Fuel Pump Internals, how are they different?

[hpfpupgrade]

Alright, time to get down and dirty with the difference in fuel pumps/internals that are on the market.

First… I have held and tested each and every fuel pump I am talking about but… I will not address them by name or make reference to the MFG of the fuel pump to protect both the MFG and myself.

Let’s get on with it:

The very first thing you should know about fuel pumps… don’t run anything other than the OEM puck that rides on the camshaft button/follower. During extensive testing and results from testing we have found that the OEM puck needs to match the hardness of the button/follower. Why you ask? Let me explain why:

The fuel pump assembly works just like a cylinder head valve and it rotates on the button/follower. This rotation is needed in order to keep even wear on the fuel pump piston stem (this is the part that moves up and down to make the fuel pressure). Without this rotation one side would eventually wear and cause fuel pressure fluctuations and eventually fail.

Here is where the problem lies:

When you remove the OEM puck that rotates on the button/follower you are left with just the end of the pump piston stem. This is not as hard as the OEM button/follower and the pump stem itself starts to wear out from this rotation. This will cause an eventual loss in fuel pressure and eventual failure from the retainers and locks due to rubbing on the retainer because the pump end was worn down past the retainer surface (see pictures).

Pictures are as follows:
OEM vs aftermarket puck design (top is OEM, bottom is aftermarket)
Worn out pump stem (you can tell from the hight of the retainer vs the pump stem)
Retainer wear because of pump stem has worn out (top edge is worn)
Down view of the follower (see the raised insert inside of it, this is very hard and will cause wear)



Now some might say, “make the pump piston harder”… and we will say… “let me know how to do this”. Reason being, the pump puck is crazy hard, it scores something in the high 70’s on the Rockwell scale C chart. More or less what I am trying to say… it would be impossible to make the pump piston this hard and still have it be reliable as a moving part.

Moving on to the next item:

Pressure bleed by holes… these are very important for lower seal longevity (VW and Audi market really have a problem with this). What we have found in testing is that a single hole is not enough to support the proper feed back into the fuel return side. You are running a higher volume/pressure of fuel and more fuel will need to be sent back. The OEM single hole is not enough, so with our fuel pumps we have two holes feeding the low pressure fuel back into the pump return (internal passages). This is a patent pending design with our fuel pumps, so nobody will be able to reproduce it. I tried to take pictures but the holes are on oppisite sides of each other, so getting both of them inside the picture is impossible.

Last…

The design of the fuel pump internals took over 15 revisions on our end. There are things we are comfortable sharing, and things we are not. Here are the things we will share:

Material H13 tool steel, this is certified tool steel that has a margin of .05% we discard three inches off each end of the round stock to eliminate possible grain shifting of the material.

Tolerances are held within the .000001 of an inch at final fitting (air gauges are used to determine fitment)

We verify final polish with and RZ machine then put them through a final process to verify the surface finish (not going to release this data).

All our pumps are hand fit and “matched” as sets. This verifies proper fitment and longevity of the fuel pumps/internals that we offer.

We are one of two companies that offer “pre-ran” fuel pumps for the Mazda, VW and Audi market. Our test bench is one of a kind that can “simulate” injectors as if it were running on the car. This test bench is the only one of its kind in the world and the competitors use a pressure control device, we actually use open and close events to give real world results vs static pressure and flow like the competition.

Now that you have an idea of the “differences”, it makes you and informed buyer.

Thanks

John​

[Oldhead]

Interesting photo,s . Approx how many klms or time taken after instalation of the pictured piston and caps did it take show this amount of wear.

[hpfpupgrade]

Interesting photo,s . Approx how many klms or time taken after instalation of the pictured piston and caps did it take show this amount of wear.

22k miles, so around 30k klms. What we have seen is fuel pressures start to fluctuate up and down (big swings in pressure) and then you will start to see pump pressure falling off up top. Please will try to tune around the pressure loss, but its just putting a band aid on the problem. The OEM retainer and puck were put in there for a reason and we did extensive testing of the other design before we released our fuel pump. Its very important to watch pump wear at this location. Also, we are starting to see cam follower wear (part that goes between the cam lobe and pump piston). There are a few pictures floating around out there showing the damage that happens, its something to keep an eye on if your fuel pump doesn't use the OEM design.

[Oldhead]

John ,thanks for info , i am under the belief that a particular manufacturer has included a titanium (puck) with internals and was concerned re the wear factor (different hardness ).
Noted that VW,Audi have released a tech info re cam wear.
The other interesting point is that the spill valve has a release pressure of 1850psi and note that the OEM pump has access to engine oil??????.
The pictures floating around ,are they of Mazda or only VW & Audi (cant seem to find ).
Well appreciated info John.

[Jmac]

What I'd like to know is what characteristics determine replacement

[hpfpupgrade]

John ,thanks for info , i am under the belief that a particular manufacturer has included a titanium (puck) with internals and was concerned re the wear factor (different hardness ).
Noted that VW,Audi have released a tech info re cam wear.
The other interesting point is that the spill valve has a release pressure of 1850psi and note that the OEM pump has access to engine oil??????.
The pictures floating around ,are they of Mazda or only VW & Audi (cant seem to find ).
Well appreciated info John.

No, there is no titanium puck included with the competitions parts nor the stock part. The stock puck is made from a pressed cold gas cooled powdered metal, it scores very high on the RC scale and from what we can tell its impossible to wear out. The competition is using TIN coatings (titanium coatings), they have near zero impact on wear (been testing new cam follower designs for the last 6 months and this coating did not perform well in this application).

Yes the OEM valve has a release point of 1850 ish psi, and yes the pump does have an oil jet that both lubes and cools the fuel pump contact point, but that is not what causes the wear... its the material difference and the surface area change that causes the greatest potential for wear.

The pictures I have seen and the pumps I have worked personally have been both Mazda and VW (Mazda pictures are the ones that I posted).

If you have any other questions feel free to post up.

Thanks,

John

What I'd like to know is what characteristics determine replacement

What we have seen is the fuel pump pressures start to get very erratic. You will see 1600 psi then 1800 psi, then 1600 psi ect. When the internals are new the pump pressure appears be a constant, then as the miles build up on the fuel pumps the pressures start to get a little crazy.

Hope this help.

-John

[Jmac]

What we have seen is the fuel pump pressures start to get very erratic. You will see 1600 psi then 1800 psi, then 1600 psi ect. When the internals are new the pump pressure appears be a constant, then as the miles build up on the fuel pumps the pressures start to get a little crazy.

Hope this help.

-John

Hi John,

So are the aftermarket pumps affected in the same way as the miles build up?

[hpfpupgrade]

Hi John,

So are the aftermarket pumps affected in the same way as the miles build up?

The only pumps that don't use the OEM puck under the fuel pump tip. Yes, they appear to be affected in the same way as the miles build up. I have seen several sets that have this problem, both VW and Mazda.

Thanks,

John