Welcome Visitor! Please take a few seconds and Hello all, I apologize for a non truck related post and offer thanks in advance for any help. I have a ski boat with a marinized 351W "GT40" engine. It has the EEC-IV fuel injection system circa 1994. Being the engine is in a boat, there are no catalytic converters or O2 sensors. Also, as this engine is an EFI there is no mechanical fuel pump attached to the block.
After about 20 hours of run time since the last oil change, I checked the oil to find the dipstick showed overfull by about 4 inches. I subsequently pumped out about 11 quarts of very thin "oil". It is almost certainly fuel in the oil (instead of water) because the oil looks somewhat normal (black in color)but is very thin (not brown/tan in color and not foamy) and no water separated from the oil when left in a glass jar for several days. It also has started idling fairly roughly. Sometimes when you bring the power back to idle abruptly, it will almost stall. At higher power settings it seems to run normally with good power. Temperature on the gauge is about 160F.
I have done the following:
1. Replaced all 8 fuel injectors with new 24 lb Ford Performance injectors.
2. Scanned the computer for failure codes. No codes are present.
3. Checked fuel pressure at the rail with a gage. Readings were 41PSI with the vacuum hose disconnected from the fuel pressure regulator and 37 PSI with the vacuum hose attached.
4. Checked vacuum line from pressure regulator to plenum for fuel (temporarily replaced the vacuum hose with a clear hose to visualize any fuel getting sucked into the plenum). No fuel in line.
5. Checked injectors with a stethoscope at idle. All injectors can easily be heard clicking on and off.
6. Changed the plugs and checked for spark at each cylinder.
7. Measured resistance in plug wires with ohm meter accounting for wire length. All wires well within specs per maintenance manual.
8. Checked compression, 135 to 150 on all cylinders.
After accomplishing the above, I changed the oil and filter and ran the boat for about 1.5 hours over a weekend. After that time the dipstick showed the crankcase over full by about 1 inch (roughly 1 quart).
I then checked the following:
1. Pulled the thermostat to see if it was stuck open. It was closed.
2. Procured a Rotunda break out box on e-bay and hooked it up to the ECM to check outputs from the the coolant and air charge temp sensors, MAP sensor and Throttle Position sensor. All values were within the maintenance manual specs. Hooked up an oscilloscope to the fuel injector outputs to see if the ECM was commanding the injectors open too long but the pulse widths were within spec.
3. This week I am going to perform a leak down check. I realize that with that much fuel in the oil the cylinders may be scored but want to see if that is the case and potentially see if any valves are leaking.
Any thoughts on how this much fuel is entering the crankcase would be very much appreciated.
Bruce
After about 20 hours of run time since the last oil change, I checked the oil to find the dipstick showed overfull by about 4 inches. I subsequently pumped out about 11 quarts of very thin "oil". It is almost certainly fuel in the oil (instead of water) because the oil looks somewhat normal (black in color)but is very thin (not brown/tan in color and not foamy) and no water separated from the oil when left in a glass jar for several days. It also has started idling fairly roughly. Sometimes when you bring the power back to idle abruptly, it will almost stall. At higher power settings it seems to run normally with good power. Temperature on the gauge is about 160F.
I have done the following:
1. Replaced all 8 fuel injectors with new 24 lb Ford Performance injectors.
2. Scanned the computer for failure codes. No codes are present.
3. Checked fuel pressure at the rail with a gage. Readings were 41PSI with the vacuum hose disconnected from the fuel pressure regulator and 37 PSI with the vacuum hose attached.
4. Checked vacuum line from pressure regulator to plenum for fuel (temporarily replaced the vacuum hose with a clear hose to visualize any fuel getting sucked into the plenum). No fuel in line.
5. Checked injectors with a stethoscope at idle. All injectors can easily be heard clicking on and off.
6. Changed the plugs and checked for spark at each cylinder.
7. Measured resistance in plug wires with ohm meter accounting for wire length. All wires well within specs per maintenance manual.
8. Checked compression, 135 to 150 on all cylinders.
After accomplishing the above, I changed the oil and filter and ran the boat for about 1.5 hours over a weekend. After that time the dipstick showed the crankcase over full by about 1 inch (roughly 1 quart).
I then checked the following:
1. Pulled the thermostat to see if it was stuck open. It was closed.
2. Procured a Rotunda break out box on e-bay and hooked it up to the ECM to check outputs from the the coolant and air charge temp sensors, MAP sensor and Throttle Position sensor. All values were within the maintenance manual specs. Hooked up an oscilloscope to the fuel injector outputs to see if the ECM was commanding the injectors open too long but the pulse widths were within spec.
3. This week I am going to perform a leak down check. I realize that with that much fuel in the oil the cylinders may be scored but want to see if that is the case and potentially see if any valves are leaking.
Any thoughts on how this much fuel is entering the crankcase would be very much appreciated.
Bruce
