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Author Topic:   Mercury 90-HP 4-stroke: Starting Problem
ZoeAnn ZoeAnn posted 07-09-2004 09:31 PM ET (US)   Profile for ZoeAnn ZoeAnn   Send Email to ZoeAnn ZoeAnn  
We have a 2002 170 Montauk with a Mercury 90-HP 4-stroke. We were thrilled with the boat until we towed it from California to Montana for a summer vacation.

When we arrived at the lake in Montana, we found that the engine with ONLY 20 hours on it would not start. We contacted the closest authorized dealer and were granted an appointment for a week later.

The first analysis (with a review by Mercury in Wisconsin) implied it needed a new coil. The coil arrived two days later. After putting in the new coil, it was determined (with a call to Mercury once again) that it was now the carburetors and they would have to be rebuilt. Another sunny weekend of boating was lost.

Surprise. surprise. that repair is NOT covered under the Limited Warranty!

Since "Mercury's reputation for strict quality control, excellence, durability, and lasting performance" are well advertised, it seems to me that the engine should not need repair at only 20 hours, and IF it does, it certainly should be under warranty.

Has anyone had a similar problem?

jimh posted 07-09-2004 10:18 PM ET (US)     Profile for jimh  Send Email to jimh     
One of the constant problems with the marine business is the difficulty in getting service during the boating season. As you mention, it is hard to get a mechanic to look at an engine during the peak boating season. Waiting a week for service is a good way to make a customer an ex-customer in a hurry.

It is very odd your engine ceased running after just 20 hours. The powerhead, the carburetors, the electricals on that engine are all made by Yamaha.

Was the haul on the trailer particularly rough? Perhaps something was jarred loose mechanically from vibration on the road.

A load of bad gas will mess up the fuel system, no matter if it has 20-hours on it or 20-years. Was there any mention that the fuel was bad?

Barney posted 07-09-2004 10:34 PM ET (US)     Profile for Barney  Send Email to Barney     
I haven't read of anyone having that problem with the 90 4-strokes. I think fuel problems also. Could it be "old fuel" creating havoc with the carbs?
saltyfly posted 07-10-2004 07:01 AM ET (US)     Profile for saltyfly  Send Email to saltyfly     
I have a 2004 90-HP 4-stroke on my new Montauk. It has less than 20 hours and I am awaiting the second repair. First time engine started, ran briefly, then stalled and would not start. That fix involved some idle adjustments. Currently the engine cranks but will not start. Fuel is good. No kinks in fuel line. It will most likely be covered but it's $50 for the service call (no trailer, the boat is in the water) and more importantly there are stripers to be caught.
Knot at Work posted 07-10-2004 07:48 AM ET (US)     Profile for Knot at Work  Send Email to Knot at Work     
I have a 2003 90-HP 4-stroke motor that is as strong as an OX. No problems.

Sorry for yours.

Why is it not covered under warranty?

AQUANUT posted 07-10-2004 08:14 AM ET (US)     Profile for AQUANUT  Send Email to AQUANUT     
It is hard to sit here, read your post, and get the big picture.

Your post brings to mind so many questions, unanswered.
I really would like to know, as Paul Harvey says, "the rest of the story."

YOU have a 2002 motor with only 20 hours on it? Did it have 2002 gas in one of the two tanks? Is this what you ran the motor on? For three carbs to need rebuilt, I suggest a fuel contamination problem. Is this what you were told by the Mercury trained technician?

I can buy into the faulty coil thing. It could happen. If you buy a brand new automobile, park it in the garage for ten years, and the darn thing won't run or start after 10 years, yes, I doubt if the dealer will warranty it. Your motor is a 2002. What warranty were you given at that time? 2 or 3 years?

Have you been in contact with mercury directly, or used a dealer as a go between or liaison?

during pre-delivery inspection all service and tech bulletins issued by Mercury should have been done. Concerning mercury 90-HP four-strokes, there is one service bulletin advising to adjust the idle adjustment screw in gear and under load. This should have been done by your dealer.

Due to the low quality of today's fuels, and the lack of quality of the fuel being delivered at the pump, I always suggest a water fuel separater. I have a 115-HP EFI on my 2004 Montauk. Bad fuel in a EFI is noteably a much higher repair than on a 90-HP 4-stroke with carburetors on same power head.

Maximus posted 07-10-2004 10:05 AM ET (US)     Profile for Maximus  Send Email to Maximus     
Do other Mercury 4-stroke owners use additional fuel water separators other than the supplied filter under the cowl? Interested to see your setup if you do.

WT posted 07-10-2004 12:45 PM ET (US)     Profile for WT  Send Email to WT     
I have 20 hours on my 90-HP 4-stroke. My boat won't start in the neutral position "in between forward and reverse". I have to push the button on the throttle to manually give it more gas in order to get it started.

I guess I need a throttle adjustment.

I will be taking my boat to the dealer in 2 weeks.


mikeyairtime posted 07-10-2004 03:23 PM ET (US)     Profile for mikeyairtime    
One of the downsides of carburetor engines is running at altitude. Do you have any idea of the altitude you were at in Montana. Also it's important to learn how to check for spark and fuel. Pull a plug, put it back in it's cap, ground the electrode and turn it over. You should see a spark jump across the end of the plug. No spark = ignition problem. If there's spark prime the fuel bulb and have someone push the throttle forward while looking through the held open carburator butterfly. You may be able to see a squirt of gas going into the carb. If you can't see you should be able to smell gas. If there's no fuel going through you have a fuel problem. If it doesn't start at idle try full throttle in neutral. If that doesn't work Try manually holding the choke open and turning it over. If you have both spark and fuel and it still won't start try a "little" starting fluid to wake that baby up. Modern outboards are sophisticated but not rocket science. If all that fails the only truly good outboard mechanic I've ever met is Rolf at Audiss Marine in Stanton, CA. I don't know his number but you can call imformation. Even if you're far from him give him a call and pick his brain.
ZoeAnn ZoeAnn posted 07-10-2004 10:00 PM ET (US)     Profile for ZoeAnn ZoeAnn  Send Email to ZoeAnn ZoeAnn     
Thanks for your responses.

The boat has been used year round about every two months and the 6-gallon tanks have been alternated as used. Gas may have been as much as four months old.

We are having second thoughts about having the carburetors rebuilt. Advancing the throttle via the button did get the engine running before the coil was changed, but it idled roughly. We have not tried it since the dealer got it.

Is there a fuel additive that keeps the carburetors clean?


Lil Whaler Lover posted 07-11-2004 12:03 AM ET (US)     Profile for Lil Whaler Lover  Send Email to Lil Whaler Lover     
Most likely a problem with altitude, especially if it will start with advancing the throttle. When one takes a snowmobile to higher elevation they have to rejet it to get it to run at elevation. This would probably not be covered under warranty as it is a change in use and also it would be necessary to change the jets back again when you return to lower elevation.
Spraying B-12 through the carbs and/or adding Techron to the gas may make it seem to run better but it must be jetted for the altitude it is operating in.
Let us know what the final resolution is.

Good luck, Dave

Knot at Work posted 07-11-2004 08:06 AM ET (US)     Profile for Knot at Work  Send Email to Knot at Work     
ZoeAnn, can you please expand on why the dealer says [the failure of the engine to start] is not covered under warranty?


AQUANUT posted 07-11-2004 11:11 AM ET (US)     Profile for AQUANUT  Send Email to AQUANUT     

True, there is a small filter under the cowling on [Mercury] four-stroke engines. It has an free floating indicator ring inside that we inspect when performing a service. It is a visual.
However, due to the size of this filter, it is much better to have a water seperator between it and the tank. Any water in your tanks you recieved at the pump will be in the bottom of the fuel tank. The mere volume of the water seperator can help avoid a situation at sea. Since the tank's pick up tubes in the Mercury tanks have a fine mesh screen and they pick the fuel up from the botom of the tank. Hopefully the quart water or so can be emptied from the water seperator filter (into an approved Coast Guard/E.P.A fuel container) more convienently than from the little filter at the back of the engine. The little filter fills more often and is a bear to reach while you are dead in the water.

Maximus posted 07-11-2004 01:16 PM ET (US)     Profile for Maximus  Send Email to Maximus     
Thanks for the response. Where have other Montauk 170 owners mounted a separate fuel/water separator?
1stwhaler posted 07-11-2004 06:49 PM ET (US)     Profile for 1stwhaler  Send Email to 1stwhaler     
I mounted my separator inside the hand hole under the rear stern seat for a clean mount.
ZoeAnn ZoeAnn posted 07-11-2004 08:11 PM ET (US)     Profile for ZoeAnn ZoeAnn  Send Email to ZoeAnn ZoeAnn     
Thanks again for the information.

The warranty is for three years and covered the coil, but the dealer, not Mercury, said the carburetor rebuild was not covered by Mercury. The warranty in the manual seems to cover parts only.

The dealer did not mention fuel contamination and no water was found in the filter/separator. The red ring did not float up.

The altitude is 3000 feet and the dealer said they did not suggest re-jetting until over 5000 feet.

We will let you know the outcome. Meanwhile, we are going white water rafting.

mikeyairtime posted 07-11-2004 11:49 PM ET (US)     Profile for mikeyairtime    
My water seperator filter is in the outboard splash well just in front of the motor. Changing it is easy and no fuel goes in the boat. You can put a shut off valve where the fuel exits the filter and run the motor out of fuel everytime you store the boat. Keeps the carbs from varnishing up. Both Mercury and Racor make water seperator filters that are good.
LHG posted 07-12-2004 01:28 PM ET (US)     Profile for LHG    
Since the powerhead is by Yamaha, perhaps a Yamaha Dealer/mechanic could help out with a solution.
ZoeAnn ZoeAnn posted 07-13-2004 11:29 PM ET (US)     Profile for ZoeAnn ZoeAnn  Send Email to ZoeAnn ZoeAnn     
Montauks do run in Montana!

Got the Montauk back WITHOUT the carburetors rebuilt. It runs great again.

Everything in the fuel system was clean except the jets. No water, bad gas or particles just goop in the gap. California (and other states) gas contains more "clean air extras" than the other states and they have a bad effect on jets. Luckily, Yamaha sells a product that dissolves the goop...Ring Free Fuel Additive. It works! It may contain Techron, as suggested by Lil Whaler Lover. To his credit the Mercury technician recommended a Yamaha product that worked. He also suggested using Mercury Fuel System Treatment & Stabilizer. He didn't recommend running the gas out of the system after each use unless I wanted fuel pump problems...fuel lubricates pump.

I will continue using the two additives and if the starting problems return, let you know.

Thanks again for your suggestions and advice.

bobeson posted 07-14-2004 08:34 PM ET (US)     Profile for bobeson  Send Email to bobeson     

Glad to hear you found and fixed your problem. For the benefit of anybody else seeking to diagnose problems, I'll chime in with the only engine starting problem I've had so far with my 2003 Montauk 170. After a few episodes of increasingly difficult starting and rough idling, one week the motor just wouldn't start and stay running, and then it just wouldn't start at all. Eventually we traced the problem to the factory-supplied fuel primer bulb, which had been leaking progressively larger amounts of air into the fuel lines, until apparently no fuel was flowing at all. This occurred after approximately 140 hours of use. It was easily resolved with a replacement primer bulb.
mikeyairtime posted 07-18-2004 12:59 PM ET (US)     Profile for mikeyairtime    
I'm having a hard time swallowing the technician's advice on not running the boat out of gas. I could see that on a fuel injected motor with a high pressure pump that he may have a point, but on a low pressure carburated motor it seems questionable. My 1986 115-HP 2-stroke is still running on the stock fuel pump and has never had the carburators cleaned or rebuilt, and I've always run it out of fuel when storing it. I took my cowling off to look at the 1990's fuel system but I stoped short of taking the fuel pump apart to see what kind it is. On Monday I'll do some research and report back whether it is a diaphram or vane type pump and see if I can get Mercury's tech people's opinion. In your tech's defense the manual says nothing about running it out of gas.
AQUANUT posted 07-18-2004 06:36 PM ET (US)     Profile for AQUANUT  Send Email to AQUANUT     
Mikey, there is a service bulletin out on not runnning mercury engines dry on fuel before storage. It cites that due to poor quality fuels that when exposed to air turn to varnish in as little as three months.

Also, it did not single out or specify 2-stroke versus 4-stroke. It further stated that today's gaskets dry out and shrink and become brittle, thus they ultimately leak. Say it in black and white. Need book chapter and verse. I'll get reference numbers if you like when I go back to work monday
email me

mikeyairtime posted 07-18-2004 09:19 PM ET (US)     Profile for mikeyairtime    
AQUANUT, the TSB on gasket failure makes more sense to me than fuel pump lubrication. I want to know because every outboard, dirt bike, lawnmower, etc., that I own I run out of gas when I park it for extended periods. If this is not the hot tip with current fuels I'm going to stop.
mikeyairtime posted 07-18-2004 10:52 PM ET (US)     Profile for mikeyairtime    
Here's what I found out from one source. Oxygenated fuel can cause gaskets to not just swell, but swell excessively, much more than they would with non oxygenated fuel. Going back to non oxygenated fuel can cause them to shrink back down. Apparently on an older outboard just switching back and forth between oxygenated and non oxygenated fuel (like California does twice a year) is enough to cause gasket swelling and shrinkage problems or failures/leaks. What my source went on to say is that all new current outboards should have gaskets that have been redesigned to work with oxygenated fuels without excessive swelling. He also stated that oxygenated fuels do varnish much more easily than non oxygenated but wondered why leaving your carbs full of easily varnished fuel would be better. There is always air present in the carb, even with gas in it. ZoeAnn's experience seems to confirm the easy varnishing of oxygenated fuels theory. If the Mercury 90-HP engine's gaskets are the old style, and have not been redesigned to work with oxygenated fuel, the only other option is to run a fuel stabilizer/de-gooper all the time. One last thing he said: be glad you have a four-stroke because the two-strokes have even more problems with oxygenated fuel.
mikeyairtime posted 07-19-2004 12:07 PM ET (US)     Profile for mikeyairtime    
Called Mercury this morning and their tech guy said that in a new 90-HP 4-stroke with current fuels, and the potential for there to be alcohol in the fuel, the prefered method is to run the motor out of gas for storage.
jimh posted 07-21-2004 08:24 AM ET (US)     Profile for jimh  Send Email to jimh     
It is good to hear that the Yamaha/Hitachi/Japanese-made electrical coil was replaced by Mercury under warranty when it failed after just two years. It was great that Mercury backed their product with a three-year warranty. It was also good that even in a remote spot like Montana you could find a Mercury dealer. Boy, imagine if you had purchased a Nissan outboard. I bet it would be tough to find a Nissan dealer in Montana.

It is also good to know that those Japanese-made carburetor jets were not defective, but were clogged by poor quality fuel. Unfortunately, your spoiled vacation and additional expense of maintaining your outboard motor is just part of the cost you have to bear to keep our environment clean. Imagine what our air and water would soon turn into if we did not add all these chemicals to our gasoline fuels. What a mess we'd be in without all that alcohol making our fuel so much more environmentally friendly.

I know it must be a disappointment that your trip to Montana was spoiled by bad gasoline and a faulty Japanese-made electrical part in your Mercury outboard, but if we want to keep our air and water clean, and also keep our trading partners in Japan able to sell their products in our open market, these are little inconveniences we will all have to tolerate.

cape_rover posted 07-21-2004 09:42 PM ET (US)     Profile for cape_rover  Send Email to cape_rover     

why do you think the coils are made by Yamaha. Last email I recieved from Merc implied just the block was from Yamahas and all the electronics/fuel were merc items.

jimh posted 07-22-2004 06:03 PM ET (US)     Profile for jimh  Send Email to jimh     
"Hitachi" sound more oriental than "AC Delco".
Uncle Pug posted 08-05-2004 10:12 PM ET (US)     Profile for Uncle Pug    
We just returned from a month long cruise towing our Montauk 170 behind our trawler. We almost didn't get to take the Montauk because on the day we were to leave, it wouldn't start! As with the original poster it had less than 20 hours (2003 model that we had recently purchased) and the fuel was fresh.

All of the local dealers were booked 2~3 weeks out and the situation looked hopeless. I was soooo disappointed as I towed the Montauk back home expecting to have to leave it there in exchange for the old Livingston dingy.

Well... there in our driveway I decided to check things out myself. I openned the drain bolts at the bottom of each carb and they were dry! I undid the fuel line going into the filter and pump the squeeze bulb to see if the line was plugged... and the bulb was rock hard without any fuel coming out. I then took the hose off the bulb and had the same result.

It turns out that the one way valve in the squeeze bulb must have been floating loose in there and this time flipped over and went in backwards. I replaced the squeeze bulb with another from the old dingy and the motor started right up once it got some fuel.

Sometimes the fix can be so simple.

chopbuster posted 08-06-2004 01:37 PM ET (US)     Profile for chopbuster    
Way to Go, Uncle Pug! Shows you what a little patience,
thinking and sticktoitivness will get you.

Saved yourself a LOT of down time and perhaps several $$.

Uncle Pug posted 08-06-2004 09:46 PM ET (US)     Profile for Uncle Pug    
Thanks Chopbuster.

The biggest thing I saved was the ton of fun we had with the 170 Montauk... what a great boat! Being able to leave the Trawler anchored and take the Whaler into town our out whale watching made the whole trip so much more fun.

If we had made the trip without it and then found out later how simple the fix was it would have added supreme insult to grevious injury.

HVGBMACH1 posted 06-30-2008 10:51 AM ET (US)     Profile for HVGBMACH1  Send Email to HVGBMACH1     
Hi, first off I read some post on starting problems with 90hp 4stroke mercs. Trying to start your engine in shallow water with engine tipped up a bit will be tough to start. The engine starts much better tipped all the way down.Also everybody around here uses a separate water seporator.
And I have a question for you guys, my 2003-90 4stroke merc is really hard on gas (burning almost double what it should be). I had carbs cleaned and set up (basic tune up stuff done), inside coil replaced, thermostate replaced. Engine runs fine, seems normal but just burn alot of gas. There are about 3 or 4 of these motors around here and nobody is having this trouble but me. Anybody see this problem before or know anything i can try?
sapple posted 07-02-2008 03:55 PM ET (US)     Profile for sapple  Send Email to sapple     
In these posts I have seen several references to primer bulbs. My Sport 130 had one but my 2007 170 Montauk (stock Mercury 90 4 stroke EFI) either does not have one or I have not been able to find it yet. Can anyone tell me if there is a primer bulb on this model/year and if so where it is located?
nemored posted 07-02-2008 04:41 PM ET (US)     Profile for nemored  Send Email to nemored     
Trade it in and buy a Honda. You will thank me later when you never break down.
jackpine posted 07-02-2008 08:35 PM ET (US)     Profile for jackpine  Send Email to jackpine     
In Minnesota we run premium gas in all our small engines it is non-oxygenated so saves a lot of problems, I also add a little sea foam whenever I buy gas has always worked for me
catty posted 08-30-2008 10:27 PM ET (US)     Profile for catty  Send Email to catty     
WT posted 08-30-2008 10:32 PM ET (US)     Profile for WT  Send Email to WT     



stumpjumper posted 08-31-2008 12:57 PM ET (US)     Profile for stumpjumper  Send Email to stumpjumper     
Interesting comments on the in-line water separator...I was told by the dealer and I thought read in the Merc manual...that 2008 mercs were not designed to run with after-market water seps? I guess the possible reduced fuel flow doesn't work well with mercs fuel management system?
glen e posted 08-31-2008 02:11 PM ET (US)     Profile for glen e  Send Email to glen e     
merc has no problem with pre-filters as long as it meets the specs of the shop manual and does not hinder the flow of and ask - 920-929-5040

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