intermittant miss and fuel problem

[RL]

I have a'71 60hp 3 cyl evinrude, that now has an intermittant miss in the mid to 3/4 throttle range.<br />It runs great at idle and up to mid throttle then it will stumble intermittantly up to about3/4 throttle where it smooths out nicely through WOT.<br /> Also the fuel primer bulb keeps sucking flat and I have to shut down after about 1/4-1/2mile to get the system pumped up again ( can't do it with the engine running, too much suction on the bulb ).<br />I made sure the vent is open and even pulled the fuel tank cap all the way off to see if the vent was restricted.<br />I have rebuilt the fuel pump( working fine), all of the fuel hoses (3/8" ) and fittings new, bulb new, tank new in october( wally world cheapie) and has only had about 3 tanks of fuel run through it.<br />Just rebuilt the carbs( soaked and blown out good) set them as per manual and info on this site in a tank, then fine tuned them at the lake today .<br />New spark plugs. Adjusted points, but did not replace them before the last time I had it out ( before the carb rebuilds)<br />Also installed a new set of Boysen power reeds.<br /><br />Any help would be greatly appreciated.<br />Thanks---------Robert

 

[OBJ]

Re: intermittant miss and fuel problem

RL....you have got some kind of obstruction before the bulb to cause it to go flat. Wally World isn't know for the best of parts and stuff related to boating. Just cheap. Could you borrow a gas can from a friend and try that? Are the bulb and hoses OEM? I've tried generic primer bulbs a time or two and through them out. Just plain junk.<br /><br />Let's talk a little Boyesen. Did you follow the instructions to the letter by working the reed cages down flat? This is important if the reeds are to work correctly. <br /><br />Let's get the "flattening bulb" issue worked through first. Chances are, you solve this and you've solved your other problems.<br /><br />Keep us posted and don't hesitate to ask if you have more questions....thanks.

 

[RL]

Re: intermittant miss and fuel problem

I didn't use oem hoses/bulb. I used some sierra marine fuel hose from the local high dollar boat dealer ( good looking hose ), and attwood bulb and fittings ala wally world. The fuel tank is an attwood as well. I used this tank a couple of times with out problem, but while at wally world tonight ,I looked inside one of them, and it would be real possible for the flat end of the pickup tube in it to get sucked up flat against one of the ribs in the bottom of the tank it appears to go to the bottom, bend to the side a few inches and rattles around in there.<br /><br />I hate to do it, but sometimes I resort to wally world for things and take a chance because it's an 80 mile round trip for much of anything else<br /><br />Yes, I followed the Boysen instructions to the letter ( I'm a semi retired auto mechanic and I ran a machine shop many moons ago, so I'm well versed in general mechanical things, but when it comes to outboards, I know just enough to be dangerous I worked them down to a perfect fit, two of the cages had a slight amout of warpage so it took a while. I could see real quick why they include that in their instructions. I definately noticed a better idle with the boysen reeds

 

[Bass Runner]

Re: intermittant miss and fuel problem

pull the fuel pickup tube out of the tank and see if the screen is plugged, if not try running with the fuel cap loose the vent may be plugged. As far as the miss i would think either a bad plug or fuel starvation, if it's the latter be careful you will burn the motor up.

 

[RL]

Re: intermittant miss and fuel problem

Would the fuel in the carb bowls not be enough right after priming to avoid the miss, if fuel related, even if the pickup was plugged, or does the level of fuel in the bowl ( ie not right near the level of the inlet needle opening)have an effect on the mid throttle running?

 

[OBJ]

Re: intermittant miss and fuel problem

If the carb floats were set right, you should have plenty of fuel. The little bit of pressure built up when priming the bulb should take care of this....and providing the fuel pump is working which is apparent since you got good low and high speed. And hopefully all hoses are tight at the connections and hoses are in good shape....not dried out and hard.<br /><br />I would tend to agree with Bass Runner. Could be a spark plug or might take another look at the point gaps. .010 is a close setting.<br /><br />Glad to hear the reeds are working good for ya'. I gottem' in both my Johnnys. Wouldn't be with out them.

 

[RL]

Re: intermittant miss and fuel problem

Looks like the points may have been the culprit. I checked and one of them had opened up to around .019<br />I'll get a new set tomorrow and see what happenes.<br /><br />I checked the plugs and they were a bit wet, but I bet those points have something to do with it. I checked the coil and it looks ok and compression is good ( 135, 128, 125 )so with any luck at all, some new points and plugs and I'll be in buisness.<br /><br />Thanks--------Robert

 

[RL]

Re: intermittant miss and fuel problem

The points did it!.<br />I cleaned out the pickup screen, but it still went flat at full throttle, the screen was just too small in that tank for a larger motor, so I pulled it out and put an inline filter in and it runs like a dream now.<br /><br />Thanks all------Robert