1993 Cat 3406 loss of power & surging idle

[Bobby]

A buddy's dump truck lost power today on the job. It surges at Idle and all through the power band.

It's one of the first generation electronics 3406's.....

Edit: by surging I mean the RPM's run up and down. It will idle OK when first started for 30 seconds or so then it starts with the surging.

Thanks for any Help.

Bob

[heavyhaulerss]

I have known of these type of symptoms caused by a sensor gone bad that is attached to the accelerator pedal.

[Bobby]

Thanks, HH
He ordered a trottle sensor.....

The parts Gal said the symtems sound like it too.

I'll let you know if that's it.

Bob

[heavyhaulerss]

do keep us informed

[bobwadas]

Depends on if its a 3406 or 3406E

1. Highly unlikey the throttle sensor.

2. If its not an electronic engine the symptoms you describe can be tons of things. You could have a bad timing advance, broken ataac boot /clamp ( have someone spray soapy water at all boot connections and the core itself while you rev it up and down. Any bubbles showing means you are losing power.

pull boot at turbo snail housing and try and move turbo blades and check for excessive play


BUT FIRST..CHANGE YOUR FUEL AND AIR FILTERS...YOU HAVE NO IDEA HOWMANY TIMES I FOUND THIS TO BE THE PROBLEM AND PEOPLE WERE PAYING $100/HR FOR SOMETHING THEY SHOULD HAVE DONE THEMSELVES !


You will also need to check the air/fuel ratio to see if the diaphram is holding ( you can use a hand pump and go to 20 psi and see if it holds.

You could have a broken broken spring in the governor or the buffer may nee a slight adjustment so it doent surge.

If its electronic you want to check turbo connections first.
you need to make sure the newest flash file is loaded into ecm;;You may very well have a broken valve spring, broken injector spring, seized injector spring, or very possibly a bad cam that you dont think because it may not cause a miss but its worn down enough to loose power.

But again..start with fuel filters..

There are a lot more things to check..but these are the begining steps needed