3406 b sudden loss of power

wore out · Feb 4, 2022

See if it will hold vacuum

tj379 · Feb 4, 2022

well i made somefittings up off my vac pump and it wont pull down when hooked to thecafr, i put my thumb over fitting gage pulls rite down so i onow gage work i put on afr nuthin, so i guess put a diaphram and try or just a complete new unit?

tj379 · Feb 4, 2022

when i start pump it pulls mabe 3-4 inches if i leave it run it dont draw down anymore

SmokinCAT · Feb 4, 2022

wore out said: ↑

When it’s sudden like that AFRC diaphragm is the usual culprit. I had one not long ago that broke the nail head off the small spool inside, spool was froze in the piston.
Click to expand...

Most wouldnt notice that though as after it broken it was basically full fuel all the time.

tj379 · Feb 4, 2022

shes got a rip rite in it , thanks for the help gyes , on my way grab a new one

wore out · Feb 5, 2022

SmokinCAT said: ↑

Most wouldnt notice that though as after it broken it was basically full fuel all the time.
Click to expand...

I’m talking about the spool inside the AFRC. The spool that goes into the big piston

qak · Feb 5, 2022

tj379 said: ↑

hello , i have a 7fb 3406 b that i lost power on yesterday, truck has allways worked really well, can only get bout 15 -19 psi boost but takes a bit, it used did junp to 32-35 psi when u got into it, i changed fuel filters and blew out fuel lines,checked air filters,checked turbo,turbo is 2 year old cat and spins n looks like new inside with zero play,, did a wuick visual of charge boots, all looked ok and never changed anything , inpuuled afr line no oil in it, injection pump was totally rebuilt 2 years ago also , lookin for ideas, to me whdn i stab the throttle its not gettin euff fuel, it used smoke black when i stood on it not now, everything else is normal, egts, fuel n oil pressure, ideling, no missing , ? stumped
Click to expand...

This might sound stupid but check along the frame for a fuel prefilter, I had an old B model that did the same thing and all the shops said they changed the fuel filters but when I looked closer I found a small pre filter tucked along the drivers frame by the edge of the rear of the engine that had been there so Long it rusted, changed it out and it ran great

SmokinCAT · Feb 5, 2022

wore out said: ↑

I’m talking about the spool inside the AFRC. The spool that goes into the big piston
Click to expand...

was thinking you were talking inside the pump about the piece the hooks into lever inside the governor housing.

tj379 · Feb 6, 2022

so when i reinstall the afr, do i put the head of the pin on the back side of that fork in the pump so it pulls on it im assuming?

Star Rider · Feb 6, 2022

Yes , the AFR pulls the fork

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