Engine die: Kill switch ?

Hello,
After about 2 years I bought my boat, on Saturday I finally went to the lake for a test as I replace the engine.
All seems perfect at the beginning, I left the dock slowly and all works fine but when I increase the throttle the engine suddenly die. I tried to turn it on again and it starded fine, tired again to increase the throttle and it suddenly die again.
I back to the dock in idle with no problems.
If I increase the throttle with neutral gear it works fine. I left the engine running in neutral idle for about 20 mins with no problems.

Please note that the way it die is not slowly like out of fuel but suddenly.

Unfortunately because of another issue I had with the shift lever I started playing with it's adjustment moving it but the day after I realized that the kill switch could be the problem !

I back to my boat and I start playing with that adjustment and I found out that my theory could be true as I noticed that with a wrong adjustment the switch is pushed when in forward or backward.
Do you agree with me that kill switch could be a suspect ?

Given my English is not very good, is there someone capable to explain me step by step with easy words how to adjust the shift lever ?

Thank you in advance !
:joyous:

Re: Engine die: Kill switch ?

Can you tell us what engine, year and the model outdrive you have and we can help you figure this out.

Re: Engine die: Kill switch ?

Eric 3.7LX Alpha 1 said:

Can you tell us what engine, year and the model outdrive you have and we can help you figure this out.

Click to expand...

Hello Eric,
MERCRUISER W/ PS 5.7L ALPHA
The outdrive is Alpha One.

Thank you !

Re: Engine die: Kill switch ?

The kill switch "cutoff switch" should only engage when shifting back into neutral and only in the water, not on the trailer. The fact that it is killing the engine means it is working correctly.

There is most likely another issue causing it to engage, either a bad lower shift cable or adjustment.
How old is the lower shift cable?

Here is an explanation on how it works:
http://forums.iboats.com/mercruiser...nterrupt-system-works-288089.html#post1930449

Re: Engine die: Kill switch ?

All seems perfect at the beginning, I left the dock slowly and all works fine but when I increase the throttle the engine suddenly die.

Click to expand...

I think messing with the shift switch is not going to help your problem. From the way I am reading it, you can put it in gear ok and idle away with no problem, it's only when you give it throttle to speed up that the engine dies, is this correct? If it was dieing when you put it into gear, then I would expect the shift cable as being the problem.

Do you have a year or better yet a serial number for your engine/drive? They aren't all the same.

Re: Engine die: Kill switch ?

Don S said:

From the way I am reading it, you can put it in gear ok and idle away with no problem

Click to expand...

Well, not really, back to the dock I was not able to go in neutral. I didn't mention that as I was unsure if it was related to the switch not killing at the right time or the other issue I had with the shift (I created another topic for that)

Don S said:

Do you have a year or better yet a serial number for your engine/drive? They aren't all the same.

Click to expand...

This is the serial in my documents: OC602940
Please note that the long block have been replaced this year.

Re: Engine die: Kill switch ?

Eric 3.7LX Alpha 1 said:

The kill switch "cutoff switch" should only engage when shifting back into neutral and only in the water, not on the trailer. The fact that it is killing the engine means it is working correctly.

There is most likely another issue causing it to engage, either a bad lower shift cable or adjustment.
How old is the lower shift cable?

Here is an explanation on how it works:
http://forums.iboats.com/mercruiser...nterrupt-system-works-288089.html#post1930449

Click to expand...

Thanks Eric, I read that link carefully (I think so) on Sunday. It's well explaining what the system is for and how it is supposed to work. I suspect that my issue is linked to the fact that mine is not adjusted well so it is not doing what it's supposed to do.
In fact I did a real life test, I messed the adjustment (I am unsure about how it was set at the time of the issue) I move the throttle and the kill switch was engaged when in forward gear, this matches the issue I faced and it's the reason why I suspect that's the cause.
The lower shift cable is probably very old, I don't know exactly as I just bought this boat 2 years ago.

Re: Engine die: Kill switch ?

We had this exact same problem. Ours would kill past 1/2 throttle or so.
It took us 3 trips to the lake to figure it out. (we thought carb issue at first)

Your shift cables are out of adjustment as many here are already suspecting.

We watched this video serveral time to understand how to correctly adjust it. As the shifting components age, keep in mind, a "perfect" adjustment may not be possible without replacing the shift level/cables.

Re: Engine die: Kill switch ?

Thanks TheHunter990 ! As reccomended I'll check il my cable is into tollerance, I'll try to make the adjustment and I'll feed you all back with the results.

Re: Engine die: Kill switch ?

Hi guys, I'm back with an update after another live test, my theory about the kill switch was wrong.

The kill switch is set well but I still face engine die when increasing throttle. At idle and low throttle it run PERFECTLY but when I increase throttle the engine miss and tend to die, if you are quick enough to remove a little bit of throttle it keeps alive.
I play with the throttle quite a lot and managed to keep it live at about 2.500 rpm or so but it do not run fine at that rpms, it looks like it miss fuel.

To provide the full picture I have to say that I have the electic fuel pump which is not the original, this is the pump I have:
Kraftstoffpumpen.com : HARDI Kraftstoffpumpe Marine 18812V

It say it can provide 100 liters per hour (should be 26.4 gallons) and pressure is 0,35 bar but just noticed in the previous page of their website they also state that this pump is for 100 hp engines while mine should be a 260 hp.
Fuel filter is pretty new, I also did a test skipping it with exactly the same result.
While the engine is new (I bought the long block) the carburetor has never been rebuilt and it's my old one.

I don't want to make the same mistake as the previous time when I was convinced I understood the issue to be the kill swirch this time, so I am asking you all, what do you think could be the cause of my issue ?
Fuel pump ? Carburetor ? Other ?

Thank you !!!

Re: Engine die: Kill switch ?

Sounds like the accelerator pump inside the carb is not performing. It provides a shot of fuel as the throttle lever is moved, if it does not work right then the engine will stumble and die unless the throttle is moved very slowly. It can be a linkage issue or internal diaphragm issue or clogged nozzles. Time for a carb check-up.

Re: Engine die: Kill switch ?

Hi Maclin, thanks !
The accelerator pump "seems" to be working, I checked this with the engine off and when I pump the throttle I can see good streams of fuel spraying from the carburetor (BTW, it also happens moving the throttle very slowly). But yes, you are right, it's probably time for a carburetor check-up.

Re: Engine die: Kill switch ?

Put a fuel pressure gauge inline just before the carb. If the pressure falls flat on it's face just as the engine dies you know it's a fuel delivery issue

Re: Engine die: Kill switch ?

The accel pump shots sounds good then.

When was the last tuneup where dwell and timing was in spec with new plugs, cap, rotor? If the timing is not correct it can act as you described. Incorrectly gapped spark plugs can also contribute to this.

Also the idle mixture on the carb could be too lean, the idle circuit is active until 1500 rpm or so, if too lean then even with a good pump shot it can stumble.

Re: Engine die: Kill switch ?

TheHunter990 said:

Put a fuel pressure gauge inline just before the carb. If the pressure falls flat on it's face just as the engine dies you know it's a fuel delivery issue

Click to expand...

Ok, I bought a fuel pressure gauge and this weekend I'll install it. I also bought an used Mercruiser electric pump as I found it very cheap.
The plan now is to install the fuel pressure gauge and the 'new' fuel pump, then to go out for a test trip, if the issue still occurs I'll have the carb checked.

Re: Engine die: Kill switch ?

Do you currently run an electric fuel pump or mechanical?

Re: Engine die: Kill switch ?

Eric 3.7LX Alpha 1 said:

Do you currently run an electric fuel pump or mechanical?

Click to expand...

Electric.
When I had to replace my block broken by ice the new I received had the mechanical fuel pump hole closed so I had to go with an electric fuel pump. The fuel pump I used was not original, you can see it in a link a few post above, now I bought the original one used and I should receive it between today and tomorrow.
The new one I bought is like this:


As the one I used was not original I thought it could easily be the root cause of the issue I have.

Re: Engine die: Kill switch ?

Maclin said:

When was the last tuneup where dwell and timing was in spec with new plugs, cap, rotor? If the timing is not correct it can act as you described. Incorrectly gapped spark plugs can also contribute to this.

Also the idle mixture on the carb could be too lean, the idle circuit is active until 1500 rpm or so, if too lean then even with a good pump shot it can stumble.

Click to expand...

Hi Maclin, I do not know the meaning of dwell, my English is probably not good enough
Rotor is the distributor ?
The engine is a pretty new long block, I just assembled it with my old carb, alternator (bought new), starter (bought new),...
Plugs are new as well.
Timing has been checked with the laser gun in front of me but then another mechanic touched my engine and I think he touched the distributor without using the timing laser gun. This happened prior my first test.
Carburetor has never been check-up since I bought this boat 2 years ago.