Superthermal
Well-known member
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- Utah, Murray, United States
Hello All, My M813 "THE BOT" which I drove 2385 miles cross country from Detroit to Salt Lake has a fuel issue. The rig runs fine on flat ground with a tailwind but is GUTLESS on any hill. I have read some of the other threads on similar issues and have taken these initial steps to figure out the problem is not fuel delivery to the PT pump.
1.Inspected and pressurized the tank pickup tube to ensure it was free of any pinholes.
2.Inspected and chased the copper 3/8" delivery line to the filter housing to ensure it was free of any obstruction. Found the tube to be totally clean.
3.Replaced the original cartridge fuel filter and sealed it the housing up with a new seal and O-ring.
4.Replaced the 5/8" hose up to the PT pump with new 10AN fittings and 5/8" rubber hose.
5.Replaced the steel fuel rail lines from the PT up to the head with 6AN high pressure line.
6.Installed a "T" on the fuel rail lines and put in a pressure gauge to inspect the pressure and later a compression testing gauge to double verify my fuel rail pressure findings.
Turns out I get a maximum rail pressure of 30 at 2000ish rpm. I did see it go to 50 once just after startup. If at Idle I am getting next to zero pressure. Both gauges used go to either 200 or 300 psi so I am guessing zero is like maybe 5 psi. To check the flow I pulled my gauge off the 6' line I had running up into the cab and the motor would still run and I had a solid stream into my bucket with no apparent bubbles. I can have the rig run and come back latter and it fires right up so I am feeling it is not loosing prime or anything like that.
There are a lot of possible causes right up to leaking fuel injectors. Any thoughts on how to verify it is the PT pump over injectors? Such as blocking off the output of the PT pump to see what its top output pressure could be (I read this somewhere here but pump damage could occur if done wrong or too long or...?)
Any pointers would be helpful! Thanks, thanks, Thank you in advance.
1.Inspected and pressurized the tank pickup tube to ensure it was free of any pinholes.
2.Inspected and chased the copper 3/8" delivery line to the filter housing to ensure it was free of any obstruction. Found the tube to be totally clean.
3.Replaced the original cartridge fuel filter and sealed it the housing up with a new seal and O-ring.
4.Replaced the 5/8" hose up to the PT pump with new 10AN fittings and 5/8" rubber hose.
5.Replaced the steel fuel rail lines from the PT up to the head with 6AN high pressure line.
6.Installed a "T" on the fuel rail lines and put in a pressure gauge to inspect the pressure and later a compression testing gauge to double verify my fuel rail pressure findings.
Turns out I get a maximum rail pressure of 30 at 2000ish rpm. I did see it go to 50 once just after startup. If at Idle I am getting next to zero pressure. Both gauges used go to either 200 or 300 psi so I am guessing zero is like maybe 5 psi. To check the flow I pulled my gauge off the 6' line I had running up into the cab and the motor would still run and I had a solid stream into my bucket with no apparent bubbles. I can have the rig run and come back latter and it fires right up so I am feeling it is not loosing prime or anything like that.
There are a lot of possible causes right up to leaking fuel injectors. Any thoughts on how to verify it is the PT pump over injectors? Such as blocking off the output of the PT pump to see what its top output pressure could be (I read this somewhere here but pump damage could occur if done wrong or too long or...?)
Any pointers would be helpful! Thanks, thanks, Thank you in advance.
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