Still @ 45psi of Fuel Pressure

[Cooker]

I'm still running 45psi of fuel pressure @ idle with a new filter.



I removed the overflow valve, it looked ok. I removed a shim/washer from under the spring and reinstalled it. Pressure dropped 3psi. I reinstalled the shim figuring 3psi wasn't enough to solve my problem.



Next I moved to the return line. I removed the return line at the first hard line to rubber line connection after the overflow valve. Once again I only lost about 3psi.



I'm thinking of trying a new overflow valve, but it seems that most times they go bad pressures are low and not high.



What else could be causing this high of fuel pressure?



Thanks for the help,

Ryan

 

[Steve Roseman]

Cooker,

I'm no expert on diesels, but I'd say your overflow valve could go bad both ways. Kind of like a thermostat being stuck open or closed. You could try running some compressed air through the return to the tank to see if there is restriction, but it wouldn't hurt to ask someone more knowledgeable on the subject about damage that could occur. Good Luck.

 

[Cooker]

Ron,



I looked in the service manual and I didn't see a test about putting air to the overflow valve. Could you explain a little more please?



Thanks,

Ryan

 

[illflem]

I may be sticking my neck out here, this is just a theory, but could your injection pump be bleeding back pressure causing the high readings? I've never torn into an IP to see what makes them tick, I leave that to the experts, but every high pressure pump I've ever worked on has valves or some other device to keep the high pressure from bleeding back to the inlet. I've heard that an IP pump bleeding back can cause very violent pulsations in the inlet fuel pressure. Just a thought.



I've never heard of using air to check the pressure and can see no reason to do so if the engine still runs. If you do be prepared for a major bleeding job.

 

[illflem]

Ron, you're reading from a 24 valve manual, the 12 valves have an entirely different fuel system.

 

[Joe G.]

Ryan,



I hate to ask you this, but have you checked the gauge to see if it's right?

 

[Cooker]

Joe G.



The gauge is brand new. I bought it just for testing fuel pressue. It could be bad, but very unlikely.



Ryan

 

[Ron Bissett]

Originally posted by illflem

Ron, you're reading from a 24 valve manual, the 12 valves have an entirely different fuel system.

Thanks i thaught the return valve was the same , i know the oil cools on the 12 but check valves work alike. I stand corrected thanks . Ron in Louisville Ky P. S will deleat other post.

 

[Don M]

Cooker, verify your gauge is reading correctly. You could use compressed air that is regulated and get close.



I dont see how, at idle, the lift pump could produce 45psi.



one last thought. . is your gauge for reading PSI?



Don~