Local car show tomorrow and I decided to put some fuel in my 69 Charger. 440 dual quad exactly what's in my signature. Never had a fuel delivery issue except for those hot summer days where the fuel evaporated. Factory fuel tank Edelbrock 110 GPH mechanical fuel pump. I can prime the bowls on both carburetors using a syringe and some fuel and that usually gets the engine going for 15 20 seconds so the fuel pump can suck fuel from the fuel tank but today we have a tantrum. I left it her up in the air I looked at the fuel sending unit and the hose was cracked so I replaced the hose. Wow under there i got an itchy to remove the fuel sending unit just in case the fuel sock was varnished or covered in crud. It wasn't but I removed it anyways.Drop the car back down prime the carburetors again which are dual 500 edelbrocks on a progressive linkage. Turn her over she goes for 15-20 seconds but I'm not getting any fuel pressure on the gauge. I usually get 6 PSI. So then I start thinking maybe the fuel has varnished in the fuel lines which are original. I take off the rubber hose from the fuel sending unit and also disconnect the hose just before the fuel pump. I put a tube to catch any dirt that would come out and I put compressed air from the rear part of the fuel line near the fuel tank. Air flows freely and nothing came out because the fuel line was dry. Reconnect at the rear check for obstructions in the dual feed lines for the carburetors and those are clear. So then I start looking at the fuel pump. If I plug the outlet with my finger I can put suction on the hose on the inlet and I can feel it pulling on my finger, so there goes the inclination that the diaphragm has burst. So now I'm at a loss I took fuel and poured it down a rubber line which goes on the inlet side of the fuel pump and then shoved that hose into a fuel tank near the passenger front fender just to see if the fuel pump can draw fuel in and it can't. I need a second set of eyes or a second set of ears cuz I'm losing it right now. I can still pour fuel down the access ports near the metering springs on the edelbrocks and she kicks over and runs for 15-20 seconds. Do mechanical fuel pumps need to get primed in order to suction properly does anybody else have any constructive criticism. I have not pulled the mechanical pump off the block but I'm really hoping it's not the cam lobe or The eccentric lever but if it had to be something I hope it's the fuel pump and not the camshaft.

Only thing I can think of is the pump rod , they do wear in length . Yes it will run pump arm in & out but not as far . Be worth a check if you pull the pump . Gary

I will pop off the pump in the morning and give the pushrod a check.

Thank you

Have you cleaned or replaced the fuel filter?
I've never had to prime a mechanical fuel pump.
Good idea to check the pushrod.

If the pushrod isn't worn, I'd be replacing the pump.