Have a 1977 ford f150 with 351m with a motorcraft 2150. Had ( who I believe was a reliable source ) rebuild carburetor for me and after putting back on I can only keep engine running with foot on pedal. I turn idle mixture screws all way in and then proceeded to back out equally. This does not appear to be doing anything. I did turn the choke 2 notches to lean and was able to get it to idle but it wasloping so bad i shut it down and put the choke back to the middle setting. Any help or insight would be greatly appreciated.

 

My struggles with my 2150 are documented in the "At my wits end with this damn 2150" if you read thru there there are instructions on how to set the choke, my tag is still on my engine and is set at 2 rich. The idle mixture screws should do something to the way it runs regardless. You might want to go back through the carb. I know you said you didn't rebuild it but they are not that complicated. There will be more knowledgable people than me will chime in here soon. Good luck with yours.

Charlie

 

If the motor is unresponsive to changes in the idle mixture setting; it's typically indicitave of a vacuum leak.

 

Is their a good manual where I can pin point or trace the problem. The haynes and chilton manuals just do not go into detail enough

 

I tell ya, the most info. I found on these carbs. was right here. Use the search function.
Start by looking for the obvious leaks. Like all the ports hooked up?
Charlie

 

I would start by taking the carb back off and removing the EGR plate. If the gasket under it is leaking or the plate is eaten through it will never idle. I just fought this on a friends 77 351M. Check all the vacuum lines for leaks, even temporarily disconnect and cap the brake booster line, while you are at it take the EGR vacuum line off just in case it is seeing vacuum at idle. Starting adjustment for emission carbs is 2 1/2 turns open on the idle mixture screws. Be advised, at best the idle mixture adjustment on these later (68 up) carbs is only a trim adustment, the idle transfer slots were extended till they sit below the throttle plates at idle.

 

Will start checking vacuum lines this weekend. Unless I accidentally pulled one off while climbing around all should be connected. EGR is brand new(3 months). Old EGR appeared to be OEM - It was so black and caked with deposits. Thanks for all replies so far

 

Welcome to FTE

The EGR valve may be brand new, but what about the EGR/carburetor spacer plate it bolts to?

This plate is aluminum and is notorious for melting internally.

D7AZ9A589C .. EGR Spacer Plate (Motorcraft CM2402A) / Obsolete

Fits: 1977 F100/350 351M/400 // 1977 LTD/Mercury Marquis 351M/400.

DOTTS MOTOR CO. in Clearfield PA has ONE.

KLIMESH MOTOR SALES in Calmar IA has ONE = 563-562-3241.

TISON MOTOR CO. in Estill SC has ONE = 803-625-2551.

No other Ford Dealer, no obsolete parts vendor has any.

 

Bill, I don't even remember how many of those I changed when I had Preston Carburation in Newport News. Untill Ford started the recalls, I used to stock them both 2 and 4 bbl. versions.