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 cat 3126 losing power and shutting down
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Thomas2000
Active Member

39 Posts

Posted - 06/19/2007 :  9:19:28 PM  Show Profile  Reply with Quote
Heres the problem.....2000 Thomas, cat 3126 engine....driving down the road running fine and then all of a sudden it starts losing power...u keep your foot on the accelerator and it just starts slowing down and eventually cuts off. After a few minutes of sitting it started up and then stalled back out again. the mechanic sprayed some brake cleaner in the back where the air filter and turbo connect....bus fired right up and ran fine another 10 miles back to the yard. I went back out in in later, drove 10 miles, ran fine, then started acting up again. Anyone experienced this? What should we be looking for? Any input is appreciated.

IBTMech
Top Member

USA
973 Posts

Posted - 06/20/2007 :  6:44:43 PM  Show Profile  Visit IBTMech's Homepage  Reply with Quote
I would check the fuel filters/flow rate first.

If it doesn't fit, FORCE it.
If it breaks, well, it needed replacing anyway.
Pullin' wrenches for 45 years.
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bbird66
Top Member

USA
881 Posts

Posted - 06/21/2007 :  07:27:03 AM  Show Profile  Reply with Quote
Something as simple as the fuel tank vent..Had it happen, same symtoms but with a 466E. Check the vent. I've had everything from mud daubers to ice plug those things up and drive ya nuts. Next time when it happens see if you can get the fuel cap off right away if not, It's pulling a lot of suction and they can be hard to turn off.

Were gonna miss you "Brent"..Good luck in "Heidi land"

"I know you miss the Wainwrights Bobby, but they were weak and stupid people...and that's why we have wolves and other large predators" .. The Far Side

"On a two hour delay when will my child be picked up??"








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ModMech
Top Member

USA
948 Posts

Posted - 06/23/2007 :  7:37:02 PM  Show Profile  Visit ModMech's Homepage  Reply with Quote
The cam sensors are notorious for getting contaminated with oil, and dropping out. But as others have mentioned, there are MANY things that can cause these symptopms, check the simple stuff first!

If you want customer service, you NEED an International!
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Dravo
Senior Member

USA
93 Posts

Posted - 07/13/2007 :  10:02:52 AM  Show Profile  Visit Dravo's Homepage  Reply with Quote
We had this problem last year in a 01 Thomas ER. I changed the throttle sensor- no luck, another mechanic had the trans serviced- no luck. Finally took it in to Thomas near Greensboro NC and they found some bad electrical connections in the front.
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Fort La Bosse
Active Member

33 Posts

Posted - 07/09/2012 :  2:09:19 PM  Show Profile  Visit Fort La Bosse's Homepage  Reply with Quote
I am having the exact same issue. Except..... mine was having a long crank issue and occasionally it wouldn't start. I replace the engine speed sensors and the long crank was gone but after about 7 miles driving the engine lost power and cut out. It started about 5 times and immediately shut down. Not it won't even start. I'm thinking about another set of speed sensors as this only became a problem after changing them. Any thoughts or Thomas 2000 can you share what was wrong with this one?
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Cal Mc
Advanced Member

245 Posts

Posted - 07/12/2012 :  2:50:29 PM  Show Profile  Visit Cal Mc's Homepage  Reply with Quote
Common failures on these engines;
-heui pump
-check oil pressures with both ET program and a gauge
-Low fuel pressure
-fuel pump on rear of heui pump failing, Put the bus into a "no start condition and deadhead the pump with a gauge. It should read 60 psi after briefly cranking the engine.If you get 60 PSI QUIT CRANKING.
-Low fuel pressure due to pressure regulator failure
- the fuel pressure regulator is on the rear of the head. If the fuel pump is working, test by putting a gauge into the port on the fuel filter base.
On our FS65 buses it is well worth the time to do a little more testing because the regulator is such a pain to get at.
Our FS65 buses have also given some problems with fuel supply lines leaking between the frame and the engine.It is a braided line that fails. Some FS65 buses also had a fuel screen installed in the braided supply line to the fuel pump(very well hidden)
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Kid Grimy
New Member

8 Posts

Posted - 10/24/2012 :  09:57:36 AM  Show Profile  Visit Kid Grimy's Homepage  Reply with Quote
The original post for this issue was in June of 2007 and I'm going to keep it going for a little while longer. My 2001 3126B shuts down when I hit the brakes hard. It has done this at 35 MPH and at a coast in the shop. Feels like an electrical/electronic shutdown as it is instantaneous. Does not loose power it just shuts down. Starts right back up and runs fine but donít give it a hard brake because it will shutdown. I performed a wiggle test on all of the wires in both harnesses coming off of the ECU while the engine was running with no shutdown. I changed the CAM sensors and the fuel pressure regulator. Iíve been working on the 3126 engines for several years and Iíve never seen anything like this. Any thoughts?
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sambrutay
Advanced Member

United States
233 Posts

Posted - 10/25/2012 :  05:20:21 AM  Show Profile  Reply with Quote
this was our problem. Embarrased to tell you how much was spent on time and throwing parts at it


Bruce
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bwest
Administrator

United States
2266 Posts

Posted - 10/25/2012 :  10:42:36 AM  Show Profile  Reply with Quote
I give up, what is that picture of? I see a connector cut from its harness with a bare wire stuck in the other end. Don't know what the thing is below it is.

Bryan
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sambrutay
Advanced Member

United States
233 Posts

Posted - 10/26/2012 :  02:55:30 AM  Show Profile  Reply with Quote
Itís both ends of a connector. I pulled the pin out of the connector body to check for arcing. Bus would lose power and randomly die. It was on end of a hook many times. Lots of parts thrown at it and this connector was the culprit. My $3000 connector at a minimum. i have this hanging over my desk just as a reminder. Might get it gold plated.

Bruce
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bwest
Administrator

United States
2266 Posts

Posted - 10/26/2012 :  09:38:39 AM  Show Profile  Reply with Quote
OK, cool

Bryan
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Kid Grimy
New Member

8 Posts

Posted - 10/30/2012 :  06:47:33 AM  Show Profile  Visit Kid Grimy's Homepage  Reply with Quote
Hi Sambrutay
Thanks for the input on the bad connector. Which connector is this? Doesn't look like the IPR, is it the IPR sensor connector? Where is the connector?
Thanks;
Kid Grimy
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sambrutay
Advanced Member

United States
233 Posts

Posted - 10/30/2012 :  09:17:02 AM  Show Profile  Reply with Quote
left rear of engine around the steering column. Freightliner wiring harness connector to Engine harness maybe... good luck with it.

Bruce
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