Questions about priming bulbs

[Vic.S]

I've often seen advice on here that a priming bulb should be held pointing upwards or "at the sky".

Does it really make any difference or will they work just as well pointing at the ground .

They have little valves in them. Does any one know what these valves are like?. Id always assumed they were little balls, presumably relying on gravity to close not on springs ?

 

[GA_Boater]

My experience, which differs from what I've read in the forum, it doesn't make any difference how the is pointed. What I have seen is when the bulb is dry and pumping air it isn't the greatest until fuel fills the bulb.

Gravity wouldn't work to open or close the check valve. Without tearing an old one apart, I think the check valves are one way flappers like in a fuel pump, no bulbs or springs.

 

[Faztbullet]

Aftermarket bulbs usually only have 1 check valve that's why they are cheaper and operate that way. Always use a OEM bulb and it wont care how it lays...

 

[racerone]

+++ ^^^^ agree buy good stuff.----Not stuff the ---" WOOFLUNGTHEDUNG " -----company sells.

 

[Crosbyman]

I am 70 .... my grandpa always said .. "buy the best tools you can they will last a lifetime" he was wrong ! :facepalm:



I still have some of his tools ...:joyous:

 

[guy48065]

Aftermarket bulbs usually only have 1 check valve that's why they are cheaper and operate that way. Always use a OEM bulb and it wont care how it lays...

Do the OEMs all make their own primer bulbs? How much can be verified vs what must be taken on faith?
My pontoon stalled on the run from the launch ramp to my dock. Acted like it wasn't getting any fuel but I was able to limp home by jamming it in gear for the couple seconds it would run at each re-start.
Troubleshooting led me to replace my premium-priced dual-valve 2-year-old hose & bulb with an inexpensive Attwood I grabbed at Walmart--the only thing open saturday afternoon on a holiday weekend.

Runs great at WOT now...but how long til I have trouble again?
I'm not a fan of these newer EPA-compliant hoses & "crunchy" bulbs and assume they're all made in China now--regardless of price.

If anyone knows of a known-superior one I'd like to have the name & part number so I can sleep better at night.
Don't respond with "mine is great" unless you intend to ship it to me. PM & I'll provide the address. :joyous:
Thanks.

 

[havoc_squad]

Buy a Mercury, Yamaha, or BRP outboard primer bulb. I cannot speak for any of the aftermarket ones.

They have to be picky enough to demand a certain level of quality control of parts because it will affect their bottom line and possible liability risk regarding certain parts function for motors covered under OEM warranty.

The biggest reason why made in China products earn such a bad reputation is the lack of enforced quality control in production contracts and the usual cause of greed on many sides of the matter.

There is some good quality stuff coming out of China involving different line of products, the problem often is the unit price is too low for it to last long or the company asking for the product to be made does not put in strong contract terms of quality control.

In short, if you want paid you better have it pass A,C, and C quality control tests and not exceed X % of failures for the product over a certain number of years (1/2/3). You fail, you don't get paid for any future orders until you can prove it is fixed and stays fixed.

 

[guy48065]

I have a new-looking Attwood EPA-compliant primer bulb I took out of a used jetski I recently bought. It had no checkvalve action in either direction so it was useless as a "pump".
I​​​​​​ decided to open it up to see what makes them work. I peeled off the clamps and wiggled the fittings out of the ends. It turns out there were 2 valves in this primer but both were so stuck open that hot water or smacking on the counter wouldn't free them up.
So I opened the fittings to see why.
Each fitting contains a shuttle-**** shaped poppet valve and a snap-in retainer. All parts look to be nylon or pp. I pried out a retainer and pulled out a valve. I found fuel varnish coating everything. "Varnish" is an appropriate name for this crap--alcohol and brake cleaner (acetone) couldn't remove it without scrubbing with a rag or swab. I had to use the wooden stick of the swab, or my fingernail to get off the really tough spots. Once clean it all went back together and both valves now work.

Is the $62 BRP assembly I've already ordered made differently, with different materials or better tolerances? I'm not going to sacrifice it to find out.

I don't quite understand why the carbs were spotless but the primer was varnished up. I bought this jetski in February from a guy who only owned it 1 year (23 year old machine) but maybe it had been recently cleaned.

I'm going to get a few feet of the latest & greatest USCG-approved 5/16 fuel hose and make a spare using this primer.

 

[achris]

..., I think the check valves are one way flappers like in a fuel pump, no bulbs or springs.

Nope, they're 'ball' type check valves, and need gravity to sit right. Point the bulb up and the check balls sit down. The lower valve closes off the 'incoming' line and as you squeeze, the air (or fuel is the bulb is already full) pushes the top ball up (and off its seat) and the air/fuel moves out of the bulb. When you stop squeezing the ball drops down and closes that valve, so the fuel/air that has just been pushed towards the engine can't be drawn back in. As you release the bulb the reduction in internal pressure opens the lower valve and draws fuel in from the incoming line. Once the bulb returns to normal, gravity drops the lower ball back down and the process repeats.

...Does it really make any difference or will they work just as well pointing at the ground .

They have little valves in them. Does any one know what these valves are like?. Id always assumed they were little balls, presumably relying on gravity to close not on springs ?

Correct, no springs, they use gravity.

Do they work when faced the wrong way? No.

Chris..........

 

[guy48065]

They do work when faced the wrong way. Pressure differences as the bulb is squeezed will move the valves. The addition of gravity may increase efficiency fractionally.

 

[rothfm]

To add to this...Just today I installed Vac gauges just after the primer bulbs on twin motors...Also Clear hoses to watch for bubbles etc.

I can say that laying the bulbs flat, after priming I did see fuel flow back through the bulb..and loose its prime. On several bulbs I used in my troubleshooting for unrelated issue.

I think orientation has an affect..Just dont know how muc it matters as long as fuel is present at start to begin its own flow. But orientation does have an affect.

 

[achris]

They do work when faced the wrong way. Pressure differences as the bulb is squeezed will move the valves. The addition of gravity may increase efficiency fractionally.

When the bulb is already full of fuel, possibly, but with air, not a chance.

Chris.........

 

[racerone]

Once carburetors are FULL the bulb can / does go soft.----That does not matter.

 

[achris]

Once carburetors are FULL the bulb can / does go soft.----That does not matter.

Yep, based on the way the system works, the bulb CAN NOT stay hard once the engine is running.

 

[guy48065]

When the bulb is already full of fuel, possibly, but with air, not a chance.

Chris.........

It worked for me. The air gets pressurized the same as liquid and will move in one direction--towards the carbs.
When testing my primer I put a short hose on each end and put the ends in a sink full of water. The suction side sucked and the pressure side bubbled--in any position.

But it's possible that IF the bulb and pressure hose is full of air and the pressure side is open to atmosphere--at least one of the carbs has a bowl not full so the floatvalve is open AND the bowl vent is unobstructed--THEN a squeeze won't build pressure and the intake checkvalve may not close if not held pointing up. My assumption here is the bowl vent is so small that a healthy squeeze of the primer bulb WILL build the pressure needed to seat the intake check and move that air towards the carbs. Sound reasonable?