1976 135 Evinrude won't start in water

[ljgill]

I have a 1976 evinrude 135 hp. It will start on the driveway but put it in the water and it won't start. I have replaced all the coils and plugs. the coils looked cracked thats why I replaced them. any suggestions?

 

[DJ]

Re: 1976 135 Evinrude won't start in water

Your engine is weak. Probably low compression in one or more cylinders.

 

[mrcj001]

Re: 1976 135 Evinrude won't start in water

DJ is right.....

Check the compression on all cylinders. You can rent a conpression tester at a auto part store.

Compressiom should be over 100 PSI and even on all 4 cylinders. If one cylinder is down it wont start with the back pressure on the exhaust.

Those old crossflows are good about this.

If the compression is OK, check the spark quality on each cylinder.

You said you changed the coils, make sure that the wire point that contacts the spark plugs penetrates the plugs wires firmly.

 

[ezeke]

Re: 1976 135 Evinrude won't start in water

The engine requires a minimum of 250 RPM to fire with 300 RPM preferred. That's much harder to reach with the motor in the water because of back pressure.

Make sure that you have a fully charged battery powerful enough to reach the minimum RPM.

Some of the 1976 135s had the cylinder heads changed after they were sold, but the originals were high compression; they take a lot of cranking power to fire correctly.

 

[ljgill]

Re: 1976 135 Evinrude won't start in water

Thanks guys. I'll try them all starting with compression test, then coil connections. the battery is good (new) but have no way to check RPM. I will assume its fast enough cause used to start fine.
ljgill

 

[emdsapmgr]

Re: 1976 135 Evinrude won't start in water

It is harder to start the engine when the boat is floating in the water. The exhaust is 2 feet underwater, causing backpressure-which does not occur when sitting on the trailer. Follow ezeke's recommendation on cranking rpm's.