Hello my name is Dave
I would like to begin by making sure you have replaced the fuel filter before coming to any conclusions about a faulty pump, if you haven't we need to start there. I would also recommend that if you have access to an air compressor take a blow gun and disconnect the fuel line at the fuel filter that runs back to the tank, take the fuel cap off and blow back through the fuel line that runs from the filter to the tank. You don't have to worry about an in tank filter it has none.
I am very familiar with these trucks and next thing I want to check is that the pump is getting fuel, a major problem I ran into with theses trucks is rust in the fuel tank contaminating the entire system, this is why I recommend blowing the line clear. Regardless I would recommend going to Harbor Freight or a similar store and buy a magnetic tool holder and go to the hardware store or similar and buy a very strong tape, I used metallic duct tape, and tape it to the bottom of the tank to trap the rust at the bottom to keep it out of the system. Rust is by far the most common cause of any fuel issue with theses truck and the most likely suspect for a fuel pump failure.
The reason this happens is the new(er) low sulfur fuel is more susceptible to water contamination because the sulfur would bond to the water dispersing it throughout the fuel were as the new fuel allows the water to accumulate at the bottom of the tank causing it to rust.
Your pump is purely mechanical so as long as the cable from the shut off solenoid moves it should start, the wire on the top is for the pump advance and the other wires are for the crank sensor however none of which can keep the truck from running.
I would start by taking the feed line off the injector pump that goes from the lift pump on the side of the injection pump and make sure you are getting fuel into the injector pump. If you are getting fuel to the injection pump and get no fuel when you loosen the fuel line(s) on the top of the pump and the shut off is moving then you have a faulty injection pump.
If you are not getting fuel to the injector pump I would get a container of fuel and disconnect the suction (input) hose from the lift pump, put a longer hose on it and place it into the container of fuel and see is this allows the engine to start. If it doesn't I would recheck for fuel to the injector pump and if you don't have any then you have a faulty lift pump, and it will pump regardless of the shutoff's position.
If you can get fuel by connecting a temporary line to the lift pump, and you have replaced the fuel filter and cleared the fuel line going from the filter to the tank there is the possibility the filter housing is restricted, you can determine this by bypassing the filter temporarily connecting a hose from input hose fitting to the output fitting. These steps should track down your fuel issue, and it would be unusual for it to be a mechanical issue with one of these engines, When I was service manager and lead mechanic for a good size fleet of these trucks actual engine failure takes a HUGE amount of abuse, we had several trucks with over 600,000 miles that didn't even use an excess amount of oil between service intervals.
I believe this will help you track down your issue and if it doesn't let us know and we will do our best to help you further. Please keep us up to date on your progress and thank you for using 2CarPros!
Monday, September 28th, 2020 AT 4:03 AM