Hard start after sitting - MC2100 Carb? - JeepForum.com
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post #1 of 7 Old 09-06-2019, 08:58 AM Thread Starter
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1983 CJ7 
Join Date: Nov 2012
Location: Austin
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Hard start after sitting - MC2100 Carb?

I have been having trouble starting the CJ after it has sat for a few days. It will turn over for a while and then finally hit. It will be a bit loaded up but clears up quickly and runs fine until it sits again for a few days. My thought is the bowl is draining into the intake so when I go to start it the bowl has to fill again before it starts. And since it is a slow drain it runs and starts fine until it has enough time to sit and drain. It is a recently rebuilt 258 motor (5000 miles) running a MC 2100 and DUI ignition. Ant thoughts? If it is draining where would it be draining from? I know the very basics of carbs so I don't want to just tear into it without some idea where to look and what to look for. Thanks for any input....


'83 CJ7 (258 5 spd)
Austin, TX
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post #2 of 7 Old 09-06-2019, 12:32 PM
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Matt1981CJ7's Avatar
1981 CJ7 
Join Date: May 2011
Location: Elbert
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I’d check the float level first. Also make sure your fuel filter is oriented correctly, sitting level with the return line at 12 o’clock.

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post #3 of 7 Old 09-07-2019, 01:06 PM
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1986 CJ7 
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I am running an MC2100 and had same issue after replacing the fuel pump. The new pump had too much pressure causing it to flood after I turned off the engine and empty the bowl. After a couple days, it would take forever to start. I adjusted the float to slow the fuel input and it no longer floods and it starts right up after a few days. There's some good reading here, you may start with "Float bowl empties overnight" https://www.carburetor-parts.com/Technical_ep_40.html

Good luck
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post #4 of 7 Old 09-08-2019, 09:29 PM
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1986 CJ7 
Join Date: Nov 2018
Location: Loveland
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Actually sounds like mine. I have to pump the throttle for seveal seconds, 10 or so and then it fires. May be longer than 10 seconds possibly up to 30 but eventually it fires. I thought the same thing, but since it always starts, I live with it. I have the mc2100 on my 258cid.
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post #5 of 7 Old 09-09-2019, 08:11 AM
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1956 CJ5 
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HI, sounds like choke issues.. when cold the choke should be lightly fully closed after you set it with a pump of the throttle. Once it starts there is what is called a choke brake or pull off and it should pull open the choke 1/4 inch or so once started.
Also check to see that your accelerator pump is working it aids in starting by squirting fuel into the motor check to see that when you move the linkage you can see a squirt of fuel down the carb.
good luck
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post #6 of 7 Old 09-11-2019, 01:18 AM
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1981 CJ7 
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if you take the air filter off and open the choke you can see if the accelerator pump is giving four or five good squirts of fuel. If so, your bowls are not empty.

^ what he said about choke

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1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
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post #7 of 7 Old 09-11-2019, 08:40 AM Thread Starter
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1983 CJ7 
Join Date: Nov 2012
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I will check the accelerator pump this weekend. I did pop the cover off the carb last weekend after it had sit a couple of days. I didn't disconnect the choke so I couldn't completely remove it but I could lift it enough to see that there was fuel in the bowl. It was about a 1/4 to 1/3 full.

'83 CJ7 (258 5 spd)
Austin, TX
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