Another Weber post, ugh (1 Viewer)

[Webster]

Ok,ok, I know the answers will be throw away the Weber and go back to stock. Which I might but not so easily reversible.

But hoping for some help from those of you who have chosen to endure with a Weber carb.

I’ve got a new Weber 38 DGAS on the 60.

Starts, idles, run beautifully. Will idle in my driveway for 5 minutes or so then apparently gets nervous and floods out.

So from previous posts and searching have tried lots of things.

I‘ve regulated the fuel pressure down to just under 3 psi.
I’ve yanked out the regulator and tried the jeep style ful filter with the return bypass.
Tried both.

Finally gave up and took to my mechanic.
Well he’s got six or so hours into it and has given up.
He did find and fix a vacuum leak I missed,
Disassembled and cleaned carb. Installed new needle valve, float, and accelerator pump.
Adjusted float multiple times.
He‘s put a pyrometer at base of carb to see if hot enough to boil bowl. It isn’t.

We’re at our wits end.

So anything I or my mechanic might be missing?
He even inspected bowl to see if it was maybe cracked and would leak out.

Seems pretty basic to me. If my pressure is correct the pump can’t push gas past needle valve. And if float and need valve is good then the bowl can’t flood.

what the heck am I missing?

Thanks!

 

[lcwizard]

does the carb have a return line?

 

[klinetime574]

Is the choke operating correctly? What dictates that it is flooding? Smell alone or fuel running out around the carb?

I ran a Weber 38 with the sandwich adapters, large open element air filter, parts store fuel pressure regulator set to 2.5psi, and the choke completely disengaged (lived In Texas then). Never had trouble starting even in “cold” Texas winters, 50 degrees.

@lcwizard The Weber 38 does not have a return line.

The style of FPR I used:

HTH

 

[jmcclusk]

Did this run nicely at one time and just now out out of the blue started acting this way? Have you ever taken the manifold off the engine/new manifold gasket? Is it still married to the exhaust manifold or are you running headers? Are you using a carb insulator or just manifold/manafre adapter/carb? Is there any vacuum lines running to smog stuff? What kind of air filter do you have on it? Are you sure it’s flooding out? Webers are pretty simple and easy so trying to understand full setup in case problem is there first

 

[Webster]

Is the choke operating correctly? What dictates that it is flooding? Smell alone or fuel running out around the carb?

I ran a Weber 38 with the sandwich adapters, large open element air filter, parts store fuel pressure regulator set to 2.5psi, and the choke completely disengaged (lived In Texas then). Never had trouble starting even in “cold” Texas winters, 50 degrees.

@lcwizard The Weber 38 does not have a return line.

The style of FPR I used:

View attachment 3008227

HTH

That’s the exact regulator I am running. Fuel overflowing into venturis. Stumbling and stalling out. Hard to start initially then runs fine until it does it again.

 

[Webster]

Did this run nicely at one time and just now out out of the blue started acting this way? Have you ever taken the manifold off the engine/new manifold gasket? Is it still married to the exhaust manifold or are you running headers? Are you using a carb insulator or just manifold/manafre adapter/carb? Is there any vacuum lines running to smog stuff? What kind of air filter do you have on it? Are you sure it’s flooding out? Webers are pretty simple and easy so trying to understand full setup in case problem is there first

New Weber, I’ve never got it running good. Still original manifold. Not replaced manifold gasket. Are you suggesting maybe a vacuum leak? Pretty confident we’ve eliminated any vacuum leaks but you never know I guess. Just the manifold adapter, not an insulator. I have one I plan to install But will need to modify linkage to do so I think. My mechanic said base of carb didn’t exceed 75 F though. No vacuum except to distributor. Air filter is small rectangular one that came with carb. This is what is so frustrating. Seems simple and I think we’ve checked everything.

 

[jmcclusk]

Sometimes vacuum leaks show up only after warming up, manifold is aluminum, head is steel so they have different expansion rates so over time sometimes the manifold gaskets give out. The manifold sometimes warps a bit so doesn’t seal so well so people put on the thick squishy gaskets and those give out sometimes on the bottom where you can’t see it. You’ve tested for leaks by squirting carb cleaner around the manifold while it’s running? Take the air cleaner off and when it dies can you squirt starting fluid or carb cleaner in the barrels and start it back up? Wondering if it is starving for fuel not flooded, it’s kinda hard to flood a 2F in my experience

 

[Webster]

Sometimes vacuum leaks show up only after warming up, manifold is aluminum, head is steel so they have different expansion rates so over time sometimes the manifold gaskets give out. The manifold sometimes warps a bit so doesn’t seal so well so people put on the thick squishy gaskets and those give out sometimes on the bottom where you can’t see it. You’ve tested for leaks by squirting carb cleaner around the manifold while it’s running? Take the air cleaner off and when it dies can you squirt starting fluid or carb cleaner in the barrels and start it back up? Wondering if it is starving for fuel not flooded, it’s kinda hard to flood a 2F in my experience

After it dies you can see and hear fuel down in the venturies. probably should just replace manifold gasket. I gave sprayed carb cleaner but probably not underneath manifold. I assumed a squirt in general vicinity would get sucked in.

 

[jmcclusk]

Well, usually a vacuum leak makes it go lean which might increase the rpm or make it tumble and run roughly, but usually not completely kill the engine. When it is warming up does it rev fine when you push the throttle?

 

[lcwizard]

Is the choke operating correctly? What dictates that it is flooding? Smell alone or fuel running out around the carb?

I ran a Weber 38 with the sandwich adapters, large open element air filter, parts store fuel pressure regulator set to 2.5psi, and the choke completely disengaged (lived In Texas then). Never had trouble starting even in “cold” Texas winters, 50 degrees.

@lcwizard The Weber 38 does not have a return line.

The style of FPR I used:

View attachment 3008227

HTH

it guess it was the 38dgms that had the return

I

 

[lcwizard]

Does the MR Gasket regulator have a return port?

 

[Webster]

Does the MR Gasket regulator have a return port?

No

 

[jmcclusk]

If he’s using the stock fuel pump it has a return on it. It normally doesn’t push more than 3psi before feeding into the return

Did the Weber come off some other car or different altitude? Maybe it has the wrong jets in it?

 

[klinetime574]

That’s the exact regulator I am running. Fuel overflowing into venturis. Stumbling and stalling out. Hard to start initially then runs fine until it does it again.

Is your choke operating correctly?

 

[Kleatus]

I fought a similar battle on a CJ7. Once I had all the leaks from adapters fixed, the float set up right, the return style Jeep fuel filter, and a Holley regulator set to 3 psi it worked fine. It came to me with no regulator and no return on the filter. The first FPR I got was the wrong one - it was their higher PSI regulator in the wrong box. Always good to put a gauge on them...

 

[Webster]

I fought a similar battle on a CJ7. Once I had all the leaks from adapters fixed, the float set up right, the return style Jeep fuel filter, and a Holley regulator set to 3 psi it worked fine. It came to me with no regulator and no return on the filter. The first FPR I got was the wrong one - it was their higher PSI regulator in the wrong box. Always good to put a gauge on them...

Well, I’ve done all that. I think. Only thing I can’t 100% vouch for if float setup. My mechanic played with that. By the way he sai the factory settings he found were wrong and would starve the carb of fuel. He kep adjusting. Anyone have a recommendation for the float setting?

Got it back today and let it idle in driveway for 20 minutes or so. Touched all around base of carb and float bowl. It was actually cool to the touch.

When I turned it off it was obvious fuel was overflowing and boiling out of the manifold.
So show fuel getting past needle valve or fuel leaking out of bowl.

 

[Paullus]

I've only been at it for two days but I have a similar issue with a stock 2f aisin carb that I rebuilt. I replaced the combined manifold, new fuel filter, rebuilt carb, desmogged while still using HAC and BVSV1, new pcv valve, etc. I've noticed that the fuel is low in the sight glass and it takes 1 to 1.5 oz of fuel to bring it up to mid level. I'm wondering if the fuel level gets to low in the bowl could extra air start flowing through the carb?

I was able to idle both Saturday and Sunday, late in the morning for almost 20 minutes and completely disengage the choke (which is nice cause that was a problem prior to the rebuild). Then in the late afternoons it is not wanting to cooperate. It likes the fresh fuel I squirt into the carb ( to fill the float bowl to the proper level before starting) with the air cleaner housing off but then stumbles and dies when it has to get fuel from the fuel pump. It is idling high at about 950.

I checked the resistance on one spark plug cable and it was like 8, so well below being a problem. But the cables and sparkplugs are not new. The have low miles but have sat around for several years. I'm thinking about getting new spark plugs and adjusting the float bowl.