Trouble starting engine on 1988 3.5 on LPG

Thanks for the info - the 4.6 is in my RRC - for off road application I drive a bit hard but use petrol as well. kinda the same on road lol its my main drive at the moment.

will be buying new plugs this weekend - tho I have to say - 10 bucks a plug is cheap... the plug I am used to buying are iridium plugs in a high performance motorcycle.... but its a low comp 4.6lt V8 I have now, tuned for gas mainly however.

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Originally Posted by bee utey

And that brings me to the last reason for hard starting, spark plug choice. My favourite gas plug is Bosch part no. WR7DC+ but you can use NGK BPR6ES if you prefer jap stuff. Make sure the gap is no more than 0.7mm/0.028" and it should handle lean mixtures better. Bosch also make a LPG specific platinum plug, part no. WR7KI33S, pre-gapped for lpg to 0.7mm.

Also make sure your plug leads are not tied together, a bit of space between them is good backfire protection.

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I think after buying a new battery and getting the engine tuned I might have stumbled on the cause to my Rangie's woes, we did a compression test on two of the cylinders, one at 100 the other at 110, I understand that this is low compression and gas needs good compression to be sucked in, Idon't know if this is right or not, what do you think? also the gas guy thought I might have a problem with the cam shaft.

There's little value in just checking 2 compressions, you need all plugs out to get a good reading, then read all 8. Variation between cylinders is a better indication of problems than a straight pressure reading. Compression gauges can be very inaccurate so I would not panic just yet.

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Originally Posted by RaZz0R

what about for a 4.6 on lpg?? This afternoon she was rough as & power loss between 2 ~ 3,00rpm :( time to rip the sparks & replace so I am wondering what is best to use??

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Well I fixed my problem... almost.

Found the dizzy itself had come loose!! Like rattle & turn by it self loose! Had an "variable" timing 4.6V8 there for a while!!

Changed all my sparks & gapped them to .8

running like a dream now.. slight ping at full throttle from idle. Me thinks she is about 7c advanced so will be adjusting timing now.. seems there wasn't a spring washer for the dizzy bolt! :o :D

Well the journey still continues, replaced battery with a 700, put in a new air filter and had it tuned, then I replaced the injectors so we can start it on petrol, with a repaired air flow meter...........that is to come. The starter turns over forever now, until it starts.

Checked timing??

Are you applying a bit of accelerator? I find that after starting cranking, you step about 1 inch on the gas pedal. Works with most older vehicles I come across. The important bit is not to apply accel before cranking. Wait approx 1 second after starter engages.

ive had 3 rangies out of 6 on gas.all could be cranky on gas. my last one is an 87 efi that has never run on petrol since i bought it.sometimes it wouldnt start for a while till one time i smelt petrol in exhaust.pulled fuel pump fuse,still kept doing it .cut wire to fuel pump,never did it again.you may have dodgy changeover switch.i think i did.