So, I recently bought an 83 F100. About a week after, I ran a can of Seafoam through the tank, and the truck started running a bit rough. Ever since, I have had a rough idle.

The defrosters are the only thing on the truck that work, so I traced the vacuum line and found a leak in the existing plastic line going from the engine compartment to the dash. I capped the tee feeding the broken line. Fixing the leak did nothing to fix the idle, so either there is another leak, or I have a different problem.

I then filled the fuel tank last night. I am getting roughly 10 -12 miles to the gallon. Now, its a bit more than a rough idle problem. So, I pulled the air cleaner today and checked around, looking at the existing vacuum lines, looking for an obvious problem. I then started the truck to see if I could hear a whistling sound. Curious about the condition of the carb, I looked down the throat with the truck running. I was greeting with a steady stream of fuel running from a nozzle on the passenger side of the carb (drew a yellow box around it in the picture below)





Anyone have any ideas what this nozzle is? what could be causing a steady stream of fuel at idle? Pretty sure that is what is killing my mileage.

 

Don't know why that is leaking, but that tube is the accelerator pump discharge
nozzle. Maybe either a ruptured diaphragham or the check ball is not seated.
That's a new problem I've never seen before. And I have a YFA on a 76 Maverick.

 

But the problem is fixable with a rebuild? I know nothing of these carbs!

 

Sounds like a ruptured accel pump diaphram. A rebuilt kit will supply the needed parts, and gaskets that should be replaced while doing the accel pump.
You'll likely see a big jump in MPG after a carb overhaul. These are rather easy to rebuild.

 

This is a common problom with this carb. That can of seafoam just finished off the diaphram down there.

This is a fairly easy rebuild. Take your time. Have the carb tanked at a carb shop. That costs about $20. A kit is about $20. Throw in $20 for carb cleaner and such and youll be good.

Take a day after you get it tanked. Last time I rebuilt mine it took 2 1/2 hours from parking the truck to testing it out. I've done them about 5 times however.

The other route is take it to a carb shop and pay a bit over a hundred to have them do it all.

Hope this helps. If you have any questions, just ask us.

 

And replace all those hard plastic vacuum lines with new rubber lines while you are at it. They are well overdue for it.

 

Definitely replace all of the plastic vacuum lines with fresh new rubber ones. You'll need a handful of vacuum T's to recreate the vacuum line setup. Not too difficult once you dive in (looks daunting though). It's well worth the time and money. It'd suck to rebuild that carb and put it back on an engine full of vacuum leaks.

Agreed with everyone else, just sounds like time for a rebuild. I personally wouldn't take it to a shop, they're much too easy to do yourself. I've rebuilt one and had a shop rebuild another. The shop charged $200+ and it didn't run any different than the one I rebuilt.

 

The shop charged $200+ and it didn't run any different than the one I rebuilt.

I just rebuilt a YF (no 'A'). The directions in the $60 kit were good for a non-mechanic like me. Luckly I had a friend look @ the $20 kit I ordered 1st. The prts store sent the wrong 1. Had a $230 quote on the work. Skipping that helped me learn how it wrks/why it will not in the future AND save $. 2 very important points 4 the future.

U may need some special guynk to remove the (don't know what that is) SeaFoam.

Good luck, check in w/us while doing it, if U want assistance.