Engine Bucking

[fulltiming]

Driving from Austin, TX to Yuma, AZ, I noticed a very slight roughness in the engine when climb grades. As I traveled further, the bucking became more pronounced until climbing the grade near Yuma on I-8 resulted in the transmission hunting between 3rd and 4th and bucking severely.

If this were a gasoline engine, I would assume that it was a spark plug fouling or a spark plug wire breaking down. With a diesel, neither of those are possible so the most logical alternatives were 1) fuel filter partially plugged, 2) air filter partially plugged, or 3) injector failing since the symptoms only occurred under high engine loads. I checked the air filter minder and it showed that the air restriction was very low.

I had both the secondary and primary fuel filters replaced in Yuma and took the coach back through the Border Patrol checkpoint and up the grade east of Yuma on I-8, then turned around about 20 miles later and returned over the grade to the foothills area. The trip was a non-event. No bucking, no hesitation.

I have retained the old fuel filters and will be cutting them open to attempt to determine if the primary or the secondary or both filters were plugged up. The filters had been replaced on August 5th and I had traveled about 9,000 miles since then.

A bad tank of fuel or moisture in the fuel tank with resulting algal growth can plug up a filter in a hurry.

I will post a follow up message after cutting the filters apart to determine the likely cause of the problem.


THE MORAL OF THE STORY:
I will also be carrying an extra pair of fuel filters in the bay (I had spare oil filter and hydraulic filter but no fuel filters) from now on. I was fortunate that the Express RV Lube in Yuma had the right filters in stock so it did not delay my trip.