fuel pump rattle

[FORZDA 1]

Originally Posted by Lex Yes, the pump comes with a higher rate spring than stock according to CPE. It has fewer windings than the stock one.......

I wasn't aware of this in the CPE pumps, I thought it was a separate deal to install. The CDI info says you will likely get increased cam lobe wear form the spring. Do the PTP pumps have it as well?

IMO there just isn't enough clearance in the piston/sleeve junction to allow such a clatter as I heard on the clips. I still say it is related to the solenoid action and the spill valve response under the high pressure. It still could be related to the spring tension causing the noise source reaction...

I'm still trying to find the cutaway drawings I have seen of the HPFP that clearly shows how the spill valve opens/closes to fill the pump cavity and cause it build the high pressure required.

[Lex]

The intriguing thing is that this happened after some high RPM runs. I did not measure the spring on the CPE pump but what if it was slightly deformed?

The cam follower looks new with no marks.

By the end of the weekend I will try the stock spring on the CPE pump and rule that out.

[djuosnteisn]

Originally Posted by FORZDA 1 I'm still trying to find the cutaway drawings I have seen of the HPFP that clearly shows how the spill valve opens/closes to fill the pump cavity and cause it build the high pressure required.

Please post when you do

[FORZDA 1]

Originally Posted by djuosnteisn Please post when you do

http://www.hitachi.com/ICSFiles/afie...4_04_103_1.pdf

This isn't the one I remember, but it gives some idea of how it works. The pumps on our cars is a are later version and only a bit more complex, but the basic principle is the same. The solenoid action controls the amount of fuel allowed into the pumping chamber, so IT is the key to pump/pressure control...

[Lex]

Could very well be the solenoid. I will eliminate the parts 1 by 1 and this should provide some answers.

[Lex]

UPDATE:

Swapped the solenoid as well as the turret, spring, and small push button inside the pump from the OEM one to the CPE one. These are all the parts at the top of the pump where the solenoid screws in and they control the pressure. FORZDA, this was for you buddy!

The CPE had more miles on the core and the tiny spring inside was a little softer. Nothing to really write home about though. I only got to test briefly this evening after fucking around with it but it appears the noise is still there. Will know more tomorrow after some more miles on it.

If it's not it, I am trying the OEM piston spring I said I would try in the first place. IF that still doesn't fix it, I am putting the stocker back in and sending it CPE. After all, I paid good money for that pump.

EDIT: Swapping out the solenoid and pressure control mechanism did nothing for the noise. It's still there - same as before.

[felt]

Didn't you just void your cp-e pump warranty by messing with it??

[Lex]

Originally Posted by felt Didn't you just void your cp-e pump warranty by messing with it??

I think you are a little under the influence of how OEM/Mazda warranties work.

If anything, I did some legwork for CPE and am helping the community understand the issue.

On top of this, CPE does not touch the solenoid of the pump. It is simply reused from an OEM core pump. They swap out the internals and spring and test the pump.

[vbt101]

FWIW, I have the same issue on my CP-e pump.

[8.5MS3]

my cpe pump makes the same noise, i have my stock pump on now, and that rattle isnt there.

[Lex]

8.5MS3 and vtb101 - how many miles did you have on your pumps? Did it start losing pressure over time?

8.5MS3 - how come you pulled the CPE pump off?

[8.5MS3]

Originally Posted by Lex 8.5MS3 and vtb101 - how many miles did you have on your pumps? Did it start losing pressure over time? 8.5MS3 - how come you pulled the CPE pump off?

I got the pump used with about 10k on it (i think the serial number is 0056). It doesnt hold 1800psi, at least not for me. just rock steady between 1680 and 1750.

I pulled the pump since my turbo started smoking and stocked out for a dealer visit.



Jake - im gonna stay stock until i can get this bitch to smoke again. so the pump will be sitting in my garage unused in the meantime. if you need one for testing or whatever i can send it your way

[bova]

glad to see there are others with this issue.

[8.5MS3]

Originally Posted by bova80 glad to see there are others with this issue.

funny thing is i initially thought it was my tensioner or something. every time i get off idle it rattled for a split sec, then goes away (or gets drowned out by engine noise) not sure which.

now that im stock it doesnt do it anymore

[Lex]

I am going to change to the stock piston spring and leave it alone until things get worse. I am really starting to think it's the piston to bore clearance. Once some coating wears off, the pump becomes noisy.

I wonder how much fuel gets by the piston and mixes with the oil with a looser clearance.

At least I got to see how all the parts look inside first hand.

Originally Posted by 8.5MS3 funny thing is i initially thought it was my tensioner or something. every time i get off idle it rattled for a split sec, then goes away (or gets drowned out by engine noise) not sure which. now that im stock it doesnt do it anymore

Yeah, everytime you increase pressure quickly it will rattle regardless of RPM but you have to really listen for it.

[super_pablo_]

mine is lound but doesnt make that rattle.... good thread, ill keep an eye on mine.

[Lex]

UPDATE - rattle identified:

OK boys and girls - here is the reason for the infamous CPE pump rattle.

Now, a little background. Remember that this metallic rattle happens as pressure is ramped up and a lot of the guys running CPE pumps for a while have this. Bova with a PG pump also has the problem.

The common denominator here unfortunately is the piston SPRING and button.

Below in Figure 1 shows the CPE pump on the left next to a no-name upgraded pump. There are 3 big differences.

1. The CPE pump uses the STOCK cam follower button. This is great because they don't wear out like aftermarket ones.

2. The CPE pump piston shaft is the same diameter from top to bottom. All other upgraded pumps that I see thicken the shaft only inside the barrell and leave it stock width in the lower section inside the spring. This is shown in Figure 2. The CPE pump shaft is thick from top to bottom.

3. The CPE pump therefore requires to use a LARGER diameter spring. The spring in Figure 1 on the left is different from the STOCK one reused with other internals on the right.

Figure 1


Now, the larger diameter spring is held at the top to a larger barrell shown by the red circle (1) in Figure 1. So the spring is well attached to the pump at the top of the pump.

However, here is where the design flaw is. At the bottom the push button is the STOCK one that does not wear out (Figure 1, blue circle (2)). It is of STOCK diameter. That means that the upgraded (larger in diameter) CPE spring does not grab onto this smaller diameter button.

The result is that after X number of miles, the push button becomes easily detached from the spring at the bottom. As the pump is moved by the cam follower, the push button RATTLES against the cam follower and spring when pressure is ramped up since it no longer is firmly attached to the spring. So that means the piston inside the pump is no longer dampened by the spring - in other words the spring is no longer doing its job and the system is underdamped.

This causes the annoying rattle sound and probably extra wear on the cam follower.

Unfortunately because of the thicker piston shaft and thicker barrel and spring attachment at the top, the stock spring CANT be used with a CPE pump - it does not fit at the top.

SOOO ... you are stuck with a rattling pump and perhaps more wear.

If yo have an upgraded spring/CPE pump, check your cam follower for extra wear and get back to me (esp guys that ran them for a while). I am not sure what the long term effects are (if any). So it's important to see what the higher mileage cam followers look like.

CPE does not know of this issue when I spoke with Josh a few days ago he had no idea about the problem. Unfortunately the problem comes up after some miles when the smaller diameter push button becomes detached from that larger diameter spring.

Figure 2

[06Speed6]

Note to self, buy a ptp pump.

[bova]

interesting...although i dont know that i feel like taking my pump out, lol. i hate messing with stuff when my car is running good.

[Lex]

Originally Posted by bova80 interesting...although i dont know that i feel like taking my pump out, lol. i hate messing with stuff when my car is running good.

While your car may be running well, there's clearly an issue. It shouldn't make that noise.

OP updated with findings.

[bova]

but like you said there is nothing we can do about it. ok so maybe i'll look at mine if i get a free moment. what is it i do again to get the fuel out of the lines going to it, which fuse gets pulled?

[8.5MS3]

wonder if cp-e is gonna chime in here. ive got their pump with almost 15k miles sitting in a box if they wanna tear into it and check for damage.

[Lex]

Originally Posted by bova80 but like you said there is nothing we can do about it. ok so maybe i'll look at mine if i get a free moment. what is it i do again to get the fuel out of the lines going to it, which fuse gets pulled?

Don't worry about pulling fuses it's not required. Just let the car cool off for a few hours.

Originally Posted by 8.5MS3 wonder if cp-e is gonna chime in here. ive got their pump with almost 15k miles sitting in a box if they wanna tear into it and check for damage.

The only damage you may see (if any) is on the bottom of the push button or on the cam follower. I am discussing this with CPE as we speak.

[bova]

alright i just gotta find my torx bit i bought for when i did it the first time. probably won't get to it this weekend though. maybe sometime next week.

[8.5MS3]

Originally Posted by Lex The only damage you may see (if any) is on the bottom of the push button or on the cam follower. I am discussing this with CPE as we speak.

well i only had it on the car for about 1-2k miles, so i dont think im gonna have any glaring damage, ill take a look at the pump when i get off work tho, see if anything looks worn

[FORZDA 1]

Originally Posted by 06Speed6 Note to self, buy a ptp pump.

Well for sure not a CPE....

[djuosnteisn]

Shouldn't there be constant pressure against the button at all times? Even if it's not attached to the spring as it should be?

Is the rattle coming from the button moving from side to side within the spring, rather than bouncing between the spring and tappet?

[FORZDA 1]

Originally Posted by djuosnteisn Shouldn't there be constant pressure against the button at all times? Even if it's not attached to the spring as it should be? Is the rattle coming from the button moving from side to side within the spring, rather than bouncing between the spring and tappet?

Yeah, IMO, the button is allowed to "wallow" around and MAY be rattling against the cam follower itself? That would be my guess...

[djuosnteisn]

Then stiffer spring may be the cure all, right?

[FORZDA 1]

Originally Posted by djuosnteisn Then stiffer spring may be the cure all, right?

Hmmm, could be, but then you might run into impact/wear issues (oil film strength) with the cam follower and camshaft lobe(s). The spring should already have a higher rate as the piston design appears much heavier than OEM. I remember reading all about the piston design/weight, spring tension, etc. on one of theses forums a while back.... Dang it sucks to get old!

[Lex]

FORZDA, you nailed it.

The spring becoming separated from the retainer (button) does not dampen the motion of the piston and you get the rattling noise. This explains why it first happened after some high RPM runs.

Let me make something clear. I DO NOT KNOW what damage it may cause. It may imapct/wear the follower, it may not. I don't think anyone knows unless they put many miles on the car and pump. This is not a VW and the follower is hardened.

CPEs quality has been the best in the aftermarket for Mazda. I really do applaud them for that and making parts that don't fail like most aftermarket ones do. This is WHY I bought their pump in the first place. This is not a shot at CPE. This is an observation of the pump I have and what others have noticed with the larger diameter and higher rate spring using the stock retainer.

Don't bring competitors in here such as PTP. Fact is that CPE has had less internal failures than anyone else out there.

It would be very good to see what the followers look like from people that have ran a rattling pump for thousands of miles. This might shed some light on the issue. If it's just a noise, I am sure we can all live with that. If impact wear happens then maybe it has to be addressed.

Originally Posted by FORZDA 1 Hmmm, could be, but then you might run into impact/wear issues (oil film strength) with the cam follower and camshaft lobe(s). The spring should already have a higher rate as the piston design appears much heavier than OEM. I remember reading all about the piston design/weight, spring tension, etc. on one of theses forums a while back.... Dang it sucks to get old!

[djuosnteisn]

Bova.... i think you need to get to it this weekend

It'd be a great example of wear from this type of rattle, even though your pump isn't the exact same setup as Lex's.

[djuosnteisn]

Originally Posted by Lex ... Don't bring competitors in here such as PTP. Fact is that CPE has had less internal failures than anyone else out there. ...

This is DAMN TRUE.

My guess is this rattle won't be an issue, especially if bova's been rocking the rattle for thousands & thousands of miles already.

Little bit of noise from upgraded pump is nothing considering that upgraded pump will likely last the life of the car, requires no suspicious break-in period or seizing episodes, and comes with a full lifetime warranty.

IMO cp-e pumps are hands-down the best option.

[06Speed6]

Can you check the seat pressure of the two pumps, I was thinking about it and it sounds like the CPE spring is too short.

[Lex]

Originally Posted by 06Speed6 Can you check the seat pressure of the two pumps, I was thinking about it and it sounds like the CPE spring is too short.

Set side by side, OEM and CPE springs are same length.

[06Speed6]

Thats not a measure of a spring being too short. Whats the installed seat pressure? That spring is thicker with one less coil.

[bova]

ok question i was thinking, why does it only occur after the car warms up? i would think that when metal gets hot it expands so if what is said is true wouldn't that tighten the tolerances?

[Lex]

Originally Posted by bova80 ok question i was thinking, why does it only occur after the car warms up? i would think that when metal gets hot it expands so if what is said is true wouldn't that tighten the tolerances?

When you first start the car the pressure is held high by the ECU. When pressure is constant you don't get the noise. It only happens when pressure is ramped up quickly.

Originally Posted by 06Speed6 Thats not a measure of a spring being too short. Whats the installed seat pressure? That spring is thicker with one less coil.

How would I measure this?

[06Speed6]

Thats why I think there is a spring measurement that is wrong, it kinda clicked last night when I was thinking about it. The spring is moving on the retainer. I am betting there isnt enough seat pressure, even though the spring is heavier, because the spring isnt long enough to be compressed to such a length to reach a point where the spring actually has more seat pressure to dampen the heavier piston.

A cheap way would be to measure the installed spring length of both springs, then take the springs out of the pumps, put them in a vice with a bathroom scale and tighten them down until you reach the same installed length.

[djuosnteisn]

Longer or stiffer spring should help, right?

Or could you use a shim between the button and spring bottom to compress the spring a bit more?

How much of that piston goes into the pump when fully depressed by the cam? Like how deep does the piston go into the pump?