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Unread 02-17-2013, 02:04 PM   #1
JCashen
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1990 YJ Wrangler 
 
Join Date: Jan 2013
Location: Fort Worth, Texas
Posts: 222
4.2 weber 38

I just installed my new weber 38 and am in the process of getting the lean best idle. Problem is if I bottom out the mixture screws with the jeep running it makes no difference to how it udles. The idle speed screw is backed out so it doesn't touch at all.

I pulled a plug and it is was tan originally now it is pretty close to completely black.

I'm also running a mad street fire (no tach yet) and distributor set on 18r slot with lighter advance springs.

I've been reading the weber set up and tune discussion. If anyone can point me in the right direction it would he much appreciated.

Edit: would not having my fuel pressure regulator installed yet cause this problem?

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Unread 02-18-2013, 06:58 AM   #2
blown50
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1987 YJ Wrangler 
 
Join Date: Apr 2007
Location: MS, MS.
Posts: 134
Ok first you do need the pressure regulator as webers hate fuel pressure, I put mine after the filter, so it can return to the tank and not be so hard on the pump. Second is are you sure you are not up on the fast idle cam? Best way I found to get lean best idle was to open the choke plates all the way up, either by letting it heat the choke thermostat or adjusting it off with the thermostat . I'm assuming you have the electric choke. If the throttle is even on the first notch it will uncover the transition port. And you can't get it lean enough to die with the port uncovered. Number three, is the throttle binding someway? I know the hyam joints or the two ball joints whichever you prefer, can and will hang if not in line with each other, so be sure to check linkage for binding. Fourth, no vacuum leak? Check the adapter plates as these are prone to leak at every gasket, I ended up yellow death ing mine as well as using blue locktite on all the bolts. Check all your install, even if you have to start over from scratch. Try all this first then let us know how it works
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Unread 02-18-2013, 11:06 AM   #3
JCashen
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1990 YJ Wrangler 
 
Join Date: Jan 2013
Location: Fort Worth, Texas
Posts: 222
Quote:
Originally Posted by blown50 View Post
Ok first you do need the pressure regulator as webers hate fuel pressure, I put mine after the filter, so it can return to the tank and not be so hard on the pump. Second is are you sure you are not up on the fast idle cam? Best way I found to get lean best idle was to open the choke plates all the way up, either by letting it heat the choke thermostat or adjusting it off with the thermostat . I'm assuming you have the electric choke. If the throttle is even on the first notch it will uncover the transition port. And you can't get it lean enough to die with the port uncovered. Number three, is the throttle binding someway? I know the hyam joints or the two ball joints whichever you prefer, can and will hang if not in line with each other, so be sure to check linkage for binding. Fourth, no vacuum leak? Check the adapter plates as these are prone to leak at every gasket, I ended up yellow death ing mine as well as using blue locktite on all the bolts. Check all your install, even if you have to start over from scratch. Try all this first then let us know how it works
I just installed the regulator, and the idle mixture screws work now. No tach at the moment so I can't tell my rpm at idle but with a vacuum gauge I'm pulling 21. Linkage also looks good, its smooth throughout the whole throttle position.

Weber turned the plugs black, but after the above they went back to tan. I also put new ones on so we'll see how they work.

On the vacuum leaks I forgot I was out of carb cleaner so I'll have to go get more. What is "yellow deathing"? I read somewhere about putting motor oil on the gaskets, so that is what I did.
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Unread 02-18-2013, 11:16 AM   #4
blown50
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1987 YJ Wrangler 
 
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Location: MS, MS.
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Quote:
Originally Posted by JCashen

I just installed the regulator, and the idle mixture screws work now. No tach at the moment so I can't tell my rpm at idle but with a vacuum gauge I'm pulling 21. Linkage also looks good, its smooth throughout the whole throttle position.

Weber turned the plugs black, but after the above they went back to tan. I also put new ones on so we'll see how they work.

On the vacuum leaks I forgot I was out of carb cleaner so I'll have to go get more. What is "yellow deathing"? I read somewhere about putting motor oil on the gaskets, so that is what I did.
Yellow death refers to the 3m weatherstrip adhesive I usually use grease, but it didn't work on the weber adapters so I used the 3m, have had no problems since
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Unread 02-18-2013, 11:30 AM   #5
JCashen
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1990 YJ Wrangler 
 
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Location: Fort Worth, Texas
Posts: 222
Is 4psi of fuel to much? None of my local auto stores carry fuel pressure gauges, so I can't get it set exactly until I order one.
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Unread 02-18-2013, 12:09 PM   #6
zeus87gn
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Location: Houston, Texas
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3.5 psi might work better if you can adjust it that way - that's what mine is set at and runs just fine
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