diesel scan tool
- Thread starter gungatim
- Start date
toolman9w
Well-known member
Duramax fuel pressure gauges have a vacuum side and a pressure side. There are specs on how much vacuum it holds under cranking to move the fuel. Big fitting near the alternator. If it is not pulling vacuum you have a fuel filter or a suction problem. Gauge required like this one.
https://www.tooltopia.com/lang-tool...MI6NHEyOHv3QIVFZ7ACh3jZwlREAQYASABEgLgmPD_BwE
I use one of these for my Duramax.
http://launchtechusa.com/crp123p-6/
https://www.tooltopia.com/lang-tool...MI6NHEyOHv3QIVFZ7ACh3jZwlREAQYASABEgLgmPD_BwE
I use one of these for my Duramax.
http://launchtechusa.com/crp123p-6/
Since the truck sits, and is used for plowing, also check for corrosion in the fuse block. A bad connection for the ECM relay or related fuses could be giving you trouble. Kinda hard to diagnose over the internet but hopefully this steers you in the right direction! Keep us updated as well when you find the issue.
I have a Dodge but one thing I added to my truck was an Edge Insight. It's not a programmer but gauges. One important thing on common rail motors is reading rail pressure. So much pressure has to be built up for the injectors to fire.
Duramax is a little different since the CP3 pump pulls fuel making it hard to find fuel leaks on the suction side. On Cummins, a lift pump supply the fuel to the CP3. A FASS is helpful (especially when changing filters) but if your truck is holding fuel pressure, there shouldn't be any leaks.
My suggestion would be new batteries and then find a scanner than can read rail pressure. If you're not getting at least ~4,000 psi on start up (at least on a Cummins and idles around 5,500 psi) the motor won't fire. If you're not getting that kind of pressure, it's mostly CP3 related. If you're lucky, it's just the FCA and not the pump.
Duramax is a little different since the CP3 pump pulls fuel making it hard to find fuel leaks on the suction side. On Cummins, a lift pump supply the fuel to the CP3. A FASS is helpful (especially when changing filters) but if your truck is holding fuel pressure, there shouldn't be any leaks.
My suggestion would be new batteries and then find a scanner than can read rail pressure. If you're not getting at least ~4,000 psi on start up (at least on a Cummins and idles around 5,500 psi) the motor won't fire. If you're not getting that kind of pressure, it's mostly CP3 related. If you're lucky, it's just the FCA and not the pump.
cvairwerks
Well-known member
Check the ground wire on the passenger side of the block for corrosion.
The Tool Tyrant
ALLIANCE MEMBER
Easy to rebuild and with your mileage, it's a good idea to do anyway. Eliminate the easy item to fix first.
With my Insight I can turn it on before I start my truck. I can watch the pressure to see if it's building up. If it's not or too low, it's CP3 related. I was assuming an actual scanner would do the same.
I'm not saying you should throw money at the problem but a FASS is a nice upgrade. With a pressurized fuel line, leaks are easy to find. Chevy might have been smarter than Dodge, but the factory filter on my truck didn't meet Cummins micron requirement. Cummins recommended 3 microns, Dodge's filter was 7 micron and the best you could get was 5. My spin on filters now meet Cummins' requirement.
FSrepair&fabrication
Well-known member
check to make sure your FCA (fuel control actuator) AKA the MPROP isnt stuck. Its on the cp3, This is what crontrols rail pressure, The fca opens and closes based on the input of the rail pressure sensor. Ive seen them go dead and throw no codes, Look up how to test for your year with a multi meter to see if it is opening up to allow fuel to the rails.
FSrepair&fabrication
Well-known member
The fitting above the alternator is useful to bleed air out i puch the scheader valve in with a pick while someone cranks it helps get the air out quicker. In my experience the duramaxs can be a PIA to get bled. Look online you need to test your sensors with a multimeter to confirm good or bad, any cheap scan tool with datastream wont always tell you what you need to know. The rail pressure relief valve is also called an overflow valve. It can wear out and let fuel bleed by and not build pressure. It is a totally mechanical part with no electronics and the only way to test it really that I know of is to replace it and see if it builds pressure after.
FSrepair&fabrication
Well-known member
The overflow valve is cheap btw like $50 and alot of guys running higher pressure than stock eliminate it with a plug instead. It is a mechanical valve designed to open up if rail pressure exceeds 28,000 psi? i believe.
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I live in the country, and the tires are flat. it's parked a ways from my shop.
it would cost a good $150 to get it towed somewhere, and an hour of diagnostic is around $150. then it has to be towed back home for another $150. (it's a farm truck, no plates or insurance).
i'll stick a $60 PRV in it and either it works or it's scrap. not willing to spend $450 on top of that to find out...rather be out $60...theres no way i'm paying $6k for injectors or $5k for a pump on a truck worth $4k....i'm better off parting out the drivetrain...I think the allison is worth a few bucks, as is the 3/4 ton axles...maybe someone would buy the motor as well once it's pulled. rockers are completely rotted from sitting, which is strange because when I parked it there wasn't any rust...apparently they rot from the inside out...which means the brakelines are probably going next...
pistolpete1313
Well-known member
BTW your scanner will work with the truck. I like torque pro but I use auto guage pro for powerstrokes
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Andybull
Well-known member
Did you replace the fuel filter?
first thing I did, then when I replaced the filter housing it came with another new one so it got changed again. like I said, I can get fuel to the pump, but not past it near as I can tell. tried running a hose from the housing into a 5 gal diesel can bypassing the lines and tank but still nothing but a sputter until the pressure is gone after pumping it up.
Security system failed. battery goes dead after a period of time, and the security needs a re-learn. I found that out after I sold the truck. My latest plow truck had the exact same issue. GM is asshoe. I'm surprised nobody on here has ever run into that, it seems to be a common issue with the ridiculous GM security setup.