lpg - sudden loss of power!

[Donald360]

We run our van almost all the time on lpg, but have noticed a problem when accelerating. When accelerating, the revs increase just as one would expect until that moment when you think to yourself 'time to change up a gear'. However, if I keep accelerating a bit more, (eg when overtaking a tractor!) it suddenly loses all power until I take my foot off the accelerator. This is more apparent when under load, but also happens if I just rev the engine hard when stationary. I feels exactly as if the gas has suddenly been cut off.

The lpg system was fitted a number of years ago, by 'Mickleton Service Station' which, unfortunately, is about 400 miles away - so popping back for a service is a bit inconvenient. I went to a local lpg fitter (Kirkcaldy) but he just sooked in his breath and suggested i spend £1000 or so on a new system!

I'm sure it is a simple tuning or cleaning out gunk problem, but I would appreciate some expert advice on how to go about this.

Cheers,
Donald.

[Ian Hulley]

Check you don't have a rev limiting rotor arm fitted. If you have ditch it a get a real one .... and possibly save up for a rev counter pod

Ian.

[ermie571]

or an after market rev counter like mine!

but yep, sounds like you are hitting the rev limiter

Em
x

[mirams]

I had a similar thing when there was a kink in the coolant pipe that keeps the evaporator warm (more gas needed when accelerating = more cooling on evaporation and the whole thing was freezing up). You can check if it is this by pulling over after it has been doing it and looking in the engine bay. There was a massive lump of ice around my evaporator!

[lloyd]

Don't know about fuel filters on these gas systems, but regular petrol / diesel fuel filters can cause this symptom when needing replaced... restricted for from being full of crud, so not enough fuel to run at full throttle under load. Might be good idea to check / replace it too.

[AngeloEvs]

How does it run on petrol?

[Donald360]

Thanks for the replies so far. I tried running the van on petrol today and it seems to run fine - no sign of the loss of power I get on lpg. It also has a good bit more oomph on petrol. I am thinking of cleaning out the vaporiser as I suspect it it this or a wrong setting on the 'power valve'.

Has anyone else here taken their vaporiser apart? I am concerned that a) there will be an uncontrollable release of gas! and b) that it will have complex parts and fragile gaskets and be impossible to put back together.

I'm trying to phone Steve at gasure, but cannot get him yet, so any advicewould be helpful.

Here are some pictures of my lpg system...

One of two cyclindrical tanks slung under the van with some sort of valve gubbins inside a protective cover.


Donut tank at front underneath with solenoid/valve bits.


Pipe from tanks goes into the brass device (on right) before continuing to vaporiser unit. The green solenoid is for the petrol fuel line, I assume it cuts off the petrol supply when the lpg system is in use.


This is, I think, the vaporiser unit. The gas goes in from the right (copper pipe with green solenoid) the large pipe at the top goes to the carb. The two pipes at the bottom are for hot water. There appears to be an idle adjust screw near the top. I don't know what the adjuster in the centre does, it seems to be filled up with rubbery gunk.


This is the so-called 'power valve'. I am assuming that turning the knob clockwise (screwing down) will decrease the flow of gas to the carburetor and ant-clockwise will increase gas supply. I have no idea how it should be set.

Cheers,
Donald.

[Mocki]

you have some issues i can see from the pictures, which may or may not be anything to do with your current problem...... apart from the generally everything being very corroded, in the picture above where you correctly identify the petrol solenoid , the gas filter has its solenoid missing, it too should have a electro magnet on the plunger tower which the two spare wires taped to the loom should be connected to.
now i dont actually thing this is part of your problem, ( although if the plunger is not being held open by the electromagnet that isnt there it may restrict the lpg flowing through the filter) however , it is a safety issue, i suggest you speak with Steve ASAP..