Hello everyone. I am having a couple of problems with my "new" 73 F250 and I can't quite track them down. If anyone might be able to shed some light on them it would be most appreciated.

First off, the engine is a 390, with a Holley 4 bbl (model 4160) attached to a c6 transmission.

I have been having issues with the truck wanting to stall out when I come to a complete stop. If it does not stall and the idle keeps, when I attempt to start from a stop I have to pump the gas a little to get it going. It's kind of like it stutters when I hit the gas but once it picks up speed it runs good. It does not do this in Park and I think it is even idling a little high in Park.

The second issue is that while I am driving, it doesn't want to shift. I have checked the fluid levels and I do have a leak but the levels are currently good. If I bump the shift lever down towards 2 from D, it will grab and downshift. Would this be transmission related or linkage related? Also, when I shift from P to R or D it will bark the tires (R) or surge forward (D).

I was planning on flushing the Transmission this weekend and replacing the Vacuum Modulator as well as the Trans filter. I also planned on a spark plug change and possibly a new alternator. Do you guys think I am on the right track or might I just be replacing parts that won't affect my issues?

Thanks guys and the information I have found so far has helped so much!!

 

I think you have the same transmission modulator/vacuum problem I referred to in this post. Check your vacuum lines. Might fix your stumbling problem too.

Ford Truck Enthusiasts Forums - View Single Post - HELP with my 1977 f150

.

 

Thanks for the quick response! I will definitely have to check out the vacuum modulator line then. I knew it could cause the shifting problems but wasn't sure if changing it would help. thanks!

 

I agree about the modulator for the transmission problems. As for the "stuttering", I would check out the excellerator pump. If the engine doesn't get a good shot of gas when it looses vacuum when you open the throttle, it will stumble.

 

Check both ends of the vacuum lines first, before replacing the vacuum modulator, make sure they aren't cracked, loose, or off.

2x on the accelerator pump for the stumble.

.

 

Well, I took a quick look at the accelerator pump and there seems to be a slight leak around it. I have a rebuild kit on order now as well as the vacuum modulator. Changed out the plugs and after a dumb move on my part also the distributor and rotor. She ran well enough to get some gas and up to the local auto parts store to check the alternator.

Thanks for all the help guys!! I am sure I will be back in the near future as it seems that I am having some wiring issues. Does anyone have the wiring diagrams for the tail lights, blinkers, reverse lights? Thanks again!!

 

Quick update before bed. I have changed the vacuum modulator, transmission filter, and rebuilt the carburetor. I am still having problems with the stumbling and the hard shifts. Can anyone give me a baseline on how much it would cost to have my transmission rebuilt? I have C6 and am new to this stuff so I really don't want to get taken to the cleaners. Thanks for all the help so far guys!!