Ford carburetor blues...

silverbear

silverbear

The Boy Who Never Grew Up
I know some of you guys used to be auto mechanics and at least a couple of you worked in the auto parts supply industry. A year ago I bought a pristine 1981 Ford F-100 Ranger from my brother, with about 25,000 miles on it. Sweet. Now it's around 31,000, but still a really nice truck with a 300 cubic inch straight six engine. This summer it started running rough at idle and I took it in to have the problem diagnosed and fixed. Apparently Ford used a mixture solenoid on their carburetors from I believe 1981-1985 or so when they switched over to fuel injection. These mixture solenoids were not the best idea and fairly often needed to be replaced which was not a big deal as they were bolted on to the outside of the carburetor.

It is a big problem now, though, since that part is no longer available... at least not through my local NAPA dealer. And not available for 1981 on ebay either. I have a mechanic trying to track one down, so far without luck. I did see that there are replacement carburetors out there which appear to be Chinese clones of the Carter carb. Don't know if they come with a mixture solenoid or if the carburetor clone is enough different that it doesn't use the solenoid.

The truck runs, but poorly at idle and will sometimes stall out at a stop. By chance does one of you reading this know of a source for this part, or whether a clone would solve the problem or if there is a way to either bypass or repair the solenoid? I'm able to drive it, but would sure like to get it fixed before winter settles in. Any ideas?
SB
 
Thanks for your response. The price is right, but I'm not ure the part is. The guy at NAPA gave me a printout showing a picture of the part and it is not at all the same as the part shown on this site. I wonder if the idle/stop switch is the same as a "mixture solenoid". Don't know so I'll my guy at NAPA in the morning to find out. Now I'm going to take a look at the carburetor...
SB
 
Best of luck in your quest!!

You may also want to make sure that the EGR valve isn't carboned up. Some of the older Fords had a big problem with buildup in the port that led to the EGR......would 'strangle' the engine at idle.
 
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A bad EGR will sure screw things up. My 01 Ranger started doing weird things at idle up to about 35mph. Rough idle and surging. Dealership checked and told me it was the EGR. Replaced it and it ran like a new truck.

Not sure if an 81 used them though. I'm not up on when all the smog/computer controls came along.

Have you explored an after market carb, like a Holly? They might offer a direct replacement that doesn't require a mixture solenoid. If the problem proves to be the carburetor.

Tom
 
2door said:
A bad EGR will sure screw things up. My 01 Ranger started doing weird things at idle up to about 35mph. Rough idle and surging. Dealership checked and told me it was the EGR. Replaced it and it ran like a new truck.

Not sure if an 81 used them though. I'm not up on when all the smog/computer controls came along.

Have you explored an after market carb, like a Holly? They might offer a direct replacement that doesn't require a mixture solenoid. If the problem proves to be the carburetor.

Tom
Click to expand...

If it won't throw a code a popular thing is to just delete the egr. It's useless other than to slightly reduce emissions.
 
Silver bear I went through the same problem with a 85 mustang with a 2300 4cyld, it was a one year design with the on board computer and still used a carburetor. It had the idle solenoid like you're talking about. I replaced the complete carburetor and solenoid with a rebuilt one from advanced auto parts in 1995, $300 for a one barrel carb. The carb helped but didn't solve all problems, I replaced all the molded plastic vacuum lines which I discovered had small hair line cracks on the sides from engine heat. The combination fixed the idle and it didn't hesitate off idle either. The 81 doesn't have a computer so a holley or edelbrock should work, fords idea with those engine solenoids was to increase the idle speed if the air was turned on it fired the solenoid. The headlight switch also fired it.
 
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If you can't find the original design Edelbrock makes a universal design that you probably can adapt to your carb.
 
Hey Walter, Is this what your looking for?
http://www.carburetion.com/Products/ProductDetails.aspx?part=MCS-9
that one has the wire pigtail, the MSC-8 doesn't. Not sure which you have.

Those Carter YFA cabs with the mixture solenoids are not so common.
Also some YFA's have electric choke, some have the diaphram type. It's the black 1 1/2" cap external on the carb. Electric has wires hanging out, the manual doesn't.
Here's a You-tube 4 part rebuild tutorial for your carb. Doesn't cover the feedback mixture solenoid though.
https://www.youtube.com/watch?v=TF1rMhCtjME

Here's one I found on e- bay for reference. the 4th picture underneath shows the feedback (idle mixture) solenoid on the front with the 2 black wires coming out of it. I assume and can only assume this is what you're looking for.

http://www.ebay.com/itm/CARBURETOR-...3597153&pid=100033&rk=1&rkt=4&sd=321896729670

Some of the Ford truck forums have said to replace the carb with a standard YF-A, non feedback type. I can't remark to that being the right thing to do or not.

I'd rebuild the one you have or replace it and roll the dice. There's a lot going on with an old carb like yours and truthfully it could be the choke pull off (vacuum diaphram externally or the idle solenoid ) Pandora's box essentially.

Personally I'd go with Rock Auto. I've bought from them DOZENS of times. They are the best around .
GOOD LUCK and all the best to you..

TiM B.
 
I've rebuilt one of these carbs about 6 months ago and the customer brought me an older carb that didn't have the mixture solenoid to rebuild in install in its place. The carb rebuild went really smooth but the truck did surge really badly and had a rough idle so I double checked everytying, the float setting for these carbs is super sensative as it plays a major role in the fuel mixture at idle and at cruise, if the float is too low it will surge badly or even cut out while cruising. The float setting in the instructions was also wrong so I raised the float just a little, on these carbs there's an arm for the accelerator pump that runs down the center of the carb and if the float level is too high, it'll leak fuel all over the manifold at just above idle so I took it apart again and set the float just a touch lower, this fixed it but there's a really fine line between getting it to run right and respond well to idle mixture adjustments or to pour fuel all over the place, or to cause a lean surge... the older type YFA carbs do work really well once tuned and the float level is set right, I ended up using trial and error to get it right on this truck tho since the instructions in the rebuild kit weren't right for the float level, and this is a very sensitive setting on these carbs.

There are also adapter plates available to run a small 2 barrel carb like the 32/36mm weber, the 38/38 weber, or the Holley 350. The small weber carbs work really well on this engine as they have a small 32mm primary that the engine will run on most the time and the 36mm secondary won't kick in on you during normal highway cruising, this carb also offers a lot of torque due to its small primary side. The 38/38 weber is more of a performance carb for smaller engines and both barrels open simultaneously so fuel efficiency isn't quite as good, but still not that bad. Both these weber carbs are very easy to tune by changing main jets, idle jets, and the high and low speed air bleeds to fine tune.
The Holley 350 is also a good carb if looking for performance but not as fuel efficient as the weber 2 barrel carbs or the stock YFA. They do make performance manifolds for this engine to run a small Holley or edelbrock 4 barrel if you want but the torque and fuel efficiency this engine is notorious for goes away if you put anything bigger than the 390 or 450 cfm 4 barrel carbs on it, unless you can get a 600cfm vacuum secondary then add in the secondary spring kit to control how fast or slow they kick in.
 
Little update here. I bought a new clone of the Carter YFA carb and finally got someone to install it a couple of days ago. Brought it home yesterday and after 10 miles it quit and wouldn't restart... the float was sticking. It got towed back to the service station and upon inspection the float was bent. Much fiddling and it still isn't right so I am without transportation. By the time it was installed the warranty was up, so now I'm looking at another carburetor and another install expense. Patience is running thin. This time I think I'll go with a rebuild through Rock Auto. Not a happy camper.
SB
 
Good morning Bear,

That wouldn't happen to be this?

Carter AFB

On the box- #9755
On the carb- #9635 SA 0386 and #8867
Made in the USA.

Looks to be in great shape & has a rebuild kit with it.

Anywho, it was given to me and if it would help you it's yours. You've already done me a solid with a skip tooth chain a few years back...

-Mr. B.
 

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That's a very generous offer and I thank you so much. As things stand I already ordered a rebuilt carb and expect it to arrive early this week. Since I'm certain it is the right one and should get me back on the road by this time next week, I'll swallow the cost and get on with life. If for some reason it is wrong or is a dud I'll take a closer look at your offered carb and try to determine if it would bolt right on and go. Either way your kindness is much appreciated...
SB
 
Sorry to hear about your troubles. Its a sad day when your everyday mechanic cant get a simple carb right. I long for the day when someone brings a carb into my shop. wish i coukd help you out. Hope you get it sorted out.
 
tooljunkie,
I wish your shop had been down the road from me. The rebuilt carburetor is working fine and I think my carburetor blues have turned into sunshine at last. Even at 20 something below zero the engine fired up the other morning and not plugged into an engine heater. In my part of the world that is the acid test. I don't like thinking about what all this has cost in terms of time and money, but such is life.
SB
 
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