1996 Force Mercury 120hp starts then dies HELP

[gica]

So we were at the bait dock and turned the motor off, when ready to go it would not start, pumped the prime ball and it started, revved it and it died pretty quick prime ball soft again. Repeated process same result. Can it be the pump? Thanks guys

 

[Jiggz]

Most likely the fuel pump. It is really easy to disassemble but just make sure you keep note of all the orientation of the check valves. Probably a leaky diaphragm or stuck check valve. This is with the assumption the motor is not misfiring then most likely a faulty fuel pump. Note the fuel pump operates on #3 cylinder. If there's a misfire, check compression on #3 cylinder.

 

[gica]

Ok compression 120 across the 4 cyls.
Took the fuel pump off and the diaphragms are good. The check valves have the clear rings one showed a kink. The other one is flat. I could not see anything else wrong. When I squeeze the priming ball I get has on tye left bottom hose. The engine starts even revs high and then dies. For a second I thought it was staying when I hold the ignition key on and stopped when I let go.
Also while I was working on the pump the motor turned on by itself twice

 

[Jiggz]

"Also while I was working on the pump the motor turned on by itself twice"
REALLY?
"When I squeeze the priming ball I get has on tye left bottom hose." ???
Need a clarification on this one.

It is also possible that the check valve on the priming valve is stuck or bad. If you can use a different priming bulb and hose and better yet an external fuel tank to troubleshoot the better. Have you installed a clear fuel filter between the fuel pump outlet and the carbs inlet. This is a very helpful tool for fuel related problems. A simple G2 or G3 Fram fuel filter will do for less than $5. It gives you a visual if the fuel pump and or the priming bulb is actually working.

 

[Mudtim]

So we were at the bait dock and turned the motor off, when ready to go it would not start, pumped the prime ball and it started, revved it and it died pretty quick prime ball soft again. Repeated process same result. Can it be the pump? Thanks guys

Over Ana’s over you lost the prime? Have you checked for leaks? They are sometimes hiding. Leaking by gravity when you sleep. Swearing someone is stealing fuel! The fuel delivery on a two stroke doesn’t care about gravity. It needs constant PSI! I install a water/fuel filter before the engine filter to “Dry Up” the fuel and installed a fuel cut off valve for checking fuel loss.

 

[The Force power]

The check valves have the clear rings one showed a kink.

I think.....the problem is right here

 

[gica]

So this is my friend's boat I am just helping, and yesterday he did the compression check. Safe to say he did not ground the leads and there is no spark to all 4 plugs.
I found a video on Youtube that shows step by step testing to determine which component needs replacement. Let me know if you guys have any tips or know which is the most probabil culprit. Thanks.

 

[Jiggz]

Well start with the easy one first. Check the safety harness key that it is not activated. This a safety switch located by the driver that you wear in your hand that will shut off the motor in case the driver is thrown overboard. With this activated, there will be no spark on the motor.

 

[gica]

Yeah, that boat has the switch bypassed. The spark disappeared after the compression test without grounding. I don't suppose there is a fuse is there?

 

[Jiggz]

Do you know if the ignition system is CDM or one with switchbox? 1996 120HP transitioned from the switchbox to CDM ignition type. The CDM type uses individual CDM's so it's very unlikely all CDM were blown, not impossible but very unlikely. If it's a switchbox then you can assume the lack of spark is with the switchbox and related wiring up to the ignition switch. A bad ignition switch can be a problem with a switchbox as this type of ignition requires a electrical power from the battery to work during starting. Here's wiring diagram for the two types of ignition. As you can see with the CDM ignition type, it's very simple and straight forward. Initial electrical power needed for ignition is taken directly from the stator ignition windings. There are two windings in the stator, ignition and charging windings.

 

[gica]

Sorry for the typos I thought I fixed it.
It's an 125HP model
I don't have any books on the 125HP. I do have the 120s books 1992 and the Clymer manual that covers a bunch of models from 1984-1999. But the 125HP is not really explained.
So I managed to fix 1990 dual 120s issueswith the help of the great peopme here. Now I am faced with this.

 

[The Force power]

Sorry for the typos I thought I fixed it.
It's an 125HP model
I don't have any books on the 125HP. I do have the 120s books 1992 and the Clymer manual that covers a bunch of models from 1984-1999. But the 125HP is not really explained.
So I managed to fix 1990 dual 120s issueswith the help of the great peopme here. Now I am faced with this.

It is my understanding that the 120 & 125 HP are essentially the same, the different was the piston-seize & jets in the carbs. that made up for the extra 5 HP (same goes for the 85 & 90 HP)

 

[Jiggz]

Well even better, 125's of all years have basically the same wiring diagram using the Prestolite ignition system. Later models just like 89 and later may have a different wire colors but the wiring is still basically the same. Here's a 125 wiring diagram.

 

[Nordin]

The 125Hp did not have the CDM ignition system.
They had the Prestolite system.

 

[The Force power]

The 125Hp did not have the CDM ignition system.
They had the Prestolite system.

Including the 150 hp

 

[Jiggz]

The 125Hp did not have the CDM ignition system.
They had the Prestolite system.

The 125Hp did not have the CDM ignition system.
They had the Prestolite system.

I'm a little confused. Are you saying the wiring diagram I posted (#13) is not a Prestolite ignition system? Can you please elaborate?

 

[gica]

Oh yeah the book mentions the Prestolite also. I will have to do some testing, you guys think the coils are toast or what?

 

[Nordin]

#Jiggz, no I am saying that the diagram you posted i #10 is wrong but the one you posted in #13 is right.
If he will troubleshooting he has to use the diagram for the Prestolite system and I imagine he will figure it out then.
The head of this thread says 1996 120Hp Force Mercury and as it is a 125Hp you and I and others that give advise were a little deceived.
You, jerryjerry, topgun3690, The Force power and deceased Frank A are those with most experience of Chrysler and Force OB.

#gica, the ignition coils rarely fails more common with the stator, CDI boxes and trigger ring to fail.
Outboardignitiondotcom has the troubleshoot chart for your engine and ignition system.

 

[Jiggz]

Oh yeah the book mentions the Prestolite also. I will have to do some testing, you guys think the coils are toast or what?

Before going any further. Disconnect the white wire from the electrical terminal located on the port side of the engine. This is the shut down wire for the two CD boxes. Check for sparks again. But make sure you are ready to shut down the motor if it starts by touching the same white wire to the terminal board any ground. DO NOT TOUCH THE BARE WIRE PORTION OF THE WHITE WIRE, IT'S CHARGED. And cooling water is connected. If no spark still, check voltage on the stator between yellow and blue wires. Technically, you will need a voltage adapter (DVA) to read proper voltage output (180+ peak to peak). However, with regular VOM, you should still see AC voltage (rms) output. If no output voltage on stator, then stator needs to be replaced.

 

[The Force power]

#Jiggz, no I am saying that the diagram you posted i #10 is wrong but the one you posted in #13 is right.
If he will troubleshooting he has to use the diagram for the Prestolite system and I imagine he will figure it out then.
The head of this thread says 1996 120Hp Force Mercury and as it is a 125Hp you and I and others that give advise were a little deceived.
You, jerryjerry, topgun3690, The Force power and deceased Frank A are those with most experience of Chrysler and Force OB.

#gica, the ignition coils rarely fails more common with the stator, CDI boxes and trigger ring to fail.

Thank you Nordin, but you & everyone else mentioned know waaaay more than me about these.
I think that gica isn't sure what he has because;
The 125 HP was only made up till 1989 and the last "version" still had the prestolite ignition.
The 120 HP had the prestolite till '94 and forward the Merc. ignition in '96 the Fly-wheel was "upgraded"