Continuing Fuel Restriction - one that is boggling many! '93 Evinrude 175 OceanPro

[Allagash]

Posted before about fuel restriction... here's the update: 1993 Evinrude 175 OceanPro. Fuel Restriction alarm at 18-20 knots (3100 RPM plus) just cruising. Turns out to be fuel restriction with primer bulb collapsing. This model outboard has Vac. switch and restriction alarm. Traced everything from tank back, ran portable tank to isolate it to engine, not in main tank, pick-up or lines. Replaced fuel lines and bulb just for good measure. Replaced pulse-line nipple, filters. Swapped out VRO to test, swapped out new vac. switch, ran portable oil tank to bypass onboard tank and pick-up. Still triggering alarm. Vacuum, when gauged, is 6-8 at idle, but cannot find where it's coming from. When engine is isolated running on port. tank, and oil from port. tank, and it still goes off, you'd think that ruled out everything from engine back, but when running on inboard tank and oil, primer bulb still goes soft/flat.
Two problems? Anyone have any insights?

 

[jonesg]

Re: Continuing Fuel Restriction - one that is boggling many! '93 Evinrude 175 OceanPr

OK, remove the fuel pickup from your main tank (onboard) , run your fuel tubing from the bulb right into the fuel, test it now. Have someone hold it in place if necessary.

If it runs good replace the pickup tube or knock the anti-syphon valve out of the elbow and re-use. If problem remains the pickup tube is clogged up. Just replace. It can't be anything else unless the main tank is full of water or something.

 

[clanton]

Re: Continuing Fuel Restriction - one that is boggling many! '93 Evinrude 175 OceanPr

Where are you connecting the vacuum guage?

 

[Allagash]

Re: Continuing Fuel Restriction - one that is boggling many! '93 Evinrude 175 OceanPr

If the alarm still goes off running a portable tank directly to engine, bypassing onboard tank and primer bulb, and lines - doesn't that rule out the pick-up and anti-siphon valve in the onboard tank? Maybe I have two problems? One is a restriction in the onboard tank and another being the vac. on engine?

 

[Allagash]

Re: Continuing Fuel Restriction - one that is boggling many! '93 Evinrude 175 OceanPr

Gauged on line going to Vac. switch.

 

[clanton]

Re: Continuing Fuel Restriction - one that is boggling many! '93 Evinrude 175 OceanPr

Yes to post # 4.

 

[clanton]

Re: Continuing Fuel Restriction - one that is boggling many! '93 Evinrude 175 OceanPr

Tap into the fuel hose going to filter on the VST. The other end of hose connects to plastic nipple in the lower cowling. If metal clamps on this nipple, check passage in nipple, metal clamp will distort nipple.

Packing for trip to Alaska, replys will be slow.

 

[Daniel33]

Re: Continuing Fuel Restriction - one that is boggling many! '93 Evinrude 175 OceanPr

Hi all. I am a newby, to boating, not so much to mechanics. Although I am not familiar with the motor I wonder if it has, like my old 85 HP, a vacuum operated fuel pump, driven by the crankcase vacuum? Could that be faulty, causing too much pressure to be drawn into the tanks, collapsing the primer bulb?

 

[jgriner]

Re: Continuing Fuel Restriction - one that is boggling many! '93 Evinrude 175 OceanPr

if the bulb is collapsing it has to be between the bulb and the tank, anywhere else it would not collapse

humm... i guess it could collapse if fuel pump was sucking harder that the gas could enter the gas hose, but unlikely.

something about your protable gas tank did not get swaped out, could be the fuel line its self between the gas and the bulb

 

[lexer440]

Re: Continuing Fuel Restriction - one that is boggling many! '93 Evinrude 175 OceanPr

Similar thoughts to jgriner, maybe you have too thin a hose. should be a 3/8" inside dia. i think.

 

[lexer440]

Re: Continuing Fuel Restriction - one that is boggling many! '93 Evinrude 175 OceanPr

A further thought, distance. there is a limit to how far away the fuel can be.

 

[jgriner]

Re: Continuing Fuel Restriction - one that is boggling many! '93 Evinrude 175 OceanPr

a simple test would be to take off fuel hose where it connects to fuel pump (fuel pump intake, (mine is at filter screen, but mine is a 1979)) get you about 5 ft of fuel hose, connect the fuel hose to pump intake drop other end into gas can, and see if it runs.

if it runs then it must be between pump - fuel

if it doesnt it must be on the engine somewhere

 

[mrhaney]

Re: Continuing Fuel Restriction - one that is boggling many! '93 Evinrude 175 OceanPr

i'm not the sharpest knife in the drawer , make sure every single little 10cents o-ring is perfect, i found my fuel problem at the fuel filter with a ever so slight tear in a >?.,'?% o ring. lol good luck