I have a 77 ford f-150 351m 2bbl carb engine. I was having carb float issues so I purchased a reman 2bbl which was the equivalent to the one I had. United carb 7-7583 2bbl ford carb. When I recieved the carb it looked almost identical to my original, everything except a large vacuume port in the back which I left closed off, and my original carb had a little switch on the top where the float bowl is and the new one has no switch just a metal tube that comes out.

I put the new carb on using the same vacuume ports my old carb had and leaving the large vacuume on the back of carb plugged. The truck fired right up and idles perfect after minor adjustments.

Hit the gas in park and the carb functions properly, linkage is not sticking goes into full throttle and comes back down immediately. Perfect......

Put the truck in reverse,,, flawless.... Give it hell tires spin, no lag no hesitation engine idle comes back down quickly the way it should...


Here is he problem, when I put the truck in drive and slightly touch the gas the gas pedal sucks to the floor and the truck takes off for aprox 50 feet then comes back to normal, as long as the truck is moving no problems, but if I come to a stop and touch the pedal again the pedal sucks to the floor and the truck takes off for 50 feet. What's going on??? Is it a vacuume problem? A bad carb? Help me out before I hurt my self or somebody else.

 

The carb is getting a false air signal. Plug the "large" vacuum port, adjust idle, and post back.

 

I have no idea what you just said.

 

He said he bought a new carb instead of adjusting floats on his old one.

 

Believe me I didn't want to buy a new carb, I rebuilt the old one twice it would be good for a year and I would run into the same problem again. I got sick of it so I bought a new carb.

Thanks for the advice HIO I will give it a shot n let you know.

 

Ok so I tinkered with the vaccume line configuration all day, the big vacuume port is for the power booster which I had directly into the intake. I hooked it up just for the heck of it and I still had the same problem.

If I touch the gas pedal the carb opens up and takes the pedal to the floor. It only does it in drive from a dead stop.

When the truck is in reverse it functions properly. When it is in park it functions properly. Put it in drive and touch the gas pedal, and it takes off,

It is not the linkage,

 

Can you post pictures of this thing? I'm curious to see if something may have been rigged in the past on the throttle connection.

Do you have cruise control? Maybe there is an issue with it?

 

Nope no cruise control, but if I had to explain it I would say it feels just like the old vacuume cruise controls, how when u pushed the cruise button the the peddle would drop away from your feet. I'm going to post pictures soon.

I'm just lost, an engine and carb doesn't know if your in reverse or drive or park. It always spins the same direction, and functions the same.... The function for drive is the same for reverse, press the accelerator and gas goes into the carb. Why in both reverse and park does the carb work and I put it into drive touch the gas and it sucks the throttle linkage and gas pedal all the way open.

 

Gotta stock linkage between your pedal and the carb? This is a very long shot, but maybe something NOT stock is binding along your shift linkage? Which...isnt typically close to the throttle...but gosh, that's such a strange situation.

I wish I knew what was going on with it, but I've never heard of this sorta stuff.

I hope you'll post your fix, when you DO get it going properly.

 

I tried to post pictures but I don't know how

 

E-mail me the pictures and I'll post them for you.
It sounds like the main throttle return spring is missing.
mikeo0o0o0@aol.com

 

Here's the illustration from the Ford parts catalog for the carb linkage.

 

Do those carbs not have an internal return spring? I made the mistake of getting a little excited about a carb swap when I was younger and forgot to attach those springs to an Edelbrock 1406. I seem to remember it being slow to reduce throttle, but I cant recall it sticking open.

Unlike my current engine swap, where I can still vividly recall the throttle getting wedged open by a misplaced bolt at 75MPH...

 

It's probable that the 2150 has a return spring as part of the throttle shaft but these shouldn't be relied on to return the throttle to idle. If they could be, Ford wouldn't have included additional springs in the linkage.
In the illustration it shows there are two external throttle return springs.

 

No no external return spring and I doubled it up thinking that I did not have enough spring to resist the vacuume from the intake. My pedal is hard as a rock but it still does it.