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Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 14305
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I have trouble starting my Mercury 9.9hp outboard after

Customer Question

I have trouble starting my Mercury 9.9hp outboard after first start (i.e. it start first normally after few hours of not working by the normal cold start procedure). However, if motor then stopped it won't start again until you let it alone for few hours. Then again it starts easily for the first time only. I need an advise from the specialist what to look at!
Submitted: 1 year ago.
Category: Boat
Expert:  Jason replied 1 year ago.
Hello my name is ***** ***** am I speaking with?
Are you re-priming the engine by squeezing the primer bulb in between starts?
Customer: replied 1 year ago.
My name is***** tried both ways - with and without re-priming. None works.
Expert:  Jason replied 1 year ago.
Hi Dmitry. The next step would be to duplicate the problem. And then check for spark output with a timing light. Is that something you can do?
Customer: replied 1 year ago.
I did that already - bought inline spark plug testing specifically for that. It indicates that the spark is always there - when motor starts and works normally and also when it fails to start.
Expert:  Jason replied 1 year ago.
Do you have any starting fluid you can try?
Customer: replied 1 year ago.
No, not at this moment. So what do you think could be the possible reason? More details: this motor works fine most of the time at idle and hi rev (when started), however, sometimes works irrationally at idle and then stops by itself. But what puzzles me that this is not happening every time. Most of the time it works stable and the only problem I can see is that I can not restart it when hot.
Expert:  Jason replied 1 year ago.
I just want to make sure of something. When you checked spark. Did you checked it when the motor was running fine. Or when it would not start?
Customer: replied 1 year ago.
I checsked it in both cases - that was my originral thought that there was an ignition problem. However, my inline indicator shows orange light (which indicates the presence of the spark) even when motor does not start. Specifically, when I pull starter rope I can see that orange light of the indicator clearly, however the motor does not start and I can not hear any sound of ignited fuel.
Expert:  Jason replied 1 year ago.
do you have a neon/glass bulb type tester? Or do you have a tester in which you can see an actual spark arc jump a gap?
Customer: replied 1 year ago.
Neon glass
Expert:  Jason replied 1 year ago.
Those things won't really work with outboards. Outboards use high voltage ignition systems, and those neons only work with low voltage stuff, like lawnmowers. What you need is an adjustable gap spark tester. Click this link below to get a youtube video up. Fast foward to the 3 minute mark. This shows the proper way to test spark on outboards.
https://www.youtube.com/watch?v=eSmNMWTDtZE
Let me know what you think after watching it.
Customer: replied 1 year ago.
Ok, I saw it online. I can get one like this. I also thought that all indicated an ignition problem and therefore I tried to troubleshoot it first. I even bought a new HV ignition transformer ASSY from Mercury parts and tried it today - same thing it did not help to solve the problem. Also, I tried to measure the input to the primary of this transformer - I know that it is pulsed but so far measured only with DVM in AC mode. The amplitude goes to about 10V. I can also measure precisely with digital scope - I have one at work. Do you know what is correct input voltage and possibly the pulse shape on the ignition transformer input?
Expert:  Jason replied 1 year ago.

All of the Mercurys are cataloged by serial number. Let me get the serial number off of yours so I can run it and see which igntiion system you have, and pull the correct books.

Customer: replied 1 year ago.
I will do it later tonight - I do not have it with me right now but I do have it in my records and on the motor itself.
Expert:  Jason replied 1 year ago.

Okay no problem, there are no time limits here.

Customer: replied 1 year ago.
Hello, Jason,Here is the S/N of my motor: OR193265
Expert:  Jason replied 1 year ago.
Good morning.
Got the serial number. Can you open up PDF files if I upload a file for you in that format?
Customer: replied 1 year ago.
I can .
Expert:  Jason replied 1 year ago.

I'm attaching a file to this response it explains how to go through the ignition system on this engine. Give it a read. If you have any questions on the steps, or need clarifying as to how it works, just let me know and I will be happy to explain it. When you test it, you need to test it when the engine actually will not start. If you do have an ignition component issue you will find it via the tests. If it all checks out then the problem is going to be in the carb. There is either a little bit of dirt in it, or the float inside of it is sticking. And that would have to come off to be rebuilt.

Expert:  Jason replied 1 year ago.

I think that should do it. But I work for tips so I do want to make sure you are happy with my service before you go. If you had a further question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.

Questions do not close out, so if you have to come back later on with follow up questions to the issue you still can even after doing a rating.

Thank you
Jason

Customer: replied 1 year ago.
Hello, Jason,Thank you for the pages from the manual. So far I was able to checked the resistance of the ignition transformer coils and ignition charge coil and it looks within the range described in the manual (except for HV secondary coil that does not seem to have any connection with the primary coil orange lead. However, my new spare ignition transformer that I just bought measures the same - no connection to primary, so it may be some design revision here?). Anyway, I tried to start the motor again this morning and it started immediately from the first pull. Then worked stable - I checked agan the idle and high rev. - works just fine, I ran it for about 4 min in the tank. Then stopped the motor and oops - never was able to re-start it. So the problem looks very repeatable. It happens every time - 100% reproducable. May it be so that when the motor sit fow a long time fuel vapors got into the chamber and the engine starts but then it does not start again because the prime does not actually pump any fuel into it? Do you know how to check that? Can you send me the pages from the manual with the description of that primer system in the carburator? Thank you, Dmitry.
Expert:  Jason replied 1 year ago.

Hi Dmitry, before we jump all over the place. Did you get a timing light or adjustable gap spark tester to see if the engine was definitely loosing spark, or definitely has it? We need an absolute thumbs up or thumbs down on that.

Customer: replied 1 year ago.
No, I did not get adjusable spark tester yet. I will order one today anyway. Just wanted to see wnat manual says on the primer circuit in a meantime.
Expert:  Jason replied 1 year ago.

There really isn't a primer circuit on the engine. It uses a standard plate style choke that restricts air when the choke is engaged. Other than that there is an accelerator pump on the carb. (which is different than what an primer is on other styles of outboards). All that does is give a squirt of fuel each time the throttle is turned up quickly.

Customer: replied 1 year ago.
I was mentioning the ribber bulb that you have to press 2-3 times before you start the engine. The comressed air it supplies goes through the hose to the fitting at the bottom of the carburator (located on pos. 29 on carburator ASSY drawing).
Expert:  Jason replied 1 year ago.

What picture or website are you looking at, do you have a link to it?

Customer: replied 1 year ago.
You can see it here: http://www.mercuryparts-direct.com/fiche_section_detail.asp?section=1661060&category=Outboard Motors&make=MARINER&year=0&fveh=49030
Expert:  Jason replied 1 year ago.

That is the accelerator pump I was talking about. It is part of it.

Customer: replied 1 year ago.
The bulb itself is called "pump-priming" (pos. 26) on this ASSY drawing.
Expert:  Jason replied 1 year ago.

It's all part of the same accceleration pump circuit. It would not be causing the issue.

Customer: replied 1 year ago.
It does exist only on manual-start motors, which is what I have.
Expert:  Jason replied 1 year ago.

It is not part of the issue. it wouldn't cause it. If there was a problem there the engine would be hard to start when cold.

Customer: replied 1 year ago.
Ok, I will check on the spark with the new tester and then get back to you. Thank you!
Expert:  Jason replied 1 year ago.

You are very welcome

Expert:  Jason replied 1 year ago.
Hello, just checking in. Any progress?

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