TB42c Carby tune problems

[MudSlut]

I'm in the process of removing my LPG setup and converting it back to full ULP with a main and sub tank, I have the factory Mechanical fuel pump still on the car (not pumping due to being broken or something) and have fitted a Electric fuel pump that is hooked up to the sub tank. The fuel lines run from the Sub tank - Electric pump (with little pre filter) - hard lines - plastic fuel filter (clean) - Mechanical pump - carby. I have left the mechanical pump plumbed in because I couldn't figure out how to run the Fuel return without it. I have fuel pressure up to the Carby where it goes through another little filter (also clean) inside a bolt (Banjo bolt?). The car runs on gas just fine, but as soon as you switch over to fuel and the remaining gas runs out of the line it dies.

I have removed the Carby now because it was loose but I couldn't see how it could be tightened, turns out it is tightened from underneath. I don't think this is the issue as it was running fine on gas even if you wobbled and pulled up on the carby causing a big gap between the carby and adapter plate.

I can't get the Manuals to open to see what screws do what, If someone could help me out with tuning it to run on ULP. I haven't used the ULP in the tank for probably over 6 months as the fuel pump stopped working around about then.

Here is a short video of how loose the carby was, could this cause it to not run on ULP but still run on LPG?

http://www.youtube.com/watch?v=xLrtmX7kN3U

The part I'm holding onto last is as far as the fuel is getting (as far as I can tell)

[taslucas]

Hey mat, the carbys are renoun for doing what your talking about. Gas destroys the carby. My mate is in the same boat... Removed gas and had problem after problem (when he got it, it would run on both gas and petrol). The gas dries out all the rubbers in the carby. Timing for gas is advanced. A backfire on gas can dent the floats. He had the carby off a few times to lube it and check everything but still no go. He even put a gasket kit through with no luck. It had flat spots, little power until above 2000 rpm and very rough idle. I hope yours isn't as bad. But if it is, a rebuild would be the go. Around $400 from procarb.

[MudSlut]

Hmm... sounds expensive for a rebuild :( Ulvi 4x4 has a EFI tb42 for $1,850 on ebay and I've been looking at Aftermarket EFI systems and a company in the states sells Carby replacement EFI setups with a stand alone ECU for $1,785. Wonder if Peter finch would have a good used carby?

[taslucas]

Yeah it is getting up there in price. My mate ended up buying a rebuilt carby (unused) instead of rebuilding and it was way cheaper. Try giving it all a good spray and soak if inox, crc etc. Work all linkages and rubber boots. Carby cleaner down the throat etc, it might help.
Are you getting fuel into the carby?

[97_gq_lwb]

Pull it down check for worn out crap if it looks ok put a kit through it.
http://www.ebay.com.au/itm/FORD-MAVERICK-NISSAN-PATROL-CQ-Y60-TB42-4-2L-RB30-CARBURETTOR-CARBY-REPAIR-KIT-/190709627995?pt=AU_Car_Parts_Accessories&hash=item2c672dfc5b

[MudSlut]

I picked up two cans of CRC carby cleaner today, I'll give it a good go with that hopefully tomorrow, would it be a good idea to blow some compressed air through its bits? After I clean it I'll put it back on and see if it runs, if not I'll rebuild it.

[97_gq_lwb]

Yeah always a good idea to blow it out and check all path ways especially on the pilot jet circuit.
Just make sure your somewhere that bit's won't end up flying off somewhere never to be seen again lol.
I find an oxy tip cleaner handy for unblocking carbs as well.

[MudSlut]

IT'S ALIVE!!! :thumbup: Not really running 100% but it's running. still has to be started on LPG but can be switched over as soon as it is running, won't idle on ULP but drives on ULP great. wasn't running great on LPG after running on ULP maybe due to some left over ULP in the system? Anyhow, I found out why I could smell a strong smell of LPG every time I drove, could have something to do with THIS MASSIVE F*&K OFF GAS LEAK! :jawdrop: Video below...


http://www.youtube.com/watch?v=vhMA5bDuve8

[97_gq_lwb]

Now that is a recipe for disaster .

[MudSlut]

Hmm... Tell me about it.

[dansedgli]

Did you take the carby off and tighten the screws?

You unscrew the 4 bolts that hold it to the manifold.

Flip the carby over and there are 3 big screws that hold the bit that was wobbling to the base plate.

Its never going to run properly moving around like that. If its wobbling like that I bet screws have fallen out.

Carbies need good vacuum signals to work and movement like that would equal massive vacuum leaks. LPG needs good vacuum too, Im surprised it runs at all.

I put a gasket kit through mine last weekend and it runs really good now.

[dansedgli]

There are some diagrams here that helped me.

http://www.nissanpatrol.com.au/forums/showthread.php?10403-GQ-Carby-Problems&p=211199

[dansedgli]

PS mine was driving on petrol fine but wouldnt idle.

A good clean out and gasket replacement fixed it. Once your bolts are tight play with the idle mixture screw. Its in the middle of all those vac hoses and points towards the battery tray. You should be able to screw it all the way in then back it out 2.5 turns and it will be close.

[MudSlut]

Thanks, yeah I tightened them up nice. They were being held in by the gasket :) thanks for the link, just what I needed. I'll warm her up and see if the idle screw helps.

[MudSlut]

Would it be worth going one of these? http://www.ebay.com.au/itm/Patrol-GQ-4X4-holley-carb-conversion-TB42-RB30-engine-/330753331277?pt=AU_Car_Parts_Accessories&hash=item4d026f504d

Just seems a safer option for me seeing as I have never ran the car for longer than 1 20 min trip on ULP with this carby since I have owned the Patrol and I don't know if there could be more wrong with it that a basic rebuild kit or a major rebuild kit could fix.

[taslucas]

Ive heard mixed results with those. Theres a guy around here that ive talked to that has the 330 holley conversion kit on his swb Mav and reckons its the best thing he's done to it..... Ive also talked to 2 other people that have fitted them and regret doing it. So who knows!?
You could get your carby fully rebuilt (stripped and dipped) and have nearly enough $ leftover for electric ignition for the $600. Then just bolt on and go. The holley kits would have to be tuned and setup.

[MudSlut]

I think it already has electronic ignition, well I was told that it had it when I got it, haven't checked. How do I tell?

[taslucas]

Take the dissy cap off, then take the rotor button off (undo small bolt) then the plastic cover should pop off and youll be able to see if you have points or not.

[MudSlut]

Oh ok cool. I'll check it out tomorrow. Unless you want to go for a drive.

[taslucas]

Where am I driving?

[dansedgli]

Keep the stock Carby.

There is nothing to them. Take it apart and spray Carby cleaner down all the holes and that will clear it out.

[taslucas]

Keep the stock Carby.

There is nothing to them. Take it apart and spray Carby cleaner down all the holes and that will clear it out.

i think he's already done that and had a fair bit of success. But when they are run on gas for extended periods of time, they dry out inside and it ruins em. All the rubbers, plungers, diaphram, etc etc and most times they are too far gone.
By the sounds of it, you might get away with a simple rebuild kit.

[MudSlut]

Wanna show me yours? No homo :)

[taslucas]

lol.......

[dansedgli]

i think he's already done that and had a fair bit of success. But when they are run on gas for extended periods of time, they dry out inside and it ruins em. All the rubbers, plungers, diaphram, etc etc and most times they are too far gone.
By the sounds of it, you might get away with a simple rebuild kit.

Have you taken one from an TB42 apart?

When I took my carby apart last weekend the only rubber bits were on the accelerator pump and that is replaceable. You get a new one in the rebuild kit.

Apart from the float which is $70 off ebay (probably cheaper from nissan) what else can be ruined?

[taslucas]

Keep the stock Carby.

There is nothing to them. Take it apart and spray Carby cleaner down all the holes and that will clear it out.

so no need for a rebuild kit??


i think he's already done that and had a fair bit of success. But when they are run on gas for extended periods of time, they dry out inside and it ruins em. All the rubbers, plungers, diaphram, etc etc and most times they are too far gone.
By the sounds of it, you might get away with a simple rebuild kit.


Have you taken one from an TB42 apart?

When I took my carby apart last weekend the only rubber bits were on the accelerator pump and that is replaceable. You get a new one in the rebuild kit.

Apart from the float which is $70 off ebay (probably cheaper from nissan) what else can be ruined?

So get a rebuild kit then?

The floats are known to get dented by backfiring (usually caused when running dual fuel)

Any carby spaecialist will tell you that running gas ruins them. To get a TB42 carby rebuilt at pro carb is around $300 for one thats only ever had petrol, and anywhere between $350 to $500 for one that has been fun on gas......thats because they need more things rebuilt.

Below is a pic of a shaft that gets real sticky and loves a good lube up (lol) apparantly it is something to do with the aircond. The clue to this playing up is that the vehicle wont rev out past 3000/3500 rpm.

[dansedgli]

so no need for a rebuild kit??


The gaskets will need to be replaced if you take it apart and clean it out properly. So yes you need the kit. You can't buy the individual gaskets separately.

That shaft is for the air con. It increases the idle by pushing on the throttle linkages so the car doesn't stall.

When the throttle is opened the linkages turn away from the rod. It is impossible for that rod to stop the car from revving over a certain amount so I don't know where you get your "clues" from. Maybe the same mechanic that charges you $200 extra to rebuild a carby that was run on gas.

[dansedgli]

As for denting the float here is a photo of my carby when it was split in half.

The float sits in the big hole on the right. This hole is fully enclosed by whatever the carb is made off except for the fuel inlet and approx 2 or 3 fuel jet sized holes.

Those 2 holes on the left are where the fuel and air goes in.

If a backfire happens in a way that affects the float it need to travel through the tiny little orifices in the carby, snake its way through all the tiny little fuel passages into the float enclosure then somehow go off inside that enclosure.

I don't see it being common damage.

http://i140.photobucket.com/albums/r3/dansedgli/IMG_0746.jpg http://i140.photobucket.com/albums/r3/dansedgli/IMG_0745.jpg

[taslucas]

Nope, I haven't pulled one apart myself so only going on what others have done.
I think the aircon switch thing must work different on an rb30, as that's where I got that info from. I've been told that they are the same in regards to that switch but your completely right, the main throttle shaft turns away from the aircon switch on a TB42.
It's not a single mechanic I talked to about the rebuild cost, it's the franchise procarb. Maybe others do it for a different price.


Tap, crackle, pop

[MudSlut]

Just snapped up one of these, lets hope it gets me out of trouble.
http://www.ebay.com.au/itm/FORD-MAVERICK-NISSAN-PATROL-CQ-Y60-TB42-4-2L-RB30-CARBURETTOR-REPAIR-KIT-MAJOR-/221087747637?pt=AU_Car_Parts_Accessories&hash=item3379db4e35

[taslucas]

The gaskets will need to be replaced if you take it apart and clean it out properly. So yes you need the kit. You can't buy the individual gaskets separately.

That shaft is for the air con. It increases the idle by pushing on the throttle linkages so the car doesn't stall.

When the throttle is opened the linkages turn away from the rod. It is impossible for that rod to stop the car from revving over a certain amount so I don't know where you get your "clues" from. Maybe the same mechanic that charges you $200 extra to rebuild a carby that was run on gas.


Nope, I haven't pulled one apart myself so only going on what others have done.
I think the aircon switch thing must work different on an rb30, as that's where I got that info from. I've been told that they are the same in regards to that switch but your completely right, the main throttle shaft turns away from the aircon switch on a TB42.
It's not a single mechanic I talked to about the rebuild cost, it's the franchise procarb. Maybe others do it for a different price.


Tap, crackle, pop

I had another look at my mates rb30 carby last night. The shaft that i pictured above (which is the aircond idle switch on a TB42) looks the same as on an rb30 carby but on the rb30 carby it is for the auto choke. The accelerator still turns away from the shaft but if the shaft doesnt moved freely then the choke is stuck on and that is why the engine wont rev out.

Just thought id clear that up:)

The denting of the float is a known occurance. It may not look like it could be a common problem but quite a few carby specialists agree that it happens.

[taslucas]

Good luck with the rebuild kit Matt. Let me know how it goes.

[MudSlut]

Done the rebuild today, still won't idle very well. Seems like the coil or dizzy is playing up to me as the tacho is a bit jumpy as if it's losing signal or something.

[97_gq_lwb]

Does it have point's or pertronix ? if points it may be the condensor and points just replace them with a pertronix anyway money sell spent.
Try disconnecting the noise suppressor.
Check for any bad connections at the coil and resistor.

[MudSlut]

Probably a stupid question but what is a noise suppressor and where is it? In the rebuild kit there was two little ball bearings, both were different sizes. I couldn't find where they went so I didn't replace them. Any ideas? All of the bits I pulled out appeared to be in good condition apart from one gasket on the sandwich plate between the top and bottom half of the carby, it was split in the middle. Had a couple of blocked holes on the main jet and a couple of paths were a little slow flowing. Apart from that everything "looked" to be in near new condition, but I replaced everything anyway.

[97_gq_lwb]

looks a little like a condensor near your coil usually i think lol it's been a while.

[MudSlut]

19638 Here is a pic of my dizzy

And my coil.
19639

[MudSlut]

19645Yeah it has points.

Drove about 130kms in it today to get some bits and on the way home it was ticking like a diesel when at full throttle going up hills and was getting quite hot, about 3/4 way up on the temp gauge and normal is usually under 1/4. The only thing I have done today was take off the dizzy cap and rotor button. I thought the heat could be from running a bit lean so I turned the "Rich/Lean" adjuster thing on the carby to more on the rich side of things to see if that would help but it didn't help. I had normal oil pressure all day. Could have I stuffed the timing when I had the dissy cap off?

[jamied]

Might be A bit late to reply to this but if you haven't done anything more I would check some things before spending the money on getting the carby rebuilt. The best bet would be to get hold of a second hand carby that has never been run on gas and rebuild it. I had the exact same thing on my old patrol. It would run on petrol but not idle. I had a kit through the carb and it made no difference. Because the gas runs dry it can wear down the throttle shaft that runs through the carby which allows it to suck through air and stops it drawing up fuel for idle. A good way to check if this is the problem is squirt oil all around where the shaft goes through the carby and if you can cover it all it will idle for a few seconds until it sucks the oil through.

[jamied]

The noise suppressor is attached to the front of the dizzy down the bottom. The thing on the coil is a resister. Pertronix is definatly worth doing regardless and very easy to install. No you can't effect the timing by taking off dizzy cap. Also is that a gt40 or gt40R coil?