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Discussion Starter · #1 ·
Hey all, I've been gone a long time...trucks been running great till now. 2000 7.3 350000 mi. Mostly stock,good maintenance.
This morning on the way to work I noticed a vibration, I pulled over thinking I had a flat tire.nope. Got back on the road and the vibration was bad under load and went away when I let off the gas. Got to work and looked at it with the diesel mechanic and we both though I had a bad injector. Some bluefish/white smoke when reved in neutral. Half way home it got dramatically worse. Had the pedal to the floor to keep chugging 40mph. Got home and checked the under valve cover and all looks good... I'm at a loss.... Any ideas
 

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Discussion Starter · #3 ·
No, he's a heavy equipment mechanic so no diagnostic tools for light trucks. Bad injector was our 1st thought but then the truck started running much worse than if it was just 1 injector. I have the vc's off I can check the injectors tomorrow. I was really hoping for a bad uvc harness.
 

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Injector orings are about $8 an injector. Do all as a set.
Make sure you clears the cylinders of fluid after installing injectors. Leave glow plugs out. Turn crank by hand with socket and ratchet. Rotate 3 times, then spin over.
Make sure injectors are seated before tightening. You should here it give a heavy iron thud. Don't hit solenoid so with rubber mallet. Uses head to lean on. Use the handle to push down on the retaining plate.
Ohm glow plugs and injector at valve cover first to check wiring and components you now have exposed.
 

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Discussion Starter · #6 ·
I'll check the fuel out of the bowl tomorrow. Although I can't rule anything out I don't think it's injector orings or a single bad injector. The truck ran fine 1 minute then bad the next. Then later it suddenly went drastically worse. I think I need to look closer at the uvch. I didn't undo the plugs, just looked to see it they were still on. They were on but both sides had about a 1/16" gap. Is that normal?
 

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Discussion Starter · #10 ·
No, it wasn't open that much. The clips were still engaged they're was just a slight gap between the 2 plug halves. I thought I read somewhere that the pins can burn up?
 

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Sounds like a fuel issue or just a bad cps.

Either a failing fuel pump or possibly clogged in tank screens.

Nicks idea is good about opening the valve checking for flow
 

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Discussion Starter · #14 ·
Ok, was digging around a bit and this is what I found. I drained the fuel bowl and. Took out the filter. I have a hose from the bowl to a gallon jug on the floor. When i turn the key on there is not a steady stream of fuel into the bowl. It's kinda gushy-intermittent for a second or 2 then it becomes steady but a lot of foam. It took about 10 key cycles to fill he gallon jug. Many,many moons ago I did the in-tank mod so I have a clear inline filter just before the pump. When I cycle the pump there is lots of air coming thru the clear pre pump filter. It seems to me that the fuel pump doesn't sound quite right. While it pumps fuel into the bowl it doesn't "shoot it" in there.
So it seems to me that I should drop the stupid tank and take a look at the pick up. And may also have a weak pump? Or maybe the pumps output is diminished because of the air getting in...? Any thoughts?
 

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Cool, you found your problem.
The pump sounds different due to the air in tank.
Did you use new 3/8 fuel line when you did the tank mod?
Yeah the boot or pipe fell off or the compression fitting you used on the pick up pipe may be sucking air.
 

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Discussion Starter · #16 ·
Actually, the clamp on the supply line coming from the tank broke. Allowing air to get in. Now I'm looking for tank straps because both off mine were 90% rusted thru. May be a blessing in disguise that the tank didn't fall while driving
 
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