I have a gremlin in my GQ and I can't find it!

[Goyney]

Hi people, as per a recent post I am still having dramas.

If anyone has any ideas I would be eternally grateful!

The lowdown is I have a 1993 GQ petrol/gas, carby, points system.

The car runs great except intermittently it stalls at the lights! Smooth as at all other times...

I have just had it checked by a mechanic who tuned, checked timing, new dizzy, new points, new leads, plugs are good and coil is good.

Mechanic was really good and thorough and had a good understanding of LPG and I may take it back to him this week but I thought I would
ask here first before it costs me more $!

Am I right in assuming the vehicle does not have a MAF sensor? Should I be looking at air intake?

Any help is greatly appreciated!

Cheers, Goyne

[threedogs]

are you loosing vacuum , change any hoses only $.25 a mtr

[mudnut]

Hello, Goyney, and welcome to the forum. As suggested by Threedogs, you may have a vacuum leak. Try spraying WD40 or CRC in and around the intake manifold.
The engine revs will change as the vacuum sucks the spray into the engine. Also if the engine is run on gas for long periods of time, some components in the carby may dry out. Some forum members have done a carby kit and then afterwards start the engine on petrol every day to keep everything serviceable. Also check that the idle revs are high enough to keep the engine from stalling.

Other cheap things to check are: Clogged fuel filter, Choke operating correctly, emission system operating correctly, valve clearance.

Also spark gaps, but the mechanic has already done them. .8 to .9 mm, (but may be different for gas).

[GQ TANK]

IS doing it on both fuels

What is the taco doing - jumping around

Im assuming you have a tb42 efi?

[my third 256]

had the same problem on my old gq and turned out to be the diafram in the mixer had a hole in it ( the round thing ) brand was impco
replaced and all was good

[threedogs]

had the same problem on my old gq and turned out to be the diafram in the mixer had a hole in it ( the round thing ) brand was impco
replaced and all was good
More on the Impco converter buy a rebuild kit and some carbie cleaner and it'll be good as new again.
FYI mixer is the bit that fits on/under carbie, I used a NEW WORLD mixer which sat on top of a 4 barrel carbie.
On the side of the Impco theres a screw with a spring you could turn it out one flat to make mixture richer. Remember where it was in the first place
You should also have another in the main gas line for overall gas delivery

[Goyney]

IS doing it on both fuels

What is the taco doing - jumping around

Im assuming you have a tb42 efi?

Thanks for the replies guys, yep doing it on both fuels.

Basically every now and then, mostly when warm the revs just drop really low and she stalls!

It is a carby model so no efi.

I notice it more after heavy load (towing the boat) or when it is really hot so
I am thinking along the lines of it not getting enough airflow? I changed the air filter over the weekend which
had a bit of crap through it and she has not stalled yet but I have not driven very far and can't imagine
this would make a huge difference?

I will have a look at the mixer tonight.

Cheers fellas!



I have tried adjusting the idle up higher which helps a little but even then it will still stall

[mudnut]

Thanks for the feed back. I hope it is an easy fix.

[warner01]

theres about 4 million things that it could be. but my father inlaw had a gq come in once with the carby loose and only held by one bolt.:animierte-smilies-f needless to say that ran (amazingly) pretty average. its amusing to see that as soon as theres a problem with a gas car everyone assumes thats its the gas. lol. Im guessing its prob an air leak somewhere since its both fuels. id run the gas from an oxy over your inlet while its running see if it changes revs and id move everything a little see if it helps find the problem. could be an old cracked hose or blown gasket. on another thought has it backfired cos thatl break stuff too.

[threedogs]

theres about 4 million things that it could be. but my father inlaw had a gq come in once with the carby loose and only held by one bolt.:animierte-smilies-f needless to say that ran (amazingly) pretty average. its amusing to see that as soon as theres a problem with a gas car everyone assumes thats its the gas. lol. Im guessing its prob an air leak somewhere since its both fuels. id run the gas from an oxy over your inlet while its running see if it changes revs and id move everything a little see if it helps find the problem. could be an old cracked hose or blown gasket. on another thought has it backfired cos thatl break stuff too.

My thinking is 99% of gas problems are electrical.

As with any Gremlin though , don't feed them after midnight and
keep them away from bright lights and water, especially water lol

With Mogwi comes great responsibility

[taslucas]

If it is happening more when it's hot it may be coil, balast or points related. A faulty coil will break down as it warms up. Although I did read you said they're all good.

[Goyney]

Thanks again fellas.

A few more things I have figured out,

Since it is happening on both fuels that rules out the mixer and the fault seems to be identical on both fuels so
I am leaning away from it being a gas problem.

It is running really smooth at all speeds above idle and 80% of the time at idle.

One thing a buddy mentioned was although it does not have a MAF sensor, he said it does have a sensor of sorts
in the air intake? I'm not too sure on this one but there is a sensor of some sort I can see and wondering whether
I should clean this out? It has an airline going to the carby and is pretty dirty! Attached is pic

4658546586

[Goyney]

theres about 4 million things that it could be. but my father inlaw had a gq come in once with the carby loose and only held by one bolt.:animierte-smilies-f needless to say that ran (amazingly) pretty average. its amusing to see that as soon as theres a problem with a gas car everyone assumes thats its the gas. lol. Im guessing its prob an air leak somewhere since its both fuels. id run the gas from an oxy over your inlet while its running see if it changes revs and id move everything a little see if it helps find the problem. could be an old cracked hose or blown gasket. on another thought has it backfired cos thatl break stuff too.

Cheers Warner. No backfires as yet. The air intake definitely looks like it is not 100% sealed, the mechanic was saying this would not
cause the problem though?

I had that exact problem with the carby in the past and you could literally move it around and watch the car run from smooth to rough! Carby has been rebuilt since then.

[mudnut]

That is the Pre-heat flap. Gives warm air to the carby to heat up the system faster. I think there is a bi-metal strip in the filter housing that opens and closes the vacuum hose to the diaphragm. (RB30 does so I assume the TB42 must also). The MAF is for fuel injected engines, it provides airflow data to the ECU.

Also check the wiring to the gas/petrol changeover switch.

[Goyney]

Hey fellas,

Another update. The gremlin is found....

Took it back to the mechanic and he fixed the problem, ignition condenser!

She now runs sweet......but now will not run on gas! Only discovered this today after trying to switch over.....It was running before.

I had a quick look at the Coil and ballast resistor and he has re- done all the wiring but missed a lead.

As you can see I am sure this is why It won't switch to gas. The lead goes through a fuse to solenoid then to the mixer.

There is also a terminal on the coil which I am sure was made for the lead however when I hook it up it won't switch!

I checked the fuse and it looks a little old and corroded, so I tried a slightly higher amp fuse I had lying around but this didn't work

Any ideas?

4702247023

[threedogs]

if it is switching and not firing on gas it could have an air lock I had this prob if I let the gas run very low then re fill'
Check the filters in that bit in the photo. Check and re do a few earths as well

[Goyney]

if it is switching and not firing on gas it could have an air lock I had this prob if I let the gas run very low then re fill'
Check the filters in that bit in the photo. Check and re do a few earths as well

Thanks for the reply mate, it was very low before I put the car in so that could be it, is there a way to get it to fire?

[rimshot]

.if its bad when its hot have a look at the dizzi. I had this prob with another car. Run good cold but like crap some times when hot.

[GQ TANK]

Put a volt meter across the gas solenoid - get some to click the ignition - the meter should show 12 volts.

There are probably 2 gas related solenoids under the bonnet - one on the mixer and one on the gas filter probably near your fire wall.

There should be a lead from the NEGATIVE of the coil going to the gas safety switch. The switch needs to see the pulses from the points - or it will turn the gas solenoids off._ sw