Another fuel problem question...
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Elder User
Joined: Feb 2004
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From: Longvalley, SD
Another fuel problem question...
I just bought an 86 F-350 with a 6.9 about a month ago. I have racked up about 120 miles on it so far and it has run great until yesterday, it started to run roughly and then eventually died on me. I got it started after about 10 seconds of cranking. I had to keep my foot in it to keep it running. Good thing I was only about 1/4 mile from my shop so I limped it back. I changed the fuel filter and still had the same problem. I started it and quickly jumped out and bled the shrader valve while it was running. It had air in the system. I bled it until it shot a steady stream of fuel out and it would run fine for about 5 minutes then it would start running roughly again and eventually die. I repeated these steps again occasionally bleeding out air while it was running. I cant find any visible leaks. I was also wondering what the fuel filter/seperator canister is for on the driver side firewall, my 7.3 does not have this. Could the air possibly be getting in from this? Thanks for any ideas.
Lead Driver
Joined: Nov 2003
Posts: 6,900
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From: Campbell River, B.C.
The canister on the drivers side of the firewall is the water seperator. The 7.3 has the seperator integrated into the fuel filter for simplicity, and because the older ones are prone to letting air into the system. You could temporarily bypass the seperator to see if this solves the problem, but don't run it like that for long.
When I replaced mine with an integrated filter/seperator, I cut the old seperator open, and discovered a good amount of dirt and sand in it, enough that is plugged the drain hole.
Since the fuel is pulled from the tank instead of pressurised like newer vehicles are, air can enter the system without always revealing a fuel leak due to the vacuum in the line. Air leaks can be hard to fine in these trucks.
When I replaced mine with an integrated filter/seperator, I cut the old seperator open, and discovered a good amount of dirt and sand in it, enough that is plugged the drain hole.
Since the fuel is pulled from the tank instead of pressurised like newer vehicles are, air can enter the system without always revealing a fuel leak due to the vacuum in the line. Air leaks can be hard to fine in these trucks.
Thread Starter
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Elder User
Joined: Feb 2004
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From: Longvalley, SD
Well I took a look at the problem today and noticed fuel dripping from the drain hose on the water seperator. I pulled the valve on it a couple times and it drained some fuel out. I started the pickup and it has ran fine ever since?? I'm guessing there was a piece of debris stuck in the seal on the drain. Hopefully I wont have any more problems with it. Can you buy new water seperator canisters? Or should I just do as you did and get an integrated filter/seperator like the 7.3's have? Thanks.
Lead Driver
Joined: Nov 2003
Posts: 6,900
Likes: 3
From: Campbell River, B.C.
Well that was an easy fix! If it gives you trouble again, you can try removing it and carefully stick a small screw driver up the drain to cleal any debries that bay be harder to reach. Whats really stupid about the older seperator, is that theres no way to take it apart to clean it out.
If it starts to give you real trouble, I would just get a filter/seperator unit from a 7.3, there should be plenty of them in wrecking yards for decent prices. Its a strait bolt on swap, the only mod might be replacing the injector return line that goes to the filter head. I think it would be too short for the new setup. If you want the WIF light to still work though, you will need to splice in a sensor.
Don't bother with the racor retrofit kit either, the filters are nearly impossible to get at most autoparts stores, I made that mistake myself.
If it starts to give you real trouble, I would just get a filter/seperator unit from a 7.3, there should be plenty of them in wrecking yards for decent prices. Its a strait bolt on swap, the only mod might be replacing the injector return line that goes to the filter head. I think it would be too short for the new setup. If you want the WIF light to still work though, you will need to splice in a sensor.
Don't bother with the racor retrofit kit either, the filters are nearly impossible to get at most autoparts stores, I made that mistake myself.
