[exel1]

I have a 1974 70 horse evinrude, it seems to run fine on the muffs,neutral,forward or reverse, but when you put it in the water and go to put it in gear, it die's, does anyone have any Idea's as to the cause. coils were checked ,different powerpack was tried & compression is good.It also has a new fuel tank and fresh gas.

[iwombat]

"coils were checked"

What does that mean? Did you do a spark check? A good chunk of the time this is a symptom of one cylinder not firing.

[tashasdaddy]

if you set the idle on muffs it will not run in the water. the idle must be set with the motor in the water and IN GEAR. there is not any backpressure on the exhaust, when running on muffs.

[exel1]

had the boat at a dealership, they said they tried different coils and did a spark check

[HighTrim]

Again like TD said, the idle must be set on the water (under load) and in gear. Ensure it is at 650 before proceeding, will probably be in the neighbourhood of around 1000 to 1100 on the muffs. You can check for a dead cylinder, by removing 1 at a time, the plug boots (with an approved tool), and listening for a clear change in RPM. If you dont notice any change, that cylinder is not firing. You could also troubleshoot this with an inline spark tester available at most auto parts stores, the spark should jump the 7/16 gap with a strong blue ZAP!!