rebuild won't run and I have tried everything

I just installed a rebuilt powerhead on a carburated 1998 Evinrude 115 E115SXEC that seized because water got in the fuel and then the engine sat outside in the heat for two months. Everything went back on fine. I removed all the old gas from the tank and replaced it with new gas. Unfortunately now the engine will start and run briefly but will not idle or keep running. When it starts it runs OK for about 10 to 15 seconds and then stops. Since I have 25/1 gas oil ratio for breakin it smokes like crazy. I can restart it by priming but the same thing happens again. I have checked the following things.
1. Detached fuel/oil line to starboard carburators and turned motor over, fuel came out hose.
2. Dissassembled one of the carburators to look for varnish, found none and orifices seemed clear, so I did not dissassemble the other three.
3. Tried pumping the gas line bulb while motor was was running to see if the problem was fuel pump. That didn't make any difference.
4. Checked fuel filter and it is clear.

What am I missing? Is there some automatic sensor function that is shutting the engine off?

Thanks in advance for your suggestions.

Re: rebuild won't run and I have tried everything

No, there are no sensors shutting it off.

When you prime it by pressing the key switch, you are injecting gas into the intake behind the carbs and throttle plate. It sounds as if the engine is running on just this gas and is not being supplied gas thru the carbs. It then runs out of the gas supplied by the primer, and stops.

Just for grins, to help prove this out, turn the red primer lever to manual position, leave it there, start it, and see if the gas flowing thru the primer system keeps it running longer.

Get into those carbs and see why there is no gas flowing in the idle circuits.

EDIT:

You will want to look behind the plates on the sides of both the black carb bodies AND the side of the throttle plate/bodies. Make sure all those tiny tiny holes that feed gas into the throttle bore are open.

Also look at the brass pickup tubes that extend into the float bowl. That is the source of the gas used in the idle circuits. Highly likely those are clogged shut.

Re: rebuild won't run and I have tried everything

daselbee said:

No, there are no sensors shutting it off.

When you prime it by pressing the key switch, you are injecting gas into the intake behind the carbs and throttle plate. It sounds as if the engine is running on just this gas and is not being supplied gas thru the carbs. It then runs out of the gas supplied by the primer, and stops.

Just for grins, to help prove this out, turn the red primer lever to manual position, leave it there, start it, and see if the gas flowing thru the primer system keeps it running longer.

Get into those carbs and see why there is no gas flowing in the idle circuits.

Click to expand...

daselbee,
I should have mentioned it but I have already tried that and turning the primer to manual override does allow the motor to keep running longer. When I took one carb off and dissasembled it I found no obstruction in the high speed jet. I could not identify an idle-speed orifice. According to my Seloc manual, there is a non-adjustable idle-speed orifice but I was unable to locate it. I am using a Seloc manual (which covers about a dozen Evinrude motors) so the descriiptions of the carburators is generic. Any idea where the idle orifices are located?

Re: rebuild won't run and I have tried everything

The clear HS jet will not automatically assure that the idle circuits get gas.

Go to shop.evinrude.com, drill down to the carb pics for your motor.

You will see that the black plastic carb bodies have metal plates on the stbd side (ref #30), held on with 5 screws. Directly on front of these plates right beside the opening of the venturi, is an idle/intermediate air bleed jet (ref# 9). This never has any gas thru it, just air. YOu must check the side passages for any obstruction, and in particular, the side passages in the throttle plate (ref# 1). The metal cover for these passages (ref# 4) is held on with two screws.

When you take off the float bowl, there will be a brass tube sticking down into the bowl from the upper part of the carb. This tube is the pickup tube for all the gas supplied to the idle circuits. It is a very small tube, and can very easily get clogged with varnish. It is hard to clean too, without damaging it. The tube is not shown on the drawings.
Use very small wires, and carb cleaner. Try blowing and sucking thru it first to see it if is clogged. Last one I did, I could not blow thru, but sucking thru, I pulled out crap that looked like grass fibers...go figure.

There are no idle orifices that you can remove. The closest thing to "idle orifices" is the holes drilled from the side into the venturis and that come out right behind the throttle plates. Probably two holes. Not sure on your motor. The idle adj screw changes the amount of gas that eventually reaches those holes, and the idle air bleed meters how much air rushes through there as the engine runs.

I will ask...when you pump the primer ball, and it gets firm, at that point, have you removed a carb drain screw to see that you actually have gas in the bowls?

Re: rebuild won't run and I have tried everything

Thanks! Thanks! Thanks! Daselbee was right on target! The brass tubes that extend into all four carb bowls were clogged. I confirmed by trying to blow through them. I could not force any air at all through them! I was able to unclog them with commercial aerosol carburator cleaner. I sprayed the carb cleaner in from both directions until I could see it come out the other side. Then, just to confirm, I tried blowing through them again and I was able to do so. After cleaning these tubes on all four carbs, I put them back on the motor and it ran! Still idles a little rough, but I have run it for about 3 hours at various speeds. I now have a functional fishing boat again!

Still need to fine tune so it will transition from idle to plane, but that is a minor problem.

Thanks again!

Re: rebuild won't run and I have tried everything

Good to see it is fixed. When you get back into them, you better look very very carefully at the overall cleanliness of the carbs.

One tool I have used to get to those tubes is a long set of welding tip cleaning files. They are very stiff thin wires that get right up in there.