Losing prime

if you think about it, the primer bulb will not stay hard if you are running the engine, the fuel pump pulls a vacuum on the line, which overrides the antisiphon valve in the tank, drawing fuel up thu the line. It will draw fuel out of the line/primer bulb till the vacuum overcomes the anti siphon valve or the resistance in the length of line/height of fuel drawn. the only time the bulb is completly hard is when you prime it up to a point of pressue ahead of the bulb against the seats in the carb. Its normal for the primer bulb to not be hard after you run the engine, for that matter, its normal for it to be soft after it sits for a long while, the check valves are not that good in a primer bulb. I do recomend using only an OEM primer bulb, either Merc/ yamaha/ or Bombardier(OMC). I have thrown dozens of fairly new Moeller and Sierra primer bulbs in the trash
 
spareparts said:
I do recomend using only an OEM primer bulb, either Merc/ yamaha/ or Bombardier(OMC). I have thrown dozens of fairly new Moeller and Sierra primer bulbs in the trash
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So where do Perko (the old one) and Attwood (the new one) fit into the primer bulb hierarchy? lol.
 
If it's old "winter gas" and you're now above 70F it might be as simple as vapor lock. Refineries blend gas differently with more C4 for winter months so it'll kick off in cold temp's. I've had a soft bulb and an engine that would bog above 2500 rpm because I was running winter gas out of the boat in spring. I ended up pulling the anti siphon valve out of the fuel line so I could burn off the old gas without vapor lock. The butane is volatile and creates lots of vapors on a warm day. Hope it's something simple.
 
Steplift 72' said:
If it's old "winter gas" and you're now above 70F it might be as simple as vapor lock. Refineries blend gas differently with more C4 for winter months so it'll kick off in cold temp's. I've had a soft bulb and an engine that would bog above 2500 rpm because I was running winter gas out of the boat in spring. I ended up pulling the anti siphon valve out of the fuel line so I could burn off the old gas without vapor lock. The butane is volatile and creates lots of vapors on a warm day. Hope it's something simple.
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If a $315 fuel pump qualifies as simple, then it was. It was definitely the easiest part to change out. We ran the boat 30 miles on Saturday without any problems.
 
Thanks Destroyer.

awthacker said:
There was a low oil alarm when the wiring harness was connected. But the engine still stalled. So the harness is disconnected again. I have run it this way for maybe 5 hrs prior to the problem.
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I wanted to point out that the replacement fuel pump I installed was designed for pre-mix and therefore didn't have the VRO (oil) side to it. What intrigued me was that there was no electrical harness. So I guess fuel pumps operate simply on vacuum and not electricity?
 
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