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MC 2150 need advice.

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BeagleRock

MC 2150 need advice.

Hello all, MC 2150 speeds up when carb cleaner or starting fluid is sprayed on the throttle shaft. I've been told by a couple of people that it's no problem if fuel isn't leaking out of the shaft area. I've also been battling a vacuum leak since April right Gary! I found many leaks and fixed them "I think" whether by capping/plugging or eliminating some component's altogether ie; smog pump and tad solenoids etc.
Well I firmly believe they're all gone which leaves 2 things, intake manifold or the remanufactured carb from National Carburetors. I'm leaning towards them since I get a whistling noise straight out of the throat of that thing and the Chinese choke pulloff was bad upon arrival. It's runs descent but there's a spot where you can just take your thumb and manually move the throttle about an 1/8-1/4" and it will die or run extremely rough. I can also duplicate the problem by turning the curb idle screw down until it too reaches the same throttle position. Ironically that's at the same place the choke positions itself upon a cold start and causes it to start excellent but quickly die, choke working well, I just thought it wasn't.
Questions and comments welcome as I eagerly await a call from the carb place.
Thanks so much guys!

Beaglerock/83f150 351W C6 Transmission 2 wheel drive.

BeagleRock

Re: MC 2150 need advice.

BTW nice new picture! Thought I was on the wrong forum

Beaglerock/83f150 351W C6 Transmission 2 wheel drive.

Gary Lewis

Re: MC 2150 need advice.

Administrator

In reply to this post by BeagleRock

If you can move the throttle shaft even 1/8", much less 1/4", then you have a problem, Houston. That's way too much wear and it'll cause erratic running since the throttle will close at a different point each time, and a vacuum leak.

I've never seen that much movement on a carb. That's really extreme.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

BeagleRock

Re: MC 2150 need advice.

I don't mean laterally, sorry 🙏

Beaglerock/83f150 351W C6 Transmission 2 wheel drive.

Gary Lewis

Re: MC 2150 need advice.

Administrator

Which way?

Gary, AKA "Gary fellow": Profile

BeagleRock

Re: MC 2150 need advice.

Just moving it back towards the cab as the throttle cable would do. Basically just giving it a very small amount of gas if you will.

Beaglerock/83f150 351W C6 Transmission 2 wheel drive.

Gary Lewis

Re: MC 2150 need advice.

Administrator

Oh, I completely misunderstood.

So, to say it another way, there's a spot in the throttle movement where it runs really poorly. Is that correct?

Gary, AKA "Gary fellow": Profile

BeagleRock

Re: MC 2150 need advice.

Yes, very early on throttle movement, I can spray starting fluid on the outside or where the throttle shaft enters the carburetor and it will speed up .I feel I've eliminated everything else Gary, I mean there's nothing else to plug. I've removed the brake booster hose, replaced transmission vacuum hose and hvac lines. I'm leaning towards the carburetor because I can duplicate the condition every time with or without the afore mentioned items in the loop.I'm very discouraged!

Beaglerock/83f150 351W C6 Transmission 2 wheel drive.

BeagleRock

Re: MC 2150 need advice.

Oh and yes the accelerator pump is functioning correctly + it doesn't matter in this particular scenario imo .I could be wrong, it happens often

Beaglerock/83f150 351W C6 Transmission 2 wheel drive.

Gary Lewis

Re: MC 2150 need advice.

Administrator

Well, you raised a question in my mind: Is the poor running while the engine is in transition between one RPM, say idle, and another RPM? Or does it continue to run poorly with the throttle cracked open that 1/8 - 1/4"?

Just want to make sure I understand.

Gary, AKA "Gary fellow": Profile

ScubaSteve

Re: MC 2150 need advice.

In reply to this post by BeagleRock

Sounds like your problem is a worn out throttle shaft. I don’t know if there is a fix for this other than replacing the carburetor.

1986 F150, XLT Lariat, 5.8, AOD, 8.8 limited slip, 4.10 gears

BeagleRock

Re: MC 2150 need advice.

In reply to this post by Gary Lewis

Gary it continues to run poorly at the 1/8" movement of the throttle, once you pass that point it's pretty good .No stumbles from that point on. It actually runs well at cruise, passing gear or kickdown, no other issues really other than that spot or location of the throttle when it's at that point or location .I can screw the curb idle screw down enough to make it die or manually via by hand or foot peddle . It's just that spot plain and simple .I don't know how else to describe it.

Beaglerock/83f150 351W C6 Transmission 2 wheel drive.

BeagleRock

Re: MC 2150 need advice.

In reply to this post by ScubaSteve

I concur!

Beaglerock/83f150 351W C6 Transmission 2 wheel drive.

85lebaront2

Re: MC 2150 need advice.

Administrator

I am a little late to this because my internet has been extremely strange since around the 1st, it would go out off and on then usually completely go out about sundown. I think it is fixed now.

I would try disconnecting the vacuum advance hose, if this eliminates the problem, I would try applying vacuum to it with the engine running, if it is not in the carburetor then it will still act up, I would check the reluctor for chipped edges and check the continuity while applying vacuum. I have seen bad pickup wires cause this exact problem (I have seen it on breaker point systems too).

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

Gary Lewis

Re: MC 2150 need advice.

Administrator

Good point, Bill. I saw something similar on Eli's truck at the GTG a few years ago. If he connected the vacuum it would die. Paul was quick to say it was the pickup in the coil, and it was. As the vacuum pulled the plate around the wires shorted.

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: MC 2150 need advice.

Administrator

I had a Cadillac years ago in the shop, same thing, a little throttle and it would die, stand on it and it would jump. Primary wire was bad, wiggle it just the right way and it would die. I kept GM, Ford and MOPAR stuff on the shelf so I didn't have to wait to get a part from the dealer.

Bill AKA "LOBO" Profile

BeagleRock

Re: MC 2150 need advice.

In reply to this post by 85lebaront2

Will do sir, at this point I'll try anything!
Thanks for guiding me towards another possibility of the problem!

Beaglerock/83f150 351W C6 Transmission 2 wheel drive.