tb42 not return to idle (hanging)

[bobbrumby]

I tried disconnecting the vacuum line running to the "ANTI-AFTERBURNING CONTROL SYSTEM UNIT" when it was at high idle did not lower the idle, i disconected the the plug running to it but then it did not want to idle, i think this was becuase the plug has two other wires in it one for the fuel cut off and auto choke? When i get more time ill try and disconect just the wires running to the unit, unless someone has a better idea.

[patch697]

I tried disconnecting the vacuum line running to the "ANTI-AFTERBURNING CONTROL SYSTEM UNIT" when it was at high idle did not lower the idle, i disconected the the plug running to it but then it did not want to idle, i think this was becuase the plug has two other wires in it one for the fuel cut off and auto choke? When i get more time ill try and disconect just the wires running to the unit, unless someone has a better idea.

All the "ANTI-AFTERBURNING CONTROL SYSTEM" unit dose is shuts of the fuel to the idle circuit on back off & shut down to prevent run on which is a fairly common feature on carbied low compression engines. I don't think it will be responsible for the problems your currently having as it only effects your fuel system & not your LPG & as your having the same issue on both fuels that pretty much rules this out.

We need to get back to basics & eliminate things step by step.

: Have you checked for sticking throttle linkages/cables including hand throttle.

: Have you checked the timing & gone over the ignition system in general.

If you are sure you have no vacuum leaks anywhere including all vac control units & the throttle linkage & associated components are in good order then it may be time to start looking at the ignition system. ie: the distributors mechanical advance, dwell plate assembly & vac advance module. If dry & sticking or warn, it could be the course of your issues & will react the same on both fuels.

Not saying this will be the course but its worth checking out as your slowly ruling out other courses & Patrol distributors are known for waring out.

[bobbrumby]

I had some thing similar with mine when it had the TB42 in it, I found that when I rolled up to a stop sign or intersection in neutral or with me foot on the clutch then it would hold the revs up until after I stopped, but if I rolled up in gear and depressed the clutch just before stopping then it didn't do it, I never found a reason for it and it never made any problems that I saw so I just changed the way I drove because it used to pee me off.

yeap tried this yesterday and if you almost stall out the engine before depressing the clutch it does not do it

[bobbrumby]

Had a look at the dizzy yesterday the vac advance was locked up but i have freed that up, how much should it advance like only a few degrees? The mechanical advance seemed nice and free. I have not got a timing light so i cant check that. It has got a crane multi spark ignition so maybe its on the fritz.

I know it is not the throttle linkages becuase the idles increase while you are rolling down a hill with the clutch in, not pressing the accelerator at all. This why i am thinking its the afterburn thing as it has a speed switch that enables/disables the solenoid. And when you search for "Boost Controlled Deceleration Device patrol" in google allot of people blame this for the same problem as i got, only i cant turn the adjuster screw as it siezed up, i wonder if i could disable the electical side of it to test it. i know you say then this would only happen on petrol but would not the evapourator see the extra air that the valve is bleeding and add gas to compensate?

[bobbrumby]

just an update got the problem fixed, turns out backing the screw out on the AFTERBURNING CONTROL SYSTEM UNIT on the passenger side of the carb half a turn fixed it, btw did this in two quarter turn increments. a squirt of inox and two days later the screw was freed up. Now dip the clutch while driving and the revs return to idle . So now i can actually engine brake going down a hill instead of riding the brakes!!!!

[Bigrig]

Outstanding!!!! Love it when it's something 'non costly'!!!! lol