GQ Patrol carburetor issue

[dom14]

Hi Guys,
I have a GQ Patrol with an RB30 motor. Its' on dual fuel. It runs and starts all good on LPG. Starts ok with Petrol but won't idle unless I keep the accelerator paddle around 2000 rpm. If I let go, it stops and won't be able to start for another five minutes or so. I eliminated any vacuum leaks or petrol pump issues.
I would appreciate any help towards finding the problem and fixing it.
Thanks

[threedogs]

A few others have had similar problems with this motor, try the search engine?
From memory it was simple , not sure if fuel pump or dizzy mod ?

[dom14]

I tried with forum search engine, but no luck. couldn't find a thread with similar issue.


A few others have had similar problems with this motor, try the search engine?
From memory it was simple , not sure if fuel pump or dizzy mod ?

[mudnut]

Hello dom14,
I have an Rb30 which is not on gas. The carby on this type of engine has a few quirks. Check the choke break diaphragm (Small unit top left on carby) and the vacuum advance diaphragm, (on the distributor) for holes or splits, especially if the engine has backfired. Make sure the second stage carby butterfly isn't getting stuck either, (I fixed mine by using some fine wet 'n'dry on the butterfly and to smoothe the carby bore). With the air filter off, and engine cold and stopped, you should see a squirt of fuel into the carby bore when the accelerator is pressed. (only do it once or the engine may backfire when started). If you have run the engine on gas only, for a long periods the carby can dry out, and cause problems too. Also make sure the fuel level in the carby is correct. I had some minor problems with the auto choke, so I fitted a manual cable. I also ran some injector cleaner with the fuel, and have had no problems with the carby for over twelve months.

[dom14]

Hi mate,
If the vacuum advance diaphragm is damaged, then it would accept LPG as well, or does it?!
Thanks

Hello dom14,
I have an Rb30 which is not on gas. The carby on this type of engine has a few quirks. Check the choke break diaphragm (Small unit top left on carby) and the vacuum advance diaphragm, (on the distributor) for holes or splits, especially if the engine has backfired. Make sure the second stage carby butterfly isn't getting stuck either, (I fixed mine by using some fine wet 'n'dry on the butterfly and to smoothe the carby bore). With the air filter off, and engine cold and stopped, you should see a squirt of fuel into the carby bore when the accelerator is pressed. (only do it once or the engine may backfire when started). If you have run the engine on gas only, for a long periods the carby can dry out, and cause problems too. Also make sure the fuel level in the carby is correct. I had some minor problems with the auto choke, so I fitted a manual cable. I also ran some injector cleaner with the fuel, and have had no problems with the carby for over twelve months.

[dom14]

I meant to say if the vacuum advance diaphragm is damaged then it would affect the LPG idling as well. Am I right?!


Hello dom14,
I have an Rb30 which is not on gas. The carby on this type of engine has a few quirks. Check the choke break diaphragm (Small unit top left on carby) and the vacuum advance diaphragm, (on the distributor) for holes or splits, especially if the engine has backfired. Make sure the second stage carby butterfly isn't getting stuck either, (I fixed mine by using some fine wet 'n'dry on the butterfly and to smoothe the carby bore). With the air filter off, and engine cold and stopped, you should see a squirt of fuel into the carby bore when the accelerator is pressed. (only do it once or the engine may backfire when started). If you have run the engine on gas only, for a long periods the carby can dry out, and cause problems too. Also make sure the fuel level in the carby is correct. I had some minor problems with the auto choke, so I fitted a manual cable. I also ran some injector cleaner with the fuel, and have had no problems with the carby for over twelve months.

[LukeV]

It could be flooding, maybe needle and seat is leaking by or I think they have a auto choke an could be stuck on. It could be not getting fuel, maybe a blockage in carby or gas system is restricting it ( mixer ). Could try hand over Carby trick at revs.

[dom14]

Hi LukeV,
What exactly is the mixer and where is it located in RB30 engine?!! Did you mean the LPG converter?!
I didn't understand the line "Could try hand over Carby trick at revs".
Please explain it bit more.
Thanks


It could be flooding, maybe needle and seat is leaking by or I think they have a auto choke an could be stuck on. It could be not getting fuel, maybe a blockage in carby or gas system is restricting it ( mixer ). Could try hand over Carby trick at revs.

[mudnut]

As Luke v said, the carby could be flooding, overfull fuel level would indicate that. Or a jet could be blocked. As for the advance diaphragm , Its just something I would check because there might be a combination of problems. I do know that the timing is different for gas and petrol. I hope someone on the forum with more experience in lpg gets back to you. good luck.

[dom14]

Thanks.
I was trying to narrow down the problems. I asked the question about the timing advance diaphragm to either include or exclude it from the problem. Car is idling perfect and going fine on LPG. And I can even drive(for the most part) on Petrol if I manage to keep the RPM around 2000 or more, which is very hard to do though.
I got a carby repair kit, but since this isn't my experties area(fuel and ignition) I thought it would be good to know where the problem is coming from before I go ahead and dismantle carby.
Cheers

As Luke v said, the carby could be flooding, overfull fuel level would indicate that. Or a jet could be blocked. As for the advance diaphragm , Its just something I would check because there might be a combination of problems. I do know that the timing is different for gas and petrol. I hope someone on the forum with more experience in lpg gets back to you. good luck.

[dom14]

And the real problem is that if I let go the accelerator paddle while on petrol, the engine stops and won't be able start for good ten minutes or more.
For that reason, I have to fix the problem. :)

[LukeV]

From memory there is a knob/mixer that you can adjust for your fuel/LPG mix. You can try adjust 1/4 turn at a time. It is usually brass fitting, on a hose running into carbs. Not big on LPG sorry, but I had a hilux with gas setup.

As for hand over carby trick, that is a a way of trying to clear out any small blockages in carry. Basically just take off air filter etc so the carby barrels are open and can be viewed. Start the car and place your hand over carby while giving it some revs. Then remove hand before it dies. The idea is that your hand acts as a vacuum and when you rev engine it will suck out any small bits of crap. Not very technical but it does work from time to time. Failing anything else maybe give an LPG mob a call for some advice.

[LukeV]

Your carby could be cactus too. Mine had a problem of flooding and overfuelling and cutting out etc. just took it up to recarb and they said everything (float, secondaries etc) was sticking and jamming open. This was caused by a slight bend in top of carby. Different motors I know, but maybe something similar. But not sure that gas would still work so maybe totally differ problem.

[taslucas]

Start by giving the whole outside of the carby a good lube up with crc or similar making sure all linkages and springs move freely. Pay special attention to the auto choke. It has a shaft that comes out of a rubber boot, make sure this moves freely. Then get some carby cleaner and with engine running and air filter off, spray down the throat if the carb. As said above, make sure the butterflies are moving freely.
Extended use of lpg does dry out the carby and do damage.
What's the condition of the fuel filter?

[dom14]

Fuel filter is fine. I just changed it.

Start by giving the whole outside of the carby a good lube up with crc or similar making sure all linkages and springs move freely. Pay special attention to the auto choke. It has a shaft that comes out of a rubber boot, make sure this moves freely. Then get some carby cleaner and with engine running and air filter off, spray down the throat if the carb. As said above, make sure the butterflies are moving freely.
Extended use of lpg does dry out the carby and do damage.
What's the condition of the fuel filter?

[dom14]

Thanks. I've already tried the fuel mixer know on carby. didn't make any change.
I'll try the other trick now.

From memory there is a knob/mixer that you can adjust for your fuel/LPG mix. You can try adjust 1/4 turn at a time. It is usually brass fitting, on a hose running into carbs. Not big on LPG sorry, but I had a hilux with gas setup.

As for hand over carby trick, that is a a way of trying to clear out any small blockages in carry. Basically just take off air filter etc so the carby barrels are open and can be viewed. Start the car and place your hand over carby while giving it some revs. Then remove hand before it dies. The idea is that your hand acts as a vacuum and when you rev engine it will suck out any small bits of crap. Not very technical but it does work from time to time. Failing anything else maybe give an LPG mob a call for some advice.

[dom14]

I tried that trick, but let it die while covering the carbi inlet barrel and at high revs.
Didn't fix the problem.
I think electric auto choke got issues. the buttefly moves freely sometime and other times it's jammed. And I think I can't get it started when I can't move the butterflys by hand.


Your carby could be cactus too. Mine had a problem of flooding and overfuelling and cutting out etc. just took it up to recarb and they said everything (float, secondaries etc) was sticking and jamming open. This was caused by a slight bend in top of carby. Different motors I know, but maybe something similar. But not sure that gas would still work so maybe totally differ problem.