Manual fuel pump making noise?


Sharpest Tool
Nov 13, 2010
Willys Model
Willys Year:
I just put on a manual fuel pump a month or two ago. When the engine is cold everything sounds great. After I cruise around for about 40 min. the fuel pump sounds like "Clickety Clack" when at idle. Everything seems to work fine, but the noise has me worried. Anyone have any idea what's up with this fuel pump.
Paul, that's a new one on me. I've never heard that sort of noise in my pump. :roll: It'll be interesting to read what others have to say about this one.
Fuel pumps can noisy if the moving parts are worn.On some engines they may make a knocking sound or clicking noises.You might want to remove the pump and temporarily run the engine to see if the noise disappears.Be a good idea to plug the fuel pump opening so oil doesn't splash out.But don't stuff in a rag so it get sucked into the moving parts.
I did a search and found out it could be a bad return spring, or worn foot. I need to take it off and inspect it. I called the retailer of the pump and he thought it was the valves making noise, but it is pretty clearly the pump making all the racket.

I may have damaged the pump screwing around. The truck was having problems starting so I put the fuse back in my electric pump and ran them both (for a short time) in tandem trying to get it to start. I did this once before for a few seconds when I put the manual pump on and it worked great. I did it a little more aggressively this last time, and maybe the fuel pressure in the line caused a problem when the diaphragm tried to compress but couldn't because of the line pressure. :oops:
My 2 cents.
If you had been running both pumps and there was an excessive pressure on the diaghram then it seems the noise would be present when cold not when warm. I would be leaning towards a hard mechanical failure with metal that is causing the noise when heated allowing it to expand.

Good luck
Make sure your pickup tube screen in the tank is not clogging and that the gas cap is correct and not causing a vacuum to form in the tank. If the fuel pump has to suck to hard it can make noise.
You guys are both right, and those are both things I am trying to figure out. I am also thinking maybe a lubrication issue, since the oil is probably thicker when it's cold. But I did hear that if the system is vapor locking that the pump would make noise. The motor seem to run good and it was starting without problems, so I don't think it's a vapor lock. Anyway, I have some exploring to do, it could be I just jacked up the pump and need to get another one which is an expensive learning lesson.
So I was drinking beer with a mechanic the other night, and I tell him about my fuel pump and he says that he's 99% sure its vapor locking. Someone else had told me this too, so it got me started thinking I am back in the vapor lock zone. So I check my fuel line, and it is not getting hot. But then I check the manual fuel pump and the thing is hotter than a pistol! I poured some water on the top of it while it was running and the water boiled off! The engine is running at about 160-170 deg.

Does anyone have a manual fuel pump that isn't vapor locking? The mechanic told me to ditch it.
I took my carb in to get rebuilt today, ouch! $390 that sucker better run good when I get it back!
I run a manual fuel pump on my 226. I installed it in 2003 and ran it all the time until I pulled the engine out in 2009. I'll probably put the same one back on when I put the engine back in (in a few months). We'll see if it dried up or not. Anyhow, I don't think the advice of ditching the manual pump is a good one. Maybe a good replacement manual pump is in order.