Primer Bulb

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,923
Everything in Rosco's post works on mine except the "Advance the throttle at least 3/4 way, without putting it in gear. -"

My motors wouldn't ever start like that.

I'm not saying he's wrong.

One thing I've found is that any difference in compression readings will make it very hard to start.
You do a compression test?
 

HotTommy

Lieutenant Junior Grade
Joined
Mar 15, 2013
Messages
1,025
One thing I've found is that any difference in compression readings will make it very hard to start.
You do a compression test?


Several times. You old heads help so many people here you likely don't remember my posts from earlier this year. I did extensive work on the engine in discussion and topped it off by replacing a leaky head gasket. Compression was 150+/- 5 on all cylinders. ... And as I said before, when I did have trouble starting, I could solve it by squirting a little fuel into any carburetor.
 

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,817
What I picked up from the original post of this topic is that with a cold engine, you have a problem starting it unless you are using starting fluid. That in itself is a giveaway on the source of the problem. The engine needs to have the choke or the enrichment valve operating properly when starting it cold. The limp priming bulb maybe a concern but "limp" is actually very subjective the same way that "firm" is. But if the priming bulb is not actually working, even with starting fluid you should not be able to start the engine without having to do it multiple times (kinda like priming the fuel system using the fuel pump). So when you get a chance you should start your troubleshooting with the choke/enrichment valve and then you can follow it up with the "limp" priming bulb.

Diagnose the priming bulb by removing the air covers on the carbs and emptying all of the bowls of fuel. Keep depressing the priming bulb to fill the bowls and watch for fuel either leaking out of the carbs' vent hole or from the main jets. Make sure, the engine is on the horizontal (in reference with the carbs or maybe vertical with reference to the LU) and not tilted. If fuel is leaking in either the vent hole or the main jets, it is an indication either a float is not properly set or the inlet seat valve is worn out. If there is no fuel leaking but the carbs' bowls are getting filled up (really hard to tell without removing the bowls after priming) then I would surmised the priming bulb is working.
 
Last edited:

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,923
Pull the tiny hose from the enricher to the carb.
Have someone hit the choke.
It should squirt some gas.
Can you tell it's the off season and people have lots of time on their hands?
Were gonna fix this until it's fixed:)
 

HotTommy

Lieutenant Junior Grade
Joined
Mar 15, 2013
Messages
1,025
Spring is here and I'm back. The problem is solved and the cause was ......(drum roll for dramatic effect) ....... primer bulb orientation. I found this issue in a Google search and discovered it was my problem. Here's what was happening. The fuel tank in my pontoon boat is located such that the fuel line goes up a foot or so before going back down about two feet to the engine. The bulb is in the section of line going down to the engine. My intuition was to leave the bulb so the side where fuel exited was pointed down toward the engine. That was what was contributing to the problem. It seems that the one-way valves on each side of the bulb are held closed by springs that are weak enough to be affected by gravity. So when the IN end is up, that valve cannot fully close. Thus, some of the pressure the bulb should be sending to the engine is escaping back to the fuel tank. I tilted the bulb so the IN end was down and it got nice and firm with just a few pumps.

As for the fuel enrichment valve, I tested it two ways and it seemed to pass both tests. With the engine warmed up and idling, I manually pressed the black button down and immediately heard the engine slow as it was running too rich. When it resumed a normal idle, I pressed the key in (electric choke) and the engine again slowed due to the excess fuel being dumped in by the fuel enrichment valve. ... Now that the bulb is priming the system correctly, I'll see if the hard start problem I had last summer returns this year.

It's almost warm enough to jump in the lake. :laugh:
 

SkiDad

Lieutenant Commander
Joined
Jul 18, 2010
Messages
1,518
cool deal. I wish it was warm enough up here in the north east. The water temp is 37 right now....at least 45 days till ski-able.
 
Top