Bitch on gas... Carby maybe? Help lol

Hey guys, I have a tb42 on duel fuel, I've had issues with gas for a bit now, but now it's real bad. Runs fine (idles rough) on petrol. Seems like I'm getting no power below 3000rpm. Coughs splitters and feels like nothing is feeding through on gas. Once up and going at a decent rpm it goes but you can feel it straining terribly. Carby rebuild? I've done leads, dizzy, plugs etc.. Helped for a wee bit but back to being a bitch.
. Any suggestions are appreciated

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Only need a hole for gas or as they call it now a mixer, 99% of any gas problem is 12v IMO
Try bleeding air from water side, may be creating bubbles or cavitation,
Park nose up invert coke bottle radiator filler to check, say it again all LPG 4x4 should be running these {see pic}

Thanks for that, slightly lost on the 12v Imo bit... Lol. And the 3 way peice what's it do and if they are worth their weight where do I get one? Bj bearings or something similar?

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Yes I would think so, If you use "Tee" the flow of water is restricted at TEE,
Gas likes it slightly advanced too BTW, Gas does not go through your Carby either Mixer
or via sequenctial injection. Butterfly /diaphram on carb controll input.
Convertor made need a kit put through it using carbie cleaner.[Messy]

Not sure if on Google or not, but try looking up John Bennet water pumps.
We spoke for 4 hours just on the cooling system on 4x4 and cars.
Absolute god on the subject, retired now so all this knowledge lost, sadly

3 dogs you always come to the party... Your a gent. Thanks mate ill pass this info on to my mechanic as I'm not screwing with lpg

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Could be a vacum leak. My Gq TB42 had one recently. Mine is EFI so many places for a leak. But yrs is carby? Still plenty of places for leaks. Look for splits close to where hoses fit up to manifold, air intake, anywhere vacum hose fit up to something. Also make sure no leaks between gas receiver and carby/ manifold. Only needs to be a small leak to create a problem. Also you should be running a hotter range spark plug/s and need to check plug leads and be using good quality leads at that. The fact that has a rough idle on petrol, points to vacum leak. But could also be points or other thing/s. How long since you replaced the points, or does it have electronic ignition?

Thanks for more info I'll check those hoses. Yes it is a carby and I have an electronic ignition fitted. I'm running good ngk leads and sparkys and probably only changed them a cpl months back

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Also consider a pertonix ignition & extended rotar button.

Also try shaking the carby - the base bolts or the screws thart hold the bottom butterfly assembly may be loose. If the scews are loose - remove the carby from the manifold - flip it and tighten the 3 screws

I had this on my RB30 carby )simalar to the tb42 crby)

Hi, have you checked the "basics"? Filters, visual check for any leakage, etc. Is there any trouble (sounds or visual) when starting the engine?
This would help us to make a disgnostic
Thanks

Ok. I've got a crow cams electronic ignition. I've checked all the basics. Filters etc are all good, they are all new. Does the petronix ignition have advantages over others? And what would an extended rotor button do also? Sorry still learning guys

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Id be checking and tightening all hose connections for the gas. My GQ was running dual fuel when I got it. It had a fully reconditioned carby, mixer, hoses etc. Twice over the period of 6 months I lost power with gas, also it wouldn't rev over 3000 rpm. Both times I fixed it by tightening the hose clamps on the gas line close to the carby. The problem being that when trying to get above 3000 rpm, it would begin to suck air in through the loose connections.

Sig test. android, MC version 2.4.7.11

Does this happen after a gas fill, you could be getting an air block.
switch from gas to petrol a few times on the move and see how you go.

Could also be dual fuelling,

I'll look at them hoses. It starts fine. It gets worse the warmer the motor gets. To take off in 1st gear now I have to get the revs up to 3000rpm at least or it will stall. Changing gears is the same really. Even that doesn't always help. I doubt she is duelling, fuel levels stay the same. It can also be rougher after a gas fill also 3dogs

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Oh and flicking from petrol to gas sometimes does fix it for 5 mind... Then back to shit gq.. Lol

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When a coil is buggered it can play up more as it heats up.
Also a faulty ignition module (the bit that replaces the points) can have a similar affect.
Does it feel like it's an electrical miss or is it more of a fuel shortage lag?

Sig test. android, MC version 2.4.7.11

Hmm ok. On gas it kinda feels like a fuel shortage but in saying that the electronic ignition stuffs up on river crossings a lot. I had a bloke say it seemed like an electronic problem once. Driving on petrol some times the revs drop right off to 0 then straight back up... Like it gasps. Not as much on gas but has done before... I'm running a bosh coil

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If it does a similar thing on both petrol and gas I reckon id be looking at the coil or ignition module. Can you get hold of another coil of a mate etc,to swap for a test run?

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I'll try another coil if I can. Shouldn't be to hard to find one. Any way of testing the electronic ignition to see if it has issues?

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I got instructions to test my pertronix ignitor. I'm not sure if they'd be the same. I posted them in the forum manuals section.

Sig test. android, MC version 2.4.7.11

Awesome thanks mate. Not sure if it's issue related or not but it's never started on petrol from a cold start. Will once it's warm with ease but not when it's cold... Only starts on gas

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Running on gas slowly destroys the carby. It dries everything up. Chances are the carby is a little sick but if it runs on petrol then it might not be too bad and probably perfect timing for a rebuild kit.
When on gas, the carby pretty much just works as a throttle body so if the car isn't running very well on gas it's probably nit the fault of the carby.
About 350 to 500 to get a full acid dipped rebuild of a TB42 carb. (Tassie prices though, probably get it cheaper elsewhere)

Sig test. android, MC version 2.4.7.11

The extended rotor button. makes the truck idle better - possibly burn less fuel and should give a longer spark.

Check all you hoses - don't forget the advance lint to the dissy.

check and make sure the carby is not lose (give it a shake).

Make sure that the inlet manifold bolts are tight.

The idle problems can be related to poor vacume. I had to put a carby kit in my tb42s - duel to the truck stop working on petrol. The gas is straight though - less of a problem. I diod have a idle issue at the light prior to putting the kit in though (LPG and petrol)

Just drove to work, thought I'd describe it. It feels like it's a fuel lag on gas. It idles ok but when you want to take off is the issue. No power at all, that's when it stalls. If I keep bit above 3000 rpm it's ok but not good. In first if I take off with good revs it doesn't do much, wants to stall but picks up kinda once revs are high again but it's still struggles. Flick it to petrol and I have power again

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Do you have any idea what the timing is set to?
As GQ tank said above, check the vacuum advance on the dissy.

I had a lpg system that was in really good order and I still got rid of it so I could have straight petrol. When running dual fuel I don't think it's possible to get the best out of either fuels. Id prefer to have one fuel type tuned to optimal efficiency.

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Don't know if this helps at all guys. This morning is cold here and I drive on gas. It didn't seem to have as many issues, had power and it took alot longer to play up. Now when it did play up it wasn't as bad and it would backfire and bam I'd have instant power again. Strange to me but I hope someone recognises it

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Backfires mean either an air leak or too lean in the gas Dept. been known to blow air filters off cars.
Also is your radiator full. ????

Quote:

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Originally Posted by threedogs

Backfires mean either an air leak or too lean in the gas Dept.

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Or the timing is out.

Did you check the vacuum advance?

Should be advanced enough to be "just 'off PING on petrol
,,But as most here have said you can only get it running well one one.

They recommend 18-22 degrees advanced for gas. That's pretty high for petrol. I fitted a pertronix ignitor kit and tuned the timing back for petrol. It's a lot more powerful on petrol now than it used to be

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Did you find it hard to find sweet spot for both Lucas.

I've often thought of replacing the electronic ignition to a petronix and also using there flame thrower coil. I've heard they are great from a few people. I'll check that radiator later. Should be good though I not long serviced her... But you never know. Haven't checked for vacuum leaks as of yet as I'm unsure how to do this... Pipes don't look or feel split

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Quote:

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Originally Posted by threedogs

Did you find it hard to find sweet spot for both Lucas.

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Thats the thing, theres not really a sweet spot. To run dual fuel there has to be a compromise meaning you don't get the best "bang for your buck" on either fuel. It was ok when gas was a lot cheaper but I don't think it's worth it now

Sig test. android, MC version 2.4.7.11