Austin,

Thanks for suggestions. In response to you questions. The car runs fine when
cold starting on petrol switching to LPG (as and when the system tells it
to). I tried to keep the motor running when hot and running rough - It
didn't like it at all. The problem didn't seem to go away, but i didn't try
for long. I was more interested in getting going, this has happened twice
outside a shop i stopped at on my way home. When home i tried starting
again, same problem. Left the car for a while and it started and ran fine.

As a self-employed gardener, I pull a small trailer the problem happened
after being in slow, heavy, stop-start traffic.

The engine is an injection 4.0 litre, straight 6, Automatic Gearbox

Cheers, Ray


Austin Shackles wrote in message
...
On or around Tue, 7 Oct 2003 02:03:53 +0100, "Raymond Ramsey"
enlightened us thusly:

My '95 4.0 Cherokee has an LPG conversion. There is a selector switch
giving
the following options 1-Petrol..2-LPG..3-Start using Petrol automatically
switch to LPG shortly after starting. I've been advised selecting 3 is
the
best option.

Cold starts do not seem to be a problem. However starting when engine is
warm either switch position 1 or 3 is murder! The engine miss-fires and
runs
rough. Obviously a problem with the Petrol feed. Switching to 2 and all
seems fine (so far) as does switching to 3 after the engine has been
running
for a couple of minutes.

It seems obvious the problem is running using petrol. Have any of you any
ideas on where to start looking? I assume the electrics are fine as all
runs
well using LPG.


does it run continuously badly on petrol, or only for a brief period?

does it run OK on petrol when cold?

if so, then I reckon whatever it has for enrichment is sticking on. I
assume it's an injection system, in which case there'll probably be a
temperature sender somewhere to tell it the engine's cold, and allow it to
deliver more petrol. This could be a fruitful place to start looking - if
it thinks it's cold all the time, it'll be running over-rich.

either that or the actual device that delivers increased petrol (these
things are very system-dependant) could be sticking "on" - this assumes
that
it doesn't do enrichment simply by doing longer fuel pulses on an EFi
system...



--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
Confidence: Before important work meetings, boost your confidence by
reading a few pages from "The Tibetan Book of the Dead"
from the Little Book of Complete B***ocks by Alistair Beaton.