Problems switching to gas

[Uglitom]

Hi, I have a 96 3.9 v8 discovery with Omvl converter and a sprint tank. recently when I start it or if I switch to gas from petrol. All 3 fuel cut solenoids repeatedly click on and off until I switch off the ignition and select petrol again (won't let me select petrol once the clicking starts). I have checked the coil feeds to the gas switch and cant see any issues there.
All suggestions gratefully accepted.

[bee utey]

It sounds like it's got a control switch with revs input so it changes over automatically after starting? I hate them with a passion. I've ripped quite a few of those out after a major malfunction. I've replaced them with a simple on/off LPG switch and gauge, an injector cut-off relay and a safety cut-out.

Injector relay Apexus CO202 or similar

Safety cut-out: Apexus CO101, APEXUS Pty. Ltd. - Safety Cut_Outs Products (http://www.apexus.com.au/cutouts.html)

Switch gauge: Apexus PG200 or GS100-2, APEXUS Pty. Ltd. - Switch Products (http://www.apexus.com.au/switches.html)

Simple, robust and easily traceable. Engine will start on gas even when the petrol system fails.

[Uglitom]

Thanks,
I'll give that a go.

[Uglitom]

Hi Bee utey, I can find the switch and the cut off you recommend, but not the injector cut relay. Can you suggest an alternative? is there any problem just using a normal relay triggered from the switch?
Thanks again.

[bee utey]

Hi Bee utey, I can find the switch and the cut off you recommend, but not the injector cut relay. Can you suggest an alternative? is there any problem just using a normal relay triggered from the switch?
Thanks again.
Injector cut relays are normally closed and feature an adjustable delay to switching off the injectors when powered up by the gas system. This delay allows the injectors to fire when you start cranking to enable fast starting. Simple relays don't assist starting at all and you usually forget to switch back to petrol for morning starts. Then it either backfires or takes a while to get going.

There are at least 4 different brands of petrol start relay on the market, AEB make a small one, Peel Electronics do a variety, the CP99 Petrol Start (http://www.peelinstruments.com.au/page15.html)being the simplest, Gore Research and Apexus both sell one but neither appear on their websites. Send me a PM if you want help getting these parts.

[Uglitom]

All parts arrived today. Many thanks especially for the diagram. I did consider taking a photo of the old installation but feared it might be considered obscene by the mods. The crimp connectors (wrong size ) in the injector harness splice have solved the mystery of the intermittent crap running on petrol. Can't wait to get to grips with it on the weekend.
Thanks beeutey!

[Uglitom]

Well, it's all in and wired up exactly as per Jildens diagram, all lights up appropriately but won't run on gas at all. Any suggestions?

[bee utey]

Gas tank empty
gas tank tap turned off
gas tank solenoid not operating, jammed, coil failure or poor earth
Main underbonnet gas lock not operating, jammed or coil failure
gas converter failed, jammed, blocked
Gas delivery hose to mixer split

Basically you need to check for gas pressure in the line to the underbonnet gas lock, then after the gas lock. Usually you use two spanners, one to hold the fitting, one to loosen the nut. Gas solenoids can be hotwired temporarily for the purpose of testing to see if they work.

[Uglitom]

And a poor earth on the tank solenoid had it!
Thanks Jilden. Now running sweetly.