1998 Mariner Mag EFI 150 - Runs Rough then Dies

[4winnsskipper]

Here's the story. Was out the time before last, and on my way back to the dock, the motor dies instantly, then 2 seconds later keeps running like nothing happened. I just thought, that was weird, then motored back another 10 minutes to dock. As i reach idle getting near the dock i thought the motor sounded like it was running a little rough but didn't think anything of it...WELL...

the next time i go to take it out, it starts like normal and sounds a little rough again, but still i don't think anything of it (hind sight 20/20). As i go in reverse to back away from pier, it sputters, put it in forward start to go away from pier it sputters even more, then dies... then i try to restart, it starts right away then immediately sputters then dies. restart, same result. i immediately call it a day and count my blessings it happened within arm's reach of the dock...

So here's what i've done, i went home and put all new spark plugs in, all new merc spark plug wires (found two bent clips inside the old boots), new merc fuel filter, new fuel line from splash well barb fitting to engine including new merc bulb with flow going the correct way.

Any ideas on what to check next? My dad came over and and checked spark and said all cylinders had spark, although one he had a hard time telling but got zapped and goes yep it's got spark! Also ran compression test just for kicks and all cylinders were between 122 and 126 psi on cold engine.

Also, below is video of the motor trying to run on muff's, and i've included a picture of something i found odd, and thats a "T" fitting with no hose on the 3rd side of the T. I do not see any hoses just laying around, but seems odd that there is no hose there. Is this right?

http://www.youtube.com/watch?v=4dk8T0wdPII

Thanks in advance

 

[Faztbullet]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

You need to check/test the following: 1) Fuel sample for water 2) Fuel pressure on fuel rail 3) Is fuel pump still running when it dies? 4) ZHave you drained the VST tank and does it refill when bulb is pumped?

 

[4winnsskipper]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

You need to check/test the following: 1) Fuel sample for water 2) Fuel pressure on fuel rail 3) Is fuel pump still running when it dies? 4) ZHave you drained the VST tank and does it refill when bulb is pumped?

With the water in fuel im sure i'd just use the primer bulb to pump water into a container then "test it" but how do i test gas for the concentration of water?

fuel pressure - where do i test for that and what type of guage is needed?

how do i tell the FP is still running when it dies?

and what is the VST Tank?

Thanks for the response and apologize for my lack of knowledge on this one, the help is very much appreciated

 

[Faztbullet]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

With the water in fuel im sure i'd just use the primer bulb to pump water into a container then "test it" but how do i test gas for the concentration of water?

Water will seperate and settle to the bottom ,like oil and vinegar salad dressing..

fuel pressure - where do i test for that and what type of guage is needed?

You need a fuel pressure tester (auto stores) that go's to 45 psi and it it tested at schrader(tire looking fitting) above fuel pump.....

how do i tell the FP is still running when it dies?

You will hear it running on port side of engine, you should hear it come on and run and quit if key is turned to ON

and what is the VST Tank?

Vapor seperator tank on port side of engine, this is where electric fuel pump is mounted mounted.....

 

[jerryjerry05]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

That fitting is supposed to look like that.You need to list the serial#.
Do a better spark check.Just yelling YOU HAVE SPARK doesn't show the true results.VERY funny but not the best.
The electric pump should make a noise when you turn the key.Take off the cowl and listen when someone turns the key on.The electric pump is in the vapor /sep tank on the other side of the motor.The tester is needed to check the fuel pump pressure.
Remove the mechanical fuel pump and take it apart.Look at the diaphram and the check valves.Any tears or bent checks can lead to these problems.
You have a water/fuel filter on the motor.Drain it into a clear container.The water/gas will seperate after a few moments.
SAS-TOOLS About $25 Fuel pump tester.See pic. Post your results.J

 

[4winnsskipper]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

That fitting is supposed to look like that.You need to list the serial#.
Do a better spark check.Just yelling YOU HAVE SPARK doesn't show the true results.VERY funny but not the best.
The electric pump should make a noise when you turn the key.Take off the cowl and listen when someone turns the key on.The electric pump is in the vapor /sep tank on the other side of the motor.The tester is needed to check the fuel pump pressure.
Remove the mechanical fuel pump and take it apart.Look at the diaphram and the check valves.Any tears or bent checks can lead to these problems.
You have a water/fuel filter on the motor.Drain it into a clear container.The water/gas will seperate after a few moments.
SAS-TOOLS About $25 Fuel pump tester.See pic. Post your results.J

http://www.youtube.com/watch?v=X9XlKEtGFxI

another video. is the alarm suppose to beep that many times before start? my dad's 40 merc just beeps once, so im not sure the ECU is trying to tell me there's a trouble code. thanks guys

 

[Faztbullet]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

The self test heard on video is fine and the ECU has no warning signals. For video it acted like it ran out of fuel, test the fuel pump...

 

[4winnsskipper]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

The self test heard on video is fine and the ECU has no warning signals. For video it acted like it ran out of fuel, test the fuel pump...

Here's some test results

1) Fuel In water Test - I used the fuel primer bulb to pump approximately 20 oz's of gas into a clear container. Let it sit for up to 5 minutes, didn't see any water in gas. Just to make sure, i then added about 5 oz's of water to gas, i saw it immediately sink to bottom and create a water line, which i did not see before adding gas. So i beleive there isn't any measureable water in gas

2) Spark Test - I bought a 6 dollar spark tester at autozone, nifty little tool. I ran spark test on all cylinders and results are in picture. Two plugs weren't getting as much sparking power as the rest of the 4 were. This is noted in the pix. Note the measurements were what the tool had on it so not sure what 10-40 means. I also pictured the tool (OEM tool) so you can see what kind of gap there was that jumped

3) Fuel Pump Test - I pulled boat out of garage, had the better half turn the key to the ON position, and i hear the fuel pump run for about what seemed like 20 seconds then turn off. We then turned key off and started motor, ran like the last video, like poo poo then died. When it did i did NOT hear the fuel pump running. So either it turned off IMMEDIATELY when the motor died, or it wasn't running at all. So we tried this again, motor was hard to start, ran for like 3 seconds and again after it died i did not hear the fuel pump on. So we then tried to try key on motor off test, we heard nothing again. We then conducted spark test. After test was completed we started motor again and it ran for 30 seconds like poo poo then died, again immediately after it died i did not hear the FP on but THINK i heard it turn off the same instance the motor died. Hard to tell.


So in the picture what is the vapor tank i should be checking next?

 

[Faztbullet]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

The fuel pump circled in 2nd picture is the mechanical one, the electric is in the VST tank. Disconnect blk/red wire from electric pump and install a jumper wire from post to a good ground, pump should run. Start engine and see if it dies, if it doesnt the ECU driver has a problem. Disconnect jumper when thru (see picture)

 

[4winnsskipper]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

The fuel pump circled in 2nd picture is the mechanical one, the electric is in the VST tank. Disconnect blk/red wire from electric pump and install a jumper wire from post to a good ground, pump should run. Start engine and see if it dies, if it doesn't the ECU driver has a problem. Disconnect jumper when thru (see picture)

Faztbullet - I did this, and the motor ran much better for about 60 seconds, then started to stumble and then it died. The fuel pump was still running after it died. So i removed the jumper and put the stock wire back on.

So i then drained the VST tank, i first stuffed lots of paper towel underneath the drain screw and opened the screw. Fuel drained out. (smelt kinda odd though like mostly gas but with a odd odor to it) I let it finish draining then without putting the screw in i squeezed the primer bulb on fuel line and as i squeezed line more gas would spill right out simultaneously. So after it stopped leaking again i put the screw back in using the german torque spec of good-n-tight without straining since i saw there was a small rubber seal around the screw head i didn't want to over-torque and rip it. I then squeezed the primer bulb till it was firm. I went to start the motor and insto presto it fired right to life like nothing was wrong, and sat there and idled like nothing was ever wrong!

So what's the deal? What did unscrewing the screw and draining the VST tank do???

Also maybe its just because i haven't heard the motor run but it seems to idle kinda high. Or am i just loosing at this point? I know the tach said ~900 rpms but when the tach "zero's with the ignition on it doesn't go all the way to zero, rather right near the first line on the tach or the 200 mark so im not sure this tach is spot on anyway...so i've attached a video to see if you think it's idling high by sound ( i know this isn't best but will give you guys an idea)


anyway, HUGE thanks Faztbullet!! So far it seems to be like new again, i let it idle on the muffs for ~10 minutes and it just sat and idled perfect like a rock, not even a studder.

But as stated, what did unscrewing this drain screw do to fix the situation? why did these symptoms come on so fast? I was driving boat back to dock, motor dies immediately, then keeps running like nothing happened for another 10 minutes. Next trip the motor runs like complete crap.

VIDEO http://www.youtube.com/watch?v=aX723-ZexrA

THANKS!!!

 

[Faztbullet]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

what did unscrewing this drain screw do to fix the situation

It drained possible water or phase seperated fuel from system(odd odor). Check your water seperator on engine to see if sensor wire is hooked to the bottom(they fall off) and dump it. As for Utube video RPM is correct as engine will idle higher on the hose than in water due to lack of backpressure...

 

[jeffersondodson561]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

Is their a small box with red light under the ECU on this motor? If it is lit that means that the water detections circuit is active. This wire is the one that attaches to the fuel filter on the engine. The one on the other side of the VST.

 

[Faztbullet]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

If it is lit that means that the water detections circuit is active.

Light should be off as light only comes on if probe in filter senses water and then it triggers alarm horn thru the warning module.

 

[4winnsskipper]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

Light should be off as light only comes on if probe in filter senses water and then it triggers alarm horn thru the warning module.

Yes there is a box with a light in it but i never saw it on nor was there any alarms going. The alarms seem to work just fine too everytime i start motor i hear the self test alarm sound so i dont think it set off anything from the fuel filter. Also when i put a new fuel filter in, the merc filter came with what appears to be a new sensor i screwed into the bottom of the filter and reconnected wire so were good to go there.

Is there anything else i should check or check while its on land i should say? Last night's trial showed nothing but positive signs but it's going to take awhile to gain the trust of this motor since all i did was drain the VST tank instead of finding a broken fuel pump or something else. I Know that sounds weird but in a way im happy that unscrewing a screw and screwing it back in seems to have fixed it but im still wondering what lead to this, is there some other preventive maintenance i should do on the VST tank or lines to prevent this situation from happening again? Is this a sign something else is broke? Or could this just been a build up over the years that just needed to be drained? I dont think our 90% gas and 10% ethanol crap gas we have in our area is helping anything...

Thanks again Faztbullet, i'd buy you a beer if i could!!!

 

[jeffersondodson561]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

You might want to pick up some Ringfree or some Quick Clean and run the shock treatment.

 

[4winnsskipper]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

You might want to pick up some Ringfree or some Quick Clean and run the shock treatment.

I've never been solutions in a can guy but why do you recomend a fuel additive? I try to run stabil that is made for gas with ethanol during the cold winter months and while it's stored. Don't get me wrong im not ripping on you im just curious as to why you think it's a good idea. And are you speaking of the yamaha ringfree product?

Thanks,

Robert

 

[Faztbullet]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

I recommend you run the Quickleen every 3rd tank as it keeps fuel system and internal engine parts clean. It also reduces carbon build up and perfer it over Seafoam.

 

[jeffersondodson561]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

I am thinking that the wierd odor and color of the gas that came out of the VST was old stale gas build up on the bottom of the VST. This is no way a solution but their have been times where a customer was not able to afford a carb overhaul and I have used my T valve and ran Powertune into the fuel system to the point where the carb opened up. This was a two stroke, no way this would work on todays 4 stroke carbs. Is this the proper way to do this? Absolutely not but when your boss is an ecentric ex racer, you do what your told and notice the results.

 

[4winnsskipper]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

I am thinking that the wierd odor and color of the gas that came out of the VST was old stale gas build up on the bottom of the VST. This is no way a solution but their have been times where a customer was not able to afford a carb overhaul and I have used my T valve and ran Powertune into the fuel system to the point where the carb opened up. This was a two stroke, no way this would work on todays 4 stroke carbs. Is this the proper way to do this? Absolutely not but when your boss is an ecentric ex racer, you do what your told and notice the results.

what are you saying about my situation? that what i did didn't fix the problem? if so where else do i look?

 

[4winnsskipper]

Re: 1998 Mariner Mag EFI 150 - Runs Rough then Dies

UPDATE: Bad update unfortunately. So when i got home from work todayt i figure i'd toss some quicksilver quickcleen in the tank according to instructions. Motor started almost right away and i was pumped. Well two minutes later it started stumbling again and it died. Tried to restart, stumble, die. So then i drained the VST again, pumped primer bulb once with screw out, fuel spits out again. Tighten screw, restart motor like a champ. Let it idle ~10 minutes. Idles just fine, again. Then i turn motor off, key to off. Then i go to restart immediately and i hear no sounds from the motor, and motor wont crank or even try, It's like there's no battery in boat!! However all my lights, bilge, livewells work just fine. I check connection on battery, all terminals tight. I then try to tilt motor, nothing, no response!!!

So im like what the heck, recheck battery terminals see nothing wrong. Try key again, and alarm tests works again, motor tries to start, runs for a few seconds then dies again, and tilt wont work again. Still all lights/livewells/bilge works

So now im wondering if a faulty battery and/or connections could be causing my issues????? I mean battery connections "seems" fine, nothing corroded or loose....

Thoughts???