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Old 11-05-2018, 01:50 AM   #1
Mini-Skoolie
 
Join Date: Feb 2017
Location: BC
Posts: 21
Year: 2002
Chassis: Saf-T-Liner MVP EF
Engine: 5.9 Cummins
Engine light on sporradically, engine low on power

I've got a 2002 Thomas with an ISB 190. Sometimes when I start the bus the check engine warning light will turn on but will go off eventually, then I'll drive the bus and it will have low power and the light will flicker on and off.


I'm not sure how to use the engine diagnostic button to flash me the codes.



Oil pressure and coolant temp gauges appear to be working fine.



All fluids are topped up, changed both fuel filters 500 km ago when this first started happening. If the bus sits for a while it seems to happen, if I drive it every day it doesn't happen. I also took my fuel tank cap off when the light was on and it went away, so I figured the tank vent must be plugged and creating vaccum. It drove fine like that for 100km and back to happening randomly. Am I losing fuel prime? Is it maybe a lift pump issue starving my pump for fuel? It's a vp44 so I hope the later isn't the issue.


Thanks in advance
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Old 11-05-2018, 07:57 AM   #2
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Join Date: Oct 2015
Location: Spring Valley AZ
Posts: 1,212
Year: 2000
Coachwork: Bluebird
Engine: 5.9 Cummins
Rated Cap: 2 elderly children, 1 cat
Our ISB in a 2000 BB showed check engine on a fairly regular basis. This light was often accompanied by an engine de-rate until it was cleared.
Ours was caused by a faulty crank position sensor. I also cleaned the multi-pin connector near the engine.
The CPS was about $60 and I changed it in a day or so.

Found post from last year:
"I replaced the crank sensor today.

Your bus will probably be a bit different.

Disconnect neg at batt.
Disconnect neg. connections at buss bar near starter.
Loosen or remove starter, 10mm 12 pt. is required.
If not removed, pry starter away from sensor and remove sensor from block.
Unplug sensor and re-plug new one.
Replace all that was loosened or removed.

I needed a 10mm 12pt. box ratchet to remove the top starter bolt. There are 3.
I had to unplug the multi-pin connector and move the dipstick tube to see the bolt.

Next time I can do this in a couple hours, this was the first time and it took me all day at a 72 y/o's pace.

Road test to come.

This bus would produce a code after being fully warmed, shut off, then re-started. The code would show as SES after 1/2 hr. or so of running FULLY warmed. The engine would de-rate to lower power and the idle had a nasty surge. It would clear after a few seconds to a few minutes., usually instantly via the Scangauge. "
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Old 11-05-2018, 06:12 PM   #3
Mini-Skoolie
 
Join Date: Feb 2017
Location: BC
Posts: 21
Year: 2002
Chassis: Saf-T-Liner MVP EF
Engine: 5.9 Cummins
My engine is quite greasy towards the rear of it, so that might be affecting the crank position sensor.



Do you know how to operate the built in diagnostic button?
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Old 11-05-2018, 06:17 PM   #4
Bus Geek
 
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Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 18,265
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
Quote:
Originally Posted by Krazyistkarl View Post
My engine is quite greasy towards the rear of it, so that might be affecting the crank position sensor.



Do you know how to operate the built in diagnostic button?
I've used it before and its easy but I can't remember right off hand. try google.

IIRC there's a switch marked "test" or something like that. You turn the key to the on position then hit that switch. The lights blink out the code.
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Old 11-25-2018, 07:52 PM   #5
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Join Date: Nov 2018
Location: Oregon
Posts: 4
Fuel Lift Pump Possible Cause

The symptoms you have sound like possible low fuel PSI from the electric lift pump or an electric fuel lift pump that is on its way out. On the Cummins 5.9 ISB with a VP44 this was a very common issue, so common in fact Cummins had a campaign to extend the warranty on the lift pump. Part of this campaign was to install a fuel PSI switch on the secondary fuel filter housing that is mounted on the cold side of the engine (intake manifold side). When your fuel PSI drops, the switch grounds and turns on the engine warning light. This can happen very frequently and is accompanied by low engine power.


When your warning light comes on, listen for the lift pump and make sure it is operating. If it is not, cycle the key to the off position and then bump the starter. This failed start attempt should cause the lift pump to turn on for 30-60 SEC. If you do not here the lift pump run, this is most likely the problem.
If the lift pump is not running, this will shorten the life significantly of the injection pump.
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