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Old 04-09-2013, 09:26   #1
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What next Merc 5hp

This motor got me beat. Its an old Merc 2 stroke 5 hp motor what could be simpler. Hard starting is the issue.

What I have done to date:
Disassembled the carb and fully cleaned it its very clean.
Installed a new fuel pump kit.
Cleaned all of the fuel lines including the tank.
Discarded the old fuel and made a fresh tank up added Seafoam.

It started and ran good.
Next day would not start. I sprayed quickstart fluid (either) into the carb still would not start. I thought spark was a possible issue.

Came back the next day with my multi meter checked the continuity from the HV wire to coil. Measured 6.8k ohms I am told between 3 and 15 is acceptable.
Installed a new spark plug it has spark.

It started ran it for 5 minutes warming it up and running through idle to full revs adjusted fuel mix, left it idling. Came back it stopped and would not start, even after spraying quickstart in the carb.

What next besides attacking it with my framing hammer

Ideas would be appreciated.

Jack
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Old 04-09-2013, 09:52   #2
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Re: What next Merc 5hp

We have an old Suzuki 2-stroke 5hp that almost always starts after 2 pulls, so I can only speculate...

If the moving metal bits are all Ok, then the engine only needs air, oily gas and a spark....

  1. Is there air? Does it have oxygen in it? moving on...
  2. Can you confirm gas is reaching the cylinder?
  3. Is the plug Ok, and gapped Ok? with the plug out, plug wire connected, plug body against engine, can you see a healthy spark at the plug when you pull the engine over?
Other ideas... compression ok?


The few times our outboard is balky is when we've had it tipped up for a while, and we tip it back and immediately try starting it. Sometimes it just won't catch, so we just give the bulb a squeeze and keep trying. It finally goes. Or we leave it down and wait 10 min, and it then starts quickly....

Good luck.
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Old 04-09-2013, 10:04   #3
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I had fits with our mariner 5hp 2stroke for a while. Turns out the float needle was getting bound and flooding the engine.
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Old 04-09-2013, 10:19   #4
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Re: What next Merc 5hp

You have not eliminated a loss of ignition. After the engine has died, check for a spark.
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Old 04-09-2013, 23:41   #5
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Re: What next Merc 5hp

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Originally Posted by MarkSF View Post
You have not eliminated a loss of ignition. After the engine has died, check for a spark.
Will do.
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Old 04-09-2013, 23:44   #6
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Re: What next Merc 5hp

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Originally Posted by Sailmonkey View Post
I had fits with our mariner 5hp 2stroke for a while. Turns out the float needle was getting bound and flooding the engine.
The reason I was leaning towards ignition was that the engine will not fire when I spray quickstart into the carb. I will check the float needle thanks.

Jack
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Old 23-09-2013, 01:19   #7
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Re: What next Merc 5hp

fuel pump diaphram may have split in it also had a 5 hp merc had lots of issues with it,tank comes off easy for flushing if needed only takes a tiny speck of dirt in fuel to kill small motors.Also quickstart scours your bore I wouldnt use it.
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Old 23-09-2013, 12:07   #8
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Re: What next Merc 5hp

Sounds to me like it is still a fuel issue. Many older 2 strokes will not start on straight ether (quick-start) if they are not getting some gas.

I would expect that if you pull the fuel line off the carb and hit the primer bulb, you will get fuel coming out. Likewise, after priming, if you pull the starting cord once or twice, you are getting squirts of gas from the fuel pump.

If you pull the plug on the bottom of the carb float bowl, you should get a couple tablespoons or so of clean fuel running out. If so, that leaves two suspects. Carb, and stuck reed valve. Reed valve is unlikely since you had it running once with new plugs.

That leaves the carb. I would expect your cleaning was with a spray can of carb cleaner, and inadequate to clean the interior passages. Carb should be disassembled and all non metalic parts removed. Remove the high speed and pilot jets as well and soak all the metal parts in a covered container of carb cleaner for 24 hrs. Blow through every passage you can see with compressed air as well as the jets. Reassemble carb and try it again.

Just went through the "carb is clean" and won't start with ether problem with an 88 Suzuki 6hp. Cleaning carb as above resolved the issue.

Luck
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Old 23-09-2013, 13:01   #9
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Re: What next Merc 5hp

My first outboard was given to me, it was an old Sears 7HP. I did manage to get it to run so with great expectations, I loaded it onto my sailboat (at that time) and got ready to do away with rowing my old Eli 8' fiberglass dinghy.

We next visited Cuttyhunk, installed the engine and pulled, and pulled and I am sure you know the routine. I did everything with that old sucker and could not get it to function.

But a funny thing happened in Cape Cod Bay while we were underway. SOMEHOW IT JUMPED OUT OF THE ANCHOR LOCKER, OVER THE LIFE LINES FOLLOWED WITH A GREAT SPLASH! I reconciled with self that it should never cause grief again

OH--- That was before Massachusetts declared the entire Atlantic Ocean a NDZ
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Old 23-09-2013, 14:33   #10
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Re: What next Merc 5hp

Quote:
Originally Posted by foggysail View Post
My first outboard was given to me, it was an old Sears 7HP. I did manage to get it to run so with great expectations, I loaded it onto my sailboat (at that time) and got ready to do away with rowing my old Eli 8' fiberglass dinghy.

We next visited Cuttyhunk, installed the engine and pulled, and pulled and I am sure you know the routine. I did everything with that old sucker and could not get it to function.

But a funny thing happened in Cape Cod Bay while we were underway. SOMEHOW IT JUMPED OUT OF THE ANCHOR LOCKER, OVER THE LIFE LINES FOLLOWED WITH A GREAT SPLASH! I reconciled with self that it should never cause grief again

OH--- That was before Massachusetts declared the entire Atlantic Ocean a NDZ
Did you check the vent in the fuel cap?
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Old 23-09-2013, 19:15   #11
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Re: What next Merc 5hp

Quote:
Originally Posted by foggysail View Post
My first outboard was given to me, it was an old Sears 7HP. I did manage to get it to run so with great expectations, I loaded it onto my sailboat (at that time) and got ready to do away with rowing my old Eli 8' fiberglass dinghy.

We next visited Cuttyhunk, installed the engine and pulled, and pulled and I am sure you know the routine. I did everything with that old sucker and could not get it to function.

But a funny thing happened in Cape Cod Bay while we were underway. SOMEHOW IT JUMPED OUT OF THE ANCHOR LOCKER, OVER THE LIFE LINES FOLLOWED WITH A GREAT SPLASH! I reconciled with self that it should never cause grief again

OH--- That was before Massachusetts declared the entire Atlantic Ocean a NDZ
LOL
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Old 23-09-2013, 19:17   #12
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Re: What next Merc 5hp

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Originally Posted by builder dan View Post
fuel pump diaphram may have split in it also had a 5 hp merc had lots of issues with it,tank comes off easy for flushing if needed only takes a tiny speck of dirt in fuel to kill small motors.Also quickstart scours your bore I wouldnt use it.
New diaphram.
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Old 23-09-2013, 19:19   #13
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Re: What next Merc 5hp

Quote:
Originally Posted by capt-couillon View Post
Sounds to me like it is still a fuel issue. Many older 2 strokes will not start on straight ether (quick-start) if they are not getting some gas.

I would expect that if you pull the fuel line off the carb and hit the primer bulb, you will get fuel coming out. Likewise, after priming, if you pull the starting cord once or twice, you are getting squirts of gas from the fuel pump.

If you pull the plug on the bottom of the carb float bowl, you should get a couple tablespoons or so of clean fuel running out. If so, that leaves two suspects. Carb, and stuck reed valve. Reed valve is unlikely since you had it running once with new plugs.

That leaves the carb. I would expect your cleaning was with a spray can of carb cleaner, and inadequate to clean the interior passages. Carb should be disassembled and all non metalic parts removed. Remove the high speed and pilot jets as well and soak all the metal parts in a covered container of carb cleaner for 24 hrs. Blow through every passage you can see with compressed air as well as the jets. Reassemble carb and try it again.

Just went through the "carb is clean" and won't start with ether problem with an 88 Suzuki 6hp. Cleaning carb as above resolved the issue.

Luck

I did disassemble but I did not soak the carb and it bits for 24 hours, I will give that a try.
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Old 23-09-2013, 19:23   #14
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Re: What next Merc 5hp

Quote:
Originally Posted by capt-couillon View Post
Carb, and stuck reed valve. Reed valve is unlikely since you had it running once with new plugs.


Luck
What is a reed valve?
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Old 23-09-2013, 20:40   #15
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Quote:
Originally Posted by Stevens 47 View Post

What is a reed valve?
A reed valve is after the carb and before the cylinder. It lets fuel and air in on the down stroke and closes for compression on the up stroke.

They generally fail by cracking and cause a loss of compression.
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