Weber 38 c.o. too high at cruise. - JeepForum.com
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Unread 08-09-2013, 05:06 AM   #1
Gausswave
Registered User
1989 YJ Wrangler 
 
Join Date: Jul 2013
Location: some where in the Cascades, WA
Posts: 354
Weber 38 c.o. too high at cruise.

Can't seem to get my 89 to pass emissions.

Test 1 new weber, basic lean idle tune. HC Just under the limit and co is 5.8%. At cruise it needs to be less than 3%.
I take it to the carb shop and the 20+ veteran says he tweaked the idle even leaner and with the vacuum advance off it passes with his gear. Claims YJ's commonly over advance the timing.

Test 2 fail c.o. again at cruise. HC dropped WAY down but C.O. is still 4.8%
back to the shop. This time he changes out the jets from 145 to 135 to lean it out at cruise.

Test 3 fail. co at cruise went up to 5.08 which doesn't make sense.

From all research I've done this should have dropped the co. I couldn't make it back to the shop and the carb guy is going on vacation. Short of dropping a smaller set of jets I'm not sure what else to do. The carb has a FPR set to 3# and passes every thing else.

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Unread 08-09-2013, 09:11 AM   #2
BlueRubiconrich
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1986 CJ7 
 
Join Date: Oct 2009
Location: worcester, Ma
Posts: 2,124
try a fuel regulater. webbers like to run at 2.5 on road 1.5 off road.

Your Jeep may be putter out as much a 7
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Unread 08-09-2013, 11:10 AM   #3
blown50
Registered User
1987 YJ Wrangler 
 
Join Date: Apr 2007
Location: MS, MS.
Posts: 134
I had to modify my power valve, seems weber wanted it to come in at like anything below 12 inches of vacuum, mine cruised on about 10 inches, so therefore my pv was open all the time! I fixed mine by trimming off the spring one coil at the time till I got it coming in at about 4 inches of vacuum! Tape a vacuum gauge to your windshield and go for a cruise, see where u are cruising at then start adjusting! Ideal would be to have it come in at 2 inches below what u cruise at! But I like mine a little lower
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Unread 08-09-2013, 11:58 AM   #4
jsawduste
Web Wheeler
2006 YJ Wrangler 
 
Join Date: Jul 2006
Posts: 3,041
[quote=Gausswave;15774110]Can't seem to get my 89 to pass emissions.

back to the shop. This time he changes out the jets from 145 to 135 to lean it out at cruise.

Test 3 fail. co at cruise went up to 5.08 which doesn't make sense.

QUOTE]

Quote:
Originally Posted by blown50 View Post
I had to modify my power valve, seems weber wanted it to come in at like anything below 12 inches of vacuum, mine cruised on about 10 inches, so therefore my pv was open all the time! I fixed mine by trimming off the spring one coil at the time till I got it coming in at about 4 inches of vacuum! Tape a vacuum gauge to your windshield and go for a cruise, see where u are cruising at then start adjusting! Ideal would be to have it come in at 2 inches below what u cruise at! But I like mine a little lower
The leaner jets made the PV open sooner/more. Do what B50 says plus check the FP pressure.
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