Problem with my Carter BBD carburetor at start up - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 12-19-2002, 11:32 PM
TWC
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Problem with my Carter BBD carburetor at start up

I have an 87 YJ 4.2 258 CI. When I start my jeep when its cold it will run for a minute and a half and then die. It acts like a vapor lock. There is no gas squirting into the carb. To get it to start, I have to cover the top of the carb with my hand. The suction from the engine compression seems to pull gas back into the carb. It will run fine until it decides to do it again. I replaced the fuel filter, fuel pump, checked fuel lines, and float needle in the fuel inlet. I thought the problem was related to the computer along with some other symptoms I was experiencing. I just did the Nutter Bypass it fixed every thing but this. I have to try and use this carb for now. Does anyone have any idea how to fix this problem ????
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post #2 of (permalink) Old 12-20-2002, 05:52 AM
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Re: Problem with my Carter BBD carburetor at start up

Try taking apart the venturi cluster and cleaning out the idle pickup tubes. They clog VERY easily. I would also suggest drilling them out to .032" (if my number is wrong please correct me), this will help prevent the smaller pieces of dirt from clogging them up.
Hope this helps.
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post #3 of (permalink) Old 12-20-2002, 06:41 AM
 
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Re: Problem with my Carter BBD carburetor at start up

ok... not really a solution but -

had same same problem with a Carter BBDd '85... only when cold too. I rebuilt carb, replaced all vacumm hoses, checked bowl vent operation and vapor purge/capture, did the nutter bypass, cleaned the idle tubes, replaced fuel pump and more ???? The float would drop but the valve wouldn't open and let in more fuel so the engine would suck the carb dry. I never figured out why... too cold to work outside.
I ended up with a small wrench kept under hood and would tap lightly the bowl at each cold start - no more problems. This kept it running thru winter and the following warm season (summer) I replaced carb with a YF. Not high performance, but it ran well cold and hot.
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post #4 of (permalink) Old 12-20-2002, 08:17 AM
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Re: Problem with my Carter BBD carburetor at start up

</font><blockquote><font class="small">In reply to:</font><hr />
To get it to start, I have to cover the top of the carb with my hand. The suction from the engine compression seems to pull gas back into the carb.

[/ QUOTE ]1. IMHO this is a clue. [img]images/graemlins/laugh.gif[/img]
2. When you put your hands over the throat of a carb and it doesn't die...
3. You've got a massive vacuum leak somewhere!
4. You should be choking off the air coming into the throat.
5. Again IMHO, it's time to:
a. Rebuild the carb with a rebuild kit.
b. Start huntin' for a vacuum leak around the base of the carb.
c. Use the Carb Spray trick to track it down.
6. A little preventative maintance is needed.
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post #5 of (permalink) Old 12-20-2002, 09:56 PM
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Re: Problem with my Carter BBD carburetor at start up

Spraying starting fluid on the manifold is a good trick, I found vacuume leaks along the head and at the carb base. what I dont understand is how the leaks could be intermetent. I have never seen this before. Eather you have a vacuume leak or you dont.
post #6 of (permalink) Old 12-21-2002, 07:36 AM
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Re: Problem with my Carter BBD carburetor at start up

I had a similar problem with the float needle binding in the seat. take a file and softly relieve the edges of the shaft of the needle--stay away from the conical seal at the tip. the little bit extra room will let the needle move.

keep a piece of stiff wire with you. if it binds, you can pop off the fuel line and poke that wire into the seat, freeing the needle.

now that I think of it, every time this happened was in the winter with a cold engine.
post #7 of (permalink) Old 12-21-2002, 07:40 AM
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Re: Problem with my Carter BBD carburetor at start up

Leve--

When he has his hand over the throat of the carb, it is not running. the vacuum created by the cranking engine with 100% choke(hand) is freeing something in the fuel system.

You are, I'm sure, dead on with #5+#6. It is, after all, a 258.
post #8 of (permalink) Old 12-21-2002, 04:44 PM
 
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Re: Problem with my Carter BBD carburetor at start up

I've been experiencing the exact same problem this week with my 1990 Wrangler! And this is a relatively new carb, well probably a rebuild but installed just last june. A couple sharp raps on the solevac bracket seems to do the trick every time. I figured it was the float valve sticking; seems to make the most sense. Perhaps moisture causes it to freeze into place? I'm going to run a few bottles of carb cleaner/dry gas to see if it helps.
I tell ya, this is the first and last Wrangler I'll ever buy! I'll take a cherokee over one of these P.O.S. any day.
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post #9 of (permalink) Old 12-21-2002, 06:53 PM
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Re: Problem with my Carter BBD carburetor at start up

</font><blockquote><font class="small">In reply to:</font><hr />
When he has his hand over the throat of the carb, it is not running. the vacuum created by the cranking engine with 100% choke(hand) is freeing something in the fuel system.


[/ QUOTE ]
1. Well Duh!
2. Wow am I red in the face... [img]images/graemlins/blush.gif[/img]
3. Sometdays it don't pay to get outta bed. [img]images/graemlins/tongue.gif[/img]
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post #10 of (permalink) Old 12-22-2002, 08:12 AM
 
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Re: Problem with my Carter BBD carburetor at start up

I have the same problem with my 89 YJ. I have a manual choke on it. At start up, I have to close the choke to keep it running until the motor reaches normal operating temp. Could I have the same problem and the manual choke acts as a band aid until the motor warms up??
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