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Question for Kevinj & Racer

D

Droid

Advanced Contributor
1993 60 degree E150 all factory....
Friend's boat, began having a thirst for oil... He isn't too handy but I told him check for fuel restriction???
He replaced fuel line from built in tank to bulb last season, no help. I verified pick up tube is clean.
This season he cleaned all sorts of debris from fuel filter on VST (no other filters present), no help & claims overheat alarm sounds.
*I get involved, replace w/p kit with BRP kit, stbd thermostat stuck open, replace it. Verify huge water flow with t-stats removed. Verified idle temps about 140 with infrared gun.
*Test both temp sensors & they sound alarm normal. But with engine stone cold, get steady alarm. Disconnect oil tank wires (approx 1/2 full) & alarm stops. Should be periodic alarm, not steady.
*Run boat & find he is getting high vacuum alarm, not overheat (alarm above 4000 RPM).
*Vacuum switch tests good, closes at 8psi, opens at 7.5. I replace fuel line including bulb with BRP 5008585. Removed line at fuel filter & fuel pumps easily to filter. PROBLEM: Fuel is blue pumping from tank! Looked in oil tank & it's empty after perhaps 5 miles of testing. Then NO OIL alarm starts beeping at me as it should.

Since most of my experience is 3 cyl & smaller, need some input:
*Actually runs OK until shortly after high vacuum alarm then pump bulb again & OK briefly.
*While not a top concern, any idea why steady low oil alarm instead of 40 sec beep? ECM goofy?
*He has owned boat for many years, always with motor tilted up when parked. Boat DOES NOT have an anti-syphon valve installed & never has. Why & how is the oil tank & fuel in the engine siphoning back to tank?
*Simply putting an anti-syphon valve in may mask the problem & I do intend on putting 1 in after it's fixed.

Current plan is clean/inspect VST & new VRO/OMS pump.

Ideas?
 
Droid said:
1993 60 degree E150 all factory....
Friend's boat, began having a thirst for oil... He isn't too handy but I told him check for fuel restriction???
He replaced fuel line from built in tank to bulb last season, no help. I verified pick up tube is clean.
This season he cleaned all sorts of debris from fuel filter on VST (no other filters present), no help & claims overheat alarm sounds.
*I get involved, replace w/p kit with BRP kit, stbd thermostat stuck open, replace it. Verify huge water flow with t-stats removed. Verified idle temps about 140 with infrared gun.
*Test both temp sensors & they sound alarm normal. But with engine stone cold, get steady alarm. Disconnect oil tank wires (approx 1/2 full) & alarm stops. Should be periodic alarm, not steady.
*Run boat & find he is getting high vacuum alarm, not overheat (alarm above 4000 RPM).
*Vacuum switch tests good, closes at 8psi, opens at 7.5. I replace fuel line including bulb with BRP 5008585. Removed line at fuel filter & fuel pumps easily to filter. PROBLEM: Fuel is blue pumping from tank! Looked in oil tank & it's empty after perhaps 5 miles of testing. Then NO OIL alarm starts beeping at me as it should.

Since most of my experience is 3 cyl & smaller, need some input:
*Actually runs OK until shortly after high vacuum alarm then pump bulb again & OK briefly.
*While not a top concern, any idea why steady low oil alarm instead of 40 sec beep? ECM goofy?
*He has owned boat for many years, always with motor tilted up when parked. Boat DOES NOT have an anti-syphon valve installed & never has. Why & how is the oil tank & fuel in the engine siphoning back to tank?
*Simply putting an anti-syphon valve in may mask the problem & I do intend on putting 1 in after it's fixed.

Current plan is clean/inspect VST & new VRO/OMS pump.

Ideas?
Click to expand...
Constant horn is either overheat or fuel restriction.
An issue with the fuel tank vent seems pretty likely. A quick easy test is to just loosen or remove the fuel filler cap and run the boat to see if the vacuum condition returns. If all is fine with the cap loose/off then you know for certain it's a venting issue. Also, if he cleaned a bunch of junk off the VST filter, I wonder what is inside the fuel tank?

Why & how is the oil tank & fuel in the engine siphoning back to tank?
That's an odd one for sure, but I have a hypothesis that is a combination of things. 1) The vent cap on the oil tanks can plug and in warm weather as the tank expands will push oil out of the tank and into the fuel system. 2) If there is a failure in the fuel piston diaphragm, it could allow that pressurized oil to enter the fuel inlet hose. 3) If there is a vacuum coming from the tank and the check valve in the fuel inlet is failed, it could draw the oil from the pump back into the tank.

Now, that is just a hypothesis so take it for what it's worth. These VRO pumps tended to fail into an over oiling state in the event there is an issue with fuel delivery. If this is the original VRO pump, I'd say there's a decent chance there is a problem with the fuel pump diaphragm, especially given this vacuum situation. The OEM VRO/OMS Pump is not a cheap part, but if this engine is still on the original pump it has probably earned it's retirement after 33 years of service.

A few years ago on my 1996 Intruder 150 I noticed I couldn't get past 4500RPM even though I had plenty of throttle left and the engine was smoking heavily. I replaced the VRO/OMS pump along with other fuel system maintenance and immediately saw a reduction in smoke and could reach the max 5,500RPM. There are test procedures to determine fuel and oil delivery volumes if you want to go that far.

Typically, the anti-siphon valves in the tanks are intended for situations where the engine is lower than the fuel tank to prevent fuel from passively being drawn out through the carbs. Until you solve the vacuum problem, the installation of an anti-siphon valve would probably make it worse.

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Thanks Kevin,
I agree an anti syphon valve should be installed after I get it right, not now.
I didn't check the oil tank cap vent, good idea.
Tank vent is plastic with a broken outer "deflector/shroud" & I have a new metal one sitting on the boat's helm.
Constant alarm at 4000 RPM & above is high vacuum. Temporary disconnecting the switch silences that. Yet switch tests good with my vac tester. I'm thinking I need to explore the internals of the VST.
My thoughts at this point is put boat on trailer & remove/clean the VST & install a new VRO/OMS pump.
All I can be sure of is oil tank is empty & fuel in the tank is blue.


*On another note, I have found on pontoons (not applicable in this case);
*Regarding fully functional VROs, since per the instructions the tank should NOT be mounted above the powerhead (How is this really possible on a typical pontoon?).
OMC also advised against disconnecting the fuel line & running the carbs dry as would typically be done end of season. Why? Because the VRO would fill the carbs with oil. But over the winter I have seen many where as the fuel evaporated & float level fell, the oil siphoned into the carbs until the floats shut it off.
If exposed to rain or spray, tank is to be installed in a group 24 battery box. I have seen a good 1/2" of water in these tanks when left exposed. I for 1 don't care for water based lubricants.
 
You are correct, it won't "fill" (my mistake) the carbs but with the fuel line disconnected the VRO pump will experience a fuel restriction & continue to add oil until there is a extra rich mixture.
Essentially the same as a fuel system restriction which is in the troubleshooting tree in the service manual.
 
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