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johnsc2c
New Member
3 Posts |
 Posted - 11/04/2015 : 09:52:15 AM
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Hello to All....I am an Auto Mechanic. Subaru is my Specialty.
That Being said...
I have a Very odd strange Wiring problem on a 1997 Thomas Pusher with 8.3 Cummins Mechanical Motor, and Allison 6 speed Electronic Trans
142,000 miles and 6600 hrs on the clock.
Here is its Back story.
I bought this Bus Used in May this Year. I drove it home 380 Miles with no Issues at all...Over some very Rough Road, towing a Car on a trailer behind it. I parked it and started Building it into a Rescue Dog Transport Vehicle. I added Shelf units inside it, along with 1/2 inch Conduit along the Ceiling to Run 3 AC units and some 110 power outlets. I run all that thru a 7k Genset I installed in the Cargo box under the bus.
During the Work time here in my Driveway, I fired and Ran the Bus bi-weekly....Never an Issue.
3 wks ago, I went to take off for its First Cross Country Road Trip, and I had the Fuel Shut off Solenoid Fail and shut motor down at 55 mph on the Hwy....Luckily I was in a Straight stretch, and I got it off the Road. It fired Right back up, and after 4 fails, I got it To a Parking lot. Originally I was thinking Fuel Delivery issue, and I replaced all Fuel Filters. Limped it almost back home 5 miles, failed and Shut off again....at this Point A Inj/Pump Mechanic/Rebuilder Buddy, told me Pull the Solenoid off motor....I did, and Got home. I bought a New Fuel Shut off Solenoid, thinking it was tired, weak.... Fired up on the New unit, Within 45 secs..It shut down.
I have Found that My Root Problem is that i am Loosing Voltage /amperage when I start to run Any Load....ie: Lights, Heater fans, interior lights.
It is Very Random though... One time All things on Full Load no fall off die...the next time, just lights on, it dies.
next time lights, and one fan...it dies.
Then All loaded no issue, rev motor to say 1800 rpm..back to idle...it dies.
Here is a list of things I have done to this point to try and Kill the Drain...
New Batteries X 3
Tested Alternator...it tests Loaded good....at 150 Amp unit.
New Shut off Solenoid.
New Fuel solenoid Relay
New Constant duty Solenoids X 3
Cleaned all wires at the Starter,
Cleaned all Hot wires and grounds at the Rear Panel box
Cleaned the Duty Solenoid bases , and Power bars in the Front panel by drivers window.
I have not replaced the Fuse breaker( thermo breaker ) units associated with the Fuel shut off circuit...I am going to do that today with Regular fuses. Thomas Bus Tech support suggested I do that , so I am about to go try and Test that theory out....
I am Here looking for any other input or Ideas,
Thanks in advance,
John in Oregon.
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krmvcs
Advanced Member
362 Posts |
Posted - 11/04/2015 : 10:46:50 AM
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ive got the same motor in a 96 blue bird. i had similar hard start/no start issues, low power/random shutdowns. odd voltage drops everywhere. ended up finding the engine wiring harness and relays were crispy all over. some hack tapped into random wires everywhere whenever there was a problem. if it is the same setup, you should have 3 main relays on a frame rail in the back somewhere near the engine. take a hard look at those too. hope that helps. and hope you dont have to do what i did and replace the entire harness.
and if you havent already, take your engine serial number and set yourself up on cummins quickserve. punch in that serial and it will tell you everything you need to know about that motor. service, parts, etc. |
-Ken- |
Edited by - krmvcs on 11/04/2015 10:50:26 AM |
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johnsc2c
New Member
3 Posts |
Posted - 11/05/2015 : 07:14:01 AM
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krmvcs.
Do you happen to have any pics of these Relays..? and are these the lil black square box type with 4-5 spaded off them, or is this Like a Bigger Constant Duty Solenoid type relay...?
My email address is johnsc2c@gmail.com
Thanks, John. |
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krmvcs
Advanced Member
362 Posts |
Posted - 11/05/2015 : 07:35:16 AM
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| small black 5 pin relays. |
-Ken- |
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krmvcs
Advanced Member
362 Posts |
Posted - 11/05/2015 : 07:38:13 AM
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| i also have wiring diagrams but they are for my 97 mpvre with a cat3126. unfortunately the book i have doesnt show any alternative diagrams for an 8.3. the body stuff outta be close to the same though. |
-Ken- |
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johnsc2c
New Member
3 Posts |
Posted - 11/06/2015 : 07:25:56 AM
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| Yes I have Replaced the 3 Black 5 pin relays in the Rear......:) I am now Going to Pull each Bus BAr panel in the Front one at a Time and Completely clean them....About the Only thing I have not done to this Point. |
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Wiring GREMLIN 1997 Thomas MVP ER 8.3 Cummins
