Fuel delivery problems

[duppie03]

Good afternoon,

I have a 1988 Evinrude 150, that I have disconnected to VRO on and run a 50:1 mixture.

My problem is that when I take off and get on plane the motor runs great for about 150 yards then it starts to die and begins surging until I pull it back to around 3000 RPM. I can run it there for a few minutes and throttle back up for another 150 yards and the same thing happens again.

Is this a fuel pump issue, or carburetor issue?

Thank you in advance for anyone's help.

Aaron

 

[Monte1961]

Re: Fuel delivery problems

Good afternoon,

I have a 1988 Evinrude 150, that I have disconnected to VRO on and run a 50:1 mixture.

My problem is that when I take off and get on plane the motor runs great for about 150 yards then it starts to die and begins surging until I pull it back to around 3000 RPM. I can run it there for a few minutes and throttle back up for another 150 yards and the same thing happens again.

Is this a fuel pump issue, or carburetor issue?

Thank you in advance for anyone's help.

Aaron

Could be both. Pull fuel line from pump to carb and without starting by pulling plug wires off, spin it over and look for good fuel pulsing from fuel pump.
If good, you will have to inspect and adjust carb/s and float/s. What I hear you saying at wide open throttle the boat acts like it runs out of fuel. When you back down to 3000 RPMs, it picks back up. If this sounds right, it's a fuel problem. Post back.

 

[Chris1956]

Re: Fuel delivery problems

It could also be a fuel pump issue or a partially clogged antisiphon valve, or fuel tank vent. If you pump the primer bulb and the problem disappears, it is likely a fuel pump problem or an air leak in the fuel line. If the primer bulb collapses it is an A-S valve or fuel tank vent issue.

 

[duppie03]

Re: Fuel delivery problems

Thank you for the fast response.

That is exactly what its doing. Starts right up at the ramp, and idles great, and at wide open it runs great for a short distance and then it acts like its starved of fuel.

What would be a good fuel pulsing? I understand it's probably hard to measure.

I met a guy at the ramp that told me to try pumping the bulb while I'm at wide open and see if it keeps running, and if it does it's a fuel pump problem. I didn't get a chance to try since I was by myself. Does this sound accurate.

 

[Monte1961]

Re: Fuel delivery problems

yup that will work. good luck

 

[duppie03]

Re: Fuel delivery problems

thank you for the responses, I will post my findings this evening

 

[toonin22]

Re: Fuel delivery problems

you know i got a 98 johnson 50hp and did that for years randomly sometime it wouldn't do it sometimes it would. evertime we put gas in it it would run fine. it was bad gas settling to the bottom of the tank and it would sputter around when it got into the carbs emptied the gas tank put fresh gas in treated it and it ran fine no problems since.

 

[emdsapmgr]

Re: Fuel delivery problems

A weak fuel pump may not deliver enough fuel to sustain high speed rpm's. Once the engine consumes all the fuel in the carb bowls, the rpm's will drop. They will stay low till the bowls fill with fuel, when the engine will take off again. If you constantly prime the fuel hose bulb, it will keep the carbs full. If it runs ok while contantly priming the hose bulb, likely the engine is starving for fuel. The pump is a likely culprit, but the hose, bulb or anti-siphon valve can also be the problem

 

[fshrgy99]

Re: Fuel delivery problems

Hi Duppie03,
Are you running on the fuel pump side of your vro unit or did you install a dedicated fuel pump and remove the vro?
fshrgy99

 

[Classics2go]

Re: Fuel delivery problems

Good afternoon,

I have a 1988 Evinrude 150, that I have disconnected to VRO on and run a 50:1 mixture.

My problem is that when I take off and get on plane the motor runs great for about 150 yards then it starts to die and begins surging until I pull it back to around 3000 RPM. I can run it there for a few minutes and throttle back up for another 150 yards and the same thing happens again.

Is this a fuel pump issue, or carburetor issue?

Thank you in advance for anyone's help.

Aaron

Did you check the fuel line for air leaks between the tank and the engine? Often that line wears out and causes that exact problem. Check the prim ball to be sure it is not leaking down. Listen for an "air sound" when you squeeze it..that is bad. Also check the plug that it is tight and corrosion free at the engine. 9 times out of 10 when the engine acts like that it is that fuel line. Good luck!