Gremlin in my GQ

G'day all,
Ok I have this problem with my 94 GQ 4.2 duel fuel, I've seach the best I could on the net and found nothing, taken the GQ to a recommended mechanic which I found to be a great service, we cleared the cars computer and he told me to bring back when fault occurs again. It happen 2 weeks ago, check light on dash came on when stalled, took back to mechanic and there was no faults on computer.This is the GQ's problem and it happens on both fuel, I will be cruzing along and engine starts surging and eventually stalls( temp on gauge shows 3/4).Now I will have to sit and wait about 20 to 30mins before car will start, engine will choke and hesitate abit until I get to about 30kph and then drive like nothing has happened and might not happen to the next family trip away which could be months . Last week at mechanics he change the LPG mixer(TIPO MPP) coming from vaporizer to a brass valve tap that is manually tuned and I was wondering does the new fitting affect unleaded fuel as problem is happening on both fuels. Also I changed the waterpump, fan,fan clutch and coil. This problem has happened 4x4 over rough gound, sand and on bitumen, normally warm over 30c and problem never happen on a cool day or nite.
Thanks.

It may be a long shot but you may have an earthing issue (or an electrical fault of some description) with the ecu, It explains (to me) it happening on both fuels, that no fault code appears and over 30 degree day tells me high resistance joint. until proven otherwise i doubt it is a mechanical fault

Cheers
Benny

This sounds like a afm problem and will affect either fuel.
possible quick diagnose, try tapping sharply with your finger the afm box and it may or may not play up on cue.
and get afm specs and check multi meter.
afm = air flow meter.

I would start by checking all earths, also inspect engine wire harness for possible damage or faulty connectors.

Other possible causes for it to only play up when hot are, ECU relay, crank angle sensor, ignition module, coil or ECU.

Was there any faults showing before you cleared the computer?.

Computer was full of faults I was told.
Thanks for the information and it time to get busy, but I think it one of those faults where I don't know if I have fixed the problem unless it happens again. Also the LPG mixer(TIPO MPP) coming from vaporizer that was change brass valve tap I feel it using alot more LPG and does it affect both fuels on computer.
Thanks.

A faulty TPS can cause this type of problem also.
do you have the fault code list for your model patrol?.
if not, sure they would be available here.
No LP system is for LP only. both fuel are supposed to operate separately.
you would find if both fuel are entering system they would suffocate one another, and chamber.
If this was happening I'd imagine you would be able to smell both fuels un-burnt.
Brass valve tap on hose from mixer to intake manifold, told it helps regulate max flow, top end power.

Thanks everyone, I've got a feeling this may have been the fault, checked most of the wiring while car was running with a wire wiggle and the earth off the distributor when moved wire caused engine to stall. Then gave a little tug on wire and snap, I wonder if thats all it was. What still concerns me is why I had to wait around 20mins to start engine. I took some pictures there in my Album as I don't know how to post the pictures here.
Thankyou.

metal expands and contracts with temp. this can cause a broken wire or suspect connection to act like a temperature dependent switch.

Electronics techs usually call them an intermittent fault, (followed or preceded by words banned by this forum), and trace them using a heat gun and can of freezer spray.