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1986 F-150 Couple of Issues

I have an 1986 F-150 with the 351 engine, automatic, XLT model. For the most part the truck is in great shape and runs good. Problem 1: I have noticed that I seem to smell gas anytime I get near the truck. I haven't found any leaks and do not seem to be losing any gas. There isn't much rust on the truck as it came originally from Texas, I haven't seen any holes in either fuel tank. I'm wondering if the vapor cannister could be bad and allowing the fumes to just leak out into the air? Is there any way to check this? Problem 2: The engine does not like to idle well while in gear. I can start it fine when it's warm or cold outside. It idles at high speed until it gets warmed up, but it seems that as the choke opens it wants to die until the engine is completely warm. If I try to put it in gear, it almost always dies....again until the engine gets warmed up. It always restarts fine also. I've had people tell me they can see black smoke out the pipe when I first start it. It doesn't seem to burn oil, so it sounds like extra fuel. No, I haven't had a chance to pull any plugs and check them (NY winter, too cold...) Going down the road the engine runs perfectly, no problems. Could the carb. need adjustment, or rebuild or ??? Any thoughts/comments would be appreciated. Thanks!

Reply to
Tom
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I would suspect that the activated charcoal in the canister is saturated. You can remove it and if it is really heavy turn it upside down and see if fuel runs out. Other than that I don't know how you would test it... Sorry.

Sounds like the choke linkage/mechanism is sticking. Possibly the flex hose from the manifold oven to the air intake might be leaking or disconnected. Easy check and easy fix, that.... DaveD

Reply to
Dave and Trudy

The float valve may not be seating properly- that will cause a small amount of gas to leak into the intake and cause the puff of black smoke on start-up. Though not cheap any more, I'm sure a carb rebuild kit can be found. RockAuto has one listed for $104 for your truck.

Good luck, SC Tom

Reply to
SC Tom

I thought of just replacing that canister. I've seen them in LMC truck. The manuals says it is supposed to be good for the life of the truck, but what do they consider the life? :) The truck is 22 years old, but only has 87000 miles. I checked to see if the choke was sticking and sprayed some cleaner around it. It seemed OK, but I didn't check that hose. I'll look at that next. Thanks!

Reply to
Tom

Would the float problem allow it to run normally, but idle bad when cold? I wasn't sure whether to consider a rebuild or just buy a new one. I've seen the rebuild kits at Summit, or new carbs from a few places. I don't think it's ever had a rebuild so that might be a good idea in any case. Thanks for the info.

Reply to
Tom

You may have a combination of minor problems.

22 years with only 87000 miles tells me it has probably spent a fair amount of time sitting once or twice. Could be some varnish in the carb or some jets partially plugged.

Partially plugged or plugged idle circuit could caus it to idle poorly. Sticking choke or improper choke operation could cause it not warm up properly. Sticking float valve could cause a variety of problems, like a little gas leaking over when sitting.

Also at that age rubber under the hood could be dry rotted causing vacuum leaks. Fixing vacuum leaks might fix your running issues. The smell of gas is probably something else though. Maybe the carb as another poster mentioned.

First, completely go over all of your vacuum lines to make sure they are in good shape and not leaking anywhere. Look for cracking when you flex them near connections.

Second, consider carb rebuild.

Reply to
Bob La Londe

Excellent suggestions, thank you. I wondered the same thing. I know it had the "normal" maintenance, brakes, exhaust, oil changes, etc. but I don't think it ever had a carb. rebuild, or new hoses, or anything like that. I'm really very happy with it, it runs great going down the road, almost zero rust. It's not a daily driver, but I'd like to make it reliable enough to be if I want. It's more of a "fun drive" vehicle for me. It was never a work truck. A lady owned it for a few years in texas, then the previous owner bought it. He used to put his boat in the lake in the spring, and take it out in the fall. He moved to New York and garaged it for the winters, drove it only some in the summer. Thanks again.

Reply to
Tom

It might-- The mixture might be too rich, since the choke is closed with a cold engine. Forcing the choke open might cause it to run better, sort of confirming the over rich condition. Some carbs also have vacuum operated metering valves that can get gummed up and stick either open or closed. This can also cause some really frustrating intermittent rich/lean symptoms.

Reply to
Chuck

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