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14th May 2014, 06:15 PM
#1
TB42s missing, wont reve & back firing though carby
TB42s (carby)
The truck has developed a fault.
The truck was running perfect- pulling well. On the way back from work it started playing up.
Its missing, wont rev and backfiring though the carby - will idle (LPG and Petrol)
I have replaced the peritonics, new coil, new dizzy cap, extended rotar button, leads, plugs, inlet manifold gasket check the exhaust - no leaks. checked and set the tappets. Checked that the dissy is in the correct position. I have a new battery
No bubbles in the water
No water in the oil
My gut feel is that it has done a head or cam
Im going to check the compression tomorrow - and run it with the rocker cover off to check that all the tappets are moving
Any suggestions?
1991 GQ LWB 4.2 Carby dual fuel, 32 mud claws, 2 inch lift, LSD's front and back
And its Toooooooo High for the Ball & chain
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14th May 2014 06:15 PM
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14th May 2014, 10:02 PM
#2
CERTIFIABLY INSANE
Not sure but sounds a little bit like what happened to Evil on our recent Dargo excursion. His was running very rich and missing all over the place.....Pretty sure his is a very similar setup to yours.
Hit him up with a pm and see where he's at with it. Have a funny feeling he was going to rebuild the carby as a start.
1997 GQ Patrol RX, TB42E. Mods: OME 2" lift, 33" BFG KM2'S, ARB winch bar & reconditioned X9 Superwinch, IPF 900 spotties HID conversion, ARB side steps and scrub bars, Kaymar rear step & spare wheel carrier & jerry holder, Rear 55W LED worklight, Safari Snorkel, 147L LRA tank, Extended diff breathers, dual batteries, GME UHF, Home built drawer and fridge slide, ARB 60L fridge.
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14th May 2014, 10:17 PM
#3
Sounds very much like a condenser
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14th May 2014, 11:13 PM
#4
Patrol God
Backfiring can be caused by: faulty EGR, ignition timing, valve clearances, damaged valve spring or sticking valve, intake leak, carby float level or thermostatic air cleaner system cactus. I hope it is one of the easy fixes for you.
My advice is: not to follow my advice.
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14th May 2014, 11:27 PM
#5
Patrol God
Lack of power is all above plus more to check : Fuel filter clogged, distributor shaft worn, faulty dissy cap or points. Incorrect spark plug gaps, dirty air filter, ignition coil, brakes binding, auto fluid low or slipping clutch. Wrong octane or shitty fuel, clogged carby jets. I would assume it is one fault causing both problems, but It could be multiple faults.
Last edited by mudnut; 14th May 2014 at 11:29 PM.
My advice is: not to follow my advice.
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14th May 2014, 11:44 PM
#6
Was running perfect on petrol and lpg. Now playing up on both missing, backfireing if IO try to rev it.
Timming right, new plugs - gap set correctly.
New leads, dizzy cap, new flame thrower coil new pertonics - old was doing the same, canot be fuel filter as both fuels are doing it. Tappets set, cannot be carby jets - both fuels, carby is NOT loose, manual / clutch has done less the 10,000km. swapped rotor button with my spare extend rotor. I have the air cleaner off and it still back fires. No condenser - running pertonics
1991 GQ LWB 4.2 Carby dual fuel, 32 mud claws, 2 inch lift, LSD's front and back
And its Toooooooo High for the Ball & chain
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14th May 2014, 11:52 PM
#7
Patrol God
Yeah, I just copied it all out of my Haynes manual. So an air leak may be the go. Spray some wd40 around the inlet manifold and outside of the carby, and see if the revs change at all.
My advice is: not to follow my advice.
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14th May 2014, 11:59 PM
#8
I replaced the inlet manifold yesterday as I was thinking the same - no change. The carby is tight - no leaks.
I'm nearly at the point of thinking its the head or head gasket.
Im going to rip the rocker cover off it tomorrow and fire it up - make sure all the tappets are movning (had a round cam in my old rangie a few years ago)
1991 GQ LWB 4.2 Carby dual fuel, 32 mud claws, 2 inch lift, LSD's front and back
And its Toooooooo High for the Ball & chain
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15th May 2014, 12:25 AM
#9
Patrol God
If it has a choke break diaphragm, it could be split, or even the auto advance diaphragm at the dissy. Did you check the manifold face against a straight edge before refitting it?
My advice is: not to follow my advice.
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24th May 2014, 12:55 PM
#10
More info-
Just done a compression test.
cylinder 4 is at 135 PSI
All other cylinders are at 150 - 155 psi
Also noticed number 1 drops down to 125 psi after short time - leaking valve?. All other cylinders hold there pressure for a couple of minutes
Also I gave it a run with the rocker cover off 0f looked like all tappets where moving correctly
1991 GQ LWB 4.2 Carby dual fuel, 32 mud claws, 2 inch lift, LSD's front and back
And its Toooooooo High for the Ball & chain
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