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dissapointed after powerhead rebuild, help needed badly

greasemonkeyjmj

Contributing Member
Some may remember i bought a 1987 Evinrude 48SPL that wouldnt idle consistently, i tore the carbs down and they were spotless, but i soaked them anyway, later on I discovered both pistons were ruined and the block was scored, i just got it back from being bored and new pistons, I put everything together, and it will not idle, i have the idle screw all the way in and it still doesnt want to run, the carbs are the fixed jet type that has no air adjustment. any help would be greatly appreciated as I am at my witts end.
 
Thanks for the reply, Since the engine hasnt been sitting up and the insides of the carbs looked good, I didnt rebuild them, I am thing about buying kits and rebuilding them, that way i can drill out the plugs that cover the idle circuits inthe carbs. I did not surface the flanges, but I will pull them off and give them a going over, I used new gaskets and new upper and lower crank seal.
 
if your going to get carb kits, also get a fuel pump kit too. welder tip cleaning tool has many tiny wires to get into the very small holes you,ll find under the idle plug cover.
 
i was wanting to add that compression is 150 on both cylinders, i pulled the top carb and drilled the plug out of it, and there are only 2 holes into the throat for the idle circuit and they are both clear. i can also shine a light into the plug hole and see it shine all the way through the fixed air jet, i was going to pick up a tip cleaner earlier this evening but the store i was at didnt have any.

 
I may have found a problem. i had it running and took a can of spray carb cleaner and shot a blast under the flywheel, and it idled up and smoothed out, so apparently there is a problem with the crank seal, i put new seals in it, but apparently something isnt right.
 
it would be interesting if a bad upper crank seal could cause or contribute to bad idling, think fuel pump gets pulses from upper cylinder, maybe low fuel pressure at low rpm's
good to see high compression readings
check charge coil , tests are easy in manual, changing mine helped
 
Scalhoun it is my understanding that if the seal isnt sealing off that the engine will pull more air into the crankase than what is is supposed to and not pull in the correct amount of fuel
 
What symptoms will leaking reeds cause on my engine i remember when i tore the engine down that on one block, that out of the 8 fingers, almost everyone of them was letting at least some light thru where they werent sealing off, and i cant remember how many on the other was letting light thru.

 
I have actually been thinking of different carbs, also i found on the upper crank seal that when i installed it i only tapped it in flush with the top of the upper bearing assembly, it still had 1/4 inch or more to go down, so i tapped it on in, which direction does the seal go in ? i put mine back the same direction that it came out with the spring side facing upseal.jpg
 
Look for ---------engine diagrams --------on this page.---The parts breakdown clearly shows the way the seal should be installed !!!!
 
I actually have the old seal back out, I guess I am through with it until i can call around and locate a new seal for it. Now I am going to go crazy wondering if this is going to help it any, LOL
 
Racer it will have to run better than it does right now with no seal in it at all, LOL, I am trying to find the real problem, but I am running out of ideas and things to check. I can partially cover the carb throat on the upper cylinder and it will try to level off and smooth out, which makes me lean toward a carb restriction, but I can see thru every jet and idle circuit hole in the carb.
 
ok, Update time, i put my new seal in so I could go back to trouble shooting, and by the way the seal didnt make a difference. With the engine running, i can partially cover the throat on the top carb and it will pick up and level off. I can cover the bottom carb throat and if anything, it dies down a bit. I swapped positions with the carbs and the test results swapped with them, now when i partially cover the bottom carb the engine picks up. also after swapping the carbs, i actually had to turn the idle screw part way in to idle it down, i was having to run it with the idle screw all the way in.
 
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