This frickin fuel supply deal, man!

[derekm803]

Im a "the simpler the better" guy. If i can put a vented gas cap on and do away with the vent system, thats the route imma go.
I pressurized the fuel lines today and sprayed all my connections with soapy water and no leaks. blew a little back in the tank for good measure. No better. Maybe it just doesnt pump enough gas to keep the filter full. It doesnt look like theres enough in there for the thing to keep running but it ran a littlle today. Gonna try a short drive tomorrow just because. maybe ill be ok, maybe ill get a jump on getting my first free tow out of AAA this year.

[derekm803]

Well. Stuck the high vume pump on yesterday. It filled the filter up about 3/4 when I started it. Let it sit til this morn. Just went out, cranked it n took about a 15 min test drive and the filter was completely full when I got back. Gonna go with that a few days driving a little more each time n see what I get. Still makes me think that maybe I do have a small hole or crack in the pickup tube. Shouldn't need a high volume pump for that, I dont think. That can be a little chore later to pull that tank back out n get a new tube put in.

[Ranchero50]

If the tank isn't able to displace fuel with air then it'll draw a vacuum. Same for pressurizing when hot and pushing fuel up to the carb and then creating a vacuum when empty. The stock pump is just a spring return rubber diaphragm and a pair of check valves. The cam lever pushes against the spring.

[derekm803]

Never mind. Went out for another drive. Popped the hood before cranking and had already lost half the level in my filter. Drove to the store n it was empty when I got there. Limped home on fumes. Gonna just go ahead n pull that tank again n get a new pick up tube put in it.

[DuckRyder]

Doesn’t the pickup tube unscrew?

[Busboy]

Nope.

[derekm803]

The frickin thing sat in the driveway n idled for over an hour today but the level in the filter stayed really low. Every once in while it would send a little rush of fuel in there but it would go back down. I could see it trickling into the filter. (Tried to upload a video but couldn't, wrong kind of file it said) I know supply demand for idling in the driveway is different than supply demand while driving.

[Ranchero50]

You'll usually have some air in the filter unless the outlet port inside the filter is higher than the reservoir that the air is caught in. Only time you'll lose it is when the choke is shut and the vacuum is helping draw the fuel.

[derekm803]

The fact that it sat there running for so long today makes me wonder if im over analyzing how much fuel it actually needs supplied to it. Ive just never seen one where the filter dont stay full. Maybe when it idles down n cuts off its actually an issue with the carb and not the fuel supply.

[1972hiboy]

The fact that it sat there running for so long today makes me wonder if im over analyzing how much fuel it actually needs supplied to it. Ive just never seen one where the filter dont stay full. Maybe when it idles down n cuts off its actually an issue with the carb and not the fuel supply.

Just gunna throw this out there. maybe I missed something too, Does the truck stall out and die from fuel starvation? I have had several vehicles with the big clear in line fuel filters that has very little to no liquid visible in the housing but ran just fine. All you could see what just the fuel kinda puffing through the paper element.

[derekm803]

Yeah. That's what it'll, do. Fill up the filter at start up then a few mins later start losing level in the filter til its empty. Coincidence or not it'll shut off after that like its starving for fuel. I've never seen one with the filter empty like that.

[My427stang]

Have you tried pulling the cap off when it happens? Often they will build vacuum if it has a bad vent in the cap and you can hear it go "whoosh"

[GaryKip]

I think that it has something to do with either a vacuum is building inside of the tank (so air isn't getting into the tank , as it should- the cap-) Or 1. there is a hole in the metal line inside of the tank, or 2. there is a pin hole in the rubber line that is under the D.S. of the cab.-The pin hole will allow the pump to suck air, a little at a time, and will increase the longer the engine runs.

[derekm803]

Ive been driving it like normal the past couple weeks. The only time it tries to stall now is when im coming up to stop signs/lights. Itll cold crank and sit there n fast idle and run now. If I roll up on a stop too quick and dont wind it down nice n steady with trans brake, it'll cut off. If i gear down n roll up on my stop slow it works better. I still have it idled a little fast for my taste. Imma pull the link off of the 2100/2150 post and order myself a new carb from those guys. Im 99.9% sure I was overreacting by the lack of fuel in the filter now since its been running and driving around.

[farmallmta]

I had this exact same problem in a bump. I did everything you've done. Finally found the problem when I checked the fuel lines for blockage. You'll need to use a thin semi-stiff wire to poke all the way through the fuel lines. Crud on the wire indicates crud creating a blockage. Simply blowing through the line will not necessarily tell you what you need to know.

If you get low fuel level in the mechanical fuel pump cannister, check the tank-to-pump fuel line, including the pickup tube in the tank. If the tank ever had crud in it, or had a "sealer" put into it, or got rusty, or had dirty gas, it can clog/partly unclog/reclog again.

If you get constant full fuel pump canister but still experience fuel starvation, check the pump-to-carb fuel line. Use your semi-flexible wire to run completely through the line.