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Re: CAT 3116 Losing Power and Blowing White Smoke


princetonshop wrote:

We have seen similar problems in various kinds of construction equipment and on road trucks.  In a truck this old the replacing the fuel lines would be a good place to start.  This would include the line from the tank to the transfer pump and any other fuel hoses.  The inner lining of a hose will deteriorate and restrict the flow.  When you idle or shut down the lining moves back to normal and flow resumes until the next time.  The fuel lines (hoses) may look fine on the outside but the problem is inside.  Hope this helps.


It took me some time to get to your solution, but you were dead on.  The fuel line from the tank to the pump was collapsing on the inside.  From the outside, the line looked perfect.  There was also a check valve right at the top of the tank that needed cleaning as well, but the fuel line was 99% of the problem.  Thanks.

Visitor

Re: CAT 3116 Losing Power and Blowing White Smoke

That is an excellent suggestion about the hoses.  I'll go ahead and replace them and see if that helps.  Sounds like good PM in any case.

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Re: CAT 3116 Losing Power and Blowing White Smoke

We have seen similar problems in various kinds of construction equipment and on road trucks.  In a truck this old the replacing the fuel lines would be a good place to start.  This would include the line from the tank to the transfer pump and any other fuel hoses.  The inner lining of a hose will deteriorate and restrict the flow.  When you idle or shut down the lining moves back to normal and flow resumes until the next time.  The fuel lines (hoses) may look fine on the outside but the problem is inside.  Hope this helps.

Visitor

Re: CAT 3116 Losing Power and Blowing White Smoke

The tank cap is vented.  I also removed the cap and ran the truck without a tank cap and it had the problem.  The fuel pressure is around 35 PSI and the fuel volume is quite high.

Trusted Contributor

Re: CAT 3116 Losing Power and Blowing White Smoke

Is the fuel tank vented?  if it is pulling a vacuum in the tank it will starve the engine for fuel after a while.  Put a fuel pressure guage on it and run it and see what happens.  Also it could have compression in the fuel, but that will usually have a hard start issue and it will run bad all the time.

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Accepted Solution

CAT 3116 Losing Power and Blowing White Smoke

[ Edited ]

I have an M35A3 2-1/2 ton military truck with a CAT 3116 engine.  The engine is dated 1993, but the truck was manufactured in 1998.  This engine only has 417 hours on it from new.  It has always run extremely well up until now.  The situation is as follows.  The engine starts easily and runs fine with smooth idling and lots of power.  After 1 - 2 hours of highway driving it suddenly starts losing power and starts blowing white smoke out the exhaust if the accelerator is pressed.  Power continues to decline over about 1 minute until the vehicle will only idle along.  After stopping, the truck continues to idle smoothly, but will only get up to 700 RPM max when the accelerator is depressed in neutral.  After letting set idling for 5 - 10 minutes, the engine again runs fine with plenty of power and no white smoke.  I can also turn off the engine and restart it 5 - 10 minutes later and the engine runs fine.  However, after 1 - 2 hours of driving, the problem repeats itself.  During normal operation, the engine does not smoke.  The engine does not have a blown head gasket and is not losing any coolant.  The fuel filter was changed and this had no impact on the problem.  Air filter is also new.  I can see no restrictions in the exhaust.  This 3116 engine has MUI.  I am totally lost with this problem.