3406b low boost and fuel pressure issues
Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by rs72z, May 28, 2022.
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Doesn’t really sound like fuel pressure to me. Is it chopping or smooth. If your running a spin on water separator change it to the washable CAT screen that will help it noticeably but isn’t why it lost boost.
I would check the pyro. With multiple boost leaks/intake gaskets pushed out it should have run warmer than 750 for sure.
I haven’t heard of a Mississippi red hot turbo, but that doesn’t mean anything.
What’s the serial number 8PN? Bottom of pump on back is a brass lug looks like it doesn’t fit no wires to it. Take a regular test light (led wont work here) and hook the clamp to battery positive. Put the probe on this brass lug. With the motor running wrap it to wide open rapidly. The light should light before the govnor catches it. If so that says rack is opening all way. Also make sure the break over spring isn’t broke and make sure when pushing throttle in cab it opens all way at pump. That 3/8 bolt can come loose and cause a little hell. If that checks out pull the cartridge out the hot side of turbo and see if it spit something outmile marker 27, ProfessionalNoticer, Another Canadian driver and 5 others Thank this. -
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Spec on fuel pressure is 42 at high idle no load. 32 under load......Falling to 20 for a few seconds is pretty well normal for most. Quit guessing and put a restriction gauge between the lift pump and water separator. 0-2 is sucking air. 3-6 or so is normal. A little higher is doable 9-10 is a restriction
AModelCat, ProfessionalNoticer, Another Canadian driver and 4 others Thank this. -
Is that roughly where your EGT's were before, or a little higher?Another Canadian driver Thanks this. -
running cat filters 256-8753 water separator and 1r-0479. Do you have a part number for the washable cat filter.
I can check pyro but it's goes up as boost goes up.
I'm going to show my ignorance. What's the break over spring?
It is getting full throttle.
I havent pulled the cartridge out but i have pulled the elbow off and it looked fine and didn't have any play in the shaft.
I dont have the truck here right now so i will have to check the serial number.Another Canadian driver Thanks this. -
Turbo looks good and has just about 125k on it.
Yes that's about where it's always been.
I was told that with the ceramic manifold i wouldn't see high egt'sAnother Canadian driver Thanks this. -
Another Canadian driver Thanks this.
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