Weber 38 DGAS PROBLEMS!!

[grex]

So, my rig starts right up, vacuum looks good, but as it warms up and the choke butterfly starts to open the engine starts to run rough and soon thereafter dies...

Any words of wisdom?

1976 FJ40
2F Engine
Weber 38 DGAS

 

[FJforty]

Will it continue to run if you pump the throttle?

 

[Pin_Head]

Sounds like a typical manifold vacuum leak. Check that your vacuum at idle is greater than 15 inches and check for leaks.

 

[grex]

Fjforty: Yes if you pump the throttle it will rev up and run OK, but once you let the throttle go back to normal, it dies.

Pin_Head: When the engine first turns on and is running OK, the vacuum is rock solid at 19 inches, then once it starts to warm up and flaking out, the vacuum bounces all over the place, drops proportionally as the engine dies.

I used the vacuum line off the power booster.

I also installed a RemFlex, badass intake/exhaust manifold.

I can see how it looks like a vacuum leak, and hell it might be...

Oh, here is another little something the accelerator pump is leaking gas. Can this cause these issues?

 

[ken_79-fj40]

It may be leaking between the carb and the manifold too. The 2 piece weber adapters are fairly well known for this.

 

[FJforty]

What is the history, did this just start, have you checked the float level, idle screw adjusted?

 

[PhilC64]

A leaking accelerator pump will cause all sorts of funky problems. Pick up a rebuild kit and get intimate with it. Should only take a couple hours to thoroughly clean and rebuild. Once done, set the base line according to instructions.

Get the rebuild kit from Redline Weber. Repair kits gasket kits and Key repair parts

Then set the carb's base line settings. 38 DGAS Tunning

 

[grex]

Fjforty: The truck was running perfect, but I don't get to drive it that often, so it sat for a while.

I noticed the leaking from the accelerator pump, and it still ran ok, but not as good as before.

One other thing that I noticed is that it would rev up then down, and continue up then down.

When it was running good, it was perfectly smooth.

 

[FJforty]

I would put a wrench on all the intake manifold bolts. Fuel filter and/or fuel pump could be an issue. PCV could be stuck open. Plug all the rubber lines to the carb and run it.

 

[Pin_Head]

If there is no manifold leak, then it isn't getting enough fuel. You could try the Okie rebuild, but if that doesn't work, check for fuel obstructions and junk in the bowl.

 

[JohnnyC]

how far out (turns out) are the adjustment screws ? there are two one by the manifold and one by the mastercyl. turn them in...not to hard when they come in contact how many turns was it?

are you sure you have a 38dgas and not a solex crap carb 36/36...where did you get the carb from ? new? pic?

https://forum.ih8mud.com/40-55-series-tech/213147-weber-carb-adjustment-thread.html

 

[grex]

About 1 - 2 turns out.View attachment 461728

 

[grex]

Couple more pictures.

Purchased the carb from Man a fre, not even 100 miles, and the accelerator pump is leaking....

 

[JohnnyC]

a few questions....that carb is way up there...why the black spacer at the bottom? did you check for leaks around those adapters? look for cracks on the intake maifold?

where is the line going off the top of the air cleaner adapter? thats not going to the manifold correct?

did you adjust out the idle screw?

 

[grex]

All the spacers (which I don't like) are to provide the correct height when using the stock air cleaner.

Still need to spray some carb cleaner and check for leaks.

Is there a better method other than using carb cleaner?

The hose on the air cleaner assembly (on carb) goes back to the charcoal canister.

The idle screw is in about 1 turn in, if you adjust it all the way out the engine will not stay on and die.

 

[Poser]

The idle screw is in about 1 turn in, if you adjust it all the way out the engine will not stay on and die.

Find and remedy all of your vacuum leaks...

 

[JohnnyC]

i always just use the carb cleaner to test...some people use propane....but thats dangerous

you meen one turn out

yes it will not run right if you have it all the way out....turn them both in and then back out to 2.5 turns each.

I have seen the webers loosen up so much that you can take it and wiggle the carb back and forth.

you definitly will need to check for leaks before hand...then let us know what happened doing this.

 

[rsbcruiser]

Find and remedy all of your vacuum leaks...

X 2, see that fuel leak indicated, that's a vacuum leak.

 

[grex]

Thanks guys, going vacuum leak hunting tomorrow, I'll let y'all know what I find.

 

[Flintlock54]

I have a 38bgas and have a few questions. I want to change to a progressive because I always choke out when I hit the gas at low speeds. At high speed it really moves out. I also have a question about the tube going from my carb intake to the head toward the back. Segway....my fj60 has no cat will that run better than with it?

Please Advise