Penta 5.0/5.7 fuel cell resolution/rebuild guidance

fognyc

Cadet
Joined
Sep 12, 2016
Messages
8
Setup:
  • 2004 5.7gxi-F 3869260 4012119425 Duoprop
  • 530 hours on the block (heavy overhaul as the engine was partially submerged during Hurricane Sandy.. Most parts new, but fuel cell original)
  • Used in brackish water
  • Religiously run engine with fresh water after every use.
Issues:
  • Terrible fuel economy
  • Starting to feel more sluggish between 3500-4000
  • Occasional hi pressure pump whine heard during idle (low pressure seems cool)
  • Long idle times the hi pressure pump gets hot, and the insulation is actually starting to melt near connection harness. Have ceased operating boat until I can resolve.
  • Despite clearing both the water intake from the t-stat and the output from the fuel cooler to the riser, when hooked up to the engine.. Water is not passing through the fuel cooling jacket (assume scaled/salted up)
So I plan on taking a stab at the following:
  1. Test fuel pressure (will likely confirm the hi-side at the rail is way out spec causing the hi pressure pump load to be excessive)
  2. Remove/clean out the the fuel regulator (leave screen in, don't plan on using e-clip right now)
  3. Test hi pressure again.. If it’s in check, then hopefully the hi-pump starts operating normally.
  4. If things function normally, I still need to flush out the water jacket on the fuel cooler.
With that being said I have these questions I hope that you guys can answer:

Would you attempt to (without the engine running) push hi pressure water (from a pretty powerful garden hose) through the fuel cooler to clear it out? Should I be concerned that water might get past the o-rings in the cooler and mess up the fuel system?

-or-

Bite the bullet and take the fuel cell apart and clear it out? (I'm assuming its do this)



If so, is it as simple as removing the pumps/filter and soaking all the remaining parts in gas for a while? I’m assuming besides the pumps and filter, all remaining parts are good for an overnight dunking. Hit the screen w/ compressed air or some throttle body cleaner.

What thread sealant do you use to put on the fittings going into the fuel cell, and the high pressure lines to the engine when I reconnect?

Can someone provide the exact listing for the all the O-rings needed to overhaul the fuel cell and replace the ones on the pump? I’ve seen a few posts, but some folks are vague and guessing. A rec on who to order from would be dynamite too.

Should I use silicone grease when applying new o-rings to all parts in the fuel cell, as well as the fuel reg, and the injectors if I pull them for service?

I have 500+ hours on the engine, I’m thinking about cleaning the entire fuel system as well. Is it as easy as pulling the rail, soaking it in gas, and sending out the injectors to be cleaned?

After subjecting the hi pressure pump to these grueling loads, and then if I successfully return the load to spec, can we assume the pump will have a reasonable amount of service life left? Or am I playing with fire?

Finally, Is 12 years to have a Penta fuel pump without a total failure a stroke of luck, and don’t mess around with an overhaul/rebuild and just get a new one?
 

Senior B

Petty Officer 1st Class
Joined
May 19, 2006
Messages
253
12 Years is fantastic for a fuel cell but cleaning it out is simple. One you remove the assembly, there are 4 screws to remove. 3 on the bottom and the one screw on the side that holds the clamp for the Hi pressure pump. Remove the high pressure pump screw 1st and slide the clamp off, then pull out the hi pressure pump. It will take a little tugging as the 2 o-rings on the pumps in-put side hold it in snug. There will be gas draining out of the cell when you remove the pump so be prepared for this. You will then remove the 3 bottom screws and remove the lower cover assembly from the fuel cell and pryoff/ remove the lower cover. This will take a bit of work as there will be corrosion. I use lots of PB Blaster and the orings inside keep it snug. When you get the lower cover off, you'll see the inside of the fuel cell and water jacket that surrounds it. I used a dental pick to clean the crap out of mine and get the water flowing again. The job isn't hard. As for the o-rings, I was able to reuse mine as they cleaned up fine after soaking them in PB blaster.
 

fognyc

Cadet
Joined
Sep 12, 2016
Messages
8
Thanks Senior B.. in the end.. I bought the new fuel cell given the long service life of the old one.
 
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