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Evinrude 115 motor slowing down on its own.

With the way the boat sits in the water I don't feel comfortable leaving the cap open without water potentially getting into gas tank
 
I wanted to run it with cap off to see if it would help.I did notice i need a pair of freakin vise grips to get my gas cap off for wheni go to get gas for the boat.
 
You notice the slight increase in rpm just before it stumbles is probably a over lean condition just before it runs out. Look at your plugs if they are white powder on the insulators don run it that way you can cook the pistons. It sounds like the fuel pump can not keep up with the demand if the vent in the tank is clear maybe replace the pulse limiter for the vro is another possibility.
http://www.marineengine.com/newparts/part_details.php?pnum=OMC0435009
Is the pulse hose in good condition and fit nice and tight on the ends?
 
Another thing to try is use a portable tank and set it on a ice chest. Those VRO pumps can struggle pulling fuel from a in hull tank if not in good condition.
 
I'm not sure. The vro pump was replaced last year when I got the powerhead put on. I don't think the lift pump was touched. If it's separate from vro pump then no it wasn't touched because I wasn't charged for it
 
And also, I trimmed the video shorter then what I had originally recorded. But after it slowed to idle speed. I trimmed back up on plane and it acted like nothing happened. Motor didn't shut off when it slowed down. I had tried to speed back up when it surged like that but it wasn't going for it. This isn't everytime I hit wide open either. It's inconsistent, but it only happens at full throttle speed.
 
Pull the pump apart it is on the side of the vapor separator. I could not find a parts breakdown on the pump so be careful of small parts. If the diaphram is stiff it could very well be your issue and once again the pulse tube to the block needs to fit nice and tight on the ends.
 
Before I start taking things apart work is letting me borrow a portable gas tank so I'm gonna run it on the portable and if it still acts up then it tells me its for sure the motor causing the issue. If it doesn't act up then it tells
me it's my gas tank causing the issue:
 
The insulator is a toasty brown if they all look the same you should be good. You have gone through the pickup tube and tank I doubt the issue is there. If it runs better on the remote tank I would put money on a fuel pump issue.
 
Motor messed up the same way on the remote tank... definitely something on the motor. I'm betting on possible lift pump since it wasn't replaced. Couldn't tell you how old it is. I know it's at least 4 years old. Motor sat for 2.5 years and I've had it for a year and a half.
 
It don't have a separate lift pump...your VRO is the pump. The vapor pump does not pump fuel only vapor.
 
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faztbullet said:
It don't have a separate lift pump...your VRO is the pump. The vapor pump does not pump fuel only vapor.
Click to expand...
Are you sure about that it looks to me like the VRO pulls fuel out of the vapor separator mixes in the oil and pumps it into the carbs. The vapor pump fills the separator with fuel and has its own float. It will only take a few minutes to replace the diaphram in the vapor pump and replace the pulse tube going to it as well just for giggles.
 
Under my model number it shows it listed as a part required for the engine. Vapor seperator pump.. they might be having a glitch on this site because almost everything I looked at yesterday with multiple parts in stock now says unavailable..
 
Georgiaboy,If it wasn't for bad luck you wouldn't have any luck at all, Hope you get this issue straightened out before summer.
 
I tried to find a fuel flow diagram for your engine and still wonder what fills the vapor separator float bowl with fuel? It looks like the VRO pulls fuel from the bottom of the vapor separator and other diagrams show a lift pump but by the sounds of it it is just not able to keep up with the demand at WOT. Racer would know how the system works. Maybe a vacuum guage for the fuel supply will tell you if it is losing suction pressure at higher RPMs?
 
Are you sure about that
Click to expand...
110%...That float has 100% nothing to due with any fuel entering or leaving vapor separator. What diagrams are you looking at that show a ilft pump????? Thought you own a 60 degree????
 
I just typed in my model number in on evinrude website and it shows a vapor seperator pump.. idk my stuff lol that's why I'm on here ��
 
Yes it has a vapor pump and it does nothing but vapor.... Here are pic from one of my old post where I broke down the fuel bracket and labeled passages and flow.
 

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Well there ya go then... guess the next question is if my fuel pump actually can't supply enough fuel for the motor at full throttle, or what the heck could be causing this. Cause it's not all the time it does this. I recorded for 7 minutes straight at full throttle, it didn't do it. Slowed down some, decided I give it one more shot before I got to the ramp, as you saw, within about 8-10 seconds it acted up. When the motor slowed down I didn't touch the throttle at all til the motor hit minimal planing speed. Then I pulled back all the way to idle speed, and within 10 seconds I trimmed it down all the way and went back on plane and hit full throttle and it didn't act up again.. like what in the world could intermittently cause this. I know it's Something on the motor since it acted up the same way on a good known portable gas tank..
 
You're right! This boat is bad luck! I got a solution for it. Accidentally drop a lighter near the gas tank and claim insurance on it! Or maybe "forget" to put the plug in. And go buy a new boat
 
I have seen the plastic nipple in cowl when fuel /oil line attaches cracked and suck air. try running WOT trimmed down for a while and see if it happens. If not try it trimmed out and if it happens line is cracked or kinked when trimming.
 
Is the nipple connected to the cowling? On mine, the fuel line runs to the outside of the cowling, there's a piece that I have to unscrew with a Phillips head to reach this tube. Then you connect the fuel line to a tube, then you put a clamp on it, after that, I see more fuel/oil lines routed around to the fuel pump and such and I really have no clue what I'm looking at!
 
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