 throttle say 2000rpm it will lose power like ive turned the ignition off then when i give it a bit it will come back alive?)

[want33s]

Brake booster diaphragm???

[Wesley]

Brake booster diaphragm???

Havnt looked at that will check it out tomorrow,

[11_evl]

valve adjustment??

[alien]

i reckon its the leads... mine did the same thing - new leads and voila!

[Brendan-s]

if it's not that coil might be dying? Both mine and a mate's 1.3s developed the same problems within a fortnight of each other, no power when the engine is loaded up, would rev fine in neutral. I guess the coil on its way out couldn't deliver a fat enough spark to keep the engine happy. Try swapping the one from your other 1.3 over?

[Wesley]

Ive done the leads, coil and dizzy just going to check out the vacuum to the brakes now

[Tim356]

It's a vacumn leak - check your inlet manifold gasket.

[Zook_Fan]

could be that the auto chokes are playing up on them. have you tried a webber or holley carby?

[Wesley]

Off to the mechanic it is, ive checked everything i could think of and more be interesting to find out what the problem is ive got a feeling its something real stupid.

[Wesley]

Found problem, Fuel tank is building up a vacuum causing my fuel pressure to go to shit, If i drive with no fuel cap on it runs and idles perfect. Im guessing it will be the pipe to the charcoal canister blocked? or are they meant to vent through the filler cap?

[christover1]

Found problem, Fuel tank is building up a vacuum causing my fuel pressure to go to shit, If i drive with no fuel cap on it runs and idles perfect. Im guessing it will be the pipe to the charcoal canister blocked? or are they meant to vent through the filler cap?

I've had 3 cannisters die on me, same result.
Blockage is possible, but new can may be needed.
A vented cap would be a good temporary fix, but if can is stuffed, hot weather parking can cause leakage out of carby over night, also ....I found a huge pool of fuel under mine one day.