The Stovebolt Site Forums The Shop Area Engine Shop Fuel Pump Problem 235 engine

My original style fuel pump is not pumping fuel to the carburetor. The glass bowl fills, but no fuel comes out the outlet side of the pump. The pump was rebuilt, and tested out OK. Any thoughts?

Did the pump work ok after it was rebuilt? That is to ask did it just begin doing this or did it begin after the pump was rebuilt? Have you disconnected the line going to the carburetor to see if any gas is being sent through?

The pump functioned when not mounted on the engine. Gas in - gas out when tested. It has not worked on the engine. The line to the carb has been disconnected. I'm pretty sure the pump I got back from the rebuild service is the same pump I sent in. However, if not, is there a difference between the pump for a 216 and a pump for a 235? Do they look similar, but aren't interchangeable?

Rusty it has been a long while since I've had a 216 fuel pump to compare and somebody may correct me on this, but I believe the two pumps were the same basic design. It seems to me that the position of the inlet and outlet might be different, however I want to say that was the only thing. It makes me wonder if your camshaft is moving the pump lever in/out. There is a lobe on the camshaft which does this. I've been known to stick my finger in while somebody cranks the starter to see if the lobe is ok or if it has been damaged. If you do this, please be really careful. It is a good way to mess up a finger real quick if you have it in the wrong place, but it is one way to know if your lever is or isn't moving.

Before you do this, however let's ask a couple of other questions. Has the truck been running? Do you know if the gas tank is plugged up, gummed up, etc? Do you know if the fuel line from the tank to the pump is ok? And do you know if the line from the pump up to the carburetor is ok? Ok meaning clear and free flowing.

Use a bright light and an inspection mirror to look at the cam- - - - -poking a finger in there is s vary good way to make the camshaft rust- - - -blood is salty!
Jerry

Yeah, Jerry is right. Plus you'll dilute your oil with the bleeding. Choose the safe approach.

Part of the orientation safety lecture for new students at the beginning of every school year was "Don't bleed on my tools- - - - -it makes 'em rust!"
LOL!
Jerry

And the pieces of flesh and bone chips will plug up the oil pump inlet screen.

And you can't hear if there is a valve tap over the screaming.

You stated that you tested the newly rebuilt pump before you installed it. I don't know how much truth there is to it but I was taught to never hand operate the lever on the pump to "test" it. The theory is that the lever only moves a small amount on the cam and the diaphragm can be damaged by moving it too far.
Fred

Thanks for the advice and suggestions. Not stinking a finger in the engine sounds like a good idea. Regarding testing, the rebuilder said he tested it and I can believe him. Not sure how he did it. Before I pull the pump off the engine again (running out of gaskets), I've got a couple questions. If the pump is filling with gas, might that imply that the arm is being actuated by the cam? Perhaps not enough to eject the gas? Second question, if the cam is faulty, what is the remedy. Does it involve major surgery on the engine? Thanks

I would try a new pump ,if the cam if messed up and won’t operate the fuel pump and the engine is otherwise in good running order I would try a electric fuel pump and block off the fuel pump opening with a plate .

Sadly if the lobe responsible for making the fuel pump work has gone bad (round and not elliptical) then you have only 2 options:
1. replace the cam (fairly major surgery) or
2. buy an inexpensive electrical pump and use it instead of the mechanical pump. This is what I did about 20 years ago and I've never regretted it even for a minute...for a number of reasons.

Here is something that must be said about electrical pumps, though. Most of them produce too much psi. You want one that will produce 2 to 4 psi, because that is all you need. Any more than that can force your needle off your seat and mess things up badly. The pump I use is this one:

https://www.amazon.com/gp/product/B00496RE82/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

Good luck.

Problem solved. I'm almost ashamed to admit my bonehead rookie error, but will go ahead just to provide closure. I took the pump off and visualized the cam. Clean, solid, and rotating. So, I put the pump back and tried again. This time I didn't even get fuel into the pump. Guess, what - out of gas (my fuel gauge hasn't worked in years). The fuel I previously saw in the glass bowl of the pump must have been the last remnants of what was in the lines. Put gas in the tank and all is fine. Of note - the pump did need a rebuild before I started fiddling with things. It was an educational experience and I thank all for the information. I will likely need it in the future.

I have bench tested many different fuel pumps. The 216 and 235 and others use the same pump. I just bench tested a unit which was apart. I don't see how the pump arm will over stretch the diaphragm. My first guess would be tank blockage or fuel line. A full copper line would take 30 to 40 lbs. of pressure from the tank fitting. If you have an old soft line that is the likely spot because the inside rubber flakes' Doc.