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Flying Finn

Truck loses power at acceleration

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I have a 2001 VNL770 with a Cummins engine/auto shift trans.  From time to time during acceleration from a stop or in motion  all power is lost.  The pedal goes to the floor and nothing.  A second or two later everything is normal.  I changed the fuel filter, run biocide in the fuel, nothing in the tank or filter looks out of the ordinary.  The engine does not sputter, no codes show up, no unusual exhaust etc. just looses power.  What could be going on?

Thanks

Brad

 

 

 

 

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Cummins have a propensity to eat CPS, so my $$$'s there, too. Early indicator is loss of power, followed by dead on the side of the road. $80 part, and 1/2 hour to swap. Always carry a spare, if you're running the big "C".

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Darryl,

Maybe GeorgiaHybrid will chime in on our “1/2 hour” sensor change.   Twelve year old plastic is very brittle and crumbles often leaving just the barrel of the sensor stuck in the hole.  Mine was a Volvo D12.  Hope the Cummins is easier.  😊

Edited by SuiteSuccess

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Ain't that a great feeling. What the.     Is happening.

 

The throttle potentiometer is a likely culprit. Now I have had a bad connection on a positive battery terminal about 100 miles after cleaning the battery post. Was lucky and got off the interstate. Just in time to stop at a Walmart.

 Original battery nut was not open on top. Dammmm wire was not tight as the nut bottomed out on top of the post.

 

 Now that new potentiometer solved my cruise problem and gave much better throttle response.

 One should change all sensors every five years.

 

just my thought,.  Vern

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Mine does this all the time, my traction control/abs is messed up and I am working on that now. Mine hates to down shift and skip shifts way too many gears. And my cruise control quit. Mines a Volvo D11. Any diagnostic ideas for the potentiometer on it?

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2 hours ago, SuiteSuccess said:

Darryl,

Maybe GeorgiaHybrid will chime in on our “1/2 hour” sensor change.   Twelve year old plastic is very brittle and crumbles often leaving just the barrel of the sensor stuck in the hole.  Mine was a Volvo D12.  Hope the Cummins is easier.  😊

Advantage Cummins. A CPS on a Cummins will never last 12 years. 😆

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54 minutes ago, Flying Finn said:

Thank you guys.

What is a throttle potentiometer?  What does it do?  Where is it located typically?

All modern diesels are "fly by wire", in that they don't have a mechanical connection between the throttle pedal and the fuel pump. There's a pair of potentiometers in the throttle pedal base. Look for the wires hooked to the pedal. I  think that a pot malfunction will set a code, though. The ECM compares the reading between the two, and if too large a difference is found, sets a code.

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  More thoughts, on  red top Cummins N14   But some may apply to your situation.

1.  throttle position sensor is on back side of throttle pedal or gas pedal.

 

 2 I would also install Baldwin fuel filters on unit . Mine has one on engine and one on the passenger side frame in front of the steer tire.  NAPA filters cause me headaches for several years.

 

 3 there are 3 small ground wires on each side of firewall on a Volvo in the engine compartment.  Yep cause me a headache back a few years

 

 4 if your engine has a fuel seliniod you may want to replace it.

 

 Hope this headache medicine will work.   Vern

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I am with rickeieio. My 2001 VNL660 showed the same symptoms after I sprayed soap on the pressure gauge lines over the throttle.  Soap ran down the wires into the potentiometer.  I think it cost $113 from Volvo.  Could not buy just the pot.  As I remember, two 10 mm head bolts hold the throttle to the floor.  Easy fix.   

I still have the old one.  Soap probably dried out and it might work.  If you want, I  check the potentiometer and send it to you if it looks good.

On edit:  The truck did not throw any codes.

Edited by NeverEasy
More info

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I have a 2000 N14. I made the mistake of installing a Baldwin fuel filter. No power, wouldn’t odle, etc. as soon as I installed a fleetgsurd filter, all was well in the world. I now carry 3 fuel filters with me. Sometimes speed o doesn’t carry them. As a side note, if you get bad fuel and need a filter changed, you can pull into speed o, purchase a filter and they will change it for free.

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After the education I got from all your comments (thanks) I took the truck into a local repair shop here in Sycamore.  Asked them to check for codes (thinking something would would show up on their PC,) the Potentiometer, etc..   The results....no codes (of course) and the Potentiometer tested good.   So after allot of head scratching we called a Cummins tech. who was kind enough to speak to us on the phone. 

He told me the symptoms are not fuel related based on what I shared with him.  The engine would sputter and for sure post a code.

His suggestion( as was spindrifts), was to check the electrical connections.  He said faulty connections can cause the symptoms I am experiencing without posting codes to my panel. So I spent the afternoon taking everything apart, cleaning and reinstalling.  Storms are rolling in so a test drive is planned for tomorrow. 

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Here’s some trivia: the first commercially available diesel powered truck available for purchase at a dealer was a Kenworth with a Cummins engine... in what year? ...

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2 hours ago, noteven said:

Here’s some trivia: the first commercially available diesel powered truck available for purchase at a dealer was a Kenworth with a Cummins engine... in what year? ...

1923 ?

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First Kenworth with a Cummins was in 1933. A 100 HP Cummins HA-4 engine.

Mine is Kenworth with a 500 HP Cummins ISX 😁 They are still a good choice.

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50 minutes ago, GeorgiaHybrid said:

First Kenworth with a Cummins was in 1933. A 100 HP Cummins HA-4 engine.

Mine is Kenworth with a 500 HP Cummins ISX 😁 They are still a good choice.

Winner, winner, chicken dinner!   😆

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8 hours ago, noteven said:

KW began business in 1923...

1st Cummins 1934 ,... I think...

Great Trivia.     Any pictures available?

Clay

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12 hours ago, rickeieio said:

Yeah, that spindrift guy knows a bit about Cummins.............😜

Thanks, Rick.  I hope it will be that easy.

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Follow up to my accelerator problem:

After cleaning all battery connections etc. I thought I was golden.  Took the truck to my brothers house on Saturday.  On the way over everything worked as it should.  On the way back (midnight, rainy) the accelerator gremlins struck again.  Totally frusturated and  ready to grenade the truck, I called Cummins (Rockford location, JX truck center, 262-709-3209) .

Brought the truck in and explained the symptoms andmy  attempts at corrective action. He hooked up the code reader and as expected no codes shown.  Thankfully the tech checked for software updates.  Imagine that,  no updates since 2003.  I bought the truck in 2006.  Seems one of the patches was for.....you guessed it.....accelerator peddle problems.  He tried to download the patches but my ECM would not recognize them.  Long story not to short, he had to wipe out the old software from the ECM and install all the new stuff.  After a test run all is well.  30 mile trip back to camp....all is well.  If it wasn't for the cummins tech (Dave)  never would in a million years would have thought of a software up grade.

Thanks again for all your input.  I hope this experience will help others.

Brad

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