CAT C9 Fuel pressure

[Jimmy Garcia]

Good day all.  Love my 06 Monterey.  Last run noticed the power seemed a little bit off while climbing and my fuel economy is about 6 mpg flat land power seems good.  I hooked up to the compucheck port next to the fuel filter and its is running 65 low idle and 67 fast idle.  From what I read seems that low idle should be in the 58 psi range and 81 high idle.  Seems strange to have a narrow spread?  Any idea why?  Planning to swap out the WIX water separator and primary fuel filter to CAT and see what happens.  Also priced out the electric fuel pump as a last straw.  Thanks all.  Have a pleasant day.  Cheers.   

[Roy Warren Co-Admin]

Have you monitored your boost pressure?  I had low power and found the Charge Air Cooler had numerous leaks and my boost pressure was very low.  Might give that a check prior to changing out everything else first.
Roy Warren

[Jimmy Garcia]

Thanks for the question.  Boost was checked on Alladin at 29psi 1820 rpm while I was driving.  Appreciate the assist.  Have a pleasant evening.  Cheers

[Joel Ashley]

Jimmy-
suggest you click the bold blue link at this page’s upper right, log in at that main BAC site, tap the “Technical” tab, and choose “Ask Dave”.  There you will find information germane to your not uncommon issue from Dave Atherton, the club’s spiritual CAT counsel.  You’re on the right track replacing with all CAT filters, and some C9 installations benefit from an added pump.

Joel

[Jimmy Garcia]

Jimmy-
suggest you click the bold blue link at this page’s upper right, log in at that main BAC site, tap the “Technical” tab, and choose “Ask Dave”.  There you will find information germane to your not uncommon issue from Dave Atherton, the club’s spiritual CAT counsel.  You’re on the right track replacing with all CAT filters, and some C9 installations benefit from an added pump.

Joel

Good day Joel, 
Thanks for the lead.  I will see how the filters do tomorrow.  I wonder how much priming I need to do before starting?  If the engine is not completely primed would that be an issue.  When i pushed the primer plunger it moved in fairly easy, but never had an issue with starting.  I read the system is not under pressure so I am thinking once the engine starts and Pumps gets going it will pressurize the entire system to the needed pressure.  Thanks again. 

[Jimmy Garcia]

Update filters changed with no improvement in pressure.   2k rpm fuel pressure was 72psi. For those that did the fuel pump upgrade what change in pressures did you get?  Thanks.

[Bryan Beamon]

Jimmy, as indicated call Dave Atherton @ 605-999-0720. He suggested new o- rings on all fuel lines and a new fuel pressure regulator for our Cat C-9 with low fuel pressure.

[Joel Ashley]

I agree with Bryan, Jimmy.  As I previously suggested, Dave Atherton is the guy to contact for the best CAT advise in the land.  Our ‘06 Monterey is relatively short and light, and thusly does just fine on hills;  so I’m not thinking of adding the additional fuel pump.   Owners of heavier Montereys usually benefit from the added pump.   I can’t advise as to the expected normal pressure of your current setup, but Dave can.  Until you attack another hill with the fresh filters, it’s hard to tell if your problem was just dirty filters.

If your filters are CAT and new, with no sign of debris in the sight bowl so far, perhaps there is something else awry.  Dave will have some ideas, so call him;  and in the interim you should review his C9 advisories at “Ask Dave” under the “Technical” tab at the main BAC website.

Joel

[Jimmy Garcia]

Thanks all.  I did send Dave an email.  Did not want to call over a holiday weekend.   I will keep the thread informed on the progress.  CAT didn't have the regulator locally when I got the filters.  I was wondering what anyone's eyes real pressure numbers vs the 58 and 81 pai recommend by CAT.  Thanks everyone.  Cheers.

[Bryan Beamon]

Our c9 fuel pressure was 63 psi at idle and 79psi at 1000 rpms. Attached picture show a 2006 c9 specification from Cat for fuel pressure ranges. Hope this gives you some piece of mind about your fuel pressure. 

[Jimmy Garcia]

Thanks all.  does anyone know what type of fitting this is?  was hoping to find a adapter or bigger fitting my oem is smaller than the cat pump opening.

[Scott Shearer]

Jimmy,

That is a VOSS 246 snap-lock adaptor, appears to be a VOSS x 1/2” NPT. If that is straight thread with an O-ring, then it would probably be a VOSS x -8 ORB.

-Scott

[Jimmy Garcia]

Jimmy,

That is a VOSS 246 snap-lock adaptor, appears to be a VOSS x 1/2” NPT. If that is straight thread with an O-ring, then it would probably be a VOSS x -8 ORB.

-Scott

Thanks Scott.  Actually had a talk with Dave and he suggested cutting them off and using Parker fittings.  Thanks again. 

[Jimmy Garcia]

So incase anyone ever sees this post and is curious about the outcome.  In summary I added the fuel pump and there was not a whole lot of noticeable change to fuel pressure.  It was awesome not having to prime the system and by itself may be worth the cost of admission.  Ended up changing the fuel pressure regulator as per Dave's recommendations the regulator was disassembled and the filter screen was removed.  The new results were obvious.  I saw an increase of pressures all around.  Idle 65-67psi, fast idle 75-77psi, and at 2k RPM 80-82psi.  Note the pressures increased when throttle applied from fast idle to 2k rpm, since I used that as a previous benchmark you can tell the higher pressures.  I am hoping to see some improvements on the road with these improved numbers.  Time will tell.  Thanks to everyone that has helped especially Dave, he is an pleasant person to call on and has been such a great resource.  Thanks again all.