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1975 25hp Evinrude Starting Issues...

C

carpking

Member
Purchased this motor last week from a marine mechanic. It is model number 25502B. Motor had been stored for years. Very clean, low hours. Seller supposedly put new points, carb kit, fuel pump and fuel lines as well as new impeller. The day I purchased it, we checked compression (106 and 110), cold started it and it ran great. I get it home, it sets for a week, I take it out and it starts fine but it dies after a few minutes and now won't start. Plugs aren't fouled but I noticed after choking carb that I have a small amount of gas coming out of choke hole on carb. Thought maybe float was stuck but gas tank bulb pumps up tight. Going to check for spark later but I am looking for any suggestions. The only problem with the motor is the kill switch was bad and had been removed so the only way to currently kill it is to throttle it all the way down. Didn't think this could cause an issue but what do I know. Help please...very frustrated...
 
Is the motor sitting fairly level? Trying to start it while partially tilted up will make fuel run out of the carburetor bore. That fuel should be going the other way, into the engine, to make it run.
 
fdrgatori verified that motor is level. Doesn't make a difference.

kimcrwbr1, yes, it acts as though it has no spark whatsoever. I will try the lighter and spark plug trick as plugs do seem slightly wet. Going to check spark when sun goes down a bit. Would I need to remove the carb completely to drain it? Also, could throttling it down possibly foul the points? And yes, fuel is 50:1.
 
**Update** Checked spark and have bright blue spark jumping 1/4" gap. Ironically, engine started on one cylinder with tank removed while checking spark. Hooked tank up and couldn't get it to fire. So im guessing its bad gas or carb is flooding when tank is hooked up. Going to try to get a fresh tank of gas mixture first. However, if this doesn't work, what should I look for in carb?
 
kimcrwbr1 said:
Pull both plugs and see if they are wet and does it burn. Make sure the choke is off and tap on the side of the carb with a wrench. Crank on it with the plugs out to clear the cylinders if flooded. Put the plugs in and see if she fires up. If it fires up and then stalls again and your sure it is not water clear the cylinders again and as soon as it starts tap on the carb with a wrench and see if it smooths out. You need to use a spark gap tester to check spark correctly looking at the plugs tells you not much. I cant remember have you checked the compression?
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I used a spark tester when checking spark. I set it at a 1/4" and it jumped it with a bright blue spark. Forgot to do the match trick with plugs. Compression is 106 on top cylinder and 110 on bottom cylinder.

kim, I've only had the motor about a week. Haven't had a chance to run all the gas out of it. Lol But I will if I can get it to run.

I actually have an extra carb for this motor that has been rebuilt. Came off of another 25hp I owned. If all else fails, I'll swap them out and see what happens. I appreciate all the input.
 
Ok...emptied carb bowl, cleaned motor fuel lines, gas tank, pump bulb, etc.. New properly gapped plugs and checked spark again with 1/2" blue spark on tester. Fresh non-ethanol fuel mix also. With the help of a little starter fluid..I get motor started and it runs rough and dies. First thing I noticed: to keep motor running after starting, I have to squeeze pump bulb a few more times immediately after starting which makes me think I have a fuel pump issue. Secondly, motor has a definite miss which eventually leads to what I would describe as a small back-fire and the motor stalling out. When the motor warmed up, it seemed to go away for a few minutes then returned. If the motor stalls, I have to use a squirt of starting fluid about half the time to get it restarted. If not, it tries to start with the "back firing" issue. Im wondering if the points aredirty or not set properly...which would be slightly disturbing since I purchased it from a marine mechanic. I thought maybe the low speed needed adjusting. According to the owner's manual, you start out at 3/4 counter clockwise turn after gently seating needle. Im at one full turn and it doesn't seem to make any difference. Any help with thst is appreciated as well.
 
kimcrwbr1 said:
The proper preadjust is 1 1/2 turns on the slow needle and they will normally cough for the first min or two until the head warms up just feather the choke a few times until it idles on its own. Never use starting fluid unless it has oil in it! Once you get it to idle in abarrel of water or on the lake shift it into forward gear and turn the slow needle out 1/8 turn at a time until the engine coughs wait a bit between adjustments then slowly turn it in the same until it stumbles then back out for a nice smooth idle. It is allways better to error on the rich side so once you get a nice smooth idle turn it rich 1/8 to 1/4 turn and just leave it alone. Running a little rich both protects the motor and help on cold starts. Give that a shot
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What about the fact I have to squueze primer bulb to keep it running? Could this be a fuel pump issue or related to the carb?
 
**Update** After beating my head against the wall I decided to quit trusting the fact a marine mechanic sold me the motor and go through everything. Started with carb. It was indeed very clean. However, the float was slightly misadjusted. Also, the tiny clip that connects the float needle to the float was missing allowing needle to stick when float dropped. I also found some tiny pieces of debris in the low speed idle jet. Im guessing these were pieces of the old needle bearing. Anyhow, completely cleaned carb and made necessary adjustments to float and replaced clip on float needle.

Next, I pulled the flywheel to examine points. The coil under the flywheel looked very bad so I went ahead and replaced it. Also went with new points and condensors and set them to .020. After doing this, I checked spark again. I noticed I had consistently good spark on bottom cylinder but the spark on top cylinder was very intermitten and weak. So, I replaced that coil as well. Fortunately, these were spares from another old 25 that I had that has a broken upper casing.

When all was said and done, after a few pulls she started up and purred like a kitten. Im going to try and video it though to get opinions on whether everything seems to be running as it should. It seems great but I want to make sure carb is not too lean. I really appreciate everyone's input. Im mot sure if there was any one issue that was worse than the other or a combination..even though I believe that to be the case.
 
carpking said:
Purchased this motor last week from a marine mechanic. It is model number 25502B. Motor had been stored for years. Very clean, low hours. Seller supposedly put new points, carb kit, fuel pump and fuel lines as well as new impeller. The day I purchased it, we checked compression (106 and 110), cold started it and it ran great. I get it home, it sets for a week, I take it out and it starts fine but it dies after a few minutes and now won't start. Plugs aren't fouled but I noticed after choking carb that I have a small amount of gas coming out of choke hole on carb. Thought maybe float was stuck but gas tank bulb pumps up tight. Going to check for spark later but I am looking for any suggestions. The only problem with the motor is the kill switch was bad and had been removed so the only way to currently kill it is to throttle it all the way down. Didn't think this could cause an issue but what do I know. Help please...very frustrated...
Click to expand...
 
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