hey guys im using a holley mechanical fuel pump it has less than 100mi on it.it seems to work ok but the other day i pulled my carb and the gas in it was brown like tea.my first thoughts were the gas tank is rusted.pulled my gas tank and it was clean as can be.well come to find out its oil.im guessing some how oil is getting past a seal or something and oil is getting into the gas.any thoughts?has anybody else had this problem in the past?

BTW this is the second holley fuel pump ive had issues with.the other one had less than 500mi and quit working.

My Holley mech pump took a dump about a month ago, thought I had a line leaking, come to find out there was something like a weep hole built into the body of the pump, with the motor started it would pump gas out that little hole, still don't know why the hole is even there, but had to replace it for the time being with a factory replacement type for now.

My Holley mech pump took a dump about a month ago, thought I had a line leaking, come to find out there was something like a weep hole built into the body of the pump, with the motor started it would pump gas out that little hole, still don't know why the hole is even there, but had to replace it for the time being with a factory replacement type for now.

the first holley pump i had issues with did the samething. i think im going to buy a electric fuel pump see if i have better luck.

I replaced my Holley with an Edelbrock Vic Jr pump + return-style regulator. It holds pressure better at WOT than the Holley did.

i got a brand new holley pump to replace my old carter just sitting there waiting for me to put in,,,i guess i'll wait then :eek:

Guys,

Most Mechanical pump failures (and im not picking on you WHAT SO EVER) and from the end user

Let me explain......

Scroll all the way to the bottom of this link
http://www.racepumps.com/Fuel%20Pump%20Animation.html

If you rotate the housing you MUST check what i'm telling you, I check it no matter what

Scroll down, see how the arms pulls the diaphragm? Notice where the diaphragm is? In-between the upper and lower half, THIS IS AN ADJUSTMENT

What you do is loosen the bolts so the diaphragm can move, COMPRESS the pump arm all the way so it is pulling to diaphragm, then torque the bolts to hold the diaphragm so it will be fine when the fuel pump are is pulling the diaphragm so it doesn't cause issues

This is 90% of the failures in fuel pumps, it puts the diaphragm in a bind if you don't do it the way i said and will fail sooner or later, usually sooner

^^^ Yeah, Edelbrock mentions this in their instructions. Whenever you clock the lower half of the pump housing, they say you must preload the diaphragm before reassembling the two halves. They want you to fully depress the arm before reassembly. That's what I did at least...

^^^ Yeah, Edelbrock mentions this in their instructions. Whenever you clock the lower half of the pump housing, they say you must preload the diaphragm before reassembling the two halves. They want you to fully depress the arm before reassembly. That's what I did at least...

I do it on all pumps even if we dont rotate the housing so i know the pump is ready for the customer or engine or both

Oh crap, I moved the bottom half of my new Holley pump on my street stock so the inlet/outlet would be where I want them....

So you're saying loosen up the 6 screws on the bottom so the diaphragm is floating, compress the arm, and then tighten them?

Oh crap, I moved the bottom half of my new Holley pump on my street stock so the inlet/outlet would be where I want them....

So you're saying loosen up the 6 screws on the bottom so the diaphragm is floating, compress the arm, and then tighten them?

I just pulled a brand new carter pump off my car to do this. I clocked it prior to installing it last week. When you remove the bottom the diaphram is floating due to the diaphram spring being unloadedand the pump arm is now also unloaded. Makes doing this pretty much impossible.
I compressed the body & the bottom portion in a vice which makes the arm functionable again and then installed the screws. Again, once you compress it together so the arm will work it's just like you tighened it up anyway. What am I missing?

I haven't used a Holley mechanical pump for years. When I did, I found that they seemed to have issues with porosity in the castings. they would allow leaks and cracks to form. sounds like this may still be happening.

Again, once you compress it together so the arm will work it's just like you tighened it up anyway. What am I missing?

Apparently, it does put some tension on the diaphragm. Here is what Edelbrock has to say about it:

RE-POSITIONING THE LOWER PUMP BODY: The lower pump body may be re-positioned as needed to allow better alignment
of the fittings for specific applications. Referring to the exploded view on the following page, remove ten allen head screws from the
perimeter of the pump pulsator cover and separate lower fuel pump body from upper fuel pump body. Rotate lower pump body to
desired new position and start but do not fully tighten the ten allen head retaining screws. Before fully tightening these screws, the
rocker arm must be actuated to and held in the “full stroke” position. This is done to ensure that the diaphragm will be pulled to and
held in its maximum working (flexed) position while the retaining screws are torqued tight (20-25 in/lbs.). This procedure will ensure
against premature diaphragm wear and subsequent failure due to over-stretching of the diaphragm material when in the full stroke position.
Another by-product of an improperly set diaphragm is erratic fuel flow and pressure.
The ten allen head retainer screws should then be torqued to their 20-25 in/lbs. specification in a criss-cross or “star” pattern, to ensure
even, progressive tightening. CAUTION: Do not overtorque these allen capscrews or serious pump diaphragm damage will occur.
This procedure can be assisted by holding the fuel pump in a vise or appropriate fixture, and holding the rocker arm down with a pipe
or similar tool.

...Could issues in quality with holley mech.fuel pumps be due to castings made in korea ? Had 2 crack on me ,myself ,won't use them again till they change where they get them made from ,going with either carter or edlebrock ,j ust my.02 , DC:bowtie:

...Could issues in quality with holley mech.fuel pumps be due to castings made in korea ? Had 2 crack on me ,myself ,won't use them again till they change where they get them made from ,going with either carter or edlebrock ,j ust my.02 , DC:bowtie:

Never had an issue with the Barry Grant Super Speedway series mechanical fuel pumps or there race pump