Two Schools of Thought...So Which One Is Right?

Everybody seems to agree that, for best results when pumping a primer bulb, you should hold the bulb vetically--in the direction of the arrow on the bulb. And most also appear to agree the bulb's arrow never should be pointed downward.

Once the outboard is running, however, two schools of thought emerge. One says the bulb should be positioned so that it continues pointing upward (see photo right). The other school says there's no problem whatsoever with just laying the bulb horizontally in the splash well. Who's right remains a topic of discussion.

According to what I read in an online article titled A Primer on Primers, "It's advantageous if the primer bulb can be positioned in such a way that, during priming, it can be oriented vertically, with the direction arrow pointing skyward. This will allow gravity and the weight of the fuel inside the primer bulb to help with the operation of the one-way valves. If the primer bulb is oriented with the flow arrow pointing downward, gravity and the weight of the fuel in the line above the inlet check valve may spoil its operation, and the primer will not work properly. (If anyone would like to read the complete online article, here's the link: http://continuouswave.com/whaler/reference/primer.html.)

"This subtle but important point--orienting the primer bulb skyward--is often overlooked in many installations, but it really helps the primer bulb do its job. In most pre-rigged boats delivered these days, the primer bulb is located within 12 to 18 inches of the engine." 

I will admit that this article is of particular interest to me. As you probably remember from last year, I had considerable problems that took up a lot of my boat mechanic's time trying to sort it all out. And I'll be the first to tell you that, except for one little problem, my Yamaha is running better now than ever before.

I now always prime the bulb with the arrow pointing skyward, and it nearly always starts right away. It also idles good, with absolutely no coughing, which it used to do constantly. And when I romp on the hotfoot to get on step, the response is instantaneous.

Once I arrive at a fishing spot, though, and spend a couple or so hours on the trolling motor, the outboard sometimes won't start very quickly when I get ready to change locations. After re-priming, the outboard usually fires, and I'm off to the races.

To this point in time, my primer bulb always has lain horizontally in my splash well, but I plan to rearrange everything to resemble the accompanying photo and find out if that makes a difference. All it can cost me is a couple of zip ties.