i have a 79 1/2 ton 4x4 with 351m i keep having this problem and im stumped as to what is causing it the jets in my carb ( motocraft 2 bbl. ) keep plugging up i can take a small drill bit and clean them out and it will work fine for a week or so then it will do it again ... i have changed where i get my gas and put brand new in line fuel filters on it and still it does this ??? any ideas guys

 

You probably have a rust scale in the tank that is starting to break down.

 

What kind of debris are you taking out of the carb when you clean it?
Where are the filters located in relation to the carb inlet?

 

it looks like tiny pebbles tan in color my filter is about 6 inches from my carb in line

 

you may have build up inside the carb that is loosening up, have you cleaned out the inside of the carb

 

yeah i have drained it sprayed it down with carb cleaner and wiped it out worked for about a week now its back to doing it again

 

Tiny pebbles huh? Ah haaa! Methinks I have an idea. Did you replace the filter that is right on the inlet of the carb itself? This little filter is a brass or bronze filter and can often break down. If it starts to deteriorate it will fall apart and pass right through the needle and seat. These small corroded pieces will take on the appearance of tiny particles or rocks. The are in fact metal pieces, either bronze or brass.
I also suspect that since this filter is the last filter in the system that the other filters do not appear to have an residue.
If they do have residue, then your dirt is comong from the tank.
Additional filters can help you determine where the source of your porblem is.
Two filters will help to determine whether or not the source is before or after the filters.

First filter in the line would indicate contamination from the tank. Clean filters and contamination in the carb would indicate a compromised line, or a fuel bowl that is corroded to the point of deterioration.

Many are not aware of this little brass filter in the inlet, and I would suggest taking the supply line off to verify that it has not fallen apart into a bunch of small pieces.

 

wow i never even thought of that i will check that out tonight and see if that is it

 

ok is it behind the factory filter in this picture or is it under the needle and seat

 

By the pic, you don't have the bronze filter 75F350 is talking about. I cut one of the filters, like in the pic, apart once and it was paper. Don't know if they used bronze or not.

 

Would it be possible for you to install an inline fuel filter? I think they are about $5, maybe a total of $10 if you get two and some clamps.

 

there is a second filter before the one in the pic it is only like a month old thats why im confused and i lookd for the brass filter 75F350 was talking about and i did'nt see one in there