3.7L Merc cranks but will not start - Please Help!!!!

[NoGin]

Hey guys. I have some questions with my 3.7L in line 4 twin mercs. My starboard engine runs great however I can't get the port engine to turn over. It cranks strong but will not turn over.

1) Do all the gauges need to be hooked up properly for the engine to run? I ask because I ran new electric with all new gauges and perhaps I didn't hook up the gauges correctly.

2) Can the kill switch under the shift cables prevent the engine to run if it's slightly off?

3) Can the shift cable adjustment prevent the engine from running?

 

[Bt Doctur]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

1: maybe
2: yes
3:yes
Is there power at the + side of the coil with the key "on"?
are the points working correctly(.018-.022 gap, opening and closing)?
remove all the wires on the + side and the grey wire on the neg. side and run a jumper from the battery to the coil and try starting
Post the results

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

Thanks BT. I will be back on the boat in a little while trying the above along with some cable adjustments. I spoke with the previous owner who was the only owner for 22 years and a boat mechanic. He is reluctant to come over and help as he is "retired" from boating. However, he did tell me that the boat ran great just a few months ago before I bought it with the exception of the port shift cable needing an adjustment.

I will first try to remove the shift cables this morning and re-adjust them and see if that helps. After much research I found that the roller ball on the kill switch is supposed to remain stationary when shifting from F-N-R. That is the case on my starboard engine but with this port engine the roller ball actually moves up out of the notch in forward and down out of the notch in reverse.

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

This post is getting some nice traffic but not much help. This is my first boat and I don't exactly have a ton of extra $$ to bring a mechanic to my boat so I am hoping to find someone knowledgeable in my application here that can help me through this.

If you are familiar with the 3.7L in line 4 merc and can help please PM or respond here.

My port motor cranks but will not turn over. No spark. I replaced the fuel pump, filters and lines.

Thanks for looking and helping!

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

I tested and do have spark. I got the engine to turn over but she died after about 10 seconds (at most). then she wouldn't turn over again. Kept cranking, but no turn over.

 

[Don S]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

I got the engine to turn over but she died after about 10 seconds (at most).

What did you do to get it to do that?

Sounds a lot like a fuel delivery problem. Do you have a water seperating fuel filter? Have you checked it to see if it's full of water. Is the carb pumping water out the accelerator pump or is it pumping gas? Or is it pumping at all?
What is the fuel pump pressure?

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

Thanks for the reply!

* Replaced the fuel/water filter.
* Cleaned the carb fuel filter.
* Replaced the fuel pump.
* Replaced the clear/yellow fuel line.

I now have excellent fuel pressure into the carb. When I give it some gas a stream of fuel shoots into both sides of the carb (yes, fuel. no water from what I can tell). I got the engine to crank and start only after trying like 5 times for about 5 seconds each time.

 

[Don S]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

Make a jumper wire and go from the + terminal on the battery to the + terminal on the coil and see if it will run.

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

Please forgive my ignorance but where is the coil?

 

[Don S]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

Go up to the Adults Only sticky and download a service manual for your engine. #8 should cover it.

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

Thanks Don. I got it. Will try in the am and post results.

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

So this morning I ran the jumper wire from the battery positive to the coil positive. As soon as I touched the wire to the battery the motor cranked and blew a big puff of blue smoke out of the top of the carb. This scared the **** out of me! I tried it again (scared me again) same result. Took a minute to clean my shorts and tried it again. The coil was clicking but the motor would not crank.

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

Any idea what the click from the coil but not engaging the starter means?

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

You have me confused. First, you crank the engine with the starter, it may or may not start. You say you attached the jumper and the engine cranked... Please clarify.

Next, coils don't click at all, are you certain that is where the sound is coming from? If so, I would say the coil is bad. You *could* get a clicking sound from an internal voltage leak from the secondary (high voltage) winding I suppose. If so, its bad.

I was having a problem starting the engine. It cranked but did not turn over. Don S recommended running a jumper from the coil to battery and see what happens. It tried to start the first 2 times but after that it wouldn't even try to start. All I heard was a click when I touched the jumper to the battery.

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

I just ran my test light to check continuity with the slave solenoid as per Dons posting in the Adult section. Turns out my test light isn't working. However, for S&Gs I tried to start it with the key and it started right up! Ran nice but when I ooked out the back I noticed water and anti freeze spraying out of the side ports of the drive unit that attaches to the transom. Hose??

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

I have pin pointed the anti freeze coming from the lower gimbal housing vents which are located just above the zinks. I guess I have to take apart the bell housing to replace a cracked hose or tighten a loose clamp.

...............................................................................................
Any professional opinions about this?

> My motor cranks but does not turn over for 3 days

> then when I run the jumper cable from the battery to the coil I get 2 big puffs of bluish gray smoke from the carb

> then on first try starting from the key after carb smoke it starts up and runs smooth!

> anti freeze leak from inside gimbal housing going out of the boat

? ? ? ? ?

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

Self night bump for help!

 

[Don S]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

I was having a problem starting the engine. It cranked but did not turn over. Don S recommended running a jumper from the coil to battery and see what happens. It tried to start the first 2 times but after that it wouldn't even try to start. All I heard was a click when I touched the jumper to the battery.

Your wiring is all screwed up. If you touched the coil + terminal with a jumper from the battery + terminal and the starter cranked the engine. You have a big problem.
Did you hook it to the coil or the starter solenoid? Do you know the difference? Not trying to be an azz, but what you discribe, can't happen.

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

I attached the jumper wire from the coil (with a red, and believe purple wire on it, to the positive on the battery and the motor tried to start the first 2 times and then just made it click.

 

[NoGin]

Re: 3.7L Merc cranks but will not start - Please Help!!!!

I will be back working on the boat today.

I will be removing the stern drive to access the water hose to see what's going on there. I will also replace the shift cable as the shaft roller shaft switch moves off center in reverse and forward. I hope that once I get all this correct and re-assembled the motor will start right up and run fine.

I am still perplexed as to why the motor would try to fire up the first 2 times I ran the jumper wire from the + Batt to the + Coil? Then when touching it a 3rd time have nothing then the boat starting and running fine from the ignition key ? ? ?