2000 Mercury/Force 120 Sport Jet Electric Fuel Pump

[kthiltgen]

Does anyone know what the purpose is of the electric pump on a 120 Force? I'm thinking it is a primer pump as the engine will fire up cold (after using the primer bulb) and runs great at top end, however it seems that once the fuel pressure bleeds off after I've been fishing for a while it's a real pain to start.

 

[pnwboat]

Do you have a picture of the pump? As far as I know, electric fuel pumps were never used from the factory due to the fire hazard. There is not practical way to turn the pump off in case the engine stalls for what ever reason.

There is a fuel enrichment solenoid valve that was used on the later motors which acts like a choke when the motor is cold. It's activated by pushing the ignition key inwards as you turn the key to the start position to engage the starter.

 

[jerryjerry05]

No electric pumps from Mercury.
​PNW.Sounds like he might be describing the primer??

You'll need 5 posts to add pics to your thread.
Unless you use photo bucket or some other photo sharing app.

Start with a compression test and then a spark test after it won't restart..

You can pinch off the primer and see if that helps in starting.

Are you using the squeeze ball when trying to restart?

 

[kthiltgen]

pnwboat - the auto enricher, that acts as the choke, is functioning correctly based on my tests. When connected to 12 volts and after ~2 minutes the valve closes leading me to believe the auto enricher is functioning properly. Also, based on the manual, it doesn't mention pushing the key in when starting. My understanding of this system is the auto enricher receives a 12v power supply from the stator once the engine is running, allowing the shut of of fuel during engine warm up, after ~2 minutes. Once the enricher closes the idle jets take over and away you go.

I wish I could post a picture of the electric pump but here it is in a parts diagram under #36:
Fuel Pump Assembly for Sportjet (Sport Jet 120 Xr2) Engine
https://www.marineengine.com



The pump looks like it should basically act as a lift pump to supply fuel. When tested the pump is "open" and does not pump when power is supplied to it. I believe the previous owner of this boat put the primer bulb in the fuel line to perhaps band aid the failed electric fuel pump, however, when I look in the shop manual for this engine it does not mention the electric pump, only the diaphragm pump on the side of the engine.

I've searched and searched and cannot really find the real use for this pump and how it is supposed to function....constantly pump, only pump when cranking, # of psi, etc.


I appreciate the help her folks! I'm not going to let this one beat me!

 

[kthiltgen]

Sorry my link didn't work in the above post.....here it is in reference to the electronic fuel pump.

 

[pnwboat]

WOW....what's the fuel pump made out of?? Solid gold! Pretty pricey.

From what I can tell, the electric fuel pump takes the place of the primer bulb and is connected to the "Start" wire on the starter solenoid. Usually a yellow wire. This way the electric fuel pump only comes on when the ignition key is in the "Start" position to prime the regular vacuum operated fuel pump when the starter is engaged. Once you release the key and the key returns to the "Run" position, the electric fuel pump turns off.

There are many generic replacement pumps of the same design that would probably work just fine. Below is a link to an example, however, if you can find one that is marine rated, that of course would be the best.

http://www.ebay.com/itm/12V-Low-Pre...30GPH-2-4-PSI-for-petrol-diesel-/291780761212

 

[kthiltgen]

pnwboat - no kidding....very pricey!

I will check with my local O'Reilly and see about getting a marine rated universal pump and hook it up. This might be the cause of my starting issues once the engine is warm.

First thing in the morning she starts up fine but once I make my run to the first fishing spot, fish for 30 min to an hour it is a bear to start back up again. Could this primer pump not working be the culprit?

 

[pnwboat]

I wouldn't think that the failure of the primer pump would cause any significant starting issues. My personal experience with my motor, which is a 4 cylinder 120HP outboard, and I'm sure other boaters with Force engines is that they only have to prime it once when cold and it is started for the very first time.

Having said that, the Sport Jet is slightly different scenario and the electric pump is there from the factory for a reason. Have you tried squeezing the primer bulb when the motor is hot to see if it has any affect? If it makes no difference, then I would suspect that there may be something else wrong. If that solves the problem, then replacing the electric pump will probably fix it.

 

[kthiltgen]

I have tried that and it does work. What works quickest is spraying a tiny bit of mixed fuel into the top carb and then hitting the key, it starts. It's like it is starved for fuel after it gets warm/hot.

 

[pnwboat]

Then replacing the pump should solve your problem.

There is another trick that you might want to try if your throttle control has this feature. Most marine controls have what is called a "fast idle position" or "neutral fast idle position" with the throttle handle. To engage it, you have to pull the handle out towards the center or middle of the boat about 1/4", or push a button at the pivot point of the throttle handle to allow it to come out 1/4" or so. Once in this position, the throttle is disengaged from the gear selector cable and remains in neutral. You can move the throttle handle forwards to advance the throttle and open the carburetor throttle plates a bit and start the motor. The Neutral start safety switch selector stays in the Neutral position which allows you to engage the starter. The Force motors will often start easier if the carburetor throttle plates are opened a little bit. To return the throttle handle back to normal operation, just pull the handle back to the neutral position, and it will pop back into position to operate the gear shift cable and neutral safety switch.

 

[jerryjerry05]

The squeezie is what's installed on all systems as a backup I'm guessing on this one.
I thought the primer only worked when the key was used.
But since the E pump is installed the computer might be operating the system.???

Old dog new tricks!!
Since they installed an E pump I wonder how it operates when the motor stalls or the key's left on??
What safety backup did they use??

If I were you I'd contact Mercury and ask their techs and get a factory manual.

 

[kthiltgen]

jerryjerry05 - By looking at the wiring of the electronic pump, it appears to be wired to only run when the key is in the starting position....priming the fuel system as the starter is engaged and cranking the engine for startup. Once the engine fires up and the key goes into the Run position, the electronic pump is in the off position and the manual diaphragm pump takes over from there.

 

[jerryjerry05]

Does the primer work when pushing the key in?

 

[kthiltgen]

jerryjerry05 - The primer, AKA auto enricher, doesn't care rather the key is pushed in or not. It simply works on off of 12 volts. The enricher is open, drawing fuel form the top carburetor bowl at cold start....once started the enricher receives 12 volts from the stator and after approximately 2 minutes the enricher closes and the idle jets take over.

I've tested the auto enricher off of the engine by supplying 12v to it and it is opening and closing like it should. I'm kind of at a loss. My only thought is that something is still clogged up in the carburetors. I've been completely through them with the exception of removing the welch plugs. perhaps something under the welch plugs is causing my issues.

To be continued.....

 

[jerryjerry05]

Unhook the enricher at the intake manifold.
Turn key on.
Does it feed fuel when you turn the key on?
Does it feed when the key is pushed in?
Does it feed when the motors running?

It's possible the diaphragm in the primer is ruptured?

​Pinch off the hose and see if that makes a difference when running?