73 85HP Rude Fuel Pump question

[kpudden]

Pulled my carbs to rebuild since i wasn't getting any fuel to the cylinders (hopefully this is the right thing to do?), but while emptying the old fuel the previous owner left in the tank, i noticed the flow from the fuel pump was not a steady flow with each pulse, rather a mild spitting of fuel. Is this normal or should i rebuild or buy another?

 

[JB]

Re: 73 85HP Rude Fuel Pump question

Wrong thing to do, kpudden. You have two twin-throat carbs on that engine; what do you suppose the chances are that both fail in the same way at the same time?

The first thing to do is find out what is wrong. What tells you that gas isn't getting to the cylinders?

I take it your engine won't start. Go to the Engine FAQs and do the troubleshooting in "Outboard won't start". I think you may be on the right track with testing the fuel pump output, but don't overlook the fuel supply to the pump.

 

[ezeke]

Re: 73 85HP Rude Fuel Pump question

And don't forget that the fuel pump only fills the float bowls. It does not pump anything into the engine. That is done by the pistons pulling the fuel from the float bowls through the carburetors.

When your engine is cold, the choke plates on your carburetors have to be 100% absolutely closed to get enough fuel to the firing chambers for a good start.

 

[kpudden]

Re: 73 85HP Rude Fuel Pump question

Fuel supply to the pump is good, no blockage. I tested by pulling Pump, and squeezing bulb. Also check O-Ring and check valve on line. Blew compressed air through all fuel lines, no restrictions. I know that fuel is getting to the Carbs and i know for a fact that it is getting spark since i just rebuilt electrical system. This thing will instantly fire with a shot of carb cleaner in the intake. When i pulled the Carb's, they were full of fuel. One needle valve had a groove in it where it seated with the orfice, the other was perfect. Could this be a flooding issue? I would think that i would at least get a backfire or a miss if it were flooding. I can't get it to anything using the existing fuel system. I am guessing the fuel in the tank was 2 years old, so that may be the problem...i have drained tank and will put in fresh fuel to see if that is the difference. Thanks.

 

[ezeke]

Re: 73 85HP Rude Fuel Pump question

If you are speaking of the float valves, yes they need to be perfect.

Also, originally they did not have the clips that connect the upgraded needle valves to the float arm. You need both.

 

[kpudden]

Re: 73 85HP Rude Fuel Pump question

Why the spring on the replacement when the stock stem doesn't use one(it uses gravity)? I didn't put the spring on the replacement stem...suppose i should take it out again and insert springs?

 

[ezeke]

Re: 73 85HP Rude Fuel Pump question

It has been many many years since they found that gravity working alone on the needle was not the best way and that is why all of the needles are grooved and why the clips are in the kits. It's still gravity, but now the float is helping to open the valve when fuel is needed.