jim x 3
1988 F-350 DRW
I Need Help Troubleshooting the classic Air Intrusion Problem
I have been fighting this issue on/off since Oct '13. After sitting 24 hours, truck starts immediately, runs for 1 second, then dies. Considerable cranking is required for restart. After this, truck starts immediately and runs without trouble all day long. Since I'm an electrician and not a plumber, maybe some of you guys who have suffered can give me some advice. To the best of my knowledge, the fuel system components are all stock - as when the truck was new.
I have:
1. Replaced all return banjos, O-rings, and return hose (Typ4) No visible fuel leaks
2. Replaced 5/16" Olives in filter head-IP steel line, both ends (Typ4) No visible fuel leaks
3. Checked Shrader valve for tightness, replaced cap
4. Replaced O-ring @ top of IP (@ check valve fitting)
5. Replaced hose @ top of IP (EL fitting to return steel line that runs back to "T" near cyl 8
6. Added a clear hose section to rubber line from #1 return banjo to filter head - overnight, air bubbles will cluster in the top portion of this hose until hose is completely empty of fuel. Very small bubbles are coming out of the filter head barbed fitting between vacuum switch and Shrader fitting.
7. Replaced the 3/8" olive in the lift pump-filter head steel line (Typ4) No visible fuel leaks
8. Removed and replaced fuel filter and rubber washer in water drain at bottom of filter. Filter was full of fuel when removed, but no fuel spilled down the filter element as I spun it off.
9. Removed and replaced the Shrader fitting and barbed fitting in the filter head, used Rectorseal on threads when replacing. Replaced the Shrader valve core and cap. (If the core is depressed with engine off, bubbles appear in the clear line rapidly and the line empties of fuel - 10 seconds to mimic the 24 hour problem). I thought there was supposed to be a check valve in the barbed fitting, but there was none. ID of that fiting is very small.
Since the problem appears to be localized to the filter head (am I wrong here?) I have not changed anything at the return line "T" fitting(s) near cyl #8 or any fuel lines, FSV, or tank connections. But there are no visible fuel leaks anywhere in those components.
I have not yet messed with the lift pump, filter head fuel heater (power wire has been disconnected since I've owned the truck), the filter head vacuum switch (which is working), or the Shrader valve for air entry at water drain at the bottom of the filter (this is not a standard Shrader core). No visible fuel leaks
My GPs, GPC, batteries, starter, and other electrics are all good, so the problem has been just a daily annoyance (and occasional embarrassment), but it sure is getting old. I know I can mask the issue by replacing the lift pump with an electric that will re-prime my fuel lines prior to start, but I'd like to find the leak.
Any suggestions for me?
Thanks guys,
I have been fighting this issue on/off since Oct '13. After sitting 24 hours, truck starts immediately, runs for 1 second, then dies. Considerable cranking is required for restart. After this, truck starts immediately and runs without trouble all day long. Since I'm an electrician and not a plumber, maybe some of you guys who have suffered can give me some advice. To the best of my knowledge, the fuel system components are all stock - as when the truck was new.
I have:
1. Replaced all return banjos, O-rings, and return hose (Typ4) No visible fuel leaks
2. Replaced 5/16" Olives in filter head-IP steel line, both ends (Typ4) No visible fuel leaks
3. Checked Shrader valve for tightness, replaced cap
4. Replaced O-ring @ top of IP (@ check valve fitting)
5. Replaced hose @ top of IP (EL fitting to return steel line that runs back to "T" near cyl 8
6. Added a clear hose section to rubber line from #1 return banjo to filter head - overnight, air bubbles will cluster in the top portion of this hose until hose is completely empty of fuel. Very small bubbles are coming out of the filter head barbed fitting between vacuum switch and Shrader fitting.
7. Replaced the 3/8" olive in the lift pump-filter head steel line (Typ4) No visible fuel leaks
8. Removed and replaced fuel filter and rubber washer in water drain at bottom of filter. Filter was full of fuel when removed, but no fuel spilled down the filter element as I spun it off.
9. Removed and replaced the Shrader fitting and barbed fitting in the filter head, used Rectorseal on threads when replacing. Replaced the Shrader valve core and cap. (If the core is depressed with engine off, bubbles appear in the clear line rapidly and the line empties of fuel - 10 seconds to mimic the 24 hour problem). I thought there was supposed to be a check valve in the barbed fitting, but there was none. ID of that fiting is very small.
Since the problem appears to be localized to the filter head (am I wrong here?) I have not changed anything at the return line "T" fitting(s) near cyl #8 or any fuel lines, FSV, or tank connections. But there are no visible fuel leaks anywhere in those components.
I have not yet messed with the lift pump, filter head fuel heater (power wire has been disconnected since I've owned the truck), the filter head vacuum switch (which is working), or the Shrader valve for air entry at water drain at the bottom of the filter (this is not a standard Shrader core). No visible fuel leaks
My GPs, GPC, batteries, starter, and other electrics are all good, so the problem has been just a daily annoyance (and occasional embarrassment), but it sure is getting old. I know I can mask the issue by replacing the lift pump with an electric that will re-prime my fuel lines prior to start, but I'd like to find the leak.
Any suggestions for me?
Thanks guys,