Fuel System - 50 HP Evinrude

[kyfike]

Engine sometimes - but not always - loses power and runs extremely rough above half throttle. <br /><br />After shutting the engine down for 5 minutes it will usually run fine - sometimes for only five minutes, but sometimes for days. Problem is becoming more regular lately.<br /><br />Remote tank was cleaned and gas lines and tank pickup tube seem to be leak free.<br /><br />Priming bulb never gets hard. Mech. replaced with generic bulb - still soft; I replaced it with a factory bulb - same problem.<br /><br />In-line fuel filter - located between the bulb and fuel pump - never gets full regardless of the number of times the bulb is pumped. Pumping the priming bulb however does pressurize the filter - evidenced by gas squirting out when I disconnect the fuel line to the filter. <br /><br />Other posts saw this problem disappear by relocating the filter to upstream of the bulb but the present location appears to have been put there by the factory. <br /><br />Is relocating the filter a realistic solution to this problem or should I look for other solutions?

 

[R.Johnson]

Re: Fuel System - 50 HP Evinrude

The primer bulb is not supposed to stay firm while running. It has two check valves to allow priming. When the engine is running, fuel just flows straight through the bulb. Same holds true of the filter, it does not have to stay clear full. There always seems to be a lot of confusion about this. A fuel restriction could pump the bulb flat, but there is nothing happening that would keep it firm. The fuel tank setting in the sun may keep the bulb firm without the engine running. The bulb is nothing but part of the fuel line when running. There is no problem with your filter, it does not matter what position it is in.

 

[kyfike]

Re: Fuel System - 50 HP Evinrude

Thanks R.Johnson, that is what I needed to know. However, the bulb never gets hard even when pumping to prime. Shouldn't the bulb get hard after I pump the fuel line full and prior to starting the engine? Mine doesn't.<br /><br />Thanks again for the quick response - this is my first outboard and I'm struggling to figure out how it works (I bought a manual but it can't answer all the questions - people like yourself that share experiences is vital).

 

[fireman57]

Re: Fuel System - 50 HP Evinrude

When it is running rough check for spark. Pull one plug wire with very well insulated pliers. If rpms change then that cylinder is fine. Pull the other one and if rpms do not change then you are not getting spark to that cylinder for some reason. I would eliminate spark as the problem first. The reason being is there are a lot of things to check for in a fuel problem. Pin it down to either, electrical, fuel, or air problem first and then go from there.

 

[R.Johnson]

Re: Fuel System - 50 HP Evinrude

In answer to your question about priming. When the carb is full of fuel, the bulb will get firm, and allow no more fuel to pass. If the primer is slow to pick up fuel from the tank, try holding the bulb in a upright position, or with the arrow on the bulb pointing straight up. This will sometimes help if there is nothing wrong with the primer itself.

 

[umblecumbuz]

Re: Fuel System - 50 HP Evinrude

Hi Kyfike,<br /><br />Your post indicates that you're concentrating on fuel as being the probable culprit.<br /><br />You may be right, but the intermittent and irregular nature of the fault - sometimes running for days with no symptoms and other times running for only a few minutes - leads me to suspect tired electrics.<br /><br />Presumbly it does not do this from cold? But only when warmed up? If so, that also suggests to me that you need to look more closely at the high tension generation side of the electrics.<br /><br />Just my tiny observations.

 

[kyfike]

Re: Fuel System - 50 HP Evinrude

It's been a while since I last posted - the problem is not completely gone but it's better. <br /><br />Since then I checked spark when it was running rough and both cylinders had spark (the motor wouldn't continue to run with either plug wire disconnected).<br /><br />Since the last post:<br />I added Chevron's Techron gasoline additive to the tank (I retired from the plant where this is made and, at that time, it was the best on the market.)<br />I found a leak at the in-line fuel filter connection (probably why the bulb wouldn't pump up hard + holding the bulb vertical does help). <br /><br />The last three times out since then: the motor bogged down immediately after advancing the throttle to take off. Shut the motor down and waited for 5 seconds and then restarted and it ran with no problems for each one hour run.<br /><br />Looks like the additive and filter leak fix have the motor on the mend? Still have no theory why stopping the motor for a bit makes all the diifference. Any ideas?<br /><br />Thanks to all for your time to offer suggestions -they are most appreciated.<br /><br />KYFIKE

 

[fireman57]

Re: Fuel System - 50 HP Evinrude

Probably had and still have some crud in the carb. you will want to remove it at some time and clean it good. While you are there put a rebuild kit in it. Try throttling up a little slower and it might not bog. Could still have a small air leak somewhere. <br />The stopping and restarting to clear a problem usually is an electrical component that has overheated to cause the problem. Once it has cooled then the problem goes away. However in your case....

 

[kyfike]

Re: Fuel System - 50 HP Evinrude

Thanks for the post, Fireman.<br /><br />My brother suggested it may be a choke problem. This motor apparently has an electric choke of some type that's activated by the ignition switch (ignition key is to be pushed in to choke while it's being turned to engage the starter motor). <br /><br />I'll pull out the manual to see what that's up to. <br /><br />Do you have any experience with electric chokes?

 

[kyfike]

Re: Fuel System - 50 HP Evinrude

I realize this problem is going on too long - if I can't find the probelm by this weekend it'll go to the shop.<br /><br />Just wanted to point out that there are some constants:<br />1. When it bogs down it will do it with no notice at all - just runs rough as heck and smooths out only by dropping the throttle back to below 2800 rpm's.<br />2. It will run no faster than 3000 rpm's - opening the throttle further has no effect.<br />3. Shutting the motor down and waiting always makes the problem disappear - for a while at least.<br /><br />I realize this problem can be caused by too many things to go into in this forum - just hoped someone has seen this problem before.