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2.8 carburetors, wth


Jimmyrig

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Last spring I adjusted the carburetor on my 85 2.8 and it ran great all summer and fall until recently. Now for some unknown reason it doesn't do high idle in the morning until I get to work, and the choke is staying closed until a good 10-20 miles down the road despite a good 15 minute warm up. Yes the temperature has gone from 40's and 50's to 20's and 30's, but I've been toying with carbs for a good two decades and this one has me scratching my head. Once it's run long enough it runs perfect still, high idle works and the choke is wide open. Of course my first go to fix for the overloading on fuel in the morning was foiled by some genius at ford who lucky for him remains nameless, because he convinced them that it would be better to rivet the choke housing in place making it impossible to adjust. Not one of their better ideas. I'm assuming there is some way to adjust the choke aside from turning the housing like on every other electric choke carburetor ever. Possibly something to do with the vacuum canister hooked to it but without a vacuum hose? I'm going to have a look at the high idle issue this weekend, making sure it's properly adjusted and might as well give the choke another try.
 


AndyB.

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The choke thermostat isn’t riveted on, it’s held in place with three screws with breakaway heads. A carb rebuild kit will have new screws. You should check for voltage going to the choke thermostat, also the choke thermostats do occasionally fail, after 32 years. The adjustment for the choke cap is to align the index notch in the cap with the V mark on the housing, the computer controls the rest.
 

Jimmyrig

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That makes more sense. I'm guessing it's closer to a computer issue knowing that, the cooling system on it works way too well, even with a new, 190 degree thermostat it stays cold forever at idle and takes about the same 20 to 30 minutes of driving to get up to temperature, which is the kind of thing that tricks computers into thinking that running with a closed choke and rich as hell is necessary. Think I'll go block half the radiator with cardboard and see if running warmer helps. Thanks
 

AndyB.

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Factory thermostat is around 192, and likely not your problem. Between the computer and choke thermostat is a relay. What vacuum canister is hooked to it without a vacuum hose? Also, if the choke thermostat isn’t opening, the high idle should be engaged for cold start. After that, the idle speed control motor controls idle rpm.

The choke will start opening almost immediately after a cold start, these carburetors are able to richen the mixture through other means, mixture soleno I’d, temperature compensated accelerator pump, etc...

I think your first step is to check for voltage going to the choke thermostat. If it is present, replace the choke thermostat.
 

Jimmyrig

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It ain't stuck till it don't move
I'll do some more poking around this weekend, the part that's got me is that it works perfectly after work, even when it's below freezing, it's only in the morning that it acts up. It gets about the same warm up time after work as in the morning. But high idle works from the start and the choke opens normally from what I can tell. Think if I don't find anything I'm going to throw my spare on and see if the problem persists.
As for the vacuum canister I'll take a picture of it, but it's on the passenger side of the carb, at the back, and has linkage going to the choke. Now im fairly sure there was a drug addict owner shortly before I got the truck and while everything looks to be in place that doesn't mean that it is.
Oh. New symptom popped up today, stopped to get gas and got that slow, dead battery style cranking and had to hold it to the floor to get it to start like it flooded out when I shut it down. Another reason to try the spare carb.
 

Jimmyrig

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It ain't stuck till it don't move
Changed my fuel filter today because it was starving for fuel on my way home, it had this cool hole poked right through the middle of it. Thinking it plugged up and some genius figured that was a good fix. A bunch of crap in the carb would explain a lot
 

Jimmyrig

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It ain't stuck till it don't move
Figured it out. Pulled the carb off and the gasket was beyond fried. The layers were separated and bubbled up. Rust on the lower side. I'm actually amazed it ran as well as it did. I have pictures but they don't want to load up on here. Got my spare carb on now. It definitely needs ran a bit, been sitting for a long time. Already adjusted it 3 times since putting it on yesterday. I'm going to give it a week of driving to get a couple of tanks of fuel through it, and at least one bottle of fuel system cleaner then give it a final adjustment. So far the only persistent problem is trying to fall on its face for a second when I take off from a stoplight, part of why I'm giving it time before getting serious about adjusting it. The other part is that the plug on the throttle position sensor is different and not being familiar with these carbs I can see that possibly having something to do with it. Gonna change that out in a day or two. Thanks for the help. I've always immediately replaced any carburetors with as much crap hooked to them as these have with older ones, so I've never had to put up with the extra crap that comes with them.
 

AndyB.

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When you adjust it three times, what are you adjusting?

Ordinarily, with s stumble at idle, I’d look for a low float level—but without a connected throttle position sensor, the timing may not be advancing.

Any idea on what the spare carburetor was originally installed? Is there a tag on either carb? Something like E57E BA?
 

Jimmyrig

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It ain't stuck till it don't move
The spare came off of an identical 2.8 ranger. I'm adjusting only idle speed and the two mixture screws.
 

Jimmyrig

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My credo
It ain't stuck till it don't move
O.K. so i got the throttle position sensor swapped and that helped a bunch. it still wants to hesitate but not nearly as bad.
I tore into the old carb, found a little crap and some moisture in the float bowel and the throttle shaft bushings were gone about 100,000 miles ago, almost sloppy enough to get a small paper clip in there. that combined with the fried gasket pretty well explain the way it was behaving. now I'm debating on whether I'm better off finding another carb, or rebuilding the one im using. i didm't think to look to see if the base plate is removable, if so i might just buy a kit and go through the old carb and put the base plate off of the spare one on it. Or option 3, duraspark and an older carb, but thats the expensive route.
 

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