Fuel filter gauge shows restriction sometimes

[Bigstank]

hey got a question for the fuel system on this demandated CM871. My fuel filter gauge will show 5-ingh and the truck runs crappy as in low power & bad fuel mileage and it also has a throttle vibration but if i shut it off and let it sit for like 30mins and restart it. It runs excellent with the fuel filter gauge showing only 1-inhg. Where should I start to find what is causing the fuel flow restriction? The engine was inframed back in sept 2019 by haggai so we all know it was done right. Thanks guys

[tree98]

Change the filter !!!!

[Bigstank]

(04-25-2020 )tree98 Wrote:  Change the filter !!!!

Not the problem but thanks anyway

[hhow55]

A good start would probably, to check the fuel pressure while acting up.

[Lonestar10]

Sounds like fuel line is collapsed

[Chamberpains]

Maybe take a really bright flashlight and have a look in the fuel tanks. Make sure the pickup lines aren't pinched some how or some garbage isn't getting sucked to the end of the line.

[Rawze]

It should not run crappy unless the fuel pressure is falling off. Is the fuel pressure falling off?

Maybe its also sucking air somewhere?.

Then again, if there is a large enough restriction in a fitting or housing or soemthing, could be cavitation in the circuit, allowing for bubbles. Would have to be fairly significant a restriction though. Collapsed line, piece of gasket or something up in the housing, etc.etc.

- just some thouhts on it.

Might also eliminate possibility of air problems in the system too while your at it. Do an overhear valve adjustment followed by an injector leak test ...





-- After that, perhaps pressurize the fuel tanks to 10 psi and let it sit for hour or so .. look for leaks in the fuel lines and circuits. Could also put the feed line to the IFSM into a bucket and pressurize the tanks ... see if you are getting air bubbles in the fuel as it is forced thru the lines out the tanks (testing for cracked pick-up tubes).


-- more guesses...
Also, there is a check valve at the electric fuel pump (sometimes there is also a screen on some of the older models). - It often goes bad and gets trash in it. Could be that it needs cleaning and/or replacement too.

[SquareOne]

How often has it been happening and when did it start? Is it consistent? Do you do mainly run highway, off-road, or both? Anything different about the areas of travel you are going into?

Reason I ask ---- I remember about 12yrs ago when I was a heavy equip operator, the material we were pushing around was wreaking havoc on fuel systems and air filters. The material was such a fine powder that it literally would sneak its way into the tanks with just the typical expansion / contraction from the temperature changes. Filters would clog rapidly and the elements would 'look' fine since the material was neutral colored. We used a parts cleaner with a clear glass bowl to back-wash the fuel filter in order to find the cause of our woes. The amount of $hit that came out was seriously unbelievable.

May not have anything to do with your situation, but in any of your environments have changed recently, you may want to start there.

[Bigstank]

Thanks guys for the info. Im gonna get over to see Jerry and have him check it out