Bench test Vacuum on fuel pump
 

Using a engine vac gauge as pictured. Bowl Gasket looked fine & still flexible, also put thin layer of grease on both sides, installed bowl to pump tightening hand crank as tight as advisable. Using finger to actuate pump arm. Seeing no Vac reading? Can I assume pump is shot? I used it for a couple years, it sat dormant for a year while refreshing engine, could that destroy the internal diaphragm?

Re: Bench test Vacuum on fuel pump
 

I don't know that you can get any readable vacuum on the gauge that way. JMHO.

Re: Bench test Vacuum on fuel pump
 

OK, understood. How should I test it & know whether it’s junk? How about sticking pull hose in a container of gas & actuate?

Re: Bench test Vacuum on fuel pump
 

Try it on the pump discharge and if that is zero I would think pump needs a rebuild.

Re: Bench test Vacuum on fuel pump
 

Anthony. Never, ass u me anything. I could be wrong, but applying vacuum to the outlet with the inlet plugged, will show if the diaphragm is leaking if the reading is not steady. Applying vacuum to the inlet, with the outlet open, will tell you if the check valves are working. Of course the best way to see what is happening inside, is to open it up.

Re: Bench test Vacuum on fuel pump
 

Thx for the help & ideas! Found out what I needed! Checked output side no reading. Also put pull side tube in gas & didn’t pull any into bowl. Being a belt & suspenders guy, also put output side in gas with no bubbles so guessing it’s junk. I was gonna get a better test run on new refresh on engine today & the reason I discovered the issue a couple days ago when I had the engin running with prime then a small amount gravity feeding from a bottle directly into the fuel block. I won’t be rebuilding this one if anyone’s interested in rebuilding it make me an offer & pay shipping & it’s yours! I’ll be going with a bowl-less fuel pump as it’s to busy on that part of my engine & I use a clear fuel filter anyway. Newish fuel line & tank & saw no sediment in the bowl after 2 years of running.
Thx again😁

Re: Bench test Vacuum on fuel pump
 

Anthony, You won't show vacuum until you APPLY vacuum. Also, the diaphram may be ok and the check valves sticky, or the bowl gasket not sealing. In any case, the pump body itself should still be good, so someone will get a good deal by your offer!

Re: Bench test Vacuum on fuel pump
 

Hi Allen & Thx for the reply! I’m not sure how you mean apply vacuum? I thought the actuator arm operating up & down as the cam does with the fuel pump rod did that? If that’s what your referring to I did operate it at approx the speed I saw the rod reciprocating ant even faster many times with no vacuum or on the output side pressure readings on output side. Also as I try what I think is practical, I fed the pull side into a can of gas with bowl held vertical pumped actuator again many times with no gas pulled into the bowl. Then one more try at putting the output tube in liquid to see if any bubbles while pumping & none. By apply vacuum did you mean actually hooked up to carb with engine spinning to create manifold vac wth carb sucking too? If yes I guess I misunderstood how to bench test. As original post said, unbelievably after 55 years working on my cars & engines I never had a problem with or occasion to test a fuel pump🤫😬😂! I ordered the prewar pump with no bowl not because of this but to get a bit more room as it got kinda busy back there with the bypass oiler installed.

Re: Bench test Vacuum on fuel pump
 

I've never been able to work a fuel pump with my finger. It takes some effort to pump it. Find a way to hold the pump steady and put some real pressure on the arm.

Re: Bench test Vacuum on fuel pump
 

Ttt

Re: Bench test Vacuum on fuel pump
 

Stick it back on the motor , connect fuel line to tank OR aux tank connect fuel pump /vac gauge to output side of pump ( the one that would go to the carb ) disconect PRIMARY COIL WIRE ( we do not want spark ) crank motor ( remove plugs to make it easier on starter ) check output on gauge . Then , if you have pressure you need to check volume . Disconnect gauge , get a gallon jug ( little overkill) install fuel line in jug or 2 liter bottle , crank for 10-15 seconds . Record volume and compare to specs . I did have them around somewhere. But even those were with a running motor , until the carb ran out of fuel or 10-15 seconds. I cant remember but its on the test procedure.

Re: Bench test Vacuum on fuel pump
 

My bad, loose nut behind the controls. As said never had one act up so never had to test. In worrying about maniac’ing the sheet metal cylindrical perch I did not put enough pressure on the actuator as it moved about 1/2” pretty easy. When I watched the pump rod cycle it didn’t look Look like more than a 1/2 “ stroke. Per 40cpe secured by carefully putting it in a vice wrapped in a towel not to damage & was secure enough to push actuator arm further than before, got good readings both vacuum & pressure on gauge.
I will use it to get engine tuned in since refresh then replace with the new no-bowl type for more room. Thx all for the great advice!!! I now know how much pressure it takes to actuate a Mech. Fuel Pump:D

Re: Bench test Vacuum on fuel pump
 

Just a point of information . Some of the pumps have the valves help with screws holding the valves and some are held by some other type of pins or at least not designed o be replaced ! Just as a point of info. The last time I rebuilt one it was in Yellow Stone for my 32// Was still working when I sold the car a year or 2 later. jm2cw kerk

Re: Bench test Vacuum on fuel pump
 

Anthony, for the cramped space issue, the pump top is able to clock around to whatever position is favorable to the installation. This goes for both types, with or without the glass bowl.

Re: Bench test Vacuum on fuel pump
 

Hi Allen thx for the tip! I tried to clock it for better room access. With two bolts 180 apart at least for mine only choice is clocked 180 the bowl ends up on a better access right side but interferes at firewall. It may just be because my engine is a bit of a hybrid, car is a ‘35, engine builder thought he was doing me a favor & said he’d build an 8BA that looked more like a 59ab as ‘35’s had, It’s got a crab distributor, 59ab intake with fuel pump & vent / draft tube in rear instead of oil input tube & fuel pump off of the fuel pump stand! I was inexperience with first Flathead early Ford project in 2012 & sounded good @ the time but has been a bit of a PIA sometimes😬😬😂!
Thx & Best

Re: Bench test Vacuum on fuel pump
 

Anthony. Ford38 was referring to clocking the top of the pump assembly, by removing the six screws that hold the top of the pump on, which will give 1/6 of a turn with each hole lineup.

Re: Bench test Vacuum on fuel pump
 

Ahh & Duh! Will try tomorrow. On another note after testing & seeing vac & pressure I reinstalled, after filling the bowl to get better prime as someone suggested. Nothing, then rechecked the rod stroke & don’t think it moving the actuator arm high enough to engage to level i bench tested? When in the vice actuating seemed @ least 1/2” even more? Could the actuator be stressed beyond normal rod actuation position? Using same stand & gasket. Will check vac / pressure again tomorrow on the bench then re-install and check for Vac / pressure while turning over. Thought I’d blow the fuel line out back to tank & there’s no blockage, with full tank heard it strong gurgling with easy air flow. I know they make a longer rods but that doesn’t make sense with everything the same as before?

Re: Bench test Vacuum on fuel pump
 

Anthony, the pushrod is loose, able to stand beside instead of under the pump arm. This incorrect position may be what you are experiencing. The correct position will compress the actuater arm slightly as you position the pump on the stand.

Re: Bench test Vacuum on fuel pump
 

My advice would be to send the pump to CharlieNY. Once it comes back from Charlie, it's A-OK and ready for modern fuel.

Re: Bench test Vacuum on fuel pump
 

Thx Allen, will be careful to engage the cylindrical perch. I’ve been taking the stand off till now, should I try leaving it on and putting the arm in from the side? Doesn’t seem like it’d be easier but thought I’d ask?