Alright I think I might have found something. I just went out to the truck to put a clear line from the back injector caps to the brass fitting and I found something interesting. The one side is fine, there is no air coming from the cap or runing back to the cap from the tank. However on the other side no fuel is coming out of the cap. I can pull the hose right off with the engine running and nothing comes out. This means nothing is returning from the one side of the engine. So I guess something must be blocking the cap, or could this mean a bad injector? Could this have been my problem all along?
clear line test, but where is the air coming from?
Ok, so my truck started getting hard to start, and it was getting progressivly worse it seemed. It would usually start after a few 10 second cranking sessions. Last weekend I decided I was going to try to fix it but that morning it wouldn't start. It took lots of cranking and ether to get it to start. The night before, I was coming home from work and started to run out of fuel in the back tank so I switched to the front, but that was also really low. Well I started putting clear lines everywhere and heres what I found out:
1) There is no air coming up from the lift pump to the filter.
2) There is no air from the filter return to the #1 injector cap, but I did take out the check valve and I can blow air backwards through it. Its the style with the flap inside not the ball and spring.
3) From the Filter outlet to the IP inlet there is a large air pocket / bubble when the engine is off, but gets pushed out towards the IP when the truck starts. Then you can't see it anymore but when the engine is shut off it returns. It never seems to get any bigger, although I'm not sure.
4) On my truck the two caps at the back go to a brass cross piece like: + . there is a hose from the injector caps that goes into the side of this fitting on each side. The back of the fitting has a hose that goes to the return line and then down to the tank selector. The front of the fitting goes to the outlet on top of the IP. When I initially pulled the hose off the front of this fitting no fuel came out. I put a clear line on and what I found out is that fuel gets pushed out of the IP and with a loop in the line it will fill to the top of the loop and then run freely down the other side to the tank. The line never stays full of fuel. When the truck starts then the line slowly fills and pushes the air out towards the tank, and then stays full. But when I shut the engine off the line imediatly starts to fill with air coming back from the tank.
I was thinking that maybe my problems were because I ran the one tank dry and the other was really low. So I just went and filled them both about half full and drove around for 10 minutes or so. When I stop the engine the line still starts to fill with air coming from tank but not as much as before.
Any idea where this air might be coming from. I'm guessing maybe there could be a crack in the plastic line running back to the tank selector, or maybe on of the connections on it are loose? After writing all this I was just thinking I should put clear lines on all sides of that brass cross at the back to make sure it is infact coming from the tank side and not from one of the caps, but it is a huge leak. I put some pictures up, the reason the fuel is black is because I was running w85 for a while but both tanks have diesel in them now. If what I wrote is to confusing I'll see if I can put up a video somewhere. The first picture is the air from the filter to the IP, it never seems to go away or get bigger. The second picture is the air thats come up from the tank to the IP, before I went and filled the tanks the whole line would fill with air except from the loop down to the IP. The last picture is of the brass fitting at the back incase your not sure what I'm talking about.
1) There is no air coming up from the lift pump to the filter.
2) There is no air from the filter return to the #1 injector cap, but I did take out the check valve and I can blow air backwards through it. Its the style with the flap inside not the ball and spring.
3) From the Filter outlet to the IP inlet there is a large air pocket / bubble when the engine is off, but gets pushed out towards the IP when the truck starts. Then you can't see it anymore but when the engine is shut off it returns. It never seems to get any bigger, although I'm not sure.
4) On my truck the two caps at the back go to a brass cross piece like: + . there is a hose from the injector caps that goes into the side of this fitting on each side. The back of the fitting has a hose that goes to the return line and then down to the tank selector. The front of the fitting goes to the outlet on top of the IP. When I initially pulled the hose off the front of this fitting no fuel came out. I put a clear line on and what I found out is that fuel gets pushed out of the IP and with a loop in the line it will fill to the top of the loop and then run freely down the other side to the tank. The line never stays full of fuel. When the truck starts then the line slowly fills and pushes the air out towards the tank, and then stays full. But when I shut the engine off the line imediatly starts to fill with air coming back from the tank.
I was thinking that maybe my problems were because I ran the one tank dry and the other was really low. So I just went and filled them both about half full and drove around for 10 minutes or so. When I stop the engine the line still starts to fill with air coming from tank but not as much as before.
Any idea where this air might be coming from. I'm guessing maybe there could be a crack in the plastic line running back to the tank selector, or maybe on of the connections on it are loose? After writing all this I was just thinking I should put clear lines on all sides of that brass cross at the back to make sure it is infact coming from the tank side and not from one of the caps, but it is a huge leak. I put some pictures up, the reason the fuel is black is because I was running w85 for a while but both tanks have diesel in them now. If what I wrote is to confusing I'll see if I can put up a video somewhere. The first picture is the air from the filter to the IP, it never seems to go away or get bigger. The second picture is the air thats come up from the tank to the IP, before I went and filled the tanks the whole line would fill with air except from the loop down to the IP. The last picture is of the brass fitting at the back incase your not sure what I'm talking about.
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I could be wrong, But it sounds like the return system is not installed right. I have the schematic for the turbo application and I only have 1 line that returns to the tank(s). Maybe someone can post the N/A return system.
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Mine is similar to that, but slightly different. Heres a schematic of what mine looks like along with where I'm seeing air. I didn't see any fuel coming out of the lines on the right side, but if you think about it, it would only be excess fuel from the injectors which I think would take a while to see anything. No air comes up the lines at the back, just up the metal tube which goes to the IP. I guess if theres a check valve at the IP then it wouldn't matter, I'll have to check for that tommorow.
If you look on this page then I think it talks about there being different applications on the return system. Ford diesel 6.9 7.3 IDI
If you look on this page then I think it talks about there being different applications on the return system. Ford diesel 6.9 7.3 IDI
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