Prins vsi

[darren]

I have a 2006 3.3 caravan with a prins vsi
The gasoline injectors are leaking down
Is this a result of running on propane all the time
And not using gas too much ?
Also with this system can you over ride the start
On gasoline mode and start it on propane
On emergencies when the gasoline system is down?

[storm]

Petrol Injectors can leak down for many reasons, old age being one of them. I wouldn't immediately blame the LPG system for it.

I don't understand the last part of your post. Is it a question or a statement? It is written like a statement but has a question mark.

[darren]

Sorry ,capitals where they should not be I was writing on my phone.
The question was , can I start the vehicle on propane as apposed to gasoline , perhaps by overriding something .
Thanks

[C3H8]

First question. You mention the leak down of the injectors but not why you want to start on propane. Leaky injectors can be a nuisance but unless it is severe they won't usually stop a vehicle from starting. If the vehicle won't start either the injectors are really bad or the fuel pump may not be working, or it is weak. Leaky injectors will also cause gasoline usage while on propane and cause the fuel trims to change. Depending on the amount of leakage the trims can climb high enough to set a MIL light eventually.

As stated by storm the propane won't cause the injectors to leak but not using gas on a regular basis for short times can eventually cause varnishing of the tips (especially as the gas gets older) and result in leaking until the varnish is cleaned off. Injector cleaner added to the gasoline might help here. Second option is a professional cleaning or even replacement.

As for starting on propane the BRC system has a procedure for a limited number of forced starts on propane if the gasoline pump fails. Researching the Prins system I only came across one reference to propane starting in the USA PERC training manual where it states the Prins system cannot be force started on propane.

[storm]

In Australia there are Prins LPG only systems running around and they do start on LPG, simply because they are not duel fuel they must start on LPG. The issue you will have with the Prins system, that is if you are running the Prins ECU connected to the injector wires of the OEM ECU, is you will have very limited ability, as pointed out by C3H8, to start on the LPG injectors. If you must have your system setup to start on a regular basis (e.g. first start every morning) you will probably need to consider an aftermarket or a modified OEM ECU and not use the Prins ECU at all. Like I said in the first sentence there are cars in Australia with Prins Injectors only running LPG so it can be done. Here's some light reading for you
http://profire.com.au/
http://www.ragelpg.com.au/

[C3H8]

Interesting sites Storm. We also have some dedicated Prins units in Canada done for specific fleets that stay in one location. This was a real challenge to Prins because of our cold climate. At a required rail pressure of 20 PSI (1.6 bar) the propane does not vapourize properly on cold starts. I'm not sure how they got around that issue. That profire system appears to use Prins hardware with their own ECU.

Just for Darrens info on why do these units start on gasoline and switch over. A few reasons. One is that a gasoline ECU has quite a rich strategy in the first few minutes of operation. Since the vapour injection systems use algorythisms based of the EOM ECU the mixtures would be too rich on propane before it is properly vapourized. Secondly the vapourizers operate at much higher pressures then the older two stage vapourizers so the manufacturer wants to ensure the propane will vapourize before they switch to propane. An additional reason is that some ECU's go through a series of self diagnostic tests after start up. Waiting until the engine is warmed up allows the tests to be performed prior to the propane engaging.

[storm]

They are interesting sites C3H8. Just after I got my LPG fitters licence I contacted Profire about fitting their system to my Toyota for testing purposes (theirs and mine). They said yes but my car had to be fitted up in Western Australia and had to stay there. That was no good to me because I live in Eastern Australia and the car was my daily driver. Because of this I did some reading and calculations and believe I could use a Delco ECU (like the one fitted to my Toyota) and run the Prins injectors from that. The only problem I believe would be a deal breaker is the pressure switch on the Prins regulator, currently I do not know what signals it send to the Prins ECU or if the Prins ECU controls it. Until I know if it can be safely discarded, or if I have to adapt the Delco ECU to use its signal or control it, I'm stuck at that point.

[C3H8]

Storm. Going to start a new post on the above sensor information. We're getting away from Darrens original question. To finalize unless some one knows different the VSI system must have an operating gasoline system to start. There is no option to force start the system on LPG.