1974 Evinrude help please

[Tall6guy8]

Hi guys, I have a 74 rude 70hp, 70973r that I have been having issues with and have started replacing some things. Started with the stator as I could start it but only seemed to run on one cylinder, then replaced the ignition coils, old ones where original. And a new fuel pump old one was leaking. Now my big issue is that I can start it in my driveway with water, but as soon as I drop it in the lake, she bogs down and doesn’t have much power. Then dies if you throttle up on the motor. Any suggestions?

 

[racerone]

A 1979 model.-----Compression test first.----And does spark jump a gap of 7/16" on all 3 leads.------Checked for plugged high speed jets in carburetor bowls ?-----Is choke solenoid adjusted properly.-----All " no money spent " work to do.

 

[Joe Reeves]

Is this engine new to you?

You say the engine is a 1974 70hp Evinrude..... That model number of 70973R indicates a 1979 70hp Evinrude.

Remove spark plugs... check compression. What's the individual psi reading of each cylinder?

Plugs still removed... check the spark using a tester with its air gap set to 7/16". The spark should jump that gap with a strong blue lightning like flame... a real SNAP! Does it?

If the two above areas check out as they should, your problem is normally contributed to fouled carburetors, but get back to us with the test results first before digging into them.

 

[Tall6guy8]

The motor is not new to me I have had it for 7 years. The compression test I will preform. But my rude slowly lost power over the last 2 years but I have always been able to get it to start. Last year she started to slow down/ not get on plane, and not fully engage at full throttle, almost choke out but then speed back up and start running fine.

 

[Joe Reeves]

The motor is not new to me I have had it for 7 years. The compression test I will preform. But my rude slowly lost power over the last 2 years but I have always been able to get it to start. Last year she started to slow down/ not get on plane, and not fully engage at full throttle, almost choke out but then speed back up and start running fine.

Good explanation.... Hopefully just fouled carburetors that is a common problem that takes place, little by little when engine sit over the winter months... or just sits for a long period of time for other reasons.

However, start with the basics... compression and spark test as described above so as not to overlook and miss the obvious if it exists.

 

[oldboat1]

Getting great advice above.

When running in the driveway as mentioned in your first post, you need to find a large barrel (plastic trash can) to test. Want to replicate running in the lake as best you can, and need some back pressure for that. Water level about half way up the leg (well above the water pump). Can't rev, but can test shifting, some throttle up.