Fuel quality can make the truck hard to start in the mornings. Treating with Diesel Extreme should clear out the fuel system. If you are still having trouble with cold starts, it’s likely that the glow plugs are not operating correctly. Listen to the glow plug relay. You will hear an audible “click” when the key is turned on. Check all the wiring leading to the glow plugs for breaks or cracks in the insulation. A single chaffed wire can throw out a whole bank of plugs. If the wiring looks good, measure the resistance across the glow plug to see if it within specifications; an “OL” reading on your Digital Multi-Meter means there is no continuity in the circuit, and the glow plug is bad.

Semi Truck Difficult Cold Start | Diesel Engine Cold Start

Problems

Several things could be causing difficult cold starts:

Problem: Poor fuel quality

Problem: Glow-plug problem

Fuel quality can make the truck hard to start in the mornings. Treating with Diesel Extreme should clear out the fuel system.
If you are still having trouble with cold starts, it’s likely that the glow plugs are not operating correctly.

Listen to the glow plug relay. You will hear an audible “click” when the key is turned on.
Check all the wiring leading to the glow plugs for breaks or cracks in the insulation. A single chaffed wire can throw out a whole bank of plugs.
If the wiring looks good, measure the resistance across the glow plug to see if it within specifications; an “OL” reading on your Digital Multi-Meter means there is no continuity in the circuit, and the glow plug is bad.

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