3.7 170 hp mercruiser-Just quit and can't start.

[Golflover]

Hi all,

I have an 85' sea ray, with a 470 , 3.7Liter 170 hp 4 cylinder mercruiser. Last year was the overhall year. New: Starter, fuel pump, rebuilt carb, coil, points, wires, rotor, cap, plugs, battery. The short of it is it has never run better. This year was no exception.....until Monday. We drove about a have hour to our destination (30mph, not hard). Hung out at the beach 4 hours or so, 15 minutes of that with the radio on. Went to start it and got a sputtering noise from the starter or solenoid like a low battery or there wasn't enough juice to push the bendix. It's not the norm but it has happened a couple other times this year. However, if I wait ten minutes it seems to recover and fires up. This time was no exception. I fired it up and sat idling for about 5 minutes and watched the voltmeter top off between 13 and 14 as usual. Upon pulling the anchor and lowering the outdrive it stalled almost like a run out of gas stall. I tried again, it fired but quickly stalled again. I never got it running again. It cranks, but does not even give an indication it wants to start.

$100 tow bill and I sit with a dead boat.

Things I noticed trying to diagnose. My fuel pump is new but fo giggles II pulled the fuel line to the carb and cranked the motor and it does spurt fuel.

While I have not done a compression test, I pulled all the plugs and cranked the motor. No water and air blowing out of the hole.

The oil is clean with no water. The fuel is new.

The last few times taking the boat out I notice a black soot on my transom after a day out and wiping it down. It meant nothing to me until I tested for spark and it appeared to be weak (yellow/pink) Now it's my belief that perhaps the combustion might be incomplete causing this soot????

I have since replaced the condensor and points which resulted in no change. (they were new last season)

I'm kind of a dim wit when it comes to testing electrical or ignition components nor do I have the equipment. I want to do this myself so if anyone has experienced a sudden death of a well running boat perhaps you could provide me some insight. Perhaps there is a kill switch wire I am unaware of. Again, the boat is old but has been awesome.

Any help would be greatly appreciated. If you need more info let me know.

Kurt

 

[EddiePetty]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

Kinda hard to keep up when you have two posts going with some of the same questions and symptoms!!! And I do believe you are chasing a couple of problems here.
Anyway:
?........Went to start it and got a sputtering noise from the starter or solenoid like a low battery or there wasn't enough juice to push the bendix.?...

Good chance at a loose/dirty connection between the battery, through the helm, relays (solenoids) and starter, possibly a ?dragging? starter.

.......I wait ten minutes it seems to recover and fires up...........

Wet cell batteries in good condition DO recover to some degree, especially when all loads are removed from them and/or hot connections have been allowed to cool.

........fired it up and sat idling for about 5 minutes ......... lower(ed) the outdrive it stalled almost like a run out of gas stall. I tried again, it fired but quickly stalled again. I never got it running again. It cranks, but does not even give an indication it wants to start.

This sounds more fuel related, as in flooding. When it happens again, remove the flame arrestor and check the carb for the presence of liquid fuel either dripping from the ventrui, out the bowl vent or gasket surface or liquid fuel puddled in the intake below the carb.

.......I pulled the fuel line to the carb and cranked the motor and it does spurt fuel.

Disconnect the inlet fuel line at the pump. Jumper-in a temporary auxiliary fuel supply and check the pump for discharge.

.......I notice a black soot on my transom

Back to the flooding issue, though it could be a choke that is not opening all the way. [Which, in an extreme way could tie in all your problems as the choke, coil (and in a backwards manner the starter solenoid) all have a common voltage source]

 

[Golflover]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

Thank you for the kind and helpful reply and sorry about the double thread.

As an update, I have not been able to refire the motor. It coughed and sounded like it was going to fire after being in the garage over night but didn't. Is vapor lock a possibility or a defective float? If so, what are my options.

Regarding the single source of voltage for the starter solenoid, choke and coil, what should I look for as a source of the problem or solution. Poor ground?????

 

[EddiePetty]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

....... It coughed and sounded like it was going to fire after being in the garage over night but didn't.

Did ya' do the inspection for liquid fuel puddling in the carb?

Is vapor lock a possibility

Certainly but not very likely.

or a defective float?

Now you're gettin' warm!!! A for-real possibility, most likely maladjusted.

Regarding the single source of voltage for the starter solenoid, choke and coil, what should I look for as a source of the problem or solution. Poor ground?????

I can't remember the color codes just now and my manuals are out in the shop...we're in the middle of a frog-chokin' thunderstorm and the XO is hollerin' for me to get off the 'puter!!!
Trace the choke wire back to the (+) side of the coil, clean and tighten that connection, then trace the coil lead back to the solenoid and ignition switch...do the same cleaning and tightening.

 

[Golflover]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

We'll do. Thanks.

 

[Golflover]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

If I have the puddling, is that an indicator of a defective choke?

 

[nola mike]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

did you check for spark this time, or only last time out when you noticed the soot? no use chasing a fuel problem if you aren't getting spark...

 

[jgoeden]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

I just got over a problem like this.

I'm new to boating so if any of my info is wrong, the pros should correct me, but here's what I did.

Had very similiar symptoms that you did. Pull your plugs and notice if they are wet. If they are you have flooded badly. Turn over the engine a couple cranks with all the plugs out. NUMBER YOUR PLUGS WIRES and don't get them mixed up. Then loosely cover the engine so that you get airflow but you won't have anything falling into the cylinders while you are running to NAPA to buy new plugs.

I've also found that buying a Pertronix Ignitor II module and flamethower coil has saved me headaches from messing with those stupid, outdated points systems.

Anyways you need to pull the carb and check float adjustments and valve needle seats. Get any pooling fuel out of the intake manifold.

I've heard from multiple people that these 470/170 engines are prone to flooding.

 

[Golflover]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

Thank you JG. I did pull the plugs yesterday and indeed two of the four were wetter than the other two. Another piece of vital information I accidentally omitted is when the boat initially stalled I thought fuel pump. So I checked the sight tube while still on the water and it was filled with gas. Despite rebuilding the carb and installing a new float is this tell tale sticky float or needle seat?????

Thanks for all your help and input everyone.

 

[Golflover]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

Thanks for the input Nola. I didn't check for a spark until I returned home. Unless the strenghth of the spark is scewed by outdoor light it appears orange or weak. But I am getting some spark at the plugs and coil. Does it reason that the soot is the result of progressive flooding problem that eventually won out causing the stall and inability to start again???? Afteralll, while I didn't appear to have poor performance, I did notice the soot a couple times before this event. I blew it off as river slime.

 

[Golflover]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

JG. Is the Pertronix Ignitor II module and flamethower coil a difficult transition install? If this is a flooding issue it's my first, but I would not be bothered if it was my last.

 

[Golflover]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

JG, what is the best and easiest way to get pooling gas (if any) out of the intake?

 

[EddiePetty]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

...... I checked the sight tube while still on the water and it was filled with gas........is this tell tale sticky float or needle seat?????

...if you are speaking of the more-or-less transparent tube from the fuel pump to the carb:

NOT a sticking float or needle......It's a ruptured diaphragm in the fuel pump!!!! [routes leaking fuel to the carb in lieu of the bilge: floods the engine with fuel so's you'll stop and fix the problem !!]

 

[Golflover]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

Eddie, Yes that is the tube I speak of which is why I initially thought is was the fuel pump despite it being new last year. Based on the info I provided you, you believe this is the only thing it could be??? Is the diaphragm replaceable or do I need a new pump? What about the wet plugs, replace them?

Last question: How does a newer diaphram rupture??????

Thanks kurt

 

[badkins50]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

your first post sounds like my outing about a month ago. come to find out it was my fuel pump was shot. I replaced it, and started it and it would just turm over but not start and boy oh boy did it dump fuel down into the intake after cranking. I had learned that there was about a 1/4" thick washer plate that needed to be reinstalled with the fuel pump that I had forgot. I placed it back in there and now it runs great. I did reset my float too. That was my first concern that the float was stuck, so I checked it. A float will cause the flooding as well.

 

[EddiePetty]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

....Yes that is the tube I speak of .....

Well, that's it's sole function in life...to detect a leaking fuel pump diaphragm.

....you believe this is the only thing it could be???

May not be the only problem but just became prime suspect #1 !!

....Is the diaphragm replaceable or do I need a new pump?

Sure it is but not worth the effort. Just procure a replacement MARINE pump. (is you present year-old pump under warranty?)

....What about the wet plugs, replace them?

If they are newish plugs, just dry them out: if older plugs, replace them.

....Last question: How does a newer diaphram rupture??????

Mis-matched internals at assembly, wrong material for ethonol based fuels, etc. . Don't waste your time trying to CSI this thing...replace the pump and see how many of your problems disappear.

 

[jgoeden]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

JG. Is the Pertronix Ignitor II module and flamethower coil a difficult transition install? If this is a flooding issue it's my first, but I would not be bothered if it was my last.

It is definitely NOT difficult to install if you have a little mechanical incline. Before I installed mine I didn't know a thing about distributers, points, timing, coils, blah blah blah. Doing some research and dad showed me how to mess with points, I found out about the Pertronix and said "screw that points crap".

Install consists of this (basically): remove distributer cap, remove piece inside that's on the metal plate (the term is escaping me), screw on ignitor module on metal plate, slide on round magnet, gap it, wire the wires to coil, reinstall dist. cap, run wire from ignition to + side of coil, and bam, you're good. You'll need a timing light to make sure you timing is spot on.

It's really easier than it sounds if you have any mechanical ability.

JG, what is the best and easiest way to get pooling gas (if any) out of the intake?

Kinda funny actually. I had a 10mL syringe in the house that I had leftover from irrigating my wisdom teeth removal a few months ago. Removed coil and used that the best I could. Then for the hard to reach places, like towards the #1 and #4 cylinders, I cut a piece of 16g electrical wire about 3 inches, removed the copper wire inside, and used the insulation like a straw attached on the end of the syringe. Yeah it was ghetto. But yeah, I got all the gas out!

Good luck, I'm still new at all this but it sounds like we're nearly in the same boat. I'm sure my float needs adjusting too, but she seems to be running decent. Not perfect but way better, and no flooding yet, knock on wood.

 

[Golflover]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

Eddie,

Thank you. That is the answer I wanted to hear regarding the presence of gas in the sight tube. It eliminates my guess work of other potential problems. Like I said it was running better than ever before this event.

I'm trying to get an answer on the warranty from the manufaturer now. It's less than a year and I would hope a warranty would be honored.

I'll post back after the reinstall. Thanks for all your wisdom and insight.

Kurt

 

[Golflover]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

JG,

Thanks for your help. I was able to confirm through Eddie Petty on this site that the gas in the sight tube from the carb to the fuel pump is directly a result of a ruptured diaphram in the fuel pump. While the pump is less then a year old I am going to replace it and see where I am before installing the Petronix. Your help has been very insightful. I will let you know as soon as I install the new pump if that is in fact my solution which I suspect it is.

Thanks again,

Kurt

 

[jgoeden]

Re: 3.7 170 hp mercruiser-Just quit and can't start.

Hey if that's the problem, then awesome! Glad you got it figured out. I'm sure there's a lake wiht your name on it yelling for you!!!