2150 motorcraft accelerator pump adjustment

[letank]

Now that California have the summer reformulated gas, it seems that depending on conditions, I have a small hesitation off idle, a little more throttle solved the hiccup...

Decided to put the lever on the top slot, #3 and it seems to be a lot better, but still could use a smidge.

As a note the cover of the accelerator pump is not fitted with even screws length, drove me off for 20min until I decided to recheck why the lower bottom outside was not catching the thread.

[devildog80]

Had that with my MC2100 on the CJ w/258. Bumped up jet size and now smooth from bone idle to WOT.
I went from .049 up to .053, but could go down to .051, and probably be good. Runs great so leaving it alone, and just loving how it drives.

[rocklaurence]

It could be the power valve. IMO, that is where a lot of the toning is needed. https://www.summitracing.com/parts/pro-67234

[letank]

Power valve is good, in fact the slot #3 did not work... went back to #2 -the midlevel and tweaked the timing and lowered the idle speed... back to 15 degrees and ... not as noticeable... not too sure if I will be able to go 65mph on our steep inclines...

[Stuka]

Power valve is good, in fact the slot #3 did not work... went back to #2 -the midlevel and tweaked the timing and lowered the idle speed... back to 15 degrees and ... not as noticeable... not too sure if I will be able to go 65mph on our steep inclines...

I don't think Rocklaurence was stipulating that the power valve is bad, but that you can tune how the carb acts with different power valves. I know you can get a full tuner kit for holley carbs that use them. And engine masters has noted having to change them at times. Not sure if there is a wide variety of them for a 2150 though.

[letank]

Thank you, yes, it could be a weak power valve, openning too soon, or low engine vacuum, currently at 2500", as I could smell at tad of richness.

My fix did not solve the near stalling issue upon take off...

Time to look at some spark plugs

[devildog80]

Try bumping up jets. Inexpensive and easy to swap.

[candymancan]

both my 76 and my 91 do this, i have yet to ever figure out why they do so when i go from a stop sign or light i make sure to feather the gas as sometimes, itll do this hesitation and when i make say a left hand turn or right hand turn itll stall the jeep if i stomp on it too hard... bad situation to stall in

[devildog80]

Stall when turning sounds like bowl level is too shallow. Would check float height to be sure correct, or at least just a tic high is better than low. Just not so high it starts pushing out the bowl vent.

Again, went up with jet size, took care of the stall from idle.

[candymancan]

no it stalls when you step on the gas, im just saying if it does it during a turn thats bad with on coming traffic ive stalled in the middle of an intersection once

[letank]

I have the same issue, a year or 2 ago I discovered that I had 53 or 50 jets. So I put 57, oem is 56 and I still have to same miss. I had replaced the power valve.

Last week, I recheked the plumbing of the emission system and they wear a bunch of errors which are corrected. But stalling persists...

We had to pull a guest that got stuck on a moderate gravel road, I used the lowrange. There were no near stalling issues or it was less noticeable, but it stalled when putting in gear... when I headed out, it was 80F... engine cold... it happens w warm engine as well ....

I need to recheck for vacuum leak...

[Stuka]

Still sounds like you are lean. And the Jeeps were on the lean side from the factory for emissions. Going a bit larger than you have now would likely be an improvement. But this assumes any possible vacuum leaks have been found.

[devildog80]

Does sound like there is still a leak somewhere, as the larger jets should comp the fuel deficiency, so keep searching. You will find that little magic smoke hiding, where you have probably checked 5 times already, and have your shooting solution

[letank]

And the solution....

1st sprayed brake ckeaner... no leaks.

2nd checked vacuum manifold which was low at 11" and fluttering.

3rd increased the timing until the vacuum was a steady 18", being at 2500", it is fine.

4th checked the timing : 25 degrees... but no hiccup upon driving back home thru many congested areas.

Yes, I had to lower the idle... and now, need figure out the ignition timing issue.

And I will go buy a lottery ticket: a deer darted in front of the jeep on a country road... a real near miss, never had to even the time to completely lift my foot!

[candymancan]

I have the same issue, a year or 2 ago I discovered that I had 53 or 50 jets. So I put 57, oem is 56 and I still have to same miss. I had replaced the power valve.

Last week, I recheked the plumbing of the emission system and they wear a bunch of errors which are corrected. But stalling persists...

We had to pull a guest that got stuck on a moderate gravel road, I used the lowrange. There were no near stalling issues or it was less noticeable, but it stalled when putting in gear... when I headed out, it was 80F... engine cold... it happens w warm engine as well ....

I need to recheck for vacuum leak...

you sure thats stock ? maybe ur right, but the carb on my 76 had 48 jets.

i hit a dead head on at 65mph on my 98 grand cherokee 5.9 limited, destroyed my bumper, grill, header panel, bent the crap outa the metal bumper under, and destroyed my charcoal canister.

took $250 and junkyard parts to fix it.. but those 5.9 grills are specific to that jeep only... 2 years later i finally found a 5.9 got a new factory grill and that jeep had a ARB solid steel bumper on it.. $1200 bumper for $80 i got it..

next deer that hits me.. isnt gonna like that

[devildog80]

OHHHHH.....DEER head on. My brain was trying to wrap around what a "dead head" was, but figured a local term for something, and it would reveal itself through future comments. It did, in your last line of your post above

[letank]

you sure thats stock ? maybe ur right, but the carb on my 76 had 48 jets.

i hit a dead head on at 65mph on my 98 grand cherokee 5.9 limited, destroyed my bumper, grill, header panel, bent the crap outa the metal bumper under, and destroyed my charcoal canister.

took $250 and junkyard parts to fix it.. but those 5.9 grills are specific to that jeep only... 2 years later i finally found a 5.9 got a new factory grill and that jeep had a ARB solid steel bumper on it.. $1200 bumper for $80 i got it..

next deer that hits me.. isnt gonna like that

Ouch for the deer hit! Glad to manage to fix the damage!

the 76 may have been equipped with the 2100 with the smaller venturi of 1.08 and the 48 is the correct jet range, so did my 74.

[candymancan]

Yea i cant tell if its a 2100 or 2150.. It has the choke plunger thing iin the back of the carb which is i guess means its a 2100 which is weird because i thought 76 came with 2150s.. but then this is a rebuilt carb "at one point i mean" per the sticker on the side so maybe someone bought a 2100 and put it on it.. No idea..

When i rebuilt it i couldnt get the jets out.. even using all my weight and the right screw driver on it, couldnt budge em.. just took brass off em.. so i gave up and stuck a wire through em to make sure they were clean lol


quick question.. i had to re adjust the entire carb when i rebuilt it and i got the high idle kick down to work right, but with the summer temps 80+ outside it doesnt high idle when i turn it on the first time in the day.. Is this normal ? or do i gatta adjust it a hair to get the high idle to kick on when i pump the pedal before cranking ? i dont think it needs it as it turns on fine but not sure if thats normal

[devildog80]

High idle cam temp sensitive just like the choke spring, so yes normal, and if starting ok just run it as is. All is right.

[candymancan]

ok thought so thanks