Ran truck out of gas - fuel pump dead
 

Hey guys,

Stock mechanical pump - I deliberately ran my 1972 K20 out of gas due to having let it sit too long and the gas going bad (I assume, would not make it up a hill and ran really rough). I let it idle while I also pumped the fuel out of the tank manually. It ran out, as planned, no odd noises or anything weird. I got 5 gallons of fresh gas, put it in, and tried to start it, no luck. Poured a little fuel into the carb, start, run 5 seconds, die. Did that a few times and realized that I have a fuel delivery problem. Did all the usual checks (fresh line without filter off pump output into bucket and turn over, nothing; run a fresh line off the pump input into a gas can with gas, nothing; had wife turnover truck with my finger over the input side of the pump, no suction felt). I feel pretty confident the pump is dead. My concern is that I read a few threads where people had similar situations and others told them to check the oil. So I pulled the dipstick and the level was normal. However, when I sniff it I think I smell fuel so I plan to change it to be safe, but seeing that recommendation (which I never would have thought of) has me concerned there are other things to worry about.

So my questions:

1. Anything else to be concerned about checking?
2. I am ordering a new pump today, and hope to have time to replace next weekend. Given the overall situation, any other recommendations/words of wisdom?

All assists are greatly appreciated!

Thank you,
Dirsuper

Re: Ran truck out of gas - fuel pump dead
 

It's possible that the diaphragm gave out. As the fuel passes through the pump it will cool the diaphragm so it's possible that your old diaphragm was worn and failed when it got hot with little or no fuel passing through.

Just to be thorough are the rubber hoses on your fuel lines in good shape?

Re: Ran truck out of gas - fuel pump dead
 

I bought three pumps from Napa before I got one that was usable. The first one didn’t work at all. The second one had mismatched threads on output port. AC-Delco is no longer an American built product also !

Re: Ran truck out of gas - fuel pump dead
 

sometimes it works force feed fuel into the f/pump thru the lines to prime it.

Re: Ran truck out of gas - fuel pump dead
 

Yes, I use one of those red and black squeeze bulbs to push a little fuel through mine. I think it's supposed to check battery acid or something other than fuel. I've never used mine for anything other than gasoline. The fuel ages the bulb pretty quickly. But it will last for at least a few months of fuel system tinkering. Totally misusing the tool, but it's handy.

Re: Ran truck out of gas - fuel pump dead
 

Besides sub standard materials being used to assemble Asian-made fuel pumps -- even good US-made NOS pumps may have compatability issues with current gas station fuel being made with additives that are corrosive with the elastic element in the diaphragm.
Replacing the mechanical fuel pump on an Old School engine is a crapshoot now.
Same thing happened to the 350 in my '71 GMC a few years ago. I don't have a working gas gauge. I rely on using a trip log and factoring my gas buys [in gallons] against miles logged.
Not a blunderproof system.
About 5:45 PM, Downtown, coming home from work, the Jimmy started sputtering and stalled, just south of an intersection. I called a friend, and I called Road Side Rescue. The friend got there first. I gave him my Shell card and an empty plastic fuel jug, and sent him off to buy some gas. Meanwhile the Rescue guy showed up. He splashed about 3 gallons into the tank. No Start. Rescue guy left. My buddy came back with about 4 gallons. We added that. still no start. Now I had to call Road Side Rescue back and request a tow. The flatbed got there about 9. I was home by 11.
When I replaced the fuel pump, it lasted about 100 miles. Then it was spraying gas all over the underside of the engine. Towed home again.
Next one lasted 90 days.
Third time was the charm.
I was lucky, my SBC block has that stop bolt, that sets up the Fuel Push Rod between the ''shoe'' on the pump and the cam lobe. Just have to remember to disengage the set up bolt for running.

Re: Ran truck out of gas - fuel pump dead
 

A rag wraped around a air nozzle pointed into fuel fill gently to pressurize and force fuel up to pump

Re: Ran truck out of gas - fuel pump dead
 

My SBC block was not drilled for the pushrod retaining bolt so installing a new pump is a royal pain in the neck. I replaced the top left bolt with a stud. This allows you to align the pump while starting the other bolts.

Re: Ran truck out of gas - fuel pump dead
 

I have greased the push rod on a cold engine with good results.

Re: Ran truck out of gas - fuel pump dead
 

That doesn't work in AZ. You get a blob of red grease in the face.

Re: Ran truck out of gas - fuel pump dead
 

Been a while , but some grease on the rod always worked for me too . Maybe I was just lucky ?