Hello, My issue is recurring with the mechanical fuel pump on my 1997 F-250 Powerstroke. I've had to replace 4 pumps in 6 years. One failed in less than 12 months and was covered under warranty but all the others were out of my pocket. They last 16 months on average. 10,000 miles + -

Truck is well maintained, purchased new, currently 230,000 miles, fuel filter replaced regularly and clean when replaced, no crud, metal fuel tanks as far as I know so no tank delamination, Obviously there is another issue that my mechanics choose to ignore. Since the trucks runs the same/great,( idle fine and smooth, just loss of MPG due to the puddle of diesel on top of the engine), with a broken pump can't I just eliminate the pump ? Thoughts? Last mechanic now suggest a "better" more expensive aftermarket pump but I am not willing to replace anything until the real issue is pinpointed. 4 pumps in 6 years also tells me I did not install a bad run of pumps from Ford....too many years from first to last pump.

All replacement pumps were Ford parts, no aftermarket.
Some of the failed pumps had a broken piston.

 

remove fuel filter and clean the small screen in the fuel bowl that is at the drivers side. mine was plugged up when I rebuilt my fuel bowl and the fuel pump was leaking.


A Ford fleet mechanic said to me that it keeps the pump cooler when screen is not clogged

 

Do you know what brand pump was used? Carter seems to be the brand of choice.

Also, are you sure the piston broke while driving? They are pretty easy to break during disassembly.

 

Hello, Thanks for the reply. Fuel bowl, filter and screen are clean.

 

All the replacement pumps were Ford/Motorcraft. No way to verify if the pump piston broke while driving but the two mechanics who have changed these pumps are very experienced and honest. Thanks for the reply.

 

I can't see any way the piston could break. You have the push tappet that runs off the cam and that is held in the bottom of the pump by just an o-ring. Maybe the mechanic thought that was connected to the piston somehow but it's not. It just pushes the piston up when the cam pushes the tappet up. When the cam goes down the piston is pushed down by the Hugh spring compressing the fuel.

Here is a picture of that assembly disassembled. The piston is a big hunk of metal:



If the piston broke then you would not have much fuel pressure but you're indicating the truck runs fine. Above the piston there is a space where if fuel gets past the top seal, just another o-ring the fuel would drain out the weep hole and into the valley. Even with a worn upper seal the truck usually runs fine, it just leaks some fuel from the weep hole.

Here is a picture of the piston hole with the piston inserted. You can see the upper seal at the top of the hole and at the bottom is the tappet seal, hard to see in the picture. Also the weep hole is located about the 8:00 position. With the pump installed on the engine the weep hole is towards the passenger side of the engine facing down, towards the valley.



I have to ask why the mechanic thinks the pump is failing, and so do you. If fuel is leaking from the weep hole again with such low miles then there must be another reason. The only thing that comes to mind is maybe the fuel pressure regulator is bad (to much pressure) as that would cause excessive pressure on the piston's upper seal causing premature upper o-ring failure. But this is just a guess. Once that upper seal is compromised the pump may work fine for awhile but is toast as there is no fixing it. Do you know what your fuel pressure is at idle?

As far as pumps go they are all made by Carter. You can spend $200 somewhere or $90 elsewhere. There are no better $$ pumps out there as they are all made by the same manufacture, but you can spend more money if you want. Prove me wrong?

There are so many places for fuel to leak in the valley, and we can give you some areas to look at so don't just assume it's the pump again, unless you know for sure it's from the actual pump.

 

Could something with the installation (pump body seating on block valley, damage to cam lobe, etc) be the pump piston "serial killer"? (shrug)

 

Hi Jim, Great photo's and comments. I may have saved one of the "broken pumps" I will take a look. Don't know what the fuel pressure is but I will start there. Agreed, many places for fuel to leak at that location. Thanks for all your time and input. It may take a week or more but I will update the post.

 

At this point anything is possible. Another great reply that I will discuss with the shop. Thank you Madpogue.

 

I am going though a CP4 fuel pump break down at this time. Purchased contaminated fuel from a Valaro in Red Buff Ca. on November 8 2019.. Corning ford has completed the work at a cost of $10,712.60. I have losses faith in this 2017 Ford F 350 6.7 diesel. Is there another full size truck out there that does not us the CP4 fuel pump. I hear that GM and Ford have Class Action Suits against them because of the Bosch CP4 pump. Is this a very rare breakdown, and how can I keep this from happening again.

 

You will probably get more answers over in the 6.7 forum. That said, I believe all 3 manufactures used the CP4 pump, until GM went to a different manufacturer (Denso? ) in the 18 or19 model year.

 

I am on my fourth mechanical pump. I figured out after my third pump ( fourth was when I lent my truck to someone) that if I run it out of fuel it kills the pump. I have a broken shower head in both of my tank's, so it took me a while to put two and two together. I didn't realize I was running out of fuel at a 1/4 tank. Don't know if that is a possibility for you or not but that's my bad pump experience.