Outer Limits 4x4 Board

Got a TB42 carb. On gas the truck runs fine. When I run on petrol it stalls if I dont let the clutch out slow and keep the revs up nice and high when taking off. When it hits mid revs around the 2500 mark, it absolutely hauls. What is the problem. Is it getting to much fuel at low revs and flooding the carb. How would I fix the problem? It has electronic ignition new top gun leads and plugs. The carby was rebuilt not long ago.

I am no expert but try taking the idle mixture screw out and blowing air into the carby through the hole.Befoer removing the screw wind it all the way in and count the turns. Should be about 2 1/2 turns. This will give you a starting point when you replace it. Then start the engine on petrol and turn the mixture screw untill it idles the fastest. Then set the idle speed using the adjuster. If that no good there will be a idle jet in there somewhere

Is that the screw on the drivers side of the carb with the spring on it? Sems to effect idle speed when I play with it. Thing is, the carb was rebuilt by a carb specialist. It had the same problem prior to the o'haul so could the problem be electrical. I have been told it will never run great, but I have mates who have the same truck and gas set up, and they drive fine.

Also when the truck is cold and started on petrol, the engine sounds like it's missing until it warms up a bit. Almost like it's just done a deep river crossing and its only firing on 3 or 4 cylinders.

Yes that is the idle mixture screw. My 88 carby dual fuel GQ runs fine on petrol. When I 1st got the car the carbys petrol pump was full of shit. The easiest fix was a 2nd hand carby fron the wreakers that had not been on gas and pull the petrol tank out and clean all the rust out of it. Keep the petrol tank full and change the fuel filter a lot untill it all came clean. Now i run it on petrol once a month or more and I can trust it to run fine in the bush on fuel. It pings a bit on petrol but i put up with that because timed as it is I get 400km out of 84litres of gas

It does not sound like an electrical problem to me. If it was electrical it would play up on gas as well

Just came in from the shed having fixed the same problem.

My issue was a blocked idle jet, and making sure the fuel cut solenoid was working correctly.

I do not reccommend removing the idle mixture screw and blowing compressed air into the carby, your not fixing the problem, merely moving it to another place for it to re occurr down the track.

As the old man is a mechanic, i asked him to give me a hand on this one.

Removed the top of the carby, removed idle jet, primary, and secondry jets one at a time and cleaned throughly. Checked float was in god condition, cleaned filter on the fuel inlet bajo, and cleaned the accelerator pump.

This is not something that i suggest you "give a go" yourself unless your an experienced mechanic.