175 - 77 Evinrude

[ROGER67]

Haveing a problem with this not sure what to do but have put new plugs , rebuilt carbs ,put new gas ball and line on ,,but on the hose she runs great but get it out on the water and push forward no go until I chocke it runs great one time then the next time the same old thing sounds like its not getting fuel the other day was rolling along at 30nts then all at once she jump to 35nts with out doing anything ,,had taken the lower unit off thought it might have been carboned up but none was found unless I'm not doing something else ,,,could it be the power pack or the coils someone plase tell me or help me get this promblem taken care of

 

[JB]

Re: 175 - 77 Evinrude

Ahoy, Roger. I can feel your frustration, but I'm having a difficult time understanding your description of the problem. Let me try to figure it out:<br /><br /> ....runs great on the hose..... Maybe, but possibly it is running "great" on less than 6 cylinders.<br /><br />....no go until I choke it. . . . Classic fuel starvation under load. Fuel flow is inadequate. Could be tank, hose, primer bulb, fuel pump or carb(s).<br /><br />....jumped to 35Kt.... Sounds like a cylinder that wasn't making power suddenly turned on.<br /><br />....could it be powerpack. . . Yep, it could.<br /><br />You need to organize your troubleshooting to find the problem. Random replacing or rebuilding of parts without knowing that they are bad only complicates things and makes you as mad as you are now.<br /><br />With the engine idling on the hose, pull each plug wire, one at a time. While you have it off, see if it will jump at least a 1/2" spark to the block. <br /><br />If engine speed drops when you pull the wire, that cylinder is making power. If there is no change, that cylinder is dead. If the plug wire from a dead cylinder makes the 1/2" spark it is not an ignition trouble. If there is no spark go to Ignition troubleshooting.<br /><br />If you have cylinders that are dead but have spark, and they are side by side, squirt some WD-40 into the carb that feeds those two cylinders. If rpm jumps up, clean that carb again and get the jets clear.<br /><br />After the above tests, the engine should be warm. Pull the spark plugs and run a compression test. All 6 cylinders should compress over 100 psi and there should not be more than 15psi difference among them. If it fails the compression test get back to us with the results.<br /><br />If you have found a cylinder that has no spark, trade coils with another cylinder and see if the problem moves with the coil.<br /><br />If none of the above points you to the real trouble, get back to us with what you have found and we'll take it from there.<br /><br />Red sky at night. . .<br />JB

 

[BKool68]

Re: 175 - 77 Evinrude

You could also be sucking air at your fuel line connection.

 

[Dhadley]

Re: 175 - 77 Evinrude

I agree with JB (again). It sounds like two problems. The "sudden" change in rpm is most likely ignition. <br /><br />One thing to keep in mind about your fuel starvation problem is the fuel. Those carbs were designed, metered and built for 1977 fuel. We have had to rejet many older motors for that acceleration problem. Just make sure you are using FRESH 87 octane, good oil (at the right ratio) and Champion L77JC4 plugs.<br /><br />Good luck!