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03-26-2016, 05:37 AM
We left WI Thursday night in the snow, pulled in for an overnight at a truck stop in South Bend (more snow/sleet) and arrived at Greenbelt Park, MD yesterday.
We're planning on exploring the DC area with the kids until Wednesday morning, then heading up to Gettysburg for a few days before heading home.
I'm having an issue with my 8.3 Cummins, if I keep it under about 15-16 psi boost, it is fine, go over and it will drop down to almost nothing, then rise / fall. Fine running down the road, but long hills kill me. EGT is fine, no smoke, fuel drops when the boost falls.
I suspect a hole in the waste gate actuator, I'm planning to plug the line to test.
Anyone have another likely suspect?
Thanks
Scott
1983 38' Classic #007
8.3 Cummins, Allison 6 spd.
"Any other Way"
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scott, hopefully our diesel gurus will offer some advice.
tom
2002 45'8" Newell Coach 608 Series 60 DDEC4/Allison World 6 Speed HD4000MH
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Changing out the fuel filters would be my first guess also. Was the fuel a summer blend?
Michael Day
1992 Newell 43.5' #281
NewellOwner.com
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My 86 8v92 had a pressure gauge in the engine compartment and one on the dash. I think one b4 filter and one after. Might be something to check to see if the filter needs replacing.
Ed and Penny Thomas
Anna, TX
98 Newell
coach #490
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Fuel filter first, look for leak downstream of turbo second, flaky fuel pump third.
What happens if you hammer it from a stop?
Richard and Rhonda Entrekin
99 Newell, 512
Maverick Hybrid Toad
Inverness, FL (when we're home
)
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Thanks for the ideas/questions, keep them coming.
From a stop and for short bursts it goes to 22 (max ever seen), normal power.
I was planning to change out filters just in case.
I have a primary with a settling bowl (looks clean), a secondary that was new last year, and a tertiary (also new last year).
Winter blend fuel with a jug of power service anyway. The last leg of the drive was in the 60's with no change in symptoms.
It didn't start until I was 6 hours into the drive, at first it would falter a few psi then come back to full power with a steady pedal, now it falls down to almost nothing, then recovers.
Scott
1983 38' Classic #007
8.3 Cummins, Allison 6 spd.
"Any other Way"
Posts: 1,167
Threads: 27
Joined: Mar 2013
If it is just the boost pressure that is falling it is possible that it is a turbo issue. Not sure how Cummins are, but on Power Strokes there is a waste gate that can have issues with the linkage for it sticking. I have an '02 that is tied wide open all the time because they couldn't get linkage to work properly on a turbo change out.
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I found a wire off of a small valve or solenoid from one of the fuel lines coming from the lift pump to the top of the intake; I'm not sure what this does.
I can't seem to find a fuel system schematic online, if anyone has one they could send that would be great. It's a 1996 mechanical 8.3.
I also plugged the line to the waste gate, I might take a test drive tonight to see if there is a change
Scott
1983 38' Classic #007
8.3 Cummins, Allison 6 spd.
"Any other Way"
Posts: 30
Threads: 0
Joined: Oct 2012
Was it only doing it when cold? Maybe fuel gelling? Filters would be a must.
Gelling
This is when diesel fuel turns to a gel-like consistency at temperatures approaching the products cloud point value. Untreated fuel will form large wax crystals which lead to the wax becoming so dense that it then drops out of solution triggering unexpected downtime. This thicker substance cannot pass through the fuel filter, so the engine may run intermittently, or may not start at all.
Water
Water is diesel fuel’s number one contaminant. It is likewise the number one issue fleets wrestle with on a daily basis and not necessarily just in the winter. Water can and will be prevalent in fuel dispensing systems by virtue of the handling and storage of the fuel. Vents breathe in atmospheric air into void tank space which starts the phenomenon. Water in fuel can freeze at temperatures below 32 degrees Fahrenheit blocking fuel lines and disabling water fuel separators. If it doesn’t’ freeze it can and will become a breeding ground for microbial contamination which independent of itself can ravage a fleets operational balance. No chemistry can replace what a good housekeeping program can do for establishing a strong prevent defense against water contamination. It is recommended throughout the year to keep tanks full to prevent condensation from forming inside the tank and lessen the chances of water getting in the fuel line.
