primering the gas pump

[willy3486]

I am stumped on my truck. It is a 1970 c10 with a 307. It has a mechanical gas pump mounted on the engine. The truck sat for a few years but was in a covered building. I put in about 2 to 3 gallons of gas in the tank. I put new rubber gas hoses on it. What I wanted to do is I put a fuel filter in just before the pump temporary so that it can collect any rust as I clean the lines. I then took the line out of the pump that goes to the carb and put a hose on that line just before the carb to run into a old gas can to collect it. I wanted to do this and run a gallon or so of gas out to clean the lines. When it turns over I can see gas in the filter move but the filter dues not fill up. Am I doing this wrong or what can I do to it to get it primered so to speak so the gas will run in the old can. I don't think the lines are clogged because I drained the lines when I put the new lines.

[Henry50]

If you prime the carb and get it to fire it should start to pump right away, If not the pumps probably bad.

[willy3486]

So will it hurt if I connect the line from the tank to the pump and then to a filter and then the carb even though it might have some dirt or rust in the gas? I don't think it would be much but I do plan to have the carb rebuilt. I can run it a little and then when it is clean put a new filter on it.

[68gmsee]

I agree. Pump is probably bad. Take the line off where it goes into the carb and place into a plastic container. The pump should pump out about 1 pint of fuel in about 30 seconds or less. If not, it could be bad or lines or filters are clogged.

[68gmsee]

Forgot to add: If you want to bypass the tank buy a short piece of fuel line (about 2½ ft) and a one gallon container of fresh gas. Place container under the truck and install fuel line on pump and container.

[Terry Crist]

That is the way it has been done for years.

Check all of your fuel line connections to be sure they are tight.

Actually it might be easier if you run the inlet to the fuel pump from a clean one gallon gas container, pull the coil wire and crank it until you get fuel pumping through the fuel pump. If that does not work then the fuel pump might be bad. If that does work out then connect your fuel pump to the carb and fire it up.

If it seems ok then re-hook up the fuel tank and try it again. If you still have problems then you might find that the fuel pickup in the tank is bad and not going all of the way to the bottom of the tank.

[willy3486]

I took off the new hoses on the line just under the gas tank and the pump. I then put a hose on the steel line and I could blow through it fine. I tried to blow into the line going into the gas tank and it seemed to be blocked. If I get a chance to run a hose from a gas can to the line under the seat to the pump tomorrow night. I am beginning to think the tank is blocked somehow.

[bigmac73]

dont these old trucks have a screen or a sock as my dad use to call them on the end of the pick up tube in the tank?? that might be clogged up

[68gmsee]

Originally Posted by willy3486

I took off the new hoses on the line just under the gas tank and the pump. I then put a hose on the steel line and I could blow through it fine. I tried to blow into the line going into the gas tank and it seemed to be blocked. If I get a chance to run a hose from a gas can to the line under the seat to the pump tomorrow night. I am beginning to think the tank is blocked somehow.

On my 68 the line from the tank to the pump was clogged with old gas residue from sitting too long. I replaced with a fuel line from NAPA and bent it like the old line.

Originally Posted by bigmac73

dont these old trucks have a screen or a sock as my dad use to call them on the end of the pick up tube in the tank?? that might be clogged up

Yes. And they can get clogged up. Best thing for PO to use is process of elimination. Lines first then sending unit.

[zeldman]

Just off the top of my pea brain..... and this has nothing to do with your problem. Check the oil and make sure there isnt gas in it just as a pre-caution.

[willy3486]

I changed the oil and filter. The oil was fine , no gas or antifreeze in it. From what I can tell the line from just under the tank to the carb is clear. I can put a hose on those lines and blow through them. But if I put a hose on the steel line to the tank and blow through it no air will go through it. So I am thinking the tank, or most likely the strainer mentioned is the issue. I plan to do as suggested and drop a hose into a jar of gas and see if the gas pump will pull it out. If that works fine tonight then tomorrow after work I plan to take the tank out and clean it thoroughly. I have a guy coming to do some work I don't want to tackle myself on Friday so I would like to have the tank done by then.

[Daner]

Unhook the line from the filter you installed before the pump. Then use an air hose and rag to pressurize the gas tank through the filler neck. It doesn't take much. This should force the gas out of the line you disconnected as long as the gas level is above the fuel pickup and the fuel line is clear.

If you dump a little gas down the carb a couple times that should be long enough for it to suck fuel.

It's pretty easy to remove the fuel pickup and level sensor from the tank. Be careful with the sock. They get brittle.

[willy3486]

As far as the sock goes if it messes up where can you get one. I looked online at places around me, napa,advance,etc and I did not find one. I may just take the tank out anyway to clean it out on the inside. If I can't find a sock can it be run without one?

[Daner]

Mine cracked on me so I just ripped it off. Just using a piece of rubber fuel line to reach the bottom of the tank now. Absolutely need a filter at some point in the system.

I've seen them for sale but I don't remember where. Maybe check the site sponsors.

[willy3486]

I have a filter between the carb and pump. I retried it tonight and I put a rubber hose from just under the tank to a jar of gas. All I saw it do was to suck in some gas then send it back to the jar. So I think from that and info above the pump is bad. I will get one tomorrow. I am also thinking of taking the gas tank out anyway to clean it out.

[willy3486]

I think I have it ok now thanks to the advice here. Here is what I have done so far. I put all new gas hoses from the carb to the tank. I blew out the steel lines as they looked good and clean as far as I could tell. I replaced the gas pump on the engine. I also took the gas tank out and have cleaned it. There was probably a quart or two of sediment in the tank from since it was new. I also ordered a new gas sender and float for the gas tank as the original was gummed up and the sending unit was falling apart. I also got one of the gas tank sealing kits where you pour the mixture in .

I currently have cleaned it and washed it out with thinner and I plan you rewash it with a rust reverse liquid they suggested at the parts place. After I do that and let it drain I will let it set until tomorrow then I will use the sealing kit. Other than surface rust on the inside I think the tank will be ok. No rust through on the tank and as far as I can tell it just has surface rust on the inside.

I did put some gas in a jug then I ran a hose in it and had the hose on the line just under the gas tank. I then turned the engine over a few times and I got it to get gas into the clear filter just before the carb. My carb may be stuck and gummed up as it did not spray into the engine. I have a good carb guy coming over to rebuild that so I am not worried on that. So I think it is on its way to be fixed. I ordered the new gas sender assembly that goes in the tank and a new seal that goes on the cab to seal the gas tank neck. Those parts should be here the middle of next week so I plan to install them on Wednesday or Thursday. And hopefully the guy will be here next Friday to rebuild the carb. So maybe next week I can drive it around my place. Thanks for all the advice as it helped to get it resolved.