HARLEYSUPERDUTY

Guys, I had the same bucking/popping problem last year with my 99 ISC 330, the primary filter was getting restricted with tank crud. It started happening in northern Maine with full throttle in the hills under full load. The engine would buck. I was on a 2600 mile hard trip from Houston to Eastern Canada and I was always running the tank to less the 1/4 which caused the fuel and contaminants in the tank to be agitated. You have to remember that the fuel pickup is about 1" from the bottom of the tank on a diesel application and with low fuel tank level the contaminates sitting on the bottom of the tank really start mixing with fuel and restricts the primary filter. The only way you can tell your primary is getting filled to capacity with contaminated is to measure the restriction with a vacuum gauge WHILE UNDER FULL LOAD. I installed a Racor tattle tale vacuum gauge on the outlet port of the primary filter. The gauge has a red indicator mark that stays at the max restriction until you reset it. This way you can do a visual anytime and see what the max restriction was when you were driving. This is the same concept as a resettable air filter restriction gauge.