Author Topic: CAT C9 and C12 Fuel Pump Comparison  (Read 611 times)

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Offline Ken Carpenter

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CAT C9 and C12 Fuel Pump Comparison
« on: January 09, 2018, 06:59:27 AM »
Why is it difficult for the C9 to maintain proper fuel flow and pressure with the original pump that CAT supplies on the engine while the C12 engine does not have this problem?
 
2005 Winnebago Journey 39K, C7 350HP
Jeep Grand Cherokee, Airforce One
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Offline Ken Carpenter

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Re: CAT C9 and C12 Fuel Pump Comparison
« Reply #1 on: January 09, 2018, 07:07:28 AM »
Here is Dave's response:
The attached pictures show the assembled C9 fuel pump as it comes from CAT. The second picture shows both a C9 (top) and C12 fuel pump disassembled. Note the difference in impeller size and thickness.  The C9 is .125 thick while the C12 is .500 thick.

Both engines are rated at 400 hp.  Consider that both pumps have to supply sufficient fuel to generate 400 hp. One might think this was poor C9 engineering on CAT’s part until one understands that C9  is designed to be less than 10 feet from the fuel tank. In our motorhomes with the tank 30-35 feet from the pump, one can begin to understand the reason for degraded performance and why the electric fuel pump CAT #206-5756 is recommended to improve fuel flow and pressure for your C9.
2005 Winnebago Journey 39K, C7 350HP
Jeep Grand Cherokee, Airforce One
Diesel RV Club Officer & Board Member