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My 2004 50hp Mercury is requiring an open throttle to start. What does this mean? Clean and rebuild carbs? Carb adjustment? Timing? It runs great but hard to start if it sits for more than 15 minutes or so. When throttle is open it immediately fires at very high rpm. Plugs, fuel filter, and primer bulb have been replaced. Also, I have verified that the choke/enricher is functioning properly.
It actually sounds like you are running ethanol fuel that has absorbed some water. The need to open the throttle shutters indicates a flooding condition. I'd take a fuel sample and inspect for the presence of water before I removed the cowling on the motor.
I agree with the "flooding" aspect, but not sure how water in the fuel would cause this. My guess would be the needle/seat leaking and when you are pumping the ball the fuel is going right into the cylinder(s). Is it a 2 or 4 stroke?
Its a 2 stroke with 3 cylinders. For the entire summer I ran ethanol free gas and I got the same result. I thought seafoam would have been my cure but it has also failed. Will the carb rebuild kit include all parts needed to fix a leaky needle seat? Is it possible that the low speed jets have some degree of clogging.
Water saturated fuel is less combustible. It requires a richer mix. If the fuel is dry, I would inspect it in this order.
Tilt motor slightly to a positive trim angle. (like a moderate shallow water drive position). Squeeze primer bulb. It should firm up solid after 4 or 5 full squeezes. If fuel begins pouring from a carb, you need the carbs cleaned as you have at least one needle valve that's not closing completely. If no fuel leaks but the bulb never gets completely firm. Squeeze it slowly. If you notice that fuel is still being moved upstream, you have a bad diaphragm in your fuel pump that's allowing fuel to travel directly into the block. If no fuel leaks and bulb firms up, walk away for 15 mins. Return and again squeeze the bulb. If you find that it is no longer firm and requires one or more squeezes to firm up, you have a bad primer bulb that is letting fuel pressure bleed back down. You may also want to elaborate on your test of the enrichener. Also, I've seen many folks that don't push in on the key until the starter is engaging. (a habit that comes from the days of choke shutters). With the enrichener, key on, push and hold, start engine. It makes for quicker starts.
You indicate that the motor runs fine once it's started which goes against the norm if a carb circuit is stopped up. Considering the age of the motor and the fact that ethanol fuels and additives made now aren't necessarily friendly with older made rubber components, it may be a good idea to have the fuel pump rebuilt with a new kit, have the carbs cleaned and adjusted and have the entire system checked over by someone who's in tune with the common problems of that particular motor design.
Be easy with the sea foam and other snake oils. They can be useful in keeping a motor in top shape. But they are used way too much in my opinion and cause problems that are difficult to diagnose.
If you are scratching your head trying to figure out how a bad primer bulb could possibly cause this. As the fuel gets passed the bad check valve in the bulb and returns down hill to the tank, it will have a siphon effect and drop the fuel pressure into the negative. The enrichener requires positive pressure in order to function. Which means the motor would have to spin over several times in order for the fuel pump to build pressure and bring the enrichener into operation. And most all motors will turnover faster with open throttle shutters. If that makes sense.
Also, if your fuel line is the original gray colored line, it has most likely become stiff. It stiffens as a result of the most inner layer becoming brittle. When it does that, it flakes off and the particles end up messing up the primer bulb, creating obstructions in the fuel pump and create problems in the carb among other things. If you have the gray line, replace it with an expensive ethanol resistant line from the auto parts store. It's less expensive and will outlast the ready made stuff.
I checked the enricher by turning key to on position and pushing the key inward; I was able to hear it click. Also, on initial startup if the engine tries to shutoff I can push inward on the key and it picks up again. Today, after reading your posts, I tilted the motor and pumped the bulb - the bulb got fairly firm but just a tad fleshy and no leakage from carbs. After 20 minutes the bulb retained the same level of firmness and still no leakage at the carbs. In addition, I held constant pressure on the bulb once it was firm and it did eventually start to collapse but just a small amount (1-2 minutes). Not sure if this is normal. Thinking back to when I changed the primer bulb, I also changed its lower hose because I could see where the interior was crumbling. I didn't change the upper hose because I was unsure about removing the factory metal clamp at the quick connector. My next move will be to replace the mercury gray hoses with 5/16 hose from the part store. Should I use zip ties at the quick connector or a traditional metal hose clamp? Maybe I should invest in a water separation filter.
I was unable to get a zip tie tight enough to not leak when I changed mine. I went with worm gear metal clamps.
A cheap zip tie tool will tighten the zip tie enough. If you prefer the clamps, go for it. Since it is recommended to always disconnect the fuel line from the engine when not in use, take an extra minute to make sure that the zip tie or clamp is free from sharp edges. Nothing worse than reaching over to pull the line and cutting a finger.
Sounds like you are on top of your game on this thing. Diagnosing from long distance has it's limitations.
I need some clarification on this, does this motor require that you give it 'some' throttle in order to cold start or is this a problem requiring the throttle be set wide open before it will start?
Also, has this problem always existed? Developed following a service or just developed over the course of a summer?
I start with throttle nearly wide open and once running I back off of the throttle; however if I back down too quickly it will die. This condition has existed every since I purchased the boat last spring. Didn't think much of it because I could tell the boat had been sitting for awhile. I have never taken it in for service but if I can't resolve the current issue with a simple solution I will definitely seek professional help. Just hate to fork over that kinda cash. Call me cheap if you like.
Ok, that's an important fact to know. If I had it here, the first thing I would check is the compression. Don't want to make you nervous but the compression needs checked. The second thing I'd look at (if the compression is good) is how the carb linkage is set. If it's been tampered with in the wrong way, it would explain everything. Ask around and find someone with a good reputation. Take it to them for service. And trust me. If you have to pay the bucks to that person, you are better off then throwing good money away, paying someone that knows very little.
yeah, I know a guy but he always seems to want $200 or more. Nevertheless, he does get the job done. Sometimes I think owning a boat is the most financially irresponsible thing I have ever done.
B.O.A.T. Break out another thousand!!!
If your boat has been sitting before you bought it, the carbs need to be taken apart and cleaned. When I bought mine it had been down for a few months (years) and the low speed circuits were all gummed up. Carb kits are about $10 or less, well worth it and pretty easy.
If the problem is in the carbs, he'll probably get another $200. If it's a compression issue, you'll wish it was $200.Quote:
Originally Posted by pauldo
Can't rule that out. But the fact that it's a starting issue and not a running issue has me thinking either a lack of compression or badly retarded timing caused by improper carb linkage adjustment.Quote:
Originally Posted by stevefishes
Problem solved. Decided I'd address the cheap stuff before making a trip to the boat shop. First problem, I think my fuel line was way too long and the valve in the primer bulb may have been working against me. Second problem, the zip ties I used to secure the fuel line were not holding tightly. The third and most significant problem was that the grey Mercury line looked to be clogged solid with bits of its plastic liner. Even the connector at the engine side of the fuel line was plugged pretty bad. Replaced all the grey line with regular black 5/16 line from Advance Auto, bumped the primer a few times, and the motor started immediately. Never had to touch the throttle. Also, I noticed that the primer bulb got much more firm than before. Cost me every bit of $4. Me and my fuel pump are smiling from ear to ear at this very moment. Thanks for all the help guys.
That amber colored plastic stuff use to be the liner of the gray line. They are bad about doing that. Glad you found that.
I replaced my fuel lines last year as a precaution since I don't use ethanol gas. One thing I would ask about the line you used is does it state it is ethanol compatible? Mine had it on the line, but seems like I read on here that the new marine lines for ethanol gas were blue. Just don't won't you to run into the same problem down the road if the replacement line is not ethanol rated. Glad that is all it was though and hope it runs good from now on.
That's not true about the blue fuel line. It just makes it pretty. I doubt you could buy fuel line that wasn't ethanol safe. Unless someone has some very old stock.Quote:
Originally Posted by SeaRay
The best fuel line I've seen in the last few years is the black rubber ones, available in auto stores. Marked "Ethanol resistant, not for fuel injection systems". Around 1.25ft and well worth it.
Good to know cause the one I got was not blue, but it said it was suited for ethanol use. I have not actually seen any of the "blue" line. I had a Mercury at the time and the fuel assembly was a Mercury product from a dealer. Funny thing is it was cheaper than an assembly from K-Mart.
It may have been cheaper because it was old stock and thus considered clearance. Seems like I read somewhere that the old Mercury lines had red print whereas the newer ethanol compatible stuff has blue print. At $3-$4, I'd rather buy the part store line and replace it each season as part of regular maintenance.
Update: After replacing the fuel line the boat started easier and even ran a little better, however I just didn't feel that it was performing at an optimal level. I pulled all three carbs, cleaned them, and replaced the gaskets ($30-$35 parts and carb cleaner). In one of the carbs I found what looked like fiber strands from a cotton ball; a very small amount but probably enough to cause trouble. Once back together the motor was running rough and wanted to idle at 1400rpm. A little tweaking of the idle/mix screws and the boat runs just fine. It fires up as soon as I tap the key.
Good job!!!!
Had a problem with my 2004 40hp to stay running. I could push in on the key and it would run good for a few seconds, idle speed was nonexistent. Took it into mechanics and they found factory hoses had been crumbling from ethanol which in turn clogged carbs. rebuilt carbs new fuel lines which weren't effected by ethanol and it runs good.