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Topic: Question for any knowledgeable folks on CAT 3126 used in FTs (Read 551 times) previous topic - next topic

Question for any knowledgeable folks on CAT 3126 used in FTs

I have the CAT 3126 in my '97 U295.  The coach label is dated 1/97 so the engine is likely a 1996 vintage.

A tech (formally of FT) recently told me that on these engine the fuel flows through the first stage filter (fuel/water separator) to the pump and on to the injectors.  Then the excess fuel passes through the on-engine CAT filter as it returns to the tank.

This is totally contrary to my previous CAT engine and to my logic.  It seems to me that CAT would design the fuel flow to go through their fine, on-engine filter before it hits the injectors to avoid any potential of clogging them.  Unfortunately, the flow to that on-engine filter is buried on this engine so, unlike my prior 3176 experience, I can't see the flow lines in/out of the CAT filter to follow it.

Does anyone happen to know, or can point me to a good source to find out?

Thanks.
Regards

1997 U295 40 with CAT 3126

Re: Question for any knowledgeable folks on CAT 3126 used in FTs

Reply #1 –
Primary filter are typically 30 microns. The fuel then travels to the secondary filter that takes out the small stuff. 10 microns on older engines, 2 microns or so on the later engines. The lift pump may be between the filters. So, fuel is sucked (unless there is a pump in the fuel tank) through the primary filter then the secondary filter typically sees 20 to 55 psi depending on engine brand.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Question for any knowledgeable folks on CAT 3126 used in FTs

Reply #2 –
That cat phone #????, Would like to find out more info on my Engine. Looked online with success.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Question for any knowledgeable folks on CAT 3126 used in FTs

Reply #3 –
Quote from: Pierce & Gaylie Stewart –
Primary filter are typically 30 microns. The fuel then travels to the secondary filter that takes out the small stuff. 10 microns on older engines, 2 microns or so on the later engines. The lift pump may be between the filters. So, fuel is sucked (unless there is a pump in the fuel tank) through the primary filter then the secondary filter typically sees 20 to 55 psi depending on engine brand.

Pierce
Per Brett Wolfe,no lift pump in tank.
My return line goes directly back to the tank.
You might want to consider new fuel lines. Mine are cracked.
Chris and Tammy White  CDA Idaho
Previous owners 1997 U295 36' 3126 Cat 300 HP Build # 4998
Former Foretravel tech & RVIA certified tech
Former owner Custom Satellite home/RV satellites 
Former owner Vans LTD  van conversions
Unemployed, panhandler, drag racer NHRA #6348

Re: Question for any knowledgeable folks on CAT 3126 used in FTs

Reply #4 –
Quote from: Old phart phred –
That cat phone #????, Would like to find out more info on my Engine. Looked online with success.

Cat RV hot line

Boost, oil pressure etc. Very helpful. Have your engine serial number ready

877 777 3126
Chris and Tammy White  CDA Idaho
Previous owners 1997 U295 36' 3126 Cat 300 HP Build # 4998
Former Foretravel tech & RVIA certified tech
Former owner Custom Satellite home/RV satellites 
Former owner Vans LTD  van conversions
Unemployed, panhandler, drag racer NHRA #6348

Re: Question for any knowledgeable folks on CAT 3126 used in FTs

Reply #5 –
Some good and some not so good information above.  Fuel flow with Caterpillar 3126 (basically same as most other properly set up diesel engine):

Fuel tank to primary filter/water separator.  Element can be between 10 and 30 microns.
Through lift pump.
To secondary (fine) filter.  2 micron for your engine-- IMPORTANT. Strongly recommend Caterpillar secondary fuel filters.
Then to the injection/ HEUI pump.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Question for any knowledgeable folks on CAT 3126 used in FTs

Reply #6 –
Thanks Brett.

That's exactly what I thought.  I couldn't believe that anyone would set up a fuel flow with the finest filter on the return line to tank, but the tech was insistent.  It's not the first time I've run into this sort of completely erroneous info stated total conviction.

I DO use the CAT-specified filter as I did with my previous coach.

With the earlier coach (CAT 3176) the primary and secondary filters were in obvious series and I could see the fuel lines that connected them.  Not so clear with this engine.

I appreciate the clarification.
Regards

1997 U295 40 with CAT 3126

Re: Question for any knowledgeable folks on CAT 3126 used in FTs

Reply #7 –
Bill,

Even on the 3176, the course filter/water separator should have been on the suction side of the pump and the fine filter on the other.  Yes, they can be located next to each other, but follow the hoses!
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Question for any knowledgeable folks on CAT 3126 used in FTs

Reply #8 –
Quote from: BillO –
I couldn't believe that anyone would set up a fuel flow with the finest filter on the return line to tank(THEY DON'T), but the tech was insistent.  It's not the first time I've run into this sort of completely erroneous info stated total conviction.
AKA as a fool, how old was this tech BTW? Find a new service location.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Question for any knowledgeable folks on CAT 3126 used in FTs

Reply #9 –
Quote from: Old phart phred –
AKA as a fool, how old was this tech BTW? Find a new service location.

The tech was not that old by my standards (everyone under 40 looks young to me these days), but had worked at FT for several years.

The service location is one of the well-regarded outfits in NAC so I won't write them off my list.

As a BTW, I've had one well-praised tech tell me similar things that I knew (or suspected) were wrong, like "regular diesel engine antifreeze with ethylene glycol is no longer a poison" or "house batteries will cycle back to bulk charge on shore power because FT didn't install enough batteries".
Regards

1997 U295 40 with CAT 3126

Re: Question for any knowledgeable folks on CAT 3126 used in FTs

Reply #10 –
Just thought of something,I thought Foretravel does not do engine work so how would he even know about the fuel systems?
96 U270 BUILD 4810
85 380SL
Drummonds TN.
 

Re: Question for any knowledgeable folks on CAT 3126 used in FTs

Reply #11 –
FT does do oil changes, etc. so I assumed he picked it up from someone there.  Alternatively, he might have simply concluded that from the location of the return fuel line.  Who knows!!
Regards

1997 U295 40 with CAT 3126