HELP, got MOT tomorrow and bus now has issues

[Zebedee]

I've got my MOT tomorrow at 1pm on my caravelle and its started playing up.

A few weeks ago all was well, it ran fine on petrol and LPG, starting, running and idling fine (900-1000rpm) on both.

All of a sudden, in the past couple of days, its become a bugger to start on gas (either hot or cold), turning over and over and over before eventually catching - it used to start on 1st turn of key.
It always started fine on petrol on the first turn of key but now it won't idle at all. I have only run it on petrol for maybe 6 miles in the past couple of months since i converted to gas. Unless the revs are held slightly above idle speed (no rev counter fitted so not 100% sure of revs) it just stalls. Could it be something as simple as a blocked idle jet or just crud in the float bowl?

Not sure the two (difficult starting on gas and petrol not idling) are related to be honest, but if i can just get it idling on petrol i'll be happy.

Can anyone quickly suggest some things i can try to get it idling?

1.9 DG engine with pierburg 2e3 (rebuilt 2 months back) including cleaning the filter in the inlet pipe.
Plugs are clean, timing correct, new air filter, dizzy cap and coil.

[Ian Hulley]

Are you setting the automatic choke ? Accelerator pedal to the floor and released before starting.

Ian

[Zebedee]

Yep.
Choke (and fast idle) are adjusted as it should be as per kevtherev's instructions too.
It used to start fine which is the odd thing. Once started it idles nicely at the correct revs on gas but just not on petrol.

Could a vacuum leak somewhere (carb base gasket maybe) cause the lack of idle on petrol AND the difficult starting on gas?

[norfolkbcs]

Ours wouldn't idle at all and was stalling at every stop (1.9 auto), after having just done a 200 mile journey perfectly. Carb jets and vacuum pipe cleared and now it is running fine.

Donna

[Zebedee]

Because its only been run on petrol very rarely in the past few months i think the lack of idle could indeed be down to muck/dust. I suspect the fuel filter under the van has been empty for weeks plus theres only a couple of gallons maximum in the petrol tank which can't help.

[Ian Hulley]

Fresh petrol, clean filter.

Keep some petrol swilling round in the tank to stop it rusting, run the van on petrol once a month for a few miles to ensure the system is working ok.

All advice your installer would have given you.

Ian

[norfolkbcs]

Because its only been run on petrol very rarely in the past few months i think the lack of idle could indeed be down to muck/dust. I suspect the fuel filter under the van has been empty for weeks plus theres only a couple of gallons maximum in the petrol tank which can't help.

This, I suspect, is similar to our probs. We bought ours 3 weeks ago - it had been part of someone's estate when they had died and I think had probably been standing for a long time whilst probate was sorted. It is sound mechanically and on bodywork - but I get the feeling that there is a lot of crap in the fuel system which has settled and we are stirring it up as we use it regularly again.

[Zebedee]

I replaced the fuel filter under the van, cleaned out the one in the carb inlet and replaced the air filter. On checking the mounting nuts for the carb-manifold i found 2 loose ones. I tightened them up and cleaned out the idle jet (there wasn't an o-ring on it - should there be?) and lo and behold it now idles. It starts on gas easy now too.

Had a play about with my new gunson gastester and found out CO was 5.7% on petrol.

After a bit of a fiddle it is now this:


Appears to idle OK now, though theres still a little miss every-so-often.

[Zebedee]

It passed its MOT today. Emissions a tiny bit high he said but still a pass.
Still doesn't like to start on gas though.