I have an Express 2500 with 5.3L 180k miles or so, that just quit running while going down the road the other day. No trouble codes or security light to follow.
After sitting for a number of hours it will fire and run for 5 to 10 seconds then quit again. While running the engine sounds perfect.
So far I verified fuel filter is clear, fuel pump working and it wouldnt fire on starting fluid.
I changed the crank sensor, plugs, wires, had battery tested and no it isn't out of fuel.
Round two: Verified spark but it is a weak light orange color. Charge up battery again, it's only two months old, ran for five minutes or so then quit.
At no time did the truck run poorly before it quit on us. I feel like I'm getting close but dont want to keep throwing parts at it.
Any help would be greatly appreciated.
There are a few questions I have. Did you do a fuel pressure test? There is a service bulletin on the fuel module where the fuel pump malfunctions and needs to be replaced but the entire fuel module inside the fuel tank needs to be replaced because it is a non serviceable unit. This means you just can't replace the fuel pump the entire module which includes the fuel screen, fuel pump and the fuel sending unit.
When was the last time you put fuel in the vehicle and is the vehicle a flex fuel vehicle? The reason I am asking is people have been listed as filling up the vehicle with E85 fuel when it is not flex fuel and the increase in Ethanol causes poor or no running conditions.
Your last resort is to bring it to the dealer to have them scan the computer system for any faults or codes. Sometimes a code can be set and not put on the check engine light. The mechanic can also see data from many different sensors to determine if there is any fault with any sensors, modules or sending units.