then the lock-off and regulator are both bad, and once repaired/replaced, you should start training the operators to turn off the gas at the tank when ever the truck is going to be sitting more than just a few minutes and for sure at the end of the day.

...And what if the vaporizer frosts-up before start-up? It also floods the mixer/intake manifold with liquid fuel at air temps below 0 c.
thanks,

as far as the impco model J, all i do to test them these days is to remove the small pipe plug in the test port, and replace the plug with a barb fitting. i then install a vacuum/fuel pressure gauge onto this barb fitting and observe the primary pressure. Pressure should hold fairly steady at 1&1/2 to 2PSI with the engine running, and hold that pressure without climbing or dropping with the truck shut off.
if the truck is equipped with a VFF30 fuelock, remove the vacuum line to the fuelock with the engine running. the truck will stall as soon as the pipe between the fuelock and the vaporiser is exhausted of fuel. this time will vary from a second if it's simply a pipe nipple connecting the two, to thirty seconds if it's a long hose. if the engine simply sputters, or does not stop at all, the fuelock is stuck partially or completely open.
if the vaporizer housing frosts up in operation, check antifreeze level and circulation through the vaporizer body.
it is far simpler to replace the units than to rebuild them, though i have had success doing so. it depends on the labour rate and parts costs in your area.

mixer related faults may vary depending on what mixer you have but the model J and VFF30 symptoms are fairly universal and easy to diagnose. i do not like model K or Cobra units as the pin seat frets at the housing and they do not take rebuilds as well as the J units.

Hello! I also noted this old post on impco training from drlifttruck and I would like to have a copy of this material in the PDF format which can be emailed. Pretty please, email me at bbideau at beachner dot com or brianbideau at yahoo dot com.

Well heck fellas. I'm here in the USA. I can still buy & sell the old model J's. I can get anything ya want on them.

I saw this old post on impco training from drlifttruck and I was wondering if it wouldn't be too much trouble if I could possible get a copy of that. Please email me at mickpo at verizon dot net

No Problem,

Email me at ulsh1 at AOL Dot Com

Hi, I'm new here and I saw this old post on impco training from drlifttruck and I was wondering if it wouldn't be too much trouble if I could possible get a copy of that. We have several fork trucks at work that have the model j converter set up, and one of them is not running right. Thanks.

Glad I could help Dave.

Just to add on to the above I have just remembered that at the same time the fuel feed pipe from the fuelock to the converter (Pigtail pipe) was also changed in length.

The change in pipe length was to reduce the amount of LPG that could be in the lines and possibly force its way into the cylinders (If I remember correctly) and this also meant that the units had to be moved closer together....so you may have seen this change as well.

I have acess to IMPCO training in PDF format, from the year 2003 if you would like contact me at my address

Daniel, Thanks for the explanation. That is really great! you have filled in all of the "grey" areas for me. What you say about the primer shroud and the German market now makes sense! I have seen the shroud on trucks built by Clark in Mulheim in the past and currently see the same on Toyota from Ansenise France. But product built in Italy (BT Cesab) has no shroud. We buy parts from HKL and find them very helpfull, but they could not answer my question anywhere near as well as you have done. Dave

Dave,

The story you have heard of the accident in Germany is kind of true, but is a lot more complicated than probably anybody would like to understand.

The story goes that the operator over time had got into the habit of pushing the primer button whilst cranking over the machine, instead of priming first and then cranking, and this led to the metal plate which the primer contacts on the Diaphragm to bend. With the plate bent the gas pressure could force the valve off of its seat and gas could flow to the engine, with the ignition in the ON position one would guess.

The operator then one morning does his usual and bends over the engine pressing the primer and starts cranking where by he gets a nasty little surprise from the igniting of the gas stored in the cylinders and lines.

There were a number of other factors that caused the accident as I understand it and the converter problem was given as a probable contributory factor on the back of which new German regulations were introduced. The first part being that an operator should not be able to prime the system manually (i.e. they shouldn't be able to bend anything), and the second being that on an annual basis every LPG converter should be stripped and components replaced, without exception.

The Cobra is as stated an updated K with the addition of the locating holes on the casing for the primer cover and I believe the slight change of the internal components with the increase in strength of the plate that the primer button contacts. With very minor changes to the K model Impco could satisfy the German legal requirements and continue to use one converter for all markets, which is why we all have the Cobra (One type suits all).

The UK has no regulation regarding the primer cover, and the only market that needed it as a legal requirement was Germany and so as Dutch manufacturer we only supplied them on machines shipped into Germany, but I can imagine German manufacturers may have had them installed on all units.

When I was still working in the UK I found HKL Gaspower very good when it came to questions about the Impco product, so if you need more info you can find them on the web.

Sorry, can't help you on the drawings...
Looked everywhere, and like you, only found drawings of j's and k's

The only explanation I come up with for the lack of a primer button is that it's cheaper to make.
Cobras are available with primers as well.
Impco classified the primer as a diagnostic tool, and thinks that it's no longer required...

As for the schreider valves: I've never seen that, so i doubt that it's an Impco item. We just plumb guages into the ports for testing.

Hi Mike Yes we do the same with lock offs and vaporisers, it costs too much in time to fit the kits. Some things I would like to know: Why has the button been removed on Cobra? It also used to have a plastic cover, what are the rules if it gets lost?
We see on some vapourisers, Schreider valves on the primary and secondary chambers, do Impco supply a pressure gauge to suit this type of valve? Do you know where I can get an explanation or cut away drawings that refer to Cobra and not the old K and J's. From what I can see the only internal change is to the Primary chamber valve. It used to be a flat spring with a rubber face valve. Now the valve has a "stem" with a rubber seat on the end. My drawings show the K's spring seat. I just think Impco must have updated the information somewhere. Then I coulld give up to date information to my technicians.
Even the lock off's show the "O" ring seal on the valve stem, yet it has had a "U" ring seal for years!

I'm still not sure exactly what info you are looking for.
The cobra is just an updated K, works exactly the same. They changed materials and did some slight design modifications inside.
From what I can tell, it was done simply because the original patent ran out. Just before the cobra's came out, a whole wack of knock-offs appeared on the market.

We don't kit lock-offs or vapourizers any more. It's cheaper to just replace the whole thing because of labour.