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Discussion Starter #1
Hey all, I need to get some help with my truck.
I have been having a lot of varying issues with my truck, but mostly it has a driveability issue. It used to run okay for 7 ish miles, and then the motor would run rough, not like a misfire, but just choppy as if it wasn’t getting enough fuel. It would also intermittently blow a puff of blue smoke, clear up and repeat the problem. When it would get choppy It would lose power and the RPM would hang around 2k. The longer I ran it this way the more these symptoms worsened, until it cooled off completely which it then would repeat. I had buzzed all injectors no problem, cylinder 8 Fails CCT. I replaced 8 with a Full Force Reman and everything went okay for about 20 miles, then the problem above happened again. I stopped on the side of the road to do a CCT and buzz test, shut off the motor and it wouldn’t crank hot. Starter seized up, so I replaced it and drove it home and when I got into the driveway it started blowing a PLUME of white smoke. It does this if I unplug the valve cover harness on either bank. Is it time for a rebuild? If I rebuild it will the block be okay? I hear these engines can round out the block and such. I’m at a loss with all the parts I have put into this truck. Thank you for reading..

https://youtu.be/0CTgTXD17eQ
 

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Ignore #8 for now. You probably have a bad UVCH. I would replace it and see if your codes go away. Changing the VC gasket is also a good choice at the time, but may not be needed.

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Discussion Starter #4
Any other thoughts? What’s the possibility of a head gasket?

Recently I have replaced:
IPR
ICP
UVCH
VC gasket
Up pipes
EOT Sensor
EOP Sensor
#8 Inj
#1 Inj
#3 Inj
Cleaned EBPS
Fuel pump
GPR
Glow plugs
Starter
CPS (Dark Blue)
 

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Not likely that you have a head gasket problem. I know of only two 7.3's that have had blown head gaskets, and one came along with a broken crankshaft (it was highly modified and blew up on the dragstrip).

I didn't see where you have checked your fuel pressure or fuel delivery. That would cause a lack of power and possibly the noise you're hearing. If your fuel pump has died, the injectors are acting like little plunger pumps and will try and draw fuel all the way from the tank.

I would stop swapping parts till you ID the actual problem. It's common for injectors #3 and #8 to fail the CCT, especially with Ford's replacement grey CPS. All parts swapping does is drain your wallet.
 

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Discussion Starter #6
Not likely that you have a head gasket problem. I know of only two 7.3's that have had blown head gaskets, and one came along with a broken crankshaft (it was highly modified and blew up on the dragstrip).

I didn't see where you have checked your fuel pressure or fuel delivery. That would cause a lack of power and possibly the noise you're hearing. If your fuel pump has died, the injectors are acting like little plunger pumps and will try and draw fuel all the way from the tank.

I would stop swapping parts till you ID the actual problem. It's common for injectors #3 and #8 to fail the CCT, especially with Ford's replacement grey CPS. All parts swapping does is drain your wallet.
I’ll see if I can get the tools together to test fuel pressure. What all do I need? You’d just hook up to the back of the fuel bowl right? Do I need idle fuel pressure?
 

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I’ll see if I can get the tools together to test fuel pressure. What all do I need? You’d just hook up to the back of the fuel bowl right? Do I need idle fuel pressure?
You'll need a #3 (IIRC) SAE boss o-ring to NPT adapter to screw into the back of the fuel bowl for a good pressure test. Along with a short hose with NPT threads and a 0-100 psig pressure gauge. Here's the adapter from Diesel-o-rings. https://www.dieselorings.com/1999-2003-ford-7-3l/fuel-bowl-parts/pressure-port-adapter-straight-1-8-fnpt.html They also sell a schrader valve that fits in the test port. https://www.dieselorings.com/schrader-valve-fuel-injection-rated-1-8-mnpt.html
You can do a quick and dirty pressure test by connecting to the drain tube from the filter housing at the front of the block, but the hose at the drain valve is just a push on fit and may blow off.
You can definitely check for fuel flow without any tools. Just have someone turn the key on and before the fuel pump shuts off, open the drain valve at the back of the filter. If your pump is delivering fuel, you should get a healthy stream out the tube.
 

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Discussion Starter #8
I’ll see if I can get the tools together to test fuel pressure. What all do I need? You’d just hook up to the back of the fuel bowl right? Do I need idle fuel pressure?
You'll need a #3 (IIRC) SAE boss o-ring to NPT adapter to screw into the back of the fuel bowl for a good pressure test. Along with a short hose with NPT threads and a 0-100 psig pressure gauge. Here's the adapter from Diesel-o-rings. https://www.dieselorings.com/1999-2003-ford-7-3l/fuel-bowl-parts/pressure-port-adapter-straight-1-8-fnpt.html They also sell a schrader valve that fits in the test port. https://www.dieselorings.com/schrader-valve-fuel-injection-rated-1-8-mnpt.html
You can do a quick and dirty pressure test by connecting to the drain tube from the filter housing at the front of the block, but the hose at the drain valve is just a push on fit and may blow off.
You can definitely check for fuel flow without any tools. Just have someone turn the key on and before the fuel pump shuts off, open the drain valve at the back of the filter. If your pump is delivering fuel, you should get a healthy stream out the tube.
Thanks for the info. I get a valve and see what I get. The pump is new and I have seen diesel run out of that tube recently, I think I need to rule out the pressure. Is there a ok way to test it under load?
 

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There's no real need to test under load. You should see at least 50 psi whether it's at idle or under load. The pump delivers a fixed amount of fuel, with the bulk of it being returned to the tank at idle, and a bit less when under load. If you really want to, you could get a longer hose and strap a gauge to your windshield wiper so you can see it driving down the road.
 

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Discussion Starter #10
There's no real need to test under load. You should see at least 50 psi whether it's at idle or under load. The pump delivers a fixed amount of fuel, with the bulk of it being returned to the tank at idle, and a bit less when under load. If you really want to, you could get a longer hose and strap a gauge to your windshield wiper so you can see it driving down the road.
So I know about the pick up that can break in the tank, and there’s the pump and the filter in the fuel bowl, but is there anything else that’s known to cause fuel restriction? Thanks for the info!
 

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There's no real need to test under load. You should see at least 50 psi whether it's at idle or under load. The pump delivers a fixed amount of fuel, with the bulk of it being returned to the tank at idle, and a bit less when under load. If you really want to, you could get a longer hose and strap a gauge to your windshield wiper so you can see it driving down the road.


So I know about the pick up that can break in the tank, and there’s the pump and the filter in the fuel bowl, but is there anything else that’s known to cause fuel restriction? Thanks for the info!

The pickup foot can break causing an issue when fuel gets low. It has a strainer screen on the bottom of it to stop large debris.There are also two screen cartridge filters (see picture) that need to be checked in the pickup assembly. Those will be eliminated if you do the Hutch Mod. If you do eliminate them, a lot of the Hutch Mod Kits have a filter base and filter to be located on the frame of the truck between the tank and fuel pump.
 

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Discussion Starter #12
Update:
I tested the compression on the engine and I got this:
1-375. 2-400
3-320. 4-340
5-340. 6-380
7-340. 8-320

I still have the glow plugs out, but when I turn the key over 4-5 times to prime the fuel bowl I am getting 50psi of fuel pressure.
 
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