Old 4hp Evinrude takes a nap

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BrianVT

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I don't know how long this sat, and it looks like hell, but it had good compression so I went ahead and rebuilt the carb. It ran great in the trash barrel. I put it on a jon boat and it ran great, even at full throttle, until about 200 yds. off shore it started to bog. It ran ok at low rpms so I was able to limp back to the dock. My feeling is the problem has something to do with heat? Maybe a problem with ignition coil? Charge coil? And I don't know the condition of the impeller. What would you do as the next step?
 
Scott Danforth

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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you should have replaced the impeller BEFORE running it.
 
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Crosbyman

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u should post the mdl# no charge coils in old 4hps

the older ones only have ignition coils usually at cracked up if you did not pull the FW to bring it back yo life...

Condensors likely shot also ....repalce! points usually just need a touch up and set .020 but new ones always helps. change GC oil to!

hopefully you did not cook it by bypassing the impeller job . If you do check and find missing blades well they may have been sucked up and blocking the engine water flow.

these are great kickers , reliable but neglect kills them.


lots of u tubes... btw check venting on the tank !
 

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saltchuckmatt

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BrianVT said:
I don't know how long this sat, and it looks like hell, but it had good compression so I went ahead and rebuilt the carb. It ran great in the trash barrel. I put it on a jon boat and it ran great, even at full throttle, until about 200 yds. off shore it started to bog. It ran ok at low rpms so I was able to limp back to the dock. My feeling is the problem has something to do with heat? Maybe a problem with ignition coil? Charge coil? And I don't know the condition of the impeller. What would you do as the next step?
Click to expand...
Do another compression check, if still good, buy an inexpensive IR gun and see how hot it's running.
 
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Crosbyman

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if compresssion lost pull the cyl head and check the head gasket ... they some times blow at the center point between cylinders.
they can get hot in a tub do not run them wot in a tub
 
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airshot

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How thorough was the carb job ....factory rebuild kit, each and every small passage cleaned with a wire, new gaskets etc ?? Sounds more like overheat, but a sloppy carb clean could be an issue.
 
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racerone

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Some of the older 4 hp do have a charge coil.-----But the impeller is highly suspect.
 
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Crosbyman

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We need model !! we just do not know what "old" is .... to yound fellows everything is old :)
answers to coils, condenser, point, and.. impeller condition ! nedded after inspection .
 
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Chris1956

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Does that motor have a fuel pump? They can collect dirt pass it to the carb, and of course just fail.
 
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BrianVT

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Scott Danforth said:
you should have replaced the impeller BEFORE running it.
Click to expand...
This old 'rude looked pretty rough but I got it cheap. It had good compression (@ 120 psi on both, I think?). I hoped I could save it with a carb. rebuild ($30 in parts + my time). I didn't want to dump any more $ and time than that into it if it wasn't up to pushing a boat so I took it out to see if it would throttle up under load. I guess I tested it a bit too far (I was having fun). Compression is now @ 105 psi on both. :-( I should have backed off the test run sooner and gone ahead and then invested in the impeller replacement. Now I need to decide if 105 psi is acceptable enough to go through with the impeller replacement ($70 kit + my time) or just junk it.
Live and learn. Thanks for all of your replies and I would like to hear what you think of 105 psi on this 2-stroke. Junk it or spend the time and $70 to fix the water pump and run it ?
 
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airshot

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How accurate is your compression gage ? Did it over heat ? You might try some ring free or other additive to regain some compression.
 
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BrianVT

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airshot said:
How accurate is your compression gage ? Did it over heat ? You might try some ring free or other additive to regain some compression.
Click to expand...
I think the gauge is good. It has the Schrader valve at the tip so it should be accurate even for small volume cylinders.
I assume it overheated but not enough to melt the piston(s).
Do you think that would cause stuck ring(s)? I assume it would just cause wear on rings or cylinder?
 
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