Engine starving for Fuel

[bigge31566]

I have a 1997 Johson 150, I went out today and after running a quarter of a mile the motor started slowing down like it was going to run out of fuel but when I pumped the bulb back up it will continue to run. I had to keep doing this every 50 yards to keep it running how frustrating. Dumped water separator out no water. I have put a new primer bulb, and separator with hoses this year and also removed the check valve in tank

 

[bktheking]

Re: Engine starving for Fuel

My first guess would be the fuel pump failing.

 

[bigge31566]

Re: Engine starving for Fuel

how would you test it

 

[kenmyfam]

Re: Engine starving for Fuel

Air leak in the fuel lines or pump is starting to fail.
Remove hose carb side of pump and crank it into a container.
Spurts out continuously, pump is O.K.
Spurts strongly to begin with and then backs off, fuel pump is failing.
trickles out, fuel pump is dying.

 

[kenmyfam]

Re: Engine starving for Fuel

When squeezing the bulb, you are the pump.

 

[bigge31566]

Re: Engine starving for Fuel

Do you rebuild the pump or just replace it, and is it complicated to do ,and the cost?

 

[kenmyfam]

Re: Engine starving for Fuel

Check your motor out here. Plug in the info and you should get your answer.

http://shop2.evinrude.com/ext/index.aspx?s1=bf6ad09c53cead335fcfd8a6471c0f7f

 

[Faztbullet]

Re: Engine starving for Fuel

The pump is repairable on the fuel side only, usually it the airmotor diaphram or a cracked airmotor housing.The kit numbers are:
airmotor kit......435921
fuel piston.......436905
airmotor hsg....174127
fuel pump assy...5007420

 

[Chris1956]

Re: Engine starving for Fuel

The first cause of this could be air leaks in the fuel line. Check the main strainer and any connections in the fuel line.

As a second cause, that motor has a vapor/fuel seperator. It has a seperate pump which assists in supplying gasoline to the OMS oil/gasoline mixing fuel pump. I would check the vapor pump diaghram, and the gaskets on the top of the vapor/fuel seperator first, before working on the OMS pump.

 

[bigge31566]

Re: Engine starving for Fuel

I replaced the diaphramn on the fuel side of fuel pump and still had same problem, took fuel pump back off and took to a shop, they said the fuel pump was not holding a vacuum that it needs to be replaced , what else could cause it not to hold vacuum if needs to with a new diaphramn, I checked o-rings and they seem to be in good order, could not see anything visually

 

[kenmyfam]

Re: Engine starving for Fuel

How did they check it was not holding a vacuum ???

 

[Faztbullet]

Re: Engine starving for Fuel

The vapor pump has nothing to due with the OMS/VRO pump as all it does is remove fuel vapor from separator and pump vapor to the air silencer cover. If it will not hold vacuum on airmotor side the cover is cracked/leaking or intermediate housing is cracked (around pulse nipple and is NLA) and leaking, option then is to replace pump.

 

[Chris1956]

Re: Engine starving for Fuel

Fazt, The vapor separator has an inlet needle and seat. The vapor separator is upstream of the OMS pump. When you prime the motor, the inlet needle in the vapor separator closes, when the separator is full. What draws the fuel into the vapor separator, when the engine is running? It seems to me that the vapor pump will help the OMS pump draw in the gasoline. Is this incorrect?

 

[bigge31566]

Re: Engine starving for Fuel

They told me they could do a bench test, tested it about 15 min. came back and said I needed a new pump because it would not hold vacuum. the fuel pump is off the boat when tested

 

[SparkieBoat]

Re: Engine starving for Fuel

i recently replace the pump on my 95 150 rude..i went with the fuel pump only model which does not have the VRO side..my opinion is this pump will last longer and work better, less to go wrong. i have been premixing my fuel since I have had the motor. i found the pump for under $300

 

[SparkieBoat]

Re: Engine starving for Fuel

here is the pump i used
http://www.dixiemarinesales.com/detail.aspx?ID=2

 

[Faztbullet]

Re: Engine starving for Fuel

Chris, in simple terms the separator fills with fuel like a float bowl but it has no vent to atmosphere except thru vapor pump, OMS/VRO draws fuel from separator bowl to send to throttle manifolds. If the separator was open to atmosphere VRO could not cause vaccum to pull fuel thru system, the vapor pump removes vapors that cause pressure in separator and send them into front air cover for engine to burn.

 

[bigge31566]

Re: Engine starving for Fuel

??? Can the fuel pump be tested off the boat for holding vacuum or for leaks on a bench, off the boat and if so how would you do it to check behind shop thats recommending a new pump

 

[Faztbullet]

Re: Engine starving for Fuel

Go to the auto parts and get you a hand vacuum pump with guage and test per chart in previous post.

 

[Texasmark]

Re: Engine starving for Fuel

Since you did what you did in the fuel supply area you probably don't have this problem but one time I had a similar problem on a Johnny 125 and the problem was blockage of the fuel line either at the entrance to the bulb or at the engine connector, can't remember which place it was as it was in 1972 when it happened.

I had a built in tank and had previously added a water absorbing fuel life extender. The agent (alcohol I guess) caught the water all right but it attached to it making a white goo that made it's way up to where I said.

Finding it and removing it solved my problem and since I was floating helplessly in the middle of the lake, wind blowing of course, I was mighty thankful. Might have another look there before going the $$ for a fuel pump even though that could very well be your problem and they aren't that much trouble to change.

Mark