? on a 1985 Evinrude 70hp

AlanT · Sep 21, 2024

I haven't used my boat in months and decided to run the motor on the hose in the driveway. I primed the bulb until it was firm and cranked the motor many times, but it's wouldn't fire. Wondering if I flooded the motor I disconnected the gas line from the engine (I have the old style snap-type connector). The engine fired and ran. I immediately reconnected the gas line and ran the engine for 15 minutes without a problem. I'm not a mechanic, but this seems like an odd symptom. Is there something I could check? Or is this just a coincidence that it fired up after pulling the gas line? I'll need to run it again next week to see if I have the same problem.

Thanks in advance for suggestions.

lckstckn2smknbrls · Sep 21, 2024

If it does it once it's an anomality if it does it again next week there might be an issue. I don't think you flooded the motor unless there is an issue with the float, needle or seat.

1pc@atime · Sep 23, 2024

It sounds like it may have been air bound in the line or at the carb.
Its just a theory but the what I'm thinking is:
The bowl is full of old gas, the float holding the needle closed, maybe even a bit stuck from sitting, and some air caused by drain back in the line. You pump up the bulb, it builds pressure but the needle is closed, the fuel can't move in the line, and it won't run on the stale gas in the bowl.
You pull the line, relieve the air bubble, reconnect it and it run on the fuel that can now reach the bowl.

I had a Mercury that would do that to me if it sat too long. I learned that if I stomped the primer ball hard enough it would blow past the needle and seat and force fuel into the carb, and even up the bowl vent. That would get it to fire and pass any old gas in the ball or line. Once it ran it would start first pull until I let it sit again. Pulling the motor off and turning it on its side and letting the carb drain out would stop it from happening but you can't do that with a big motor.

LDUBS · Sep 23, 2024

Is it normal to prime the bulb before starting these older two strokes?

thill · Sep 24, 2024

I agree, probably air trapped in the system, combined with old gas.

I had a motor that if it sat a long time you had to squeeze the bulb, then crank for a bit, then squeeze the bulb again and then it was fine. Had an air leak in there somewhere, but that engine ran like clockwork.

Anti-Theft device!

AlanT · Sep 24, 2024

1pc@atime said:
It sounds like it may have been air bound in the line or at the carb.
Its just a theory but the what I'm thinking is:
The bowl is full of old gas, the float holding the needle closed, maybe even a bit stuck from sitting, and some air caused by drain back in the line. You pump up the bulb, it builds pressure but the needle is closed, the fuel can't move in the line, and it won't run on the stale gas in the bowl.
You pull the line, relieve the air bubble, reconnect it and it run on the fuel that can now reach the bowl.

I had a Mercury that would do that to me if it sat too long. I learned that if I stomped the primer ball hard enough it would blow past the needle and seat and force fuel into the carb, and even up the bowl vent. That would get it to fire and pass any old gas in the ball or line. Once it ran it would start first pull until I let it sit again. Pulling the motor off and turning it on its side and letting the carb drain out would stop it from happening but you can't do that with a big motor.

I'm buying into your opinion. A few things I didn't mention that may further support your comments. I typically run the gas out of the engine since the VRO was disconnected on this engine many years ago and I use an oil/gas mix. When I pulled the gas line from the engine, there was some pressure in the line. I didn't smell gas as would be typical if it was flooded. It will start fine for days after getting it started. It's only an issue when it sits for weeks. On a side note, I only use non-E gas and I believe the gas is good.