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CATEGORY LISTINGS > CATERPILLAR > C-15 fuel aeration [ REFRESH ]
Thread Title:

C-15 fuel aeration


Created On Monday March 31, 2008 18:00 Diesel Talk
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TERMINATOR8
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Note Monday March 31, 2008 18:00 View thread in raw text format
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I have a 2005 c-15 acert rated at 550hp that has had a rough idle and rough running since I bought it. Had it checked several times and it always passed cylinder cut-out and vva tests. Was constantly told the roughness was normal. On last diagnostic I was told the fuel pressure was 10 to 15 lbs low so I replaced the transfer pump and changed the filters.(All prev. service was done by KW) Thats when I found the primary filter was only half full. So far I have replaced all fuel lines and pressure tested the pick-ups in the tanks. Still had the problem so I pressure tested the old lines and went back to them.(the fittings on the new lines were slightly different) No matter what I do I can't seem to get rid of the air. I called the Cat OHE call center and was told by the "technician" that according to the fuel system engineers this is normal!! I bit my tongue and didn't call him an idiot but I wanted to. The engine runs smooth and has great power until it gets the air again so I am constantly refilling the primary and bleeding the fuel system. Is there anything on the pressure side of the system that could possibly cause pump cavitation or cause the primary filter to pull half empty? I also replaced the check valve just in case but still have the problem. The primary has the Cat filter base for increased flow and I have tried Cat water separator filters with and without the stovepipe. Local Cat dealer wants to replace injectors but I have a hard time seeing them as a cause and don't want to spend 4 grand on a fishing trip. Can anyone help while I still have hair left?confused

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 jlsj05t2
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TDcrash63
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Note Monday March 31, 2008 20:16 View thread in raw text format
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I would check the fuel return line for air by installing a clear section of hose after the fuel check valve, or run the return into a bucket. Sometimes you will only have air under a load as cylinder pressure increases. You can also install a section of clear line before the cylinder head after the fuel filter base. This would eliminate any doubts of air in the fuel suction. Sounds as if the air is coming from the engine itself. I was always told that a fuel filter on the suction side will never run full unless it is plugged. A clean filter will run half full. You may have a cut oring on an injector, a bad injector or maybe a problem with a hold down bolt or injector bore. You did not say how or when this started. A very very small amount of air in the fuel system will not have ay effect on the way the engine runs. If you have air in the return but no air coming in you could plug the fuel outlet out of the head and put regulated air pressure on the fuel in to the head, 40 psi or so. Fuel system should hold this pressure and not bleed down. If it does I would Blow all the fuel out of the head and pull the injectors to verify the orings or check for other possible problems. Good luck.
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TERMINATOR8
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Note Tuesday April 01, 2008 05:23 View thread in raw text format
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I'm not sure I understand the half full theory but I have been using clear hose to try to find the problem. I am still seeing air bubbles going into the transfer pump. All of the injector o-rings have been replaced along with nos. 5 and 6 injector. I am slowly working my way forward from the tanks with my homemade sight glasses to try to find where this air is coming from. Would compression getting by the O-rings affect the suction side? My thinking was that it would follow the path of least resistance through the return line to the tanks. I have run it and checked the tanks with a mirror and haven't seen any aeration in the return or in the tanks. I am slowly eliminating possibilities and appreciate your help. You've given me something to look at.

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 jlsj05t2
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catmech
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Note Tuesday April 01, 2008 18:29 View thread in raw text format
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there are different types of primary filters, some are just a screen type and some are an actual filter media. cat has put a check valve in some of these to stop fuel from siphing back to tank. also how high is your primary filter from the transfer pump or how low is it?
what begining serial number do you have and what arrangement number?
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TERMINATOR8
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Note Wednesday April 02, 2008 03:06 View thread in raw text format
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bxs 28405

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 jlsj05t2
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TERMINATOR8
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Note Thursday April 03, 2008 12:38 View thread in raw text format
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Today I installed a sight glass before and after the water separator/primary filter. Found no air from tank side but considerable air coming from primary to transfer pump. Bypassed primary and engine runs great again. I'm currently looking for a primary filter system with electric step up pump to replace existing spin on

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 jlsj05t2
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catmech
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Note Thursday April 03, 2008 18:25 View thread in raw text format
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glad you put the tube before and after. once a primary is full it should stay full unless it is siphoning back to tank. some filter bases just don't seem to seal well, unless you over tighten the filter to it. had one not to long ago that if it set two or three days machine would start and die, restart it and an it would die again, this would happen up to five times then start and run fine. it was the primary filter base not sealing well, letting air get in around the seal.
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