Booyah45828
Full Access Member
I'm looking to bounce some ideas off someone's head.
I have an IH school bus with a 6.9. The bus is a 1984, engine is a jasper reman, unsure of the year or when it was installed. It definitely has the ford rpm governed pump fwiw.
I'm having what I believe to be air intrusion issues. Glow plugs are on a manual switch, and were replaced last year. They all are working fine. The engine will start, run for a second or two, and then die. Crank it for about another 10 seconds and it will start back up and run normally. Stereotypical air intrusion issues right?
Well, I've replaced the O-rings, caps, and lines with a delphi kit, so I don't think I have issues there. They were originally leaking fuel last year, and dumped a bunch of fuel into the valley, so I replaced them. All the o-rings were shot and broke upon removal, so that was definitely an issue. After replacement, there is no more fuel leaking, but I know that doesn't necessarily mean that air isn't leaking.
I also installed a check valve by the tank, because the onboard generator, that shares the same fuel pickup with the engine, was drawing air back through both engine filters. There is a check valve in each supply line now, and running the generator no longer pulls air back through the primary or secondary filters, so I don't think my air issue is on the supply side of the fuel pump either.
What I don't know, is that there is a hose that runs from the #2 injector cap to what they call a "bleed orifice elbow" on the filter head. I assume this is to bleed off air in the filter head similar to what is done on certain idi equipped ford trucks. This elbow is on the outlet of the secondary filter and is connected to the line that supplies fuel to the injection pump. My question is this. Is this "air bleed elbow" nothing more then a metered leak from the fuel filter, or is there a check valve of some sort in there similar to what is found on the 7.3 filter head?
I'm thinking that it's supposed to be some sort of check valve, otherwise what would prevent that from letting air from the return system into the filter head when the engine isn't running?
So IH experts(if there are any here) what say you? I'll eventually figure this out come spring time, but I figured we could discuss it before then.
*I'm not installing an electric or eliminating the mechanical lift pump. I considered installing a smaller cube type primer pump parallel to the mechanical pump, or installing a different filter head equipped with a primer pump, but I'd rather fix my issue then mask it with either of those option.
I have an IH school bus with a 6.9. The bus is a 1984, engine is a jasper reman, unsure of the year or when it was installed. It definitely has the ford rpm governed pump fwiw.
I'm having what I believe to be air intrusion issues. Glow plugs are on a manual switch, and were replaced last year. They all are working fine. The engine will start, run for a second or two, and then die. Crank it for about another 10 seconds and it will start back up and run normally. Stereotypical air intrusion issues right?
Well, I've replaced the O-rings, caps, and lines with a delphi kit, so I don't think I have issues there. They were originally leaking fuel last year, and dumped a bunch of fuel into the valley, so I replaced them. All the o-rings were shot and broke upon removal, so that was definitely an issue. After replacement, there is no more fuel leaking, but I know that doesn't necessarily mean that air isn't leaking.
I also installed a check valve by the tank, because the onboard generator, that shares the same fuel pickup with the engine, was drawing air back through both engine filters. There is a check valve in each supply line now, and running the generator no longer pulls air back through the primary or secondary filters, so I don't think my air issue is on the supply side of the fuel pump either.
What I don't know, is that there is a hose that runs from the #2 injector cap to what they call a "bleed orifice elbow" on the filter head. I assume this is to bleed off air in the filter head similar to what is done on certain idi equipped ford trucks. This elbow is on the outlet of the secondary filter and is connected to the line that supplies fuel to the injection pump. My question is this. Is this "air bleed elbow" nothing more then a metered leak from the fuel filter, or is there a check valve of some sort in there similar to what is found on the 7.3 filter head?
I'm thinking that it's supposed to be some sort of check valve, otherwise what would prevent that from letting air from the return system into the filter head when the engine isn't running?
So IH experts(if there are any here) what say you? I'll eventually figure this out come spring time, but I figured we could discuss it before then.
*I'm not installing an electric or eliminating the mechanical lift pump. I considered installing a smaller cube type primer pump parallel to the mechanical pump, or installing a different filter head equipped with a primer pump, but I'd rather fix my issue then mask it with either of those option.