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Motorcraft 2100 for 258 - carb hesitates

1K views 3 replies 2 participants last post by  skizriz 
#1 · (Edited)
Hi.
First of all, about my self.
Name is Udi, Age 37, and i'm from Israel.
Time difference is +8 Hours, So 09:00 AM here is 01:00 AM Forum time.

The car is a 1975 CJ6, Local assembly.
Engine - 258
Body - A local version of the YJ (called Storm m240 mk1).

Just installed a Motorcraft 2100 instead of the old BBD.

Vacuum at idle - 19HG
Jets - #47
Current altitude - 550m above sea level (i think it's 1800ft)
Outside temp - about 15-20C (59-68F)

Choke converted to manual (i didn't forget to plug the hot air vacuum port)


When i pull the throttle fast, engine chokes and hesitates.
If i pull it slowly, engine response is OK.
Also, when pulling throttle, i don't see a burst of gas inside the carb, which makes me believe that the acceleration pump is the cause.
Or maybe does it look like the power valve?

Got a video of it, but as i'm a newbie, forum laws don't allow me to post URL links (if i could PM the URL to someone and he'd post it as a reply, that could be great)

Thanks.
Udi :smile2:
 
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#2 ·
When i pull the throttle fast, engine chokes and hesitates.
If i pull it slowly, engine response is OK.
Also, when pulling throttle, i don't see a burst of gas inside the carb, which makes me believe that the acceleration pump is the cause.

Thanks.
Udi :smile2:
Definitely the biggest part of your problem.
As the air rushes in under hard acceleration, you aren't feeding it enough gas and it leans out.
Get that working first. Whether it's a mechanical linkage problem, a torn diaphragm, warped or missing umbrella valve, or just some dirt blocking a tube.

That's gotta be the place to start. You need two nice strong streams of fuel when you first pump the throttle.
 
#3 ·
Solved !
yep - it was the acc pump.
The spring was... in the wrong side. it was between the cap and the diaphragm instead of between the diaphragm to the body.
As i found this, i just wonder what other surprises am i gonna find...

Anyway, as it works OK now, now i can rebuild it.

Many thanks Skizriz!
 
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