1976 fj40 Weber carb question (1 Viewer)

[Deepmarsh1889]

Ok, sorry if this is too much info but I hope I can explain it well enough that someone can point me in the right direction.

I have a 1976 fj 40 with the supposedly "original" 2f and 4 speed. I haven't done anything to the engine since I've bought it except a new upper thermostat gasket. The following was done before I purchased it: The smog pump has been removed. It has electronic ignition. Electric fuel pump. A fuel pump regulator and a Weber carb that supposedly has electric choke but I don't think it works. It also has what looks like an aftermarket header. The carb says Weber 11046 and from what I can tell its the 32/36. The wire going to the carb gets 12 volts when the key is switched on but it doesn't idle up when cold. There are also two metal plugs on the intake manifold that are taped off and there is a wire between the water temp sensor and the carb that isn't hooked up. I will try to post a pic of.

My biggest concern is that randomly when cold or at normal operating temp, I will all of a sudden get a loud backfire and the the whole vehicle will shake violently when this happens. I have recorded a video I will try to post of this happening.

I also only get about 11 mpg

I have read that the Weber 38 should be used if you have a header. Or just on 6 cyl in general. I've also read not to use a fuel pressure regulator.

My question is:
A) should I take out or adjust the fuel pressure regulator?
B) since the electric choke doesn't work and It appears to be the 32/36 carb, should I just buy a new 38?
The truck runs great most of the time. Starts good and idles good. I just have to hold the gas a while when it's cold since the choke doesn't work and I'd like a little better mpg and no back fire. The back fire / miss fire is too inconsistent for me to diagnose.

Sorry if this is too much to read

 

[Deepmarsh1889]

 

[Weber Sarge]

More than likely someone has adjusted or played with the choke and it's settings . There is also a high idle screw located under the choke assembly head . To start it on a cold morning - give the throttle a push down about halfway and remove your foot , try starting it . If it doesn't start - look at the main throttle linkage and see if it's sitting against the base idle screw . Also , take off the air cleaner and verify if the choke blade is open or closed - it should be closed all the way . You shouldn't have to hold the throttle up during a cold start - the choke has a bi-metal spring load inside of it's housing and that is intended to cycle the choke flap shut and lock the linkage against the stepped cam for the high idle . If it doesn't want to run rich enough or close the choke on a cold engine you need to adjust the choke farther closed . There is a ring with 3 retaining screws that hold the choke element housing - on some 32/36 carbs it's hard to figure out which direction to lean and richen it's base setting . The trick is to loosen the choke housing retainer , hold the main linkage open just a bit off the idle screw and rotate the choke - most are clockwise when facing the element . It should close the choke flap all the way shut when the engine is cold . Base setup is to go about 1/2" past the point of the choke flap closing . Once you lock that choke element down the linkage should not be returning to the idle screw setting , should be about 1/8" gap or slightly more .

Initial cold start high idle speed should be 1500 revs . Do not walk away from the carb for long - as the engine warms up this semi-automatic choke will wind the choke flap open , but it will NOT drop the idle speed on it's own . You may go back inside for awhile and come out to find an engine screaming at 3500 revs . The carb will not let off that stepped cam for the high idle until the throttle linkage is cycled enough to release the cam . If it's set right , you should be able to tap the throttle , start the engine on the choke , give it a few seconds and drive it - the engine should not die when you let off the throttle - if it's dying the choke isn't set rich enough .

Make absolutely certain there are no vacuum leaks , either at the carb / intake manifold / vacuum brake booster .

Electric pumps can be a pain - and that junk fuel pressure regulator is only good as a paperweight . Best setup is to use the stock mechanical pump , a bypass type fuel filter (like the CJ Jeep version and others) and a return line off that filter . Weber DGV series are designed for 3psi of fuel pressure - good mechanical pumps push 5-7psi , too much . The fuel filter's bypass is smaller than the main fuel lines and can be plumbed back into the system's return line to the tank on your '76 . This keeps the pressure down against the carb and bleeds off the excess to the tank .

Need to verify the choke closing first , we can go from there on the rest of the setup .

Sarge

 

[Deepmarsh1889]

Sarge, thanks so much for your reply. I'm a diesel mechanic and the only gas engines I know about are 22re so I have ZERO knowledge about carbs. I'm guessing the flap in the top of the carb is what you mean by the choke being closed? This pic shows how it normally sits. I pushed it completely closed with my finger and pressed the gas pedal and cranked it and it just opened back up to this point. I see the white plastic choke and three screws. I just loosen the screws and rotate the white plastic thing to make the flap close?

 

[Weber Sarge]

It all depends on the temperature - that position is during fairly warm weather . If you're in AL , probably spot on .
Yes , that flap is the choke blade or flap - depends upon who you ask ...

The white plastic thing is the bi-metal choke element . The wire needs to feed it a solid 12v when the ignition is in the run position . That element will get pretty warm in just a few minutes if it isn't burnt out . I've only ever seen 2 fail in 20+yrs .

When the engine is cold , push the throttle down 1/3 , release the pedal and look at your carb linkage in your first photo - at idle position there is a screw the linkage rests against - if the choke is working the linkage arm should not be touching that idle speed screw . This is how you can verify the high idle cam and choke linkage is working properly .

Picture below shows the idle speed screw .

To increase the choke setting , your choke element can be rotated once you loosen those 3 screws on the retaining ring . Due to the way the mechanical linkage works on the choke the main linkage has to be held open while you rotate the choke element or you won't see a change in the choke flap . From your description , it sounds like it needs to be increased a bit - probably turn the element 1/2" or so .

If you need to adjust the high idle speed (1500 revs , cold engine startup) , this photo shows the location of the high idle speed screw -

It may help on yours to clean around the choke linkage - it's pretty fouled with dust and dirt .

Sarge

 

[Downey]

Weber Sarge has forgotten more about Weber carbs than most of us will ever learn, but after reading some of his post, I'm not sure he himself is a Weber carb lover. The single largest problem Weber's have is their float bowl is vented directly to the atmosphere, no air passageways, fuel merely bounces out of the float bowl and directly into the throat of the engine on every bump encountered in off road terrain. This makes the engine crap out (flood) on every bump, and to the best of my knowledge none of the guys attempting to race with Webers on their Baja Bugs in Baja races have been able to remedy the problem, even their home made fuel cell foam plugs bounce out and get swallowed. If you had to change carburetors anyway, a possible choice might be a fully baffled Holley 350, fully baffled for off road use (see the copy and drawings at ebay #261935392147- - -educational).

 

[Weber Sarge]

I'm not a hater , and for nearly 10yrs I modified DGV series carbs for off road use - mine would run nearly upside down . Appreciate the compliment , Jim , btw...

The only dislike I have is directly associated with Land Cruisers - there is no decent way (without a really expensive kit) to fit any DGV series Weber onto a Cruiser due to the way the truck is built . The DGV just doesn't belong on a 1F or 2F engine as they are not big enough in cfm's to start with - a 40DCNF would work a lot better but that carb starts at about $500.00 . Adding the necessary bell crank parts , adapter plates and a custom air cleaner or adapter and you're at $750 for a kit to fit a Cruiser - that's just stupid on a tractor engine .

Sorry , I am no fan of the Holley's either on a Cruiser . The fully baffled model leaves a lot to be desired too .

There is no decent alternative that works any better than the original designed carbs from Toyota or the aftermarket copies . Just the heat soak issues alone take any aftermarket carbs out of consideration - if the head design was a cross flow type , then something could have been worked out much easier and a lot less expensive . I've been on Redline's (WorldPac) butt for a long time to simply drop the kit off the market for the Cruiser - it causes more grief than anything .

Sarge

 

[corleykj]

I have had really good luck with my weber on my 78. I have learned a lot reading this post! Some people swear by electric fuel pumps and fuel pressure regulators. When I have issues with how mine is running a buddy always suggest to put an electric fuel pump in. I have refused. I think a good mechanical fuel pump, a clean filter and clean lines and you will be in better shape in regards to fuel supply than your current set up. As for the random backfire, could it be the float needing adjusted, or is your accelerator pump letting fuel by? I have rebuilt some carbs, but do not understand what would be causing the backfires randomly. My weber runs rich climbing up a mtn, about 2,500 ft and feels bogged down. I have been holding off on rebuilding it or cleaning it out, but should. I wonder if what is causing your backfires could be similar to what is causing mine to run rich climbing long assents.

Besides adjustments like Sarge suggested, have you thought of rebuilding your carburetor and setting it up from start to finish?

 

[handcannon]

Since the backfire seems to only be back through the carb, and intermittent, is it possible that you have an intake valve randomly hanging up? In past years I have used carb cleaner, poured it in through the carb throat, almost to the point of killing the motor. Did this for about half a can of the liquid in order to get the valve stem/head soaked with the cleaner. Then I poured in enough cleaner fast enough to kill the motor, and let it set for a while, memory says about 15 to 30 minutes. Then I restarted the motor and ran it somewhat hard to clean out all the deposits on the valve and in the chamber. Seemed to work for me.

This may not be your problem, but worth checking out.

Don

 

[piecemeal]

Wow, a lot of great info here for the carb I have on my 74. I have a carter electric fuel pump on mine that explicitly stated on the box that it'd push out 3-5 psi. I have a pressure gauge inline that says it's putting out about 3 psi, at least I know that's right. Mine runs pretty decently, but just seems under-powered. I might have a vacuum leak somewhere too as well, but either way, I feel like the engine has more to give that I'm just not getting. 11 mpg sounds about in line with what I get as well with this setup although I think it's running a little on the rich side.

Thanks for the info. I'm going to check all the setting described above to see if I can get a little more out of it

 

[piecemeal]

Pretty sure we have the same set up

 

[Deepmarsh1889]

Thanks for your replies everyone. Out of frustration, I ordered a new 38 Weber since I determined mine was in fact the 32/36 and a Weber fuel pump to get rid of all the autozone junk under the hood. There are just too many aftermarket variables in my equation for me to be able to try to adjust the carb after what I've read. I'll report back with my results after installing the new Weber 38.

 

[subzali]

Thanks for your replies everyone. Out of frustration, I ordered a new 38 Weber since I determined mine was in fact the 32/36 and a Weber fuel pump to get rid of all the autozone junk under the hood. There are just too many aftermarket variables in my equation for me to be able to try to adjust the carb after what I've read. I'll report back with my results after installing the new Weber 38.

Did you consider getting a Trollhole carb? Gets rid of EVERYTHING aftermarket except for the carb itself. But the carb is the same size/configuration as stock.

 

[micruz60]

Stock carb..... I have yet to understand why anyone goes to a weber or holley, sooo much heartburn evident with finetuning them.... Sure, sometimes they get lucky. Might as well find a fourleaf clover, rub your lucky rabbits foot, hop on the left foot three times and fart!

Sorry, I am not helpful.

 

[Weber Sarge]

Trollhole's carb would have been over a hundred bucks cheaper , and feed that engine the cfm it needs . The bottom line is the Weber , as an aftermarket kit , doesn't fit the Cruiser's engine very well at all .
Now you really need to spend the time to fix the adapter plates and their stupid overly thick gaskets (plates are always warped , use thinner gasket material) and deal with a crappy linkage system . Be very careful with any return springs - the DGV series uses a floating throttle shaft/plate design and side loads will destroy the throats quickly .

Sarge

 

[JohnnyC]

When I switched to the weber almost 20 yrs ago it was because ... Nobody seemed to be able to get the correct carb kit... And dealers were not interested to open the books and find parts for us... I was used to working on webers as I had lots of dealings with them on British products... Weber was the carb of choice to replace crappy SU's or stromberg's

I jetted mine down a ways... Not the power it used to have when I 1st installed it... But... Gets about what I was getting with the oem in the way of mileage ... And same power IMO ... And it is a LOT easyer to work on ... A much simpler carb overall IMHO

For the most part the carb has been worry free for 200,000+ miles

 

[Weber Sarge]

You probably have an older Spanish casting when they were first moved , or an Italian one . The current market castings are junk ....
Sarge

 

[Deepmarsh1889]

Just to let everyone know, I put the new 38 Weber carb, Weber gas pedal and Weber cable on and wow what a difference. I also got what is supposed to be a Weber fuel pump. (I purchased everything from TPI) no more back fire and it idles smooth as I figure a Toyota can. I didn't adjust anything and it seems fine. My fuel pressure gauge used to show a steady pressure but now it moves between 0 and 6 pounds so fast you can't read the gauge but I don't guess it matters considering how well it runs. It's too warm today to check the electric choke. I also might add I will never spend another dime with TPI simply for the fact that both times I called, the person I spoke to acted as if I completely ruined his day to ask a question. Shipping was fast but service was terrible. But anyhow, thanks for everyone's help!