C15 Cat wont start

There is a check valve at the inlet on the Davco. You could have trash in it, or it could be bad. I have had the same problem with a Detroit and a Davco. It ended up being a piece of aluminum sucked up from the tank holding the check valve at the Davco open and letting the fuel drain back into the tank after sitting a while.

 

No it should recover quickly unless its the check valve that is draining the fuel from the head

 

It won't fire on initial startup, typical problem for the check valve.

 

Yes, thats why I said "Check valve would be the likely cause for the "won't start after a day or so", but then he said "I restarted it (I always have the engine running while adding Lucas) It ran for about 45 seconds, started to skip and shut down. I stroked the primer pump, again, gave it a shot, again, it fired and ran for about a min and shut down; again." which prompted me to add "but shouldn't account for the "starts, runs for a minute or so then quits" and does this twice back to back". A bad check valve shouldn't cause it to quit once it's running.

 

close off your right fuel tank make sure your fuel cap is tight on left tank. Then pull your vent hose out of holder on tank. Take an air blower and add air to vent hose not alot of air but enough to create about 2-3 psi in tank. If you have leaking hose on suction side it will show just be carefull dont remove cap with pressure in tank. It will slowly leak out of tank because fuel cap will leak. If you don't close the right tank it will push all the fuel from left into right tank. This will find a leak if indeed you have one.

 

Be very CAREFUL if you pressurize the tank with air. They will not take much pressure before they will pop a weld joint.

The first thing I would do is change the check valve in the secondary filter base

 

Is this one of the Internationals that had a problem with the baffles in the fuel tank breaking loose with a little age, you will hear it banging around in the tank if you stop abruptly. I can't remember the year I saw several that came loose. The reason I ask, I had a friend that had this problem on a Pete, he was at his wits end trying to find it, when he finally pulled the suck tubes from the tanks, and one of the tubes had a crack in it at the top. If you bought this truck new, then you would know if one was ever loose. If you bought it used, and you haven't heard a baffle banging around in the tank, then check the weld where the tank end cap is welded to the tank tube, check each end of each tank, if it looks like the factory weld on both ends of both tanks and you don't hear a loose baffle, then the suck tubes are probably okay, if one of the tanks has a different looking weld on one of the end caps, I would pull that suck tube and check it, the baffle banging around in there very long could bang the tube back and forth a couple of times and crack it.

Another thing I found once myself was a crack in the filter housing on the surface where the filter gasket meets, factory defect? I have no explanation for that one. Another time I found a crack on the filter housing where someone over tightened a fitting in the filter housing so that it would point in a certain direction, but one round to many and cracked the housing.

One last thing, I have pressure checked the suction lines also trying to find a leak, but it doesn't always show up when you do that, because the hoses are made in layers, and it is possible to have a crack in one of the inner layers, but the rubber will still move somewhat, acting like a check valve, pump it up, no leak, put a vacuum on it and it will leak. Seeing the age of the truck, my opinion is that the hoses are due to be replaced, so take that for what it is worth, opinion only. Let us know what you find out if you would, it will help someone else down the line.

 

Thank you for this info. I have a 95' intl. it always had a clanging sound in the drivers side fuel tank. never knew what is was. been hearing it for 13 years. one day 7 years ago my dash fuel gauge quit working. replaced sending unit in tank & it worked again, until recently. now the needle bounces all round until tank is 1/2 full, then it reads accurate from there on down. I also had what I think is a air in fuel problem, by the way the truck started & ran at idle. replaced all my fuel lines, except the 2 from the tanks. still getting very little air bubbles in my davco. the pick up tube.. would that be in the front of the tanks ? I think my fuel lines in the rear of the tanks are my return lines, cause they are very warm. is the pick up tube attached to the el brass fitting in the front part of tank ?