Outer Limits 4x4 Board

Just fitted another TB42 to my GQ.

Started first go, drove it all good but idled high around 1200 rpm. Adjusted the idle down to 900 and now when restarted it is on full throttle all the time.

I am at a loss to explain it.

Because the motor was out of an auto and mine is manual had to swap some carby parts but it did drive well before the idle adjustment.

Most likely choke linkages or something you've missed. Take air cleaner off and see if butterfly is closing fully and if not, look at rear of carb and move linkages until you find it. Assuming you havn't done this. Process of elimination with each thing that moves.

The secondaries were jamming on the alloy insert in the manifold. Removed and all ok. Apparantley these are known also to lodge in a valve.

I've had this problem with my GAS only TB42. Carby is in good condition and the mixer has been rebuilt. The idle varies between 1000 and 600 and this is not related to eng temp. The linkages are tight and the return to idle spring works well.

Ideas ?? Gas flow not responsive enough ??

LOCKEE wrote:The secondaries were jamming on the alloy insert in the manifold. Removed and all ok. Apparantley these are known also to lodge in a valve.

I have this exact problem atm, just have to bring some open enders home from work to get the carby off. You said you took the insert out, what is the insert meant to do?

Also the carby looks to be an absolute bastard to get at the pass side back bolt, any tips? Also what seals or gaskets do i need to get, just the base gasket between the carby and manifold? or is there more, or do i just get a sheet of gasket paper?

marin

Supposed to improve airflow.

Use a new Carby base gasket from Nissan.

Not too hard to take carby off just hard to reach.

LOCKEE wrote:Supposed to improve airflow.

Use a new Carby base gasket from Nissan.

Not too hard to take carby off just hard to reach.

can you believe i was quoted $45 for the gasket?? Even the guy on the phone was suprprised! So i went to the local carby place and payed $4 instead.

marin

Well... I have the same issue (to a lesser degree) and I thought it was ignition related. Any luck let me know.

Now that its cold mine revs at about 2000rpm until it warms up!

Unfortunatly that is almost by the time I get to work.

I was thinking of dissabling the choke and using the hand throttle a little until it warms up.

Can this be done without taking the carb off?

When I am stopped in traffic idling at 2000 I can see the fuel gauge go down haha.

cheers
Eric

Sounds to me you all have a vacume leak somewhere on the manifold..
Check with aero start, spray around the manifold area even under the carby. Dont sray heaps, just little squirts see if there is a difference in RPM.
The reason the RPM's are going up at idle, is because the fuel is being mixed with air after the air has gone through the carby, So when you turn down the screw to adjust the idle, the mixture will lean out, and run like a dog, or start hunting (IE idle rising and dropping), this is a normal process for a vacume leak.

You need to check all the rubber lines to and from the carby, also check things like vacume brake lines, vacume advance line, etc etc...

Casey