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Buddy, Technician
Category: Heavy Equipment
Satisfied Customers: 730
Experience:  25 years experience
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cat c15. Replaced all suction lines. Checked return fuel check

Resolved Question:

cat c15. Replaced all suction lines. Checked return fuel check valve. Still 10 lbs low on fuel pressure. What now?
Submitted: 7 years ago.
Category: Heavy Equipment
Expert:  Buddy replied 7 years ago.

HiCustomer Welcome to JA. I am Buddy, and i will try and help you out.


What is your fuel pressure?

What symtoms are you having?

What is your engine serial number?




Customer: replied 7 years ago.

SER#MBN03730 Fuel pres. From 95 down to 80 now. Came home earlier and idled up. Engine "coughed" several times until up to full idle. Makes me think with that, its sucking air some where.Pressure was 85 this morn. Supposed to be a check valve on the injector pump I could check for maybe too much return fuel?

Expert:  Buddy replied 7 years ago.
Thanks for the info.

Sounds like you are loosing prime or possibly sucking air on the primary side.
That fuel pressure is normal. Normally it is around 75 at idle and 95 at full throttle.It is also normal for some engines to vary a little on pressures.I would first start off checking and possibly replacing the return check valve.It is located in the fuel filter manifold.
I am attaching picture of location of return check valve. It is callout 5 in picture.I would inspect it and make sure there is no debris in it. If valve is good, i would recommend bypassing primary fuel system and running straight out of tank or 5 gallon bucketwith test line straight to fuel pump and see if engine looses prime. That will let you know if anything on suction side is bad. I would also check oil level and make sure there is no fuel in the oil.I hope this helps you out. If you have anymore questions, just ask.



Edited by Buddy on 2/19/2010 at 2:51 AM EST
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