Priming a fuel pump????

[ronzet]

LBC fans, Good Morning....

Just a quick query... My '57 A now fires off and is ready for a steady stream of fuel rather than a few drops in the SUs...

Problem -- fuel feed. I rebuilt the pump. It <u>appears </u>to work -- clicks nicely but no fuel is drawn from the tank. Lines are clear... Sooo..

The query, Is there a need and a process to 'prime' the pump and or fuel lines??? OR should I just bite the bullet and buy a new pump??? or put more fuel in the tank?? OR ad infinitum...

I am all ears.. /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

I have a pump on my Moss wishlist and ready to order.. Unless??? /bcforum/images/%%GRAEMLIN_URL%%/rolleyes.gif

 

[David_DuBois]

Ron - See my article Fuel Delivery Troubleshooting Guide in the Carburetor & Fuel section of the Library on this site. A SU fuel pump doesn't ordinarily need priming to get started pulling fuel out of the tank (provided there is enough ful in the tank to cover the pickup tube). I assume that you have the original type pump, a high pressure L type. If so, you may have somve severly grooved valve disks that are not sealing properly, particularly when dry. Sometimes pressurizing the fuel tank slightly will be enough to get fuel into the pump, making a better seal around the grooved valve disks. The other problem you may be having is an air leak on the inlet side of he pump. This is caused by any of the fittings being loose enough to all ow air to be drawn into the line.
Cheers,

 

[ronzet]

David,

Thanks for the advice... Now, although I have tried, where on this site can I find your article???

 

[Gearhead]

Electric pumps don't really need "priming" does the tank have enough gas? lines clear? leaks any where else ? how does one rebuild a electric pump?

 

[David_DuBois]

Ron - Oops, wrong forum. Here is the link: https://www.mgexperience.net/article/fuel-tsg.html
Sorry 'bout that

Gearhead - As I stated in my previous post, priming is not normally needed if the check valves are sealing properly. That said, it is not uncommon in the pumps used in the MGAs for the valve disks to become severley grooved, in which case it is necessary to get some fluid on the valve disks to develop enough vacuum to pull the fuel out of the tank. In fact, when I restore these type of pumps, I squirt a little machine oil on the valve disks and seats to insure that I can get a good vacuum reading on them when doing my tests. To see what I do to restore a SU fuel pump, see my write up at: https://www.custompistols.com/cars/dave/ddsu_fuel_pump_services.htm
Cheers,

 

[Billm]

A very low-tech way to prime the pump is to turn the ignition "on", remove the gas cap and blow into it with as much of a seal as you can, for as long as you can. You may get some funny looks from those around you but this has worked for many of who couldn't afford a new pump when we were younger!! /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
Bill

 

[ronzet]

Gearhead,

Yep, yep, and yep... checked all that...

rebuilding an electric fuel pump??? replace contacts, springs, diaphram, etc... lots of little parts but fun to do on a CLEAN workbench... /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif

BY the way.. I gave up and bought a new pump from Moss... comes tomorrow... Wish me luck guys.. /bcforum/images/%%GRAEMLIN_URL%%/cheers.gif

 

[ronzet]

Billm...

Tried your technique this evening... Doctor sez I can go home on Sunday....No major lasting damage /bcforum/images/%%GRAEMLIN_URL%%/jester.gif

 

[DrEntropy]

Umm... it DOES work. As long as ya DON'T INHALE. /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif

 

[David_DuBois]

"Umm... it DOES work. As long as ya DON'T INHALE." And arenot smoking.

 

[Rob_Edwards]

A very low-tech way to prime the pump is to turn the ignition "on", remove the gas cap and blow into it with as much of a seal as you can, for as long as you can. You may get some funny looks from those around you but this has worked for many of who couldn't afford a new pump when we were younger!! /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
Bill

Easier to stick a piece of hose into the filler, seal the hose & filler with your hand, then blow on the hose. Also a good way to start a siphon -- while keeping the hose & filler sealed, stop blowing & quickly direct the hose into your gas can. The pressure in the tank forces the gas back up the hose and starts the siphon....

HTH!

 

[DrEntropy]

"Tune in NEXT week kids! We'll teach ya to pick a five pin LOCK!" /bcforum/images/%%GRAEMLIN_URL%%/jester.gif

 

[ronzet]

OH?!?!? I was supposed to BLOW into the tank...no wonder it didn't work... /bcforum/images/%%GRAEMLIN_URL%%/crazy.gif

Smoking??? It is amazing how loud a gas explosion is and how bad hair smells after it is singed. I needed a haircut anyway... /bcforum/images/%%GRAEMLIN_URL%%/jester.gif

You can send me flowers at the DumbA#$ Community hospital... /bcforum/images/%%GRAEMLIN_URL%%/square.gif

 

[Nunyas]

it worked for me... I rebuilt my SU fuel pump not too long ago, and I ended up huffing and puffing into the tank until it built up enough pressure to force the fuel into the pump.

 

[ronzet]

Nunyas,

Thanks to you and everyone else for the suggestions... With a new pump that I will install tonight I will huff and puff my way to success... /bcforum/images/%%GRAEMLIN_URL%%/banana.gif

/bcforum/images/%%GRAEMLIN_URL%%/cheers.gif

 

[DrEntropy]

With a NEW pump the huff 'n puff is excess to requirement!

...where's th' challenge in THAT?!?! /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif

We didn't spend YEARS dedicated to finding all these elegant work-arounds just so YOU could go off 'n buy a brand-new pump and negate all that effort, research and toil!

*sheesh*


ingrate. /bcforum/images/%%GRAEMLIN_URL%%/jester.gif

 

[ronzet]

DrEntropy,

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]We didn't spend YEARS dedicated to finding all these elegant work-arounds just so YOU could go off 'n buy a brand-new pump and negate all that effort, research and toil!
[/QUOTE]

Now I feel like a real putz... /bcforum/images/%%GRAEMLIN_URL%%/square.gif

I will hang my head in shame as I realize how ungrateful I appear... /bcforum/images/%%GRAEMLIN_URL%%/cryin.gif

I have had trouble answering your post... I was laughing so hard that I couldn't type... /bcforum/images/%%GRAEMLIN_URL%%/lol.gif

Thanks guys... /bcforum/images/%%GRAEMLIN_URL%%/cheers.gif

 

[ronzet]

David,

With what I have seen of your expertise in LBCs and the quality of the articles that you have posted... /bcforum/images/%%GRAEMLIN_URL%%/bow.gif

We should petition to have you promoted to a full <u>YODA</u> status before you hit the posting number!!!/bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif

Thanks for your help... /bcforum/images/%%GRAEMLIN_URL%%/cheers.gif

 

[ronzet]

Rob_Edwards,

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]...to stick a piece of hose into the filler, seal the hose & filler with your hand, then blow on the hose. [/QUOTE]

This is deffinately easier to visualize than blowing into the gas tank fill pipe directly...

My neighbors already think I am /bcforum/images/%%GRAEMLIN_URL%%/crazy.gif and going to my knees and blowing into the tank would absolutely bring a cease and desist order to my door... /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif

Decorum, gentlemen, decorum, please... /bcforum/images/%%GRAEMLIN_URL%%/jester.gif

 

[Nunyas]

heh...


I remembered that when I rebuilt my pump, it ticked away happily until I primed it with my lungs. After which, it only ticked enough to build up pressure. A few days later, I found that I hadn't rebuilt it to the spec I should have. The points weren't ticking over as effectively as they should have, and took me a couple of more days of tweaking the points assembly to make them trip as effectively as they should.

Now, (a month later) it still only ticks enough to build up pressure after sitting for a couple of hours, but I no longer have to worry about it completely stop pumping fuel while I'm on the road. /bcforum/images/%%GRAEMLIN_URL%%/smile.gif