ilovefords31

Have a 86 f150 4.9 i6 and I am getting a koeo code 41. Running lean for more than 15 seconds. When I go to start it in the morning, it stalls like crazy until it is warmed up and driven for at least 5 minutes, then it runs great but with a slight hesitation from take off. The truck has the following new parts within the last year.
New feedback carb.
New T.P.S
New Coolant Temp Sens
New Plugs, wires, coil
New fule pump and filter
New Fuel Lines from pump to carb


I was wondering if maybe the Map sens might cause this. I've tried all kinds of adjustment on the carb. I also sprayed around the carb with carb cleaner, and I cant find any leaks. New vacuum hoses. I put a new carb gasket in it, including the one beneath the egr plate. I use a torque wrench and torque the carb to 15 ft lbs. which is max. I tightened all of the carb bolts to make sure the gaskets were not leaking. They were pretty loose. Don't know why. It came from the factory only 1 year ago. When I got the carb, the choke thermostat was broken in shipping, so I had to use my old one and I have no idea where they had it set. So I have been trying different positions with that. I put a vacuum guage on and set the idle mixture screw till it got the most vacuum and it was a lot of turns like around 6 full turns out.


Please someone help me I have no idea what to do now.

Chris_1

iTrader: (1)

You have a carb and a TPS ?
Whatever, setting a carb we used to turn it in (gently, don't bottom it hard) then back out 2 1/2 turns. It should run at that point. Then turn it in till the engine starts bucking a little, turn it out till the same thing, the set it halfway between the 2.
The choke is a little touchy. When it's cool in the morning loosen the screws and just turn it enough for a hair of movement. That should keep it from coming on hot and let it come on if it gets cold. You'll have to play with that till you get it just right for where you live.
For the warmed up stumble, check if your accelerator pump is squirting.
That's all I remember right now. Been a long while since I had to mess with a carb. Race cars is fun, daily drivers I don't miss them at all.

ilovefords31

Yeah, I have the feedback system, the crazy system they came up with for a year or two before fuel injection. So it has all the components of fuel injection, but with a carb. I will look to see if it squirts, I just found today that it has no ***** going up hill either. Couldn't get over 35 up a 15% grade hill. It really sucks because there is only 67,000 original mile son it, and practically everything is like new. Even things I have not changed still look new.

ilovefords31

I checked and it does squirt. I Can't get the o2 sensor out it is stubborn. But, I think it may be faulty.

ilovefords31

I was wondering though, How much squirt should there be. There was not a lot. I don't know really how to explain how much, but it was like a gleek, if you know what that is. When saliva comes out from under your tongue when your talking.

ilovefords31

I was wondering if anyone knows how I could test my fuel pump with a vacuum gauge? Although it is not old, I was thinking maybe it got weakened somehow?

Matthew Burr

depends on the vac gauge if its designed to do that, you can get one at harbor freight for $15. if you have to turn the idle mixture screw that far out then you have a vacuum leak or a very poorly adjusted choke (which sounds like its the case) I would turn the choke while cold until it just barely closes without setting the fast idle. the idle mixture screws should be turned all the way in, and then back out 1 and 1/2 turns. then adjust the choke open until it runs.

other part that could affect lean run is the solenoid on the side of the carb. you can test it by connecting it to a 9v battery or wiring it up to the trucks batter, you should hear it click when connected. if it doesnt, that could cause you to run lean