1985 F150
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The temp sending unit is for the gauge. The coolant temp sensor has 2 wires on it and the temp sending unit only has 1 wire for the gauge. The computer does not control the carb at all so why does the computer need to know what position the throttle is in?
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The computer is going to use that info (throttle position/coolant temp) to control emision controls like the egr (doesn't open when cold) and other engine management functions. I.e. shut off A/C at WOT etc 
Why do you ask... problem?
Why do you ask... problem?
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I have had lots of problems with the carb. This was a newly rebuilt carb from the auto store and the engine runs lean when it is off idle. If it wouldn't be a whole lot of trouble I would like to change it to a 4 barrel Holley and that problem would be easy to deal with. I was also debating pulling the 5.0 and putting a 351C in its place. Not really sure about the torque converter bolting up to the flywheel. It's a AOD. If I changed all of this of course all of the computer stuff would be done away with. Decisions decisions.
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First off, check the basics. Vacuum hoses/elec connectors all plugged in etc. Check timing per timing instructions (should be on sticker under hood). You'll probablly need to remove the spout (spark output) connector. I've seen a lot of problem arise from simply wanting to bypass those pesky emission controls and plugging vacuum lines. You might want to check fuel pump output as well. I'm not positive what adjustments you have on your particular carb. Assuming you O2 sensor is working properly, it may be as simple as a low float adjustment. Some carbs have an electric metering valve with adjustable dwell to enritchen/lean out the mixture (shop manual time). It sounds like it idles fine, which should rule out massive vacuum leaks.
What are the symptoms to say it runs lean? (guess I should have asked first!)
What are the symptoms to say it runs lean? (guess I should have asked first!)
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I took it to a tune-up shop and they ran all the tests on it and told me it runs lean off idle. They said that there was nothing I could do about it but replace the carb again. Also it does not have an o2 sensor. The computer does nothing with fuel delivery.
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From: Winnipeg, Manitoba
Lean in the off idle position would indicate the jets are to small. You don't need to replace the carb, it simple needs to be jetted. If it were running to lean or rich at idle, it would be a simple turn of a screw. Lean conditions can also be caused by a vacuum leak, as previously posted. I wouldn't take a shop's advice on this necessarily. You may want to take it to another shop if you're not comfortable looking over things like vacuum lines yourself, but I'd also start there, before tearing off the carb and replacing it again. Could be that you forgot to hook something up, or plug off a port that normally would be plugged. Could also be that a line has cracked, or a plug has cracked, and is causing this condition. Changing jets isn't that hard of a job either, but it does involve removal of the carb.
Elder User
Joined: Dec 2002
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From: Effingham,IL USA
an 85 needs a tps for the ecm that runs the ignition- if you have a tfi4 ignition, which you probably do. thats the one with the ignition module on the distributor instead of on the fender splash shield.
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R L Sullivan
1973 - 1979 F-100 & Larger F-Series Trucks
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