The Diesel Stop banner

1 - 8 of 8 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
Hi guys,
I have a 2000 F450 with a 7.3L and a 4R100, DRW 2WD.
I have a 198k and about 500mi on a rebuilt motor.
re-used injectors, new bearings, pistons, and the likes. I am basically stock, I have a studded motor, FRX, and a PHP Hydra (which is disabled)

I have an issue with my truck that began as a intermittent knock when warmed up and in drive, accompanied by a lack of power, Which became a constant knocking noise. It sounds like a “clack clack clack”. I am thinking it is a fuel knock.
Currently when hot the noise is loud and constant and the truck basically falls on its face. It will make other noises and refuse to accelerate as well.

At idle I get a oil pressure of 450-550 PSI at 10-14% IPR DC; WOT 2750 PSI at 38% IPR DC.
The fuel pump sounded weak so I replaced it, which helped with the power loss but the engine is still making the clacking. I notice a bit more black smoke from take off as well.

Basically where I’m at is I have two spare injectors of unknown functionality that I want to swap into Cyl 5 and 7.

Do you guys have any other suggestions/ideas/concerns?


F30925AE-B03D-4A76-8287-24E808B547F4.jpeg
This was scanned after idling prior to driving.

D12ACF6B-4688-4E18-9356-35FD5D351AF0.jpeg

This is taken hot after driving, symptoms present.
 

·
Super Moderator
Joined
·
25,409 Posts
First pull the valve covers and confirm that the Under Valve Cover Harnesses are fully seated. You're probably hearing a miss, with your first set of codes, indicating bad connections to 5,7, and 8.
The contribution test failures on #3 and #8 are common with the newest Cam Position Sensor (grey one that replaced the original black CPS that was recalled).
 

·
Registered
Joined
·
11 Posts
Discussion Starter #3
First pull the valve covers and confirm that the Under Valve Cover Harnesses are fully seated. You're probably hearing a miss, with your first set of codes, indicating bad connections to 5,7, and 8.
The contribution test failures on #3 and #8 are common with the newest Cam Position Sensor (grey one that replaced the original black CPS that was recalled).
Thanks for the info. I think the UVCH are good. I didn’t test the electrical portion but I did pull the covers and check for clean terminals and tight connections. They’re fairly new so I don’t think the gaskets need modded yet.

Update:
I swapped fuel injector 5 and 7 out for some Alliant Remans that were unknown in condition, problem persisted.
I hooked up a fuel pressure gauge to my truck and was only getting 20 psi at idle. I recently changed out the fuel pump, so I just swapped out the fuel bowl as I had a spare. This took care of the fuel knock and idle issues. Truck still is running sub par and now ONLY cylinder 8 fails cyl contribution. Perhaps I trashed #8 with low fuel pressure considering its last in the firing order?
 

·
Super Moderator
Joined
·
25,409 Posts
#8 will almost always fail the CCT with the grey recall CPS. Not an issue that you need to deal with. But there are some aftermarket CPSs that will cure the issue. Link
 

·
Registered
Joined
·
11 Posts
Discussion Starter #5
I have the dark blue CPS sensor.

I don’t think the CPS is the issue, because cyl 3 isn’t failing contribution now.

I am going to swap out #8 and see if that makes a difference.
 

·
Registered
Joined
·
13 Posts
Thanks for the info. I think the UVCH are good. I didn’t test the electrical portion but I did pull the covers and check for clean terminals and tight connections. They’re fairly new so I don’t think the gaskets need modded yet.

Update:
I swapped fuel injector 5 and 7 out for some Alliant Remans that were unknown in condition, problem persisted.
I hooked up a fuel pressure gauge to my truck and was only getting 20 psi at idle. I recently changed out the fuel pump, so I just swapped out the fuel bowl as I had a spare. This took care of the fuel knock and idle issues. Truck still is running sub par and now ONLY cylinder 8 fails cyl contribution. Perhaps I trashed #8 with low fuel pressure considering its last in the firing order?
I'm sure you probably know this but as I just dealt with the same low fuel pressure issue wanted to suggest just checking the fuel pressure regulator relief valve plunger next time. I recently was only making 28 psi (at the pump) because my fuel pressure regulator had a blown out o-ring which had also hardened. It was actually surprising I was making any pressure at all.
157696


You can get by with a regular oring in a pinch but the correct oring is tapered to match the seat. I installed a rebuild kit I bought off riffraffdiesel.com that comes with all new orings, plunger, and seat. I should have taken pictures but the new plunger was revised, it looks like, for better flow characteristics and less turbulence. Just thought I would mention it as swapping your plunger out would have been significantly easier than swapping out the whole fuel bowl.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #7
So I ended up taking the truck to the shop. The truck is a 2000 F450 cab and chassis. These C&C trucks have a coating in the fuel tank that is known to delaminate and clocks up the fuel system up to the fuel filter. Now that I have had a poly tank installed, fuel pump, fuel filter and the lines cleaned the problem is solved.
 

·
Registered
Joined
·
941 Posts
Congratulations on solving the problem, Sorry it was such hassle. Thanks for sharing the answer so others can learn.
 
1 - 8 of 8 Posts
Top