DD15 wont fire after fuel filters changed.

First you should not be using starting fluid.

Second, I assume you have a Davco water separator, and if so, then ...

if you are filling the separator up, it has to go near the top and then you prime the system, you should go through almost 2 gallons of diesel before it will start. The line of fuel should never go less than 1 inch above the bell ring on the separator.

If you have no prime or the level isn't going down, pull the primary filter and see if it is filling up when you prime.

If I remember right, the DD15 has a priming port, get a little hand primer or you can make a pressure primer if you want or pay for the expensive one - we made one.

 

Any possibility of a gasket missing on the davco?

 

I lost prime once on my 12.7 after changing an injector. Ether wouldn’t work. Finally pressurized the fuel tanks using a portable air compressor hooked up to the fuel vent. I crimped off the other vent. Took a long time, about 30 minutes to build up 17 lbs. Tanks were less than half full, so a lot of cf to fill. 17 lbs was way too much. I hear 3-5lbs is plenty. It started right up, ran about 15 seconds and died. I had to bleed the pressure off by loosening the fuel lines at the filter. Afterwards, It started with just a bit of ether for good luck. Everyone told me to just keep cranking it. I spent about 5 hours cranking it, jumpers hooked up, smoking batteries. Since then I’ve seen on Utube that putting air into one fuel tank, using a blow gun and a shop rag works great. Your Truck probably has the fitting on the fuel pump to prime it. Maybe that’s what you mentioned already, and using the mechanics makeshift primer. I think your Detroit has a lot higher fuel pressure than mine. Maybe try filling, priming, and the blow gun and rag trick. Pressurizing the tank and pushing the fuel through. Maybe a shot of ether to boot. That’s up to you. Everyone frowns on ether with good reason. I wouldn’t hesitate to spray some ether in it. I’d give it 4-5 seconds, then crank it up, It’ll surge, then bog down. Hit it again before it stalls. I’d do it 3-4 maybe 5 times. Each time just enough to keep it running. But that’s just me. It definitely can damage the cylinder walls. I’ve used it quite a few times on mine. When I first bought it, I ran it out of fuel a few times because of bad gauge readings. Still lasted 1.3 million miles. They say it’s much worse than a dry start. Still some oil on rings even on a dry start. They claim the ether washes out the oil on the rings. We even started mine with ether first start after an overhaul. That’s almost considered a sin, Lol. I think once it’s running, the ethers so volitile, it explodes and burns immediately. A good argument to start cranking first before spraying. Still takes the same amount. I have no idea. A good 5 second dose seems to work best. It’s like pulling a tooth, just get it over with. Might put some premature wear on it. But it’s not going to immediately destroy the engine. Just don’t go crazy running it for over 10 seconds or so. The cylinders will get so hot, they’ll lock up the engine, till it cools off. I’ve foolishly done that, still didn’t destroy my engine.

 

Another great way to safely get it primed would be to pull it around the yard or parking lot, while in gear, key on. As long as the fuel pumps mechanical, it’s the same as cranking it. Higher the gear, faster it’s cranking. Considering they usually prime it at the Truck stops using their little machine. Not sure if that would work. Im sure it would on my old Truck.

 

The priming port is different from the primer pump. It’s a connector, I think it’s located on the fuel pump. TA etc. have a special primer machine they hook to it. My old Truck doesn’t have a port. That’s why I had to pressurize the tanks themselves. Once the fuel leaves the head, and prime is lost. It’s almost impossible to get it primed again just by cranking it. Fuel needs to be pushed.

 

If you rock the filters sideways hard enough taking them out it will crack the stand. Short of replacing it, nothing will make it run.

 

Is it possible that the primer is bad?

 

The fuel return valve could have failed. That will kill prime too. I'm thinking it's a o-ring. I would put Lucas grease on the o ring and reseal it. It couldn't hurt.