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Author Topic:   Mercury 90 FOURSTROKE, Problem in Starting, Noise
Andrewdavis34 posted 11-30-2008 11:38 AM ET (US)   Profile for Andrewdavis34   Send Email to Andrewdavis34  
Hi all,

I have a 2008 170 Montauk. Recently I changed the installed fuel water separator. The initial time after changing the filter, I attempted to start the [Mercury 90-HP FOURSTROKE which uses the Verado block or L4NA or Verdito] engine and no go. I then turned the key off and attempted again. On the third attempt the engine started. I attributed this to a air lock from changing of the fuel water seperator filer. The next time I used the boat the same thing happened. I had a local mechanic who is very good go on a sea trial with me several days ago and he was able to reproduce the symtoms twice.

This problem was intermittent for the mechanic and the only time it happened at initial start up was for me. All electrical connections have been checked and are secure and corrision free. Has anybody else experienced symtoms similar to this? If so, what was done to correct the problem?

I am also experiencing a very intermittent change in engine noise below 1,600-RPM. The best way I can describe the sound, is that it sounds very similar to the sucking sound that the air cleaner makes when shutting the engine down. This sound like I said happens only below 1,600-RPM and does not [affect] any performance. The mechnanic heard this sound as well and was a little perplexed. I have been told that he is going to contact mercury and see if this is part of the normal operation for the L4 engine. Any thoughts??


Chuck Tribolet posted 11-30-2008 10:18 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Does "no go" mean

A) "the engine wouldn't turn over" or
B) "the engine turned over but wouldn't start".



Andrewdavis34 posted 11-30-2008 10:45 PM ET (US)     Profile for Andrewdavis34  Send Email to Andrewdavis34     
NO GO=Engine won't turn over. Even after putting the gear shifter forward neutral and back again.
WT posted 11-30-2008 10:52 PM ET (US)     Profile for WT  Send Email to WT     
Have your dealer check the Fuel Supply Module. I had mine replaced under warranty.

Turn your ignition switch on for a few seconds but do not crank the motor over. (Especially if your boat has been sitting for a few weeks.) Give the Fuel Supply Module a chance to fill up with fuel prior to cranking the motor over.

Good luck,


BlueMax posted 12-01-2008 09:18 AM ET (US)     Profile for BlueMax  Send Email to BlueMax     
I know this doesn't answer the "won't turn over" question, but in response to WT's post about waiting a few seconds before starting, I have the same engine on my 2007 170 Montauk and it has a high-pitched signal that sounds for that few seconds on mine when I turn the key to the "on" position. I always wait for the signal to end before turning to start as I figure this must be a warning of some sort to wait while the fuel supply pump is working to fill the lines (or something of that ilk).
jimh posted 12-01-2008 09:53 AM ET (US)     Profile for jimh  Send Email to jimh     
These fuel injected engines typically have two fuel pumps: a lift pump pulls fuel from the tank to the fuel module; the fuel module has an electrical fuel pump that pressurizes the fuel rail of the fuel injector system.

When changing a fuel-water separator filter it is possible to introduce air to the fuel system, but this should be bled out in the course of normal operation by the fuel module. The fuel module is designed to separate fuel and vapor. Check your engine manual to see if a manual bleeding of air from the fuel system is necessary.

When an engine starter motor will not crank over at all, this is not related to the fuel system. It is an electrical problem. Follow the trouble-shooting suggestions given in my REFERENCE article:

Electric Starting Circuits

L H G posted 12-08-2008 04:01 PM ET (US)     Profile for L H G    
Get rid of the external water separating fuel filter. It's not needed with an on-deck fuel system, as the engine already carries one, and can choke off fuel supply. Bet it wasn't installed by the factory?
dbrown posted 12-08-2008 08:35 PM ET (US)     Profile for dbrown    
The Verado block based Fourstroke engines do not have an engine mounted fuel/water separator filter. I have used a separate fuel/water separator on my 2007 Manufactured 90 HP Fourstroke for 2 seasons (107 hours total) with no fuel problems. If you are using the proper size fuel lines and fuel/water separator, in my experience, it will be fine.
BlueMax posted 12-09-2008 12:04 AM ET (US)     Profile for BlueMax  Send Email to BlueMax     
The "No Go" as described still points to electrical as Jim points out - if it were fuel related, it would at least try to turn with no ignition occurring.
Traveller posted 12-10-2008 07:19 PM ET (US)     Profile for Traveller  Send Email to Traveller     
I had a similar experience last summer when I pulled my boat to Florida for teh Greater Jacksonville Kingfish Tournament. I happened to be staying at the same hotel that the Mercury tournament support team was using.

They took the cowling off and determined that a bundle of wires on the starboard side of the motor was loose. I was unable to move the wires by hand, but they said that the wires only appeared to be tight. They got a socket wrench and tightened them up even tighter than they had been. The motor fired off perfectly, and has every time since they tightened that connection.

They said it was a problem they had seen many times with the Mercury 4-stroke on the tournament trail - most people had no idea how tight that particular connection had to be.

I thought it was tight enough, but their tightening fixed the problem.

BlueMax posted 12-10-2008 07:38 PM ET (US)     Profile for BlueMax  Send Email to BlueMax     
Sounds like they got you out of a tight spot... ^@^
jimh posted 12-11-2008 12:21 AM ET (US)     Profile for jimh  Send Email to jimh     
I'd keep the external fuel filter, too. You never know what sort of junk might be pumped into your tank.
Feejer posted 12-11-2008 07:41 AM ET (US)     Profile for Feejer  Send Email to Feejer     
I agree with Jim. I've been running an external fuel / water separator on my 170 for two years now and have not had any problems. My local BW dealer installs them on all the boats they sell.
Andrewdavis34 posted 12-11-2008 10:11 PM ET (US)     Profile for Andrewdavis34  Send Email to Andrewdavis34     
Hi All

Thanks for all the replys. I spoke with mechanic this morning and he and mercury want to start with replacing the key switch. I am not sure how this is going to make a difference, but it is listed as a possible cause for the engine not turning over.

I will keep everybody posted on the outcome.


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