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Chris Elzie
07-17-2015, 05:12 PM
I have a 74 S&S that Im trying to get running on its own. It has a fuel issue not getting any fuel from the tank. I have checked the pump and its good, I removed the tank and checked it and it was clean; so I pulled the sending unit and it looked good and clean. I did replace the strainer and made sure the lines were clear ont the unit. While I had the tank off I replaced all rubber lines that connected the metal ones to the tank and blew the metal ones out while I had them disconnected. I have traced the lines and did not find any kinks or rust holes. I put the tank back on hooked everything up and still cant get any fuel from the tank. I was thinking maybe its the pump and even though it doesnt seem bad it might be. Any ideas?

Daniel Scully
07-17-2015, 05:39 PM
I have a 74 S&S that Im trying to get running on its own. It has a fuel issue not getting any fuel from the tank. I have checked the pump and its good, I removed the tank and checked it and it was clean; so I pulled the sending unit and it looked good and clean. I did replace the strainer and made sure the lines were clear ont the unit. While I had the tank off I replaced all rubber lines that connected the metal ones to the tank and blew the metal ones out while I had them disconnected. I have traced the lines and did not find any kinks or rust holes. I put the tank back on hooked everything up and still cant get any fuel from the tank. I was thinking maybe its the pump and even though it doesnt seem bad it might be. Any ideas?

Sounds like a bad pump? How did you check the pump? With the lines off of the pump you should have a slight suction on the inlet and slight pressure on the outlet while cranking the engine. Could be something strange like the eccentric is loose but most off the time it is just a bad pump.

Paul Steinberg
07-17-2015, 05:40 PM
Just thinking outside of the box, and wondering if you might have the return and the supply crossed? Not familiar with your year car enough to know for certain how it is plumbed. The only other thing, is that it might be sucking air somewhere in the system. The last thing that I can think of is that there isn't enough gas in the tank for the pick up to reach. If you have a way of putting some air pressure into the tank, it will help to diagnose the problem. What I do with these types of problems, is with a helper giving short blasts of air into the tank filler, and the line disconnected from the fuel pump, see if fuel is flowing through the lines. You can do this with a air blow gun that has a longer nozzle end, and stuff the fuel filler opening with some rags after you insert the air blow gun. Do not try to put air into the tank from the fuel pump side, because you will blow off the pick up tube sock, and there is a strong possibility that you will damage the fuel pick up. This is what happened to a PCS members car on the way to the Tennessee meet. The local dealership put air to the tank from the fuel pump side, and ruined the gauge and pick up. It would only draw down to half way when the tank was full.
Final thought is that the filter in the pump is clogged, and needs to be changed. It is a long skinny paper type of filter.

Chris Elzie
07-17-2015, 06:38 PM
After putting the tank back on I primed the carb and ran it off a bottle for bit to try and get the gas flowing even after this the line was dry when I took the rubber line off from the pump. I ran a hose off the pump into a jar with some gas and it sucks it right up and ran till the gas was out.

Chris Elzie
07-17-2015, 07:15 PM
Just thinking outside of the box, and wondering if you might have the return and the supply crossed? Not familiar with your year car enough to know for certain how it is plumbed. The only other thing, is that it might be sucking air somewhere in the system. The last thing that I can think of is that there isn't enough gas in the tank for the pick up to reach. If you have a way of putting some air pressure into the tank, it will help to diagnose the problem. What I do with these types of problems, is with a helper giving short blasts of air into the tank filler, and the line disconnected from the fuel pump, see if fuel is flowing through the lines. You can do this with a air blow gun that has a longer nozzle end, and stuff the fuel filler opening with some rags after you insert the air blow gun. Do not try to put air into the tank from the fuel pump side, because you will blow off the pick up tube sock, and there is a strong possibility that you will damage the fuel pick up. This is what happened to a PCS members car on the way to the Tennessee meet. The local dealership put air to the tank from the fuel pump side, and ruined the gauge and pick up. It would only draw down to half way when the tank was full.
Final thought is that the filter in the pump is clogged, and needs to be changed. It is a long skinny paper type of filter.

The lines in this coach are a small and a large that runs down the passenger side and one large that runs down the driverside.

John ED Renstrom
07-17-2015, 09:11 PM
one vent line one return line and a suction line. so you ran it off a bottle on the floor threw you fuel pump? should say there is enough draw for the pump to work.

so disconnect the line from the pump and from the tank. and blow threw both ways just to be sure that it is clear. might be something working as a flapper in there if it is clear both ways. hook it back up. then Like Paul said dump 5 gal of gas in the tank. you just might be to low to pick it up.