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| Normal fuel pump lever actuating force? https://slantsix.org/forum/viewtopic.php?t=66784 |
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| Author: | Sonic Purity [ Mon Sep 26, 2022 1:48 pm ] |
| Post subject: | Normal fuel pump lever actuating force? |
Existing high-mileage fuel pump leaking fuel out the weep hole and fails the diaphragm leakage test. Usual deal where the oil level goes up on the dipstick and dipstick has smell of unburned gasoline. Yes, i’m changing the gasoline-diluted oil and oil filter… again already. Got a new Carter M60576 mechanical fuel pump from my local auto parts store. Having learned the valuable lesson of testing new parts before installing from the collective wisdom here on this site, i proceeded to do so. Could not push the actuating lever by hand, at all. The failed pump requires moderate force (about 1.5 kg pressed against a kitchen scale), yet is easily actuated/operated by hand. No matter how hard i push the lever on the new part, it doesn’t move. Figuring the new part is defective junk which needs to be returned, but wondering if somehow there’s some break-in with a new part after which it would move more easily? Also wondering what typical force is required to move the lever arm. Any ideas/thoughts? Thanks (as always)! |
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| Author: | Rick Covalt [ Mon Sep 26, 2022 5:19 pm ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
They do actually push pretty hard, but you definitely should be able to move it. Get a good grip on the pump and push the arm against the work bench. See if it moves. As a side note almost all the new pumps I have put on in the last 10 years are made out of tin foil. Be extra careful to use a back up wrench when you tighten the fuel line to the pump. Unless you want a leak where the fitting is crimped into the tin foil. Ask me how I know. 
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| Author: | Sonic Purity [ Mon Sep 26, 2022 5:35 pm ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
Quote: They do actually push pretty hard, but you definitely should be able to move it. Get a good grip on the pump and push the arm against the work bench. See if it moves.
Good idea, and nope: can push so hard i’m digging into the wood of the workbench, and no movement. Not knowing about the internals, i can’t imagine what happened during assembly to totally lock the lever up.Quote: As a side note almost all the new pumps I have put on in the last 10 years are made out of tin foil. Be extra careful to use a back up wrench when you tighten the fuel line to the pump. Unless you want a leak where the fitting is crimped into the tin foil. Ask me how I know.
Thanks for this. More great advice.
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| Author: | Greg Ondayko [ Tue Sep 27, 2022 3:56 am ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
The new pumps require a bit of force.. Pressing it against the bench or clamp the pump's lever arm in a vise with some soffJaws or blocks of wood to not mar up the arm that rides against the cam eccentric, then try actuating it. maybe you just need a workout torquing wheel nuts with a short bar 'just kidding. Good Luck, Greg |
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| Author: | Sonic Purity [ Tue Sep 27, 2022 10:24 am ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
Quote: The new pumps require a bit of force..
Instead i went with pressing it against the standing area of a typical balance beam home body-weighing scale. To my amazement, i finally did get it to move. Nearly wore out my hands (should have worn gloves) getting a measurement: 58 lbs. on the scale when the lever finally moved.Pressing it against the bench or clamp the pump's lever arm in a vise with some soffJaws or blocks of wood to not mar up the arm that rides against the cam eccentric, then try actuating it. New pump: 58 lbs. Old pump: 3.7 lbs. on the same scale. 3.7 is close to the 3.3 (1.5 kg) i measured with the old pump on the kitchen scale previously. That’s a massive difference. I understand that a failed pump with 70,000-some (don’t make me look up the actual number right now, please. Major technical issues with my tech here due to Big Tech arrogance and incompetence) miles of wear-in will require less force than a new one, but beyond a whole order of magnitude difference?! With that much force being required to actuate the pump, no wonder i read about fuel pump lobes on cams getting deeply grooved or otherwise wiped out! So my new one’s not totally locked up like i thought, but i’m wondering whether it’s a defective cam-killer or whether way back decades ago the one i just removed was like that when it was new and fully functional. Does anyone have a NOS good-quality fuel pump whose lever they can press against a scale to give me/us a number of what is typical? Is the new pump normal, and the old one very low force because of failure and wear? Or is the new pump far too stiff and the old one closer to normal? Or both/somewhere in between? It’s going to completely ruin my year if i install this pump and it takes out the cam lobe in short order. I’m not understanding why this high degree of force (spring pressure in the pump?) is necessary for it to function properly. If this is normal and it has always been so, please let me know. Seems excessive to me. Thanks! ))Sonic(( |
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| Author: | Dart270 [ Tue Sep 27, 2022 11:20 am ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
I cannot see that 58 lbs is OK, and it seems it would wear down the eccentric lobe on the camshaft. Good to know this goofy stuff is out there. I have so many good used pumps I haven't bought a new one in many years. Lou |
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| Author: | SlantSixDan [ Tue Sep 27, 2022 12:55 pm ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
Not to mention that if it takes 58 pounds to push the lever against the spring, then that same spring is going to put 58 pounds' pressure behind the fuel. That's way too much; the spec is 3 to 5 pounds. See here. The AC pumps I'm talking about are this kind, easily findable with a search like this one. |
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| Author: | volaredon [ Tue Sep 27, 2022 1:18 pm ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
I just put an (old) new Carter fuel pump on my engine, and though I didn't "work" it like I sometimes do with a new mechanical fuel pump maybe I should have? I do know that the cam core I sent into Oregon cams for a regrind ,(original cam from a 74 model/6) had to have it's fuel pump lobe welded up and re machined along with the regrinding of the rest of the lines. I had never heard that engine run, and I'm not the one who took it apart either. It had come to me in pieces. Runs fine now though. I think I have another of those "old" new Carter pumps around here still in it's box "somewhere". |
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| Author: | Rick Covalt [ Tue Sep 27, 2022 3:39 pm ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
I have never measured the actual "pushing" pressure, but I would have guessed it took 20 # or so to move the arm? Of course it is possible that I may have installed dozens of them that were wrong??? Question.  Is the spring only to keep the arm on the lobe? Or is the spring what is pumping the gas?
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| Author: | Charrlie_S [ Wed Sep 28, 2022 3:48 am ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
The lobe on the cam "cocks" the pump arm against the spring and draws fuel into the pump. The spring pushes the arm/diaphragm against the fuel in the pump to supply the carb. The spring controls the maximum fuel pressure. The amount the arm moves the diaphragm controls the volume of the pump. PS: I had several bad replacement pumps for my 318 engine, that had too much free play in the arm, and the pump could not supply enough volume. The car would run out of fuel. if I hit passing gear. Took me about 2 years before I found some pumps that did not have excessive free play. All the bad pumps were in several different manufacturers boxes, from different parts houses. |
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| Author: | Rick Covalt [ Wed Sep 28, 2022 3:54 am ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
Thanks Charlie! I know for a sure that every one I have installed took more than 5 pounds to move the arm.
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| Author: | Charrlie_S [ Wed Sep 28, 2022 4:49 am ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
I never actually checked how much force it took to move the lever on any mechanical pump. I should have one or two mechanical pumps somewhere around here. Still have a little more prep to do before the hurricane hits. If I get done in time, and we still have power I'll see if I can check them. You people have me curious. |
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| Author: | Dart270 [ Wed Sep 28, 2022 5:34 am ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
Good luck w/the hurricane, Charlie! I bet it is not the spring that is causing the high pushing force but some binding? Lou |
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| Author: | Sonic Purity [ Wed Sep 28, 2022 12:41 pm ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
Quote: The lobe on the cam "cocks" the pump arm against the spring and draws fuel into the pump. The spring pushes the arm/diaphragm against the fuel in the pump to supply the carb. The spring controls the maximum fuel pressure. The amount the arm moves the diaphragm controls the volume of the pump.
Thank you for typing that out. To me, it’s a clearer explanation than my very recent re-read of the fuel pump section of the Stockel book.Quote: PS: I had several bad replacement pumps for my 318 engine, that had too much free play in the arm, and the pump could not supply enough volume. The car would run out of fuel. if I hit passing gear. Took me about 2 years before I found some pumps that did not have excessive free play. All the bad pumps were in several different manufacturers boxes, from different parts houses.
FWIW, for Slant 6 pumps, both the failed high-mileage and new excessive force pumps have zero up-down (lever actuation direction) free play, and about 1-2 mm lateral (shaft axis) free play. The failed pump has about 2 mm of actuator travel at its tip. The new excessive force pump is too difficult to measure, but felt roughly the same when i forced it against the scale.Great discussion here; one of the reasons i love this site and those of you here who make it happen—thanks! I’ve yet to have SlantSixDan’s advice steer me wrong, hence a NOS AC pump has been purchased from an ebay seller and should be here by 5 Oct. I intend to do the same measurements on it and basic integrity testing before installing, so i’ll report back here with the as-new lever actuation force, etc. Quote: Good luck w/the hurricane, Charlie! I bet it is not the spring that is causing the high pushing force but some binding?
Hurricane well-wishes seconded!Lou My original thought with the over-stiff pump was something binding, but the lever itself seems to have reasonable movement/very slight axial free play, and when i finally got it to move, the motion was smooth and even, not rough/hitched. If something is binding, it’s being very smooth about it. If i had the skills and equipment to carefully dismantle it to figure out the failure mode, i’d almost be inclined to take a loss on the cost of the part to understand what the heck happened. ))Sonic(( |
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| Author: | Sonic Purity [ Mon Oct 03, 2022 8:32 pm ] |
| Post subject: | Re: Normal fuel pump lever actuating force? |
NOS AC 6972 pump is here. Actuation force on lever: approximately 1.3 kg or 3 lbs. Actuator travel: 2 mm Free play in direction of actuation: 0 Side-to-side free play on shaft: 1 mm I was aware that the angle of the fittings differ from later production, but didn’t know that the output fitting of the 6972 seems to be something like 3/8"-32? rather than the compatible 5/16" inverted-flare i (without thinking) expected: Attachment:
File comment: Not going to fit
What sort of fitting(s) do i need to adapt to my installation?AC 6972 fitting with hard line - nope.jpg [ 25.01 KiB | Viewed 2416 times ] Is it necessary for there to be hardline between the fuel pump and fuel filter inlet? Is there anything special about the shape of the existing hardline, pictured below?: Attachment: hard line side view.jpg [ 11.11 KiB | Viewed 2416 times ] ))Sonic(( |
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