1974 85 evinrude

[leaseman]

Question for the gurus out there.... we have a '74 85hp V4 evinrude that we have been fixing up...runs like a charm now BUT is impossible to start after sitting for a couple of days unless you prime it...once primed it fires at the touch of the key for the rest of the day... done the usual pump test etc and get a good pulse...any ideas...

 

[ezeke]

Re: 1974 85 evinrude

You will always have to prime it. If you have a back-flow preventer at the tank, you won't have to squeeze so much, but you will still have to get fuel to the motor.

You should also always need to choke it when you first start it cold. That allows the pistons to pull more fuel through the reeds.

 

[leaseman]

Re: 1974 85 evinrude

I guess I didn't make my sell clear...the only way to fire up is by squirting gas mix into the intake and then crank immediately....otherwise it just turns over but doesn't even try and fire....then for the rest of the day (even when we anchor for 2-3 hours) it fires at the touch of the key.....:'(

 

[DJ]

Re: 1974 85 evinrude

Time for a carb rebuild. Your needle(s) and seat(s) are leaking.

EASY on that engine.

While you have the carbs off, do this.
.
1. Replace the water pump. The gear shift rod is EASY to access with the carbs off.

2. Replenish the fluid in the lower unit. Use OMC/Bombardier "Hi Vis" lube and replace the fill and drain plug seals.

Do that stuff and you'll have an engine that will run great-FOR years.

By the way, you can get a generic manual (Seloc) my recommendation, for that engine here on iboats for about $30.00.

Best money you'll ever spend.

 

[ezeke]

Re: 1974 85 evinrude

That is equally my fault for not making myself clear. You have to make sure that the choke is 100% closed on both carbs for a cold start on this series of motors.

The only reliable way to assure that they are closed is to look in the carb throats while someone else hits the choke switch at the control. Once you establish that the chokes are fully closed, you will not need to spray. The vacuum created by the cylinders will do as they are supposed to do and pull the fuel through the carbs. Once fuel is in the system, the motor continues to start easily until the next time that it has set awhile and dried out.

"As the piston begins its upstroke, it closes the intake and exhaust ports and begins to compress the fuel and air mixture trapped in the cylinder. The upward travel of the piston also reduces the pressure in the crankcase compartment. The resulting suction opens the leaf valves which admit additional air and fuel from the carburetor into the crankcase, thus preparing the next cylinder charge." From "theory of operation" in your service manual.

The very fact that the motor runs so well once fuel is established tells you that it is not a carb problem but a choke problem.

The only other common thing that will make this motor difficult to start cold is a battery that cannot turn 300 RPM. Dual purpose deep cycle with at least 650 cca and fully charged will help.

 

[DJ]

Re: 1974 85 evinrude

ezeke, makes a good point. The V-4's had a tendency to corrode the negative battery terminal, on the engine block.

Remove it and clean it, battery disconnected-of course.

If you don't replace the water pump, all will be for naught.

Noone to blame, but yourself, for not following basic maintenance.