89 Carbuetted TB42 Idle problems

Hi, hopefully somebody out there has had this same problem, as its driving me mad not being able to find the cause.

Basically she runs smooth as butter, but she will not idle properly, once you back off the throttle she will idle at about 350 rpm for about 7 - 10 seconds then completely die, another symptom shes doing is say I was cruising along in 3rd gear at 2600 revs or something around that, and I put the clutch in straight in ,take my foot straight off the throttle and roll/brake to a stop (say at a set of lights) she will idle really high at about 2000 rpm, but as soon as I give it a little stab of throttle it will drop down to about 350 again then die soon after.

Due to my model being fitted with points, and the fact that I know they have not had attention lately, I whipped them out and they were stuffed, so I put new points, rotor button and distributor cap on, (the leads were already new, as were spark plugs) and she still does the exact same thing, so I am happy to rule out the ignition side of things being the problem, My gut is telling me it needs a carby kit put through it, but I'd rather not jump straight to that option as its not the cheapest. I have checked all vaccum lines and none are split or perished, and it doesn't appear to be losing vaccum anywhere. It has me absolutely stumped.
Has anybody else had this problem with a carburetted tb42 patrol before?
I should mention its on dual fuel, but it does the exact same thing on both fuels, so its nothing to do with the gas or petrol system inpacticular I dont think

Thanks
Ethan

Hi a mate of mine had the same problem he crossed plugs wire 3 and 4 to make it backfire through the carby to blow out the jets (probley not good for it ) and it worked for a while ended up getting a kit through it was not cheap i think around $380.00 to get it done now its running great.

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Originally Posted by Etho

Hi, hopefully somebody out there has had this same problem, as its driving me mad not being able to find the cause.

Basically she runs smooth as butter, but she will not idle properly, once you back off the throttle she will idle at about 350 rpm for about 7 - 10 seconds then completely die, another symptom shes doing is say I was cruising along in 3rd gear at 2600 revs or something around that, and I put the clutch in straight in ,take my foot straight off the throttle and roll/brake to a stop (say at a set of lights) she will idle really high at about 2000 rpm, but as soon as I give it a little stab of throttle it will drop down to about 350 again then die soon after.

Due to my model being fitted with points, and the fact that I know they have not had attention lately, I whipped them out and they were stuffed, so I put new points, rotor button and distributor cap on, (the leads were already new, as were spark plugs) and she still does the exact same thing, so I am happy to rule out the ignition side of things being the problem, My gut is telling me it needs a carby kit put through it, but I'd rather not jump straight to that option as its not the cheapest. I have checked all vaccum lines and none are split or perished, and it doesn't appear to be losing vaccum anywhere. It has me absolutely stumped.
Has anybody else had this problem with a carburetted tb42 patrol before?
I should mention its on dual fuel, but it does the exact same thing on both fuels, so its nothing to do with the gas or petrol system inpacticular I dont think

Thanks
Ethan

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Sounds like dirty carby.

also maybe worth checking
Had on vacume break, a broken linkage.
It caused very rough idle on mine.
not to be confuse with fast idle nudger vac cyl.
It's in behind that.

May work.
when cold a good spray of carby clean.
soak.
respray and soak.
start engine, and another good spray again.
you'll need a few revs, enough to stop it from stalling.
This all should be done cold, as heat will evaporate cleaner quickly.

also may work,
" but beware "
few revs and simulate sudden throttle close.
can help to move rubbish.
seen this done by hand, can work, done it myself when stuck.
say 3k+ rpm sudden close throttle, block/open/block carb intake.
But beware of backfire etc.
and don't use something that could be sucked into engine.
the massive "sudden" vacume can help to shift stubborn rubbish.
dont recommend this procedure, but it's a trick that may work.

I had the same plastic part of that linkage break as you, Robbo - and got the whole linkage posted up from Melbourne - Ni22bits - delete the 2s and replace with the letter that looks similar.

Mech neighbour also with TB42 put me onto regular carb cleaning - he reckons cheap sprays are as good as the name brand expensive ones, and I've used both, inside and out of the carby per his advice.

And years ago another mech showed me the hand over the carby throat at revs trick. Have done it and still have trouble with the idea :-) but it can suck stuff through the idle circuits. The vacuum doesn't hurt - the max it can be is 13 psi vac which is not much for a hand to deal with. Just don't drop anything in there :-) As to backfires, well, I suppose they could happen if you lean the mix in the carbie too much, and perhaps under other circumstances I don't know about. Hasn't happened to me yet. As a kid it used to happen quite a bit when I was holding the auto choke open on the old man's Mopar 318 fireball with dodgy auto choke. No hairs on my hands and arms to scorch off in those days, and didn't ever get even a warm arm. Made me let go of the choke linkage in a hurry though :-)))

Not idling properly on both fuel suggests that its possibly something they have in common.Timing,dissy mechanical advance,inlet manifold gasket,carby not bolted down tight or leaky gasket,screws on top of carby loose.All these are easy to check, are the pionts opening properly?

Yeah Little Mick normally I'd agree.
but these carbys are a little troublesome at times, especially with dual fuel.
And going by what I've read here on this forum and personal experience's, leaning towards carby.
Yes you have very valid points and also worth investigation.

And yes Silverman that little plastic linkage should never of made it into a vehicle that can take you to the black stump.
How weak is that little thing.

Idle compensator is also worth checking.
Air temp sensor also.

This maybe a coincidence but had a little trouble BCDD, with this also gunked up.
slowing down it allows a little extra fuel to help cut emission's.
not supposed to work below 5kph.
I know it doesn't make sense but when I cleaned It out made an improvement to idle smoothness.

Personally, get your hands on a maint manual + carby kit and go for it.

Just wondering what gas system are you running?

Give the carby a good spray of wd40 on the outside, it works a treat for mine when it does that.

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Originally Posted by spring_ridge_guy

Just wondering what gas system are you running?

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Landirenzo.
was on car when I got it.

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Originally Posted by patmav

Give the carby a good spray of wd40 on the outside, it works a treat for mine when it does that.

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do you know why/how Wd40 its fixen it?.

I have had a TB42 carbie for near on 7 years running a imco 3A gas system that was fitted when I got it. I have had no trouble what so ever with the gas system and rarely run it petrol, only when I run out of gas until January this year. I was camping on the beach at Beachport SA and went to run on petrol for a bit and it would idle but when I put my foot on the throttle there was no responce. I could much about it at the beach so went back to gas and filled up with gas again at Robe. I tried to run it again on petrol on the trio home hopeing it could clear itself at highway speed. Nope.
When I got to have a look at at home I found that the there was no fuel getting through the booster into the ventury. If i sprayed some carbie clean whilst holding the throttle open then I could get some revs. I sprayed the carbie with heaps of carbie clean but didnt improve. I turned it off and sprayed the carbie again and left it over night. Tested it the next day and all fixed. Runs fine again. This trick also worked on my demo saw that I hadnt been able to start for near 6 months. I think I have fallen love with my first tin of carbie cleaner.

think i'll have to grab myself a tin of carbie cleanner

Guys my Gq is also doing exactly the same thing now except mine's dedicated petrol. When you say get a 'carby kit' do you mean a new carby or recondition the old one?

Carby repair kit.
seals etc