I thought I could tackle this myself, but I need help, here are the facts and history to date, it reads like a book…
1) Over the last 2-3 months I noticed increasing audible humming noise coming from floorboard area under driver seat.
2) A month ago: threw CEL on a grade, went into limp mode. Autel 802MD = P0087 Fuel Rail/System Pressure too Low. I changed the fuel filter, reset the code. Upon hard accel, engine shuts down, Code returns….Humm Me thinks… NOT FILTER. -$50 & 1 hour of enjoyable labor…
3) 3 Weeks ago: Because of the sound under the floorboard, I begin to investigate LP fuel system. I come across the well documented problem of T1N Fuel Line vibrations/floorboard noise due to Fuel Quality Valve at the HP pump… I think I have it nailed, upon touching the lines, one of the them is vibrating wildly! I purchase a new Fuel Quality Valve from europartsSD. A couple days later, I replace and test drive after, but CEL returns, again on hard accel. Nuts! me thinks… NOT FUEL QUALITY VALVE -$230 and 3 Hours of puzzle-solving but enjoyable labor (that bugger’s not easy to get at)… SHAME ON ME FOR THROWING PARTS AT IT!
4) 2 Week Ago: Further research (here) leads me to a proper LP fuel pressure test, that weekend, it takes me about 3 hours to rig up a T before the filer and get a good quality gauge. My LP pressure from the tank is 34-48 PSI (well below the required 48-65 psi). On test drives, when it drops below 40psi, the CEL is thrown… OK, it’s the lift pump or plugging in the LP system… I drain and drop the tank, I pull the pump, I find the inlet grid on the suction tube plugged solid! (see picture) CONTAMINATION, HA!! I think I have it nailed! I clean the little grid, I clean the entire tank, and I put it back together. Upon testing the CEL returns, MH in limp mode, LP fuel pressures still in the 35-45 PSI range. SOB!! -7 hours of messy, upside down, neck and core fatiguing work, MY WIFE WON’T EVEN LET ME IN THE HOUSE BECASE I SMELL LIKE A DISEL REFINERY… Drinking my beer alone, Me thinks, “I like the smell of diesel…Failed Lift Pump? Must be. That “*^(*%!” tank must come back down…”
5) Last week, I drain and drop the tank again, easy this time, 1 hour out to the ground… I remove, blow out and verify the fuel supply line is clear…it is… (another hour), but before buying a new lift pump assembly, I think “What the Hay… lets tear this apart and look inside”. This begins a 3 hour long surgery on the Lift Pump Assembly that was obviously never intended to come apart. I take my time, I enjoy the work. I find an entirely plugged inlet screen on the bottom of a perfectly good pump! (see pict below… I partially cleaned the screen for comparison…) HA HA HA!! I found it! Me thinks!! - I put it all back together, I take a deep breath before turning the key… THIS IS WHERE IT GETS INTERESTING… - 6 hours of lift pump surgery and tank reinstall…
Upon Starting it immediately throws a different CEL, Autel802MD = P0088 Fuel Rail/System Pressure too high.
a) The LP pressure is now 55-60PSI at idle
b) The code is thrown about 5 seconds after starting, when CEL is thrown it immediately goes to LHM.
c) When the code is thrown, LP pressure spikes to 63. Drops back to 55-60 after LHM
d) When code is thrown, FRP builds to 9-10k drops back to 4-5k after LHM.
e) During the first 30 seconds of start, I can reset the code repeatedly, the above pressures will build repeatedly, throw the code and return back down.
f) After the first thirty seconds or so, the code will not return, the engine idles fine, the pressures are stable at 55-60psi LP and 4-5K HP.
g) Why this issue only during the first 30 seconds of start?
1) Over the last 2-3 months I noticed increasing audible humming noise coming from floorboard area under driver seat.
2) A month ago: threw CEL on a grade, went into limp mode. Autel 802MD = P0087 Fuel Rail/System Pressure too Low. I changed the fuel filter, reset the code. Upon hard accel, engine shuts down, Code returns….Humm Me thinks… NOT FILTER. -$50 & 1 hour of enjoyable labor…
3) 3 Weeks ago: Because of the sound under the floorboard, I begin to investigate LP fuel system. I come across the well documented problem of T1N Fuel Line vibrations/floorboard noise due to Fuel Quality Valve at the HP pump… I think I have it nailed, upon touching the lines, one of the them is vibrating wildly! I purchase a new Fuel Quality Valve from europartsSD. A couple days later, I replace and test drive after, but CEL returns, again on hard accel. Nuts! me thinks… NOT FUEL QUALITY VALVE -$230 and 3 Hours of puzzle-solving but enjoyable labor (that bugger’s not easy to get at)… SHAME ON ME FOR THROWING PARTS AT IT!
4) 2 Week Ago: Further research (here) leads me to a proper LP fuel pressure test, that weekend, it takes me about 3 hours to rig up a T before the filer and get a good quality gauge. My LP pressure from the tank is 34-48 PSI (well below the required 48-65 psi). On test drives, when it drops below 40psi, the CEL is thrown… OK, it’s the lift pump or plugging in the LP system… I drain and drop the tank, I pull the pump, I find the inlet grid on the suction tube plugged solid! (see picture) CONTAMINATION, HA!! I think I have it nailed! I clean the little grid, I clean the entire tank, and I put it back together. Upon testing the CEL returns, MH in limp mode, LP fuel pressures still in the 35-45 PSI range. SOB!! -7 hours of messy, upside down, neck and core fatiguing work, MY WIFE WON’T EVEN LET ME IN THE HOUSE BECASE I SMELL LIKE A DISEL REFINERY… Drinking my beer alone, Me thinks, “I like the smell of diesel…Failed Lift Pump? Must be. That “*^(*%!” tank must come back down…”
5) Last week, I drain and drop the tank again, easy this time, 1 hour out to the ground… I remove, blow out and verify the fuel supply line is clear…it is… (another hour), but before buying a new lift pump assembly, I think “What the Hay… lets tear this apart and look inside”. This begins a 3 hour long surgery on the Lift Pump Assembly that was obviously never intended to come apart. I take my time, I enjoy the work. I find an entirely plugged inlet screen on the bottom of a perfectly good pump! (see pict below… I partially cleaned the screen for comparison…) HA HA HA!! I found it! Me thinks!! - I put it all back together, I take a deep breath before turning the key… THIS IS WHERE IT GETS INTERESTING… - 6 hours of lift pump surgery and tank reinstall…
Upon Starting it immediately throws a different CEL, Autel802MD = P0088 Fuel Rail/System Pressure too high.
a) The LP pressure is now 55-60PSI at idle
b) The code is thrown about 5 seconds after starting, when CEL is thrown it immediately goes to LHM.
c) When the code is thrown, LP pressure spikes to 63. Drops back to 55-60 after LHM
d) When code is thrown, FRP builds to 9-10k drops back to 4-5k after LHM.
e) During the first 30 seconds of start, I can reset the code repeatedly, the above pressures will build repeatedly, throw the code and return back down.
f) After the first thirty seconds or so, the code will not return, the engine idles fine, the pressures are stable at 55-60psi LP and 4-5K HP.
g) Why this issue only during the first 30 seconds of start?
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