Mercury 60-HP ELPT Problems

[Dutchman]

I went for one of the last outings yesterday with my 2008 Whaler and Mercury 60-HP BIGFOOT. All season long I quite often had problems running at 1,400 to 2,000-RPM and anywhere in between, a swing of 400 to 600-RPM. When I tried she would constantly, every one or two seconds, fluctuate between these two engine speeds. I could run smoothly anywhere above that upt o WOT at 6,000-RPM. As the engine always started, and normally I don't plow thru the water at those engine speeds, I thought I wait until this winter to find out what is wrong.

Now yesterday at 50-degree-F she started fine as always, but was running what sounded like at three cylinders at idle at 800- to 900-RPM. I had to goose her a little and bring it back to idle to get her to purr on four cylinders.

After about an hour of running at 1000 to 1200-RPM the Mercury 60-HP BIGFOOT would stall. I did notice when I changed trim either by me moving aft or using engine trim she would stall. Started up easily every time and if I would try to run slow and idle she would stall.

I did not get any alarm soundings and of course I'm using clean new gasoline. Hence based on trim change causing stall I would expect this to be a fuel problem. But this isn't a carburated engine with a float so how could it? Has anybody else run into this problem?

At the end of last season I had a full service done and under warranty received three new coils (and one was replaced previously). The engine has brand new plugs, too, with less than 25-hours. Could this be [caused by] the injectors? By the fuel pump? Or what?

As mentioned the Mercury 60-HP BIGFOOT runs fine between 2,500 and all the way to 6,000 RPM with standard expected fuel economy. It was that pesky 1,400 to 2,000 RPM and now no good idle. Help

[jimh]

A change in the engine trim could affect the engine running characteristics in two ways:

--running the trim motor adds a load to the engine from the electrical power being generated by the alternator, and

--the exhaust back pressure can change if the through-hub exhaust flow decreases from too much water pressure due to the exhaust being more deeply immersed.

[jimh]

Are you sure the c.2008 Mercury 60-HP BIGFOOT has fuel injection?

Is there a throttle position sensor? If so, then perhaps the throttle position sensor has become intermittent at the lower throttle setting positions.

Do you have the factory service manual? If you are attempting to make a diagnosis and repair with any modern outboard engine, you really need to have the factory service manual.

Since this is a Mercury engine, it will be not possible to get the diagnostic hardware and software--it's just too expensive. It may be more practical to take the engine to a good dealership with trained and certified technicians, and let them investigate the problem with diagnostic software and the specialized hardware tools that Mercury engines need.

[goldstem]

I had a Yamaha 50-HP outboard engine that also had problems running at 1,400 to 2,000-RPM and anywhere in between, a swing of 400 to 600-RPM]. [The cause of the problem] turned out to be water in the fuel. I thought water would take out all the cylinders but it didn't happen that way. A complete [fuel] system flush, and especially the draining of the vapor-separator-tank or VST, cleared [the water in the fuel]. It was lucky the engine didn't need new injectors.

[Dutchman]

...turned out to be water in the fuel...

No water in the fuel unless somebody poured it into one of my six-gallon external tanks. This is a Michigan fresh water boat, I always get my gas from marine fuel outlets here in Michigan [that have] no ethanol in the gasoline and therefore no water problem. Even if the fuel had ethanol in the gasoline this engine from the factory is rated to handle that. Still, thanks for the comment.

[Dutchman]

Are you sure the c.2008 Mercury 60-HP BIGFOOT has fuel injection?

YES this is a Electric start, Long shaft, Power Trim, EFI (electronic fuel injected) 4 stroke 4 cylinder engine.

Is there a throttle position sensor? If so, then perhaps the throttle position sensor has become intermittent at the lower throttle setting positions. Do you have the factory service manual? If you are attempting to make a diagnosis and repair with any modern outboard engine, you really need to have the factory service manual.

possible but I don't know about a [throttle position sensor], because I don't have a service manual.

Since this is a Mercury engine, it will be not possible to get the diagnostic hardware and software--it's just too expensive. It may be more practical to take the engine to a good dealership with trained and certified technicians, and let them investigate the problem with diagnostic software and the specialized hardware tools that Mercury engines need.

Been there done that and [before] doing it again I want to make sure I don't get shafted, hence my questions and some self checking and diagnosis.

[Dutchman]

Last evening I took off the [vapor separator tank] to make sure [it] had no dirt in the tank and pump filter. It was not an easy task. All was very clean. Now have to get new clamps and try to hook up a pressure gauge on the pump outlet to see if I have 35-PSI. Spark plugs showed clean burn and no wear. Float did not show a leak and low fuel seems to flow unrestricted into the [vapor separator tank].

[Dutchman]

Going in to the pro tonight, I'll let you know what the verdict will be and their solution.

[Dutchman]

I got back [the Mercury 60-HP ELPT engine] last evening, and, as we had fantastic weather here in SW Michigan (74-degree-F air temperature), I immediately took the boat for a spin to make sure [the engine] was fixed: it was. The boat runs excellently. A printout says the engine has 191-hours and only 20-percent of it at over 4,000 RPM. No codes except that the engine was always running cold.

The service shop said the problem was caused by the thermostat being stuck slightly open, [which was causing] the [engine controller] to think the engine was running cold and needing a richer fuel-air mixture. The effect of the richer fuel-air mixture was exaggerated at the [1,400 to 2,000-RPM range] but not so much at WOT engine speeds. The service shop replaced the thermostat.

The service shop also replaced the gray Mercury-brand fuel hose with red writing. The previous owner already had replaced the fuel line from the tanks to the fuel primer bulb, but not the fuel line from primer bulb to the engine. He also must have used gasoline [containing ethanol], as the fuel line was completely deteriorated. We cut open the gray Mercury-brand fuel line to see the damage (pictured below). I was lucky that no debris got as far as my fuel filters, but still [this deteriorated fuel line] was bad. I'm glad they replaced it. I should not have assumed that the previous owner would always have used non-ethanol fuel (or at least ValvTect-treated gasoline). I can't blame him; the Mercury Owners Manual says the engine is good with running fuel that contains as much as ten-percent ethanol.

The service shop also replaced all four spark plugs.

The Mercury 60-HP ELPT outboard engine now runs great. I had mirror-smooth water and with some trimming the engine accelerated to 6,000-RPM and the boat ran 36-MPH. I now can winterize, change oil, fog, lube, etc, the engine and put the boat away for the heavy winter here in Michigan and know I can go boating next April without any worries.

Again thank you everybody for your input.

[jimh]

That gray fuel hose with a somewhat metallic finish sold under the Mercury or Quicksilver brands is notorious for failure of the inner liner of the hose. As you suspected, it seems that exposure to gasoline fuel containing ethanol is the cause of the deterioration of that gray, metallic-finish Mercury-brand fuel hose. It has been frequently recommended in prior comments from many participants that any of that gray, metallic-finish Mercury-branded fuel hose be removed from boat fuel systems if there is any chance of having been exposed to gasoline-ethanol blended fuel.

By removing that gray fuel line you no doubt have avoided future problems.

Your photographs are good evidence of the problem with that gray fuel hose and the deterioration of the inner hose liner from ethanol-gasoline blended fuels. Thanks for taking the pictures and posting them.

[Phil T]

Good news.

Now that she is purring like a kitten,I say get back on the water till the snow starts!

[Dutchman]

That gray fuel hose with a somewhat metallic finish sold under the Mercury or Quicksilver brands is notorious for failure of the inner liner of the hose. As you suspected, it seems that exposure to gasoline fuel containing ethanol is the cause of the deterioration of that gray, metallic-finish Mercury-brand fuel hose. It has been frequently recommended in prior comments from many participants that any of that gray, metallic-finish Mercury-branded fuel hose be removed from boat fuel systems if there is any chance of having been exposed to gasoline-ethanol blended fuel.

Jim--I heard through the grapevine that the gray metallic fuel hose with the RED writing is bad and that the same color gray hose with blue writing is better. I'll look for the identifier numbers on my black hose and report back.

Phil--yes, you are right: the water isn't hard yet so I could still boat, but the admiral asks at least once a day when I'm putting the boat up as she thinks the season is over after Labor Day. Memorial Day to Labor Day is not a long enough season. I have always boated my big boats from late March or early April until November 15th, but those boats have heaters in them. It does get cold in the center console boat, so I have to put her up and in the Quonset hut with the other trailers and boat.

[Dutchman]

Cannot read the numbers on my black line going from tanks to bulb under the sole. This hose must be five-years old (and [dates from before] my ownership). The lettering and numbers are seems faded or wiped off. The Mercury dealer did put on the new Mercury gray or silver hose, but this time with the blue lettering. From what I understand [the gray hose with blue lettering is] the newest hose and is a revised and better fuel line from Mercury.

[jimh]

After c.1987 fuel hose must be clearly marked for its resistance to alcohol, the date of manufacture, and the rating to which it conforms. The rating system is known as SAE J1527 and it provides for grades as follows:

A1--fuel feed hose; has a fire resistant cover; is designed to have fuel in the hose at all times.

A2--fuel vent hose; has a fire resistant cover; is not designed to have fuel in the hose at all times; often used for fuel tank filler hose.

B1--fuel feed hose; without fire resistant cover; is designed to have fuel in the hose at all times; intended for non-enclosed spaces, like on deck with outboard engines.

Rubber fuel hose rated A1 is the best grade for use as a fuel line in a boat, and in most Boston Whaler boats the original fuel lines were installed with rubber hose rated A1. Typically fuel hose rated A1 is a black rubber hose with a substantial OD compared to its ID. It is not the relatively thin-wall silver or gray hose often seen used for outboard motors, typically rated B1.

Hose rated B2 is usually for fuel vent hose; it is without fire resistant cover; is not designed to have fuel in the hose at all times; used for diesel vent lines.

I wouldn't take a chance on any fuel hose that is not rated or marked for use with alcohol. I believe on my boat the fuel hose to the engine from the fuel tank is all rated A1 and clearly marked to be able to tolerate alcohol-gasoline blends.

[jbourg]

Flash forward nearly 11 months since the last post in this thread. I have a 2005 150 Sport purchased new in 2005 with the Mercury 60 HP four stroke EFI Bigfoot standard concern power at the time. Have just under 200 hrs on the motor, used year-round primarily in fresh water in FL and, now, NC. Have the boat out every couple of months, more frequently in summer. In mid-August, I experienced power reduction/bogging down after running at about 4500 RPMs for 20 minutes to a frequently used swimming area on Jordan Lake in NC. First trouble with the motor in 11 years. Spent several hours with friends at a beach area down the lake and returned to the ramp after dark with no recurrence of the problem. Took the boat out for another test myself two days later. Same power reduction/bogging down behavior after ~20 minutes of running; was able to return to the ramp at low power, <2500 rpms. 'Felt' like a fuel delivery problem. Broke out the service manual for the first time in 10 years. Checked the low pressure fuel filter for the first time in 8 years when last full service was performed on the motor (I know, I know... ). FIlter was clogged with debris/sediment and there was quite a bit of similar debris in the filter sight bowl. Ah ha, this must be it! Ordered and installed new filter and cleaned the bowl. Tested motor, same behavior. More reading in the manual... Symptoms didn't point to a cylinder-specific problem. Was frightened off inspecting the VST and HP fuel pump screen filter after removing the lower cowl to see what I was up against. Took the boat to shop for service suspecting that VST inspection was the next step. After a month in the service queue during this busy season, mechanic immediately replaced the original 2005 gray B1 fuel line (not ethanol-resistant) which looked like Dutch's photos above with B1, ethanol-resistant non-Mercury line and the primer bulb yesterday. In retrospect, the debris in the filter and sight bowl was the deteriorated fuel line liner. I never suspected the fuel line itself as the source of the problem. Have been naively using regular fuel with ethanol for however long ethanol has been in my local fuels. Also had some other basic maintenance done (plugs, impeller). Mechanic suggested I test the motor before servicing the HP fuel pump and VST. Tested motor for an hour under various loads and conditions yesterday. Symptoms gone with the smooth running I've always had. Changed the three year-old motor oil, filter and gear oil this morning. After viewing Dutch's photos of the clean VST and HP pump screen, I'm not inclined to have that serviced at this point. Am I being penny-wise but pound-foolish? Still in love with this boat, always stored in my garage, after 11 otherwise trouble-free, low cost and very happy years.

[Dutchman]

You know the saying when it isn't broke don't fix it so I would leave everything alone if it is running fine and blame it on that ethanol fuel deteriorating your fuel line