Moke seems to have gotten jealous of me spending too much time with the clubbie and has decided to play up.

I was driving home from work yesterday when I started to get shudder and power loss like a cylinder wasn't firing.

Changed the points, cap, rotor and spark plugs... and noticed the carbeurettor is running for a bit and then seems to backfire puffs of air out of it's vaccuum. I checked the oil level and topped it up a bit inside the carby, and the piston rises and falls easily.

Engine will start, idle for anywhere up to a minute and then cut out after a few carby puffs. I can keep it running if I push the accelerator a bit.

Any ideas?

Shard

herman did this kinda, except instead of puffing air out the carby
he'd puff out smoke

he kept going for a little while, but if you kept starting him over and over
he turned over but would choke and huff

it was his head gasket.
or if worse,
valve.

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Head gasket hmm. Anyway to test for sure?

I just ran it again and drops of fuel were splashing out of the vaccum with the puffs .

Shard

take one plug out (one at a time).
put your finger over the hole
get someone to turn the engine over
it should compress the air and puff out from under your finger.

this will work if there is compression.
you wont feel the compression if a head gasket is totally gone.

if you say it fires up sometimes, the head gasket may not fully be gone.
_______________________________________

if theres splashes of fuel coming out have a look at your carby
take the bell thing off and make sure everythings right first

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Just did it then, got enough compression to lift my thumb on all four.

That's a good thing right?

Shard

yep good thing.

when you say fuel was coming out the vaccuum
is that the tube thats sposed to be going to the dizzy

if so then youve got something wrong with your carby
not that much fuel should be coming up that far

so first look at needle and (cylidner with hole at the bottom - jet?)

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Nar out of the carby bit where it sucks air in under the air filter. It's backfiring a bit from there, and fuel sputtered out lightly from there (only happened once so far).

Shard

edit: just adjusted the throttle screw on the carby, and what seems to be happening is that it starts ok, then puffs then the fuel builds up and eventually there's enough unburnt fuel in the vaccum that it spurts out with the puffs. How come fuel is building up here??

Bad fuel? backfiring carby usually means running too rich...?

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check if theres a fur ball down the throat
hang on a minute...

im stumped. have you opened up the bell thing and inspected the needle, spring and seat?

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Hmm now that I think about it, the last petrol fillup was co-incidentally the first time I put prem unleaded into it with valvemaster... could that have anything to do with it? I put 20L into it and 20ml of the valve stuff in one of those little tubes. It's been ruinning fine till now though (haven't filled up since).

I'll try lean it right out before I play around with the carby, never pulled one apart before so it'll be a steep learning curve for me. I'm tempted to just pull out the clubbie one and put it in except that it's got a lead to the distributor vaccum that the moke doesn't have and is dirty and grimy as hell whereas my moke one is relatively clean outside.

What exactly am I looking for if I pull off the bell shaped cover bit, or is it going to be pretty obvious is something is stuffed?

Shard

Don't pull nothing apart. I bet it's the petrol.

What type of unleaded did you put in it? try filling up on BP ultimate or any other 95+ octane fuel and add flash lube. I bet your problem instantly dissapears...

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Was bog standard BP prem unleaded...

so I'm guessing it's gunna require a drainout of the fuel tank and a refill yeah before I do anything to the carby?

Shard

if you're game

you undo the two (or three if you have a 1.5 SU) bolts holding down the bottom of the bell (the one with the black plastic cap)

slowly extract the thing and theres a big spring that will stretch as you pull out

the spring comes out and theres a long tub attached to a base which you grab and pull out.

from here you cant put the thing down because its like holding a cup with a needle sticking out the bottom (tube is filled with fluid)

have a quick squizz, look down the hole and replace it back very carefully, dont scratch the needle
replace everything and i dont think that will actually tell you anything so you might be wasting your time.
still, you wouldve seen the inside of an su carby

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stick a litre of av gas in there that should sort out any thing like that.
sounds like its firing thru a vlave so it could be a burnt valve or an unseated valve but has been made worse by low octane fuel.
put a higher octane into it and see if it helps.

I had one the other day doiny the same but i ripped the head off and had new seats cut after a lap in couldnt bring it right and car runs like a dream now.

Stupid question alert: what's av gas? .

Going to drain it now and grab some better petrol back soon :/.

Shard