explain the primer system and the primer lever please?

[tbrownarcher]

I have a 1999 Johnson 150 hp (J150PLEES) on a 1999 Triton 18' boat

I am having intermittent starting problems. There is plenty of SPARK, but I have not checked the timing (there is no visible damage of any kind to the timing wheel or anything associated with it)!

I, however, can get it started by putting the primer lever in the up position and then it seems to start very easily in the up and the down position for a while especially if it's still warm. If it's cold again then it may or may not start.

Yesterday my son had the boat at a local tournament. He prefished the day before to find the bass and the motor ran all day. Tournament day it would not start the whole day. He squeezed the primer bulb the prefish day and could not get it to pressurize but it ran all day as I said. The tournament day the bulb would pressurize so that you could not squeeze it anymore as you would think was correct but it would not start (all day).

so in the garage today (day after tournament) I tried to start it and it would not start. I pulled #1 spark plug and there was very very satisfactory spark but i have not looked at the timing other than the timing wheel and pointer and all that is in OEM manual position.

After determining the spark was ok I put the primer-lever in up positon and it started immediately. I took the filter out (and it runs way more gas than is needed AND I cleaned it the other day there was very very little in it to come out) and put the filter back in and it started immediately. I put the primer lever in the down position and it started immediately. (I am not running it in water so I can't let it run for more than a millisecond).

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I do not understand what the primer system is doing exactly. I don't understand why a bulb is needed if there is a primer system and i don't understand why a primer system could not be bypassed in some way since there is a primer bulb.

When I put the lever in the up position the OEM book tells me that there should be gas coming out in 2 places and does not mention volume. I can't tell if it's coming out in 2 places but it's coming out at different volumes each time it's put in the up position. One time there will be a pin hole stream the next time it will have a fan like spray coming out so to me that means something is plugged up.

Can someone help with this? a real good explanation of how the primer system works could help me a lot. I know it's a solanoid so it's opening and closing some valve i'm assuming but I would like as detailed an explanation as anyone can give me and any suggestions on what to do would be really appreciated.

Thanks very much,
Nate

 

[ezeke]

Re: explain the primer system and the primer lever please?

The primer solenoid is a valve that allows fuel to bypass the carburetor so that it can be injected directly into the intake. The purpose of this is to enrich the fuel so that the engine can be started when cold.

The initial charge of fuel is supplied by squeezing the primer bulb; after that, you should have additional pressure from the fuel pump as you crank the engine.

The handle on the primer soenoid is there for emergency use when and if your battery dies and you have to rope start the engine. At all other time, the handle should be aligned with the cylindrical base of the solenoid.

Again, the primer solenoid is for cold starts and should be activated by pushing the key in while cranking when required.

Please see the thumbnail for the normal operating position of the lever.

While the primer bulb is providing pressure and lifting fuel to the primer solenoid, it is also filling the float bowls at the bottom of each carburetor.

Once the float bowls have fuel in them, the vacuum created by the movement of the pistons pulls fuel through the carburetor.

The fuel leaving the float bowls is pulled through to the firing chambers, not pushed.

 

[tbrownarcher]

Re: explain the primer system and the primer lever please?

ezeke:

Thanks!

The OEM manual says to test the primer valve by turning the lever exactly oposite that it is in in your picture. When you do that and push the primer bulb gas should come out both tubes. And when I do that if it has been hard to start then it starts. So what would have been keeping it from starting when the lever was in the correct position for normal use?

Thanks,
Nate

 

[tashasdaddy]

Re: explain the primer system and the primer lever please?

it floods the motor, (too much gas to air mixture). i have only had one primer that needed that. the owner kept trying to start the motor, (which the fuel tank was empty) the OMS pump kept pumping oil, so the system was full of oil and no gas. had to use the test knob, to pump the oil out of the primer system, and drain and clean the carbs.

 

[ezeke]

Re: explain the primer system and the primer lever please?

If the primer solenoid is functioning, pushing in the key allows the fuel to flow, same as it would if the red handle is turned perpendicular to the unit. You should be able to feel that if someone pushes the ignition key in while you touch the primer solenoid.

 

[tbrownarcher]

Re: explain the primer system and the primer lever please?

We disabled and disconnected the oil injection.. We add oil when we put gas in now.

I just discovered that one of the nipples on the back of the solanoid is broken i cant keep the tube on it so that must be at least part of the problem.

How much is one of those solanoids and where do i get one ... would a dealer have it on hand ????

thanks,
Nate

 

[ezeke]

Re: explain the primer system and the primer lever please?

There are two repair kits for the primer solenoid. They only take a few minutes to replace.

The top is part #0437228 or aftermarket 18-0993.

The schrader valve is #0175158 or aftermarket part 18-0871.

The hose nipples are very small, so if the hose is the wrong size, it won't stay on.