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Old 07-22-2021, 02:18 PM   #1
Bus Crazy
 
ewo1's Avatar
 
Join Date: May 2015
Location: Central Tx.
Posts: 1,951
Year: 1999
Chassis: Amtran / International
Engine: DT466E HT 250HP - Md3060
2nd gen 5.9 ISB crank sensor issues

Ok so I bought another bus, got 3 in my yard now.... I need a VACCINE !!!

I got a 1999 Thomas MVP RE with a 24v 2nd gen 5.9/vp44 pump.
The engine is a hard start, dead pedal and surges at idle.

I replaced the lift pump and fuel filter just so I would know that it is at least new /fresh.
What I learned so far is that the 5.9's they put into busses are not 100% identical to production motors that are installed into passenger cars. In busses they install an "Industrial" version of the 5.9.

So after replacing lift pump and filter bus actually started up and ran at a smooth normal idle but still had the dead pedal.

Next step - replace the CPS- Crank Position Sensor.
On a production model engine the CPS is supposed to be sandwiched between the starter and the black which would require starter removal.

On the industrial engine, the starter is actually on the opposite side of the block making the CPS removal easy! But watch ouT for the dipstick tube, I snapped mine trying to bend it out of the way.

So when I removed the original CPS I noticed the face of the sensor was not flat, it was bulged out and has what appears to be a burn hole in it.

Got one from NAPA ( p/n CSS636, cost about %50 bucks and swapped it out.

Bus started right up, normal RPM, smooth idle...But...when I pressed down on the accelerator pedal the RPM started to go up then quickly stopped, check engine light came on and we went back to a dead pedal, rough-surging idle again.

I pulled the CPS and noticed that this one too now has a small burn hole on the face.

I'm waiting for a new CPS to arrive but in the mean time...has anyone seen anything like this before?

I have not checked voltage on the CPS connector, simple thing to do, should see 5-8 volts and a good clean ground too. I'll get that done when the new CPS comes in.

Here are some pics of what is going on with the CPS burn holes.

WHAT IS BURNING THESE UP LIKE THIS??
Attached Thumbnails
IMG_5130_A.jpg   IMG_5133_A.jpg  

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Old 01-01-2022, 12:05 AM   #2
Bus Nut
 
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Join Date: Oct 2021
Location: Jacksonville, FL
Posts: 709
Year: 2003
Coachwork: BlueBird
Chassis: TC2000 28ft
Engine: Cummins ISB 5.9 24v, MD3060
Rated Cap: 14
Did you burn up a third?
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