Kind of a long story. I bought a '77 f250 Custom with a 351M with only 19,000 miles. It's a retired fire dept. truck and has/had some jimmy riggin' work done to it but all in all it's in damn good shape. The mechanical fuel pump no longer works and now has an electric fuel pump installed by the fire dept. behind the seat by the fuel tank. My dad and I replaced all the brake lines, parking brake cables, radiator hoses, heater hose, and changed the fuel lines last. And in the fuel line were three of these style fuel filters . My dad and I thought this was kind of stupid considering you wouldn't know which filter to change if one were to plug up so we removed the two by the engine and left the one under the cab, this may be my problem, not sure. Truck started and idled fine for the months we worked on it. Got it inspected last week and started driving it. Everything was fine for a week until Saturday night at a red light it started sputtering and engine seemed to slow and almost stall. This is a 4 speed so I just disengaged the clutch and kept the engine speed up. I pulled over and checked to see if the choke was sticking or something but saw smoke coming out the exhaust and the smell of unburnt fuel. The truck stalled but I eventually got it started. Truck ran fine all the way home and up until yesterday afternoon. It started acting up at a red light again but just outright stalled. Had a hell of a time getting started. Eventually got it started but has not idled right since. I asked a few people already what it could be and have already had a few possible answers. But my question is this, is the electric fuel pump pushing too much fuel to the carb at idle? Or does it in fact need 3 fuel filters? I did some research and saw there is a filter that threads into the carb but mine did not have this setup when I got it. Give me some input please. And I'm getting a new mechanical pump anyway, regardless if the electric is the problem.

 

Sounds like varnish in the needle seat, keeping the float open and flooding the carburetor. This is a common problem with a vehicle that has sat for long periods of time between use. It's unlikely that the fuel pump is the problem; I can almost gaurantee you the problem is within the carburetor itself.

 

In addition to what FMC 400 stated I beleive having three inline filters is needed; unless the fuel tank is dirty. Then the old mechanic figure to reduce the fuel contaiments he install three filtes. I would only run one new one. also disconnect the fuel line place the hose in a glass clear jar, and turn the igintion over acouple times see if debris is flowing into the carb. Partical's are a pita to carb.

Mitch

 

I think I would have eliminated the filter under the cab, and let the other filter under the hood. I would rather bend over a fender, than lay on the ground to change a filter. I would have to agree with the two previous posts. I would check for excessive dirt flowing through the line, and would be a good time to rebuild the cab.

I ran into dirt in the line which would clog a filter with in a quarter of a tank. I ended up replacing the tank. But after 32 years of service, I guess ya just complain about that! IT was full of rust and dirt, and the top of the tank was peppered with small rust holes.

 

Thanks for the input. I tried some Gumout and it ran good at first but then it started doing the same thing again. Except this time after I shut it off and got out, popped the hood, looked at the carb, gas was running out fast. Any ideas?

 

Look up at the first reply you recieved from FMC400, sounds like he's on track.

 

Time for a carb rebuild.

 

+1 for sure!

 

The reason they were running three filters were to try and keep the rust and dirt from reaching the carb.
A fire truck sits idle a lot of the time and if the tank is not full to the top with no air pockets it can rust.
Most of the filters you can buy over the counter, filter an "average" particle size of about 40 microns. This would be sufficient if all particles were round in shape and larger than 40 microns. But what about particles that are 20 microns wide but 80 microns in length. Sometimes these larger particles can pass right through. That can be detrimental to the carb. This is why it can be good to use more than one filter hoping that more than one will catch the particles the other one missed.
For proof run three filters for a year then cut them apart and see what particles were caught. I think you will be surprised.
If it were mine I would put the three filters back in place after I rebuild the carb.
Change the one first in line, on a regular basis. The other two will last a long time but not forever.

 

The best set-up for me is to place a plastic see-through filter in the rubber line at the outlet of the tank. The see-through filter allows you to monitor the condition of the filter.
Then place a metal filter (safe for high heat) near the carb on the positive side of the fuel filter, where fuel pump pressure will keep fuel flowing even if its a little stopped up.
If you want extra protection run the screw-in carb filter also.
This should keep you from getting stranded or dirtying up the carb.

 

Did I read that correctly? The "Fire Dept" installed an electric fuel pump inside of the cab???? Inside of the cab? Irony at its best.

Any reason why the mechanical pump was simply not replaced? A couple of bolts and viola, you are good to go again.

Im thinking after a good re-build of the carb, and getting the fuel pump replaced you are probebly in business again.

 

Depends on how you look at it - ever read "Fahrenheit 451"?

 

Yes, either someone at the dept. or some lazy mechanic. They also cut a hole in the grill and radiator to run a water pump off the crank shaft. They must have had an electric fan. My dad changed the mechanical fuel yesterday and got rid of that noisy thing while I was at work. It seems to rev smoother. Before it would cut out if you revved it quick, now its a smoother reaction. Anyway, the carb is still leaking after I shut the truck off. So where would I be able to get a rebuild kit for the 2bbl? I don't have the numbers off of it but its a Motorcraft on a 351M. I came across this today. http://www.therangerstation.com/tech..._2150_carb.pdf I don't know what my carburetor is, but it looks like that one. Is that a safe illustration to go off of if I rebuild it myself? Thanks for the input, and keep it comin'.