Hi guys. I have a 1976 F100 that has had a 1986 302 installed. The late model 302's fuel pump location is cast solid and I had to go with an electric fuel pump. I recently installed a carb repair kit in the Motorcraft 2100 it has on it and set everything to the specs listed in the kit and the truck will not run unless the choke is engaged. I have even played with the idle mixture and went as far as 3 turns out and still no luck. Does anyone have any suggestions as what I may be doing wrong? Thanks in advance.

 

Either vacuum leak or starving for fuel caused by not enough pressure or dirty fuel filter, wrong gas cap(unvented), just guessing.

 

Thanks Merlynr ! I replaced all the vacuum lines when I put the kit in the carb. The only reason I even repaired the carb was that the diaphragm in the accelerator pump started leaking. I have even tried to start the truck with the gas cap off because I thought about the possibility of a clogged vent on the cap. Should I run the idle mixture screws out to say 4 turns and see if it makes any difference? Would the float level have any effect on this issue? Any suggestions greatly appreciated.

 

Check the float level. I did mine and the float needle didn't seal. Gave me the same trouble.

 

Thanks fordman! I'll check it again but I set it to the 31/64ths recommended and it seemed the needle was operating correctly. Also it is a Motorcraft 2150 sorry for the confusion.

 

After rechecking, the needle seems to seal. The kit didn't come with a check ball apparently it was omitted. My father recently purchased the same kit and rebuilt his carburetor. He didn't use the ball included when he did his rebuild so I used the new check ball. My only question is "Is the check ball supposed to seat on the angled seat or fall all the way through the hole?"

 

The check ball is for the accelerator pump discharge path. It's supposed to seat into the chamfered opening (the hole should be a smaller diameter than the ball itself). As such, it should NOT fall through the hole. There is a small weight that rides on top of the ball, to push the ball back down into the seat once fuel is discharged to the venturis. However this is not related to your issue.

You should also check for vacuum leaks using the spray test, instead of just visually inspecting or replacing vacuum hoses. A cracked vacuum hose won't necessarily keep an engine from running - the big problem areas are underneath the carburetor base, the power brake booster (if equipped), and so on. With the engine running, use a can of spray carburetor cleaner to spray suspect areas, and listen for a jump in idle speed. If the idle speed jumps, then you've found a leak. Sometimes you have to lean the engine out to the point it barely runs, so that the jump is noticeable.

It would also be a good idea to set the idle mixture with a vacuum gauge. To get in the ball park, you can thread both screws in all the way, then take them out 1.5 to 2 turns. The vacuum gauge goes to manifold vacuum, and you tweak the screws little by little until maximum vacuum strength is observed on the gauge (19 to 21 inches of mercury is ideal for a stock engine).

The engine needs the choke to be engaged as it's warming up, but once the engine is warm, if it dies with the choke open, then one way or another it's a lean condition, and a vacuum leak or improper carburetor adjustments are the most common culprits.

 

Thanks for the info fmc400! I went a picked up a gallon can of B12 carb cleaner and bought the right rebuild kit this time. The Power valve was completely wrong in the first kit I bought. After a thorough cleaning and proper rebuild and adjustments, the truck runs fine. The only problem I have now is I am not getting power on the electrical connector that hooks to the choke and due to a late model engine I do not have the pipe that loops through the intake. Will the choke open with only the electrical connection? If so, where do I need to get my power source from? BTW fmc400 your write up and choke settings and fast idle index made the whole process easier. Thanks in advance.

 

That's a good question; to be honest I haven't tried it so I don't know. The original intention was simply an assist - meaning it gave it enough "push" to open a little more quickly than without the electric setup. So I'm not sure if it will get hot enough to run without the hot-air stove setup.

Since you asked, however, the connector comes from the stator terminal of the alternator. Note that you'll only see power at this connector if the engine is actually running, because the alternator has to be turning (and "excited") to produce a signal here. You also won't see 12 volts DC - it's actually a complex AC signal. If you look at it with a run-of-the-mill multimeter, you'll see around 7 volts or so (that's not what it really is, however).

If the choke doesn't work without the heat tube, you might see about an aftermarket electric choke, and run fused 12 volts hot-in-RUN to it. A manual choke is another option - some here have also come up with creative solutions to fabricate the hot-air stove setup.

Thanks for the feedback; I'm glad the write-up helped.

 

Thank you for the help! and again the write up made it simple for me. I have not tested the connection with a multimeter yet, I tested it with my test light with the truck running. If I switch to a manual choke, I will hook it directly to the choke flap, correct? Thanks again Fmc you and the others on here are a lifesaver.

 

BTW which of the 3 connections on the alternator goes to the stator? Just for future reference and the knowledge it may help a future FTE member, if I know if the choke will operate without the hot-air stove.

 

That's the idea - when you install a manual choke conversion kit, you remove the automatic choke cap. The manual choke connects to the slotted linkage to which the spring from the automatic choke originally connected. Rotating this linkage back and forth opens and closes the choke plate. There's a small linkage setup to convert the back and forth movement of the choke cable to the rotating motion that emulates the original automatic choke cap's movement. Most kits come with a replacement cap to hide the linkage and make it look original.

The stator terminal should be labelled "S" or "STA" on the back of the alternator. The two other connections are for the battery ("B" or "B+") and the field ("F" or "FLD"). Some alternators have another post for a ground reference, which shares continuity with the alternator housing itself.