Gas Problem 85 carb RRC

[UncleHo]

G'day bee utey :)

Got a question for you, :confused: I have an OMVL gas system on an 85 RRC carby model 19D motor 9.35:1 comp it has a R90/E converter, and a OMVL brass filter/relay fitted before the R90/E as of the last week this gas system has taken to cutting out whilst on the move, usually around the 2000/2500 RPM mark,this is while the motor is at normal running temp. first question,could it be there is wax/jelly in the filter or would it be in the converter/mixer? if so is there a repair/service kit for the R90/E as it looks like it can be disassembled by the allen screws,I presume that one would turn the gas off at the tank run it dry, then disassemble and clean the filter and the same with the converter/mixer.

I would presume that it is a job that a competent mechanic should be capable of if care is taken and all joints are checked with soapy water ;)

Your reply would be appreciated, this has only started since the weather has cooled.I have always used BP gas from one or two servos locally (BP card) at the moment it is getting about 5 KLMs per Litre and uses NGK-BKR 6 EKB-11 plugs with which it runs quite happily

thanks in advance:)

[bee utey]

Terminal disease!

Random cutting out is almost always due to loose and dirty electrical connections. Each and every terminal connected to the gas components should be removed, squashed gently with pliers and made to fit with moderate force. Any bare metal terminal should be covered with heat shrink or replaced with fully insulated terminals. All earth connectons must be checked for tightness and cleanliness. Moisture will quickly corrode open connectors, and any current passing through grot will heat up and disconnect the terminal temporarily. Remember paint and rust are not good conductors.

The only other common issue with random cutting out is a box called the "safety cut-out" which prevents the gas valves staying open after the engine stalls. It usually has an input from the negative side of the coil as an engine-running signal. Sometimes their circuit boards get loose connections for the same reasons ans the other connections. Usually a new one will fix it if the board connections are too small to resolder.

Forget cleaning out the converter or the gas lock, waxy residues are usually involved with cases of "doesn't start at all when cold" issues.

[UncleHo]

G'day bee utey :)

Thanks for the reply,all terminals on the relays from the filter to converter are clean and tight (did them yesterday)including the one on the petrol line just below the coil by the pet filter, also the earth wire of all, where should I look for the "safety cut out" as I am unsure where that would be and what it looks like,would it be in the tank end near the gauge? any ideas?


cheers

[bee utey]

The safety cut out is usually between the gas/petrol switch and the rest of the gas valves, trace the wiring loom and look for suspicious boxes hanging about. It is electrical, so has no gas pipes through it. There are numberless different brands/styles that essentially do the same thing. Some are built in to the gas switch/gauge even. It's identity will be confirmed by the negative coil connection I mentioned before. Trace it through the loom, you should be able to identify its colour to the device. Some systems use moulded nylon multi-plugs, they ususally fail by melting and leave a tell-tale black spot in the connector.

Did you look at the connectors/earth connection for the gas tank valve too? Earth connections are often just screwed to a dirty piece of chassis under the back.

On the subject of ignition, the failure if the ignition system will also cause your random cutting out as the safety cut-out will switch off the gas when the ignition stops. So look for loose terminals all around the coil too. You may of course be suffering from Lucas disease of the ignition system, that is another matter.

[UncleHo]

G'day bee utey :)

Would the safety shut off valve be the one up by the tank connections (80+ltre tank in rear load area :() as it is an OMVL valve,it reads,shut off valve,minimun working pressure2.44Mpa ,it has a shielded cable that exits down the pipe connections, but appears to go down to a wire connection and earth screw under the rear of the vehicle,this looks like it hasn't been serviced since 1996 when the gas was installed:( so I will give both the connection and the earth a good clean and see what happens, it couldn't get much worse.


cheers

[bee utey]

G'day bee utey :)

Would the safety shut off valve be the one up by the tank connections (80+ltre tank in rear load area :() as it is an OMVL valve,it reads,shut off valve,minimun working pressure2.44Mpa ,it has a shielded cable that exits down the pipe connections, but appears to go down to a wire connection and earth screw under the rear of the vehicle,this looks like it hasn't been serviced since 1996 when the gas was installed:( so I will give both the connection and the earth a good clean and see what happens, it couldn't get much worse.


cheers
Nonononono!
Please read my reply below, it is electrical only and is not a solenoid valve on a tank. It is separate from the plumbing. Also if the system was installed in 1996 has the tank been tested since?

[UncleHo]

G'day bee utey :)

Yes, the tank and fittings were tested when I bought the car and transfered the rego to my name,as required in Qld,the only thing I had to replace was the filler cap assy as the plastic tag between the cap and filler was broken, so a complete plastic filler/cap assy was fitted before he would pass it :)

So I wil still go hunting for the safety switch, it will have to wait until tomorrow PM as it is booked into have exhaust work done the pipe is leaking at the "Y" joint to the muffler.

[UncleHo]

G'day bee utey :)

I think that we have narrowed down the problem :) all the electrical connections are clean and tight, the relays are working, BUT the fuel/gas changeover switch/gauge could be the culprit,it seems to contain the safety cutout switch,it is an AEG little black rectangular box, I have been told they are a known problem,what is your opinion,I would assume it is the original unit fitted when the gas was,1996.

If so are they easily replaced, we have had it out, (unclips from loom) cleaned contacts,but it has cut out once since then,but the gas Ind lights still register quantity, Terminal? :(

But, now that I know the problem I change over to petrol, drive 5-10klm and change back, run the carbs dry and away it goes, there is no problem with it on petrol.


cheers

[bee utey]

APEXUS Pty. Ltd. - Safety Cut_Outs Products (http://www.apexus.com.au/cutouts.html)

Apexus sell separate safety cut-outs and switch gauges, or combimed units. They all use proper sized 1/4 inch spade lugs and don't give me any trouble. Those switch gauges with moulded nylon plugs and little pins are useless when they get even slightly dirty, they can't handle 2-3 amps in Australian conditions.

Another method you can use to reduce the load on the output pins is of course wire a relay so the switch box only carries minimal current. A 20 minute job for a sparky. Gas side only as there are often 3 solenoids on that side, 1 on the petrol side.