Motor starts, dies immediately

[livemusic]

Still trying to get this 1997 Tracker (Mercury) 40hp motor to start more easily. It will start, then die immediately and that is only after choking it heavily and do it many times. Finally figured out that I can, after many attempts, advance the throttle way high while in neutral and crank it and, eventually, when I slam it in gear, it will take off at that high speed. If I then decrease the throttle, it will die but if I leave it near full open, it will keep running until I stop it.

 

Fearing bad gas or gas gone bad (it was not used much over two years), I siphoned out the gas. Was dismayed that I could only draw it down such that there is, oh, about 3/4 inch still in there. Do you think that it is normal that you will be left with that much? I can't see how I could siphon/pump more out.

 

I normally use 87 octane e-free but I then put fresh 92 octane e-free gas in with a good dose of Sea Foam for good measure.

 

Other than that question... just now, when I pumped up the bulb just for the heck of it until I get to the lake when I will pump it again before attempting to start it, I note that now, it will not pump up that well, the bulb does not firm up much. I don't recall this being like this a few days ago when I ran the boat but maybe it was. At any rate, could this bad bulb gas line be the culprit for this starting behavior?

 

[Jigfishn10]

I am by no means a mechanic, but had a similar problem.

I was told that the older engines really don't work with the higher octanes. I was advised to replace with the lowest octane I could get.

I changed the gas bulb out as well as the gas lines. Had no problems after that.

BTW, mine was a 2 stroke Yamaha if that means anything to you.

[InfantryMP]

My father had this similar instance on his Johnson 150 just last week. We changed the fuel pickup and everything in between to the motor. It was not getting enough fuel pressure to ensure the motor would stay running. They only need maybe 4 to 5 psi or maybe even lower for your motor. 

 

I slapped a new battery on his boat, new fuel setup as mentioned. Ensured the choke was functioning, we also advanced the throttle as you mentioned. That 150 fires right up every time now without any issue and stays running. I believed the fuel pick up, and the filter was clogged up from sitting for a while. 

 

 

[Way2slow]

Unless you have a good, spare lower unit laying around, DO NOT be slapping in gear at high rpm.

If you don't know what you are doing or how to trouble shoot the problem, taking it to a shop for repair is going to be cheaper than replacing the lower unit.

It seems very obvious you have a fuel delivery problem.

If you want to shotgun the problem (do something and hope it works) the most logical place to start it doing a proper cleaning and rebuilding the carburetors.  That only works if you know how, just taking one apart and cleaning it out is not how.  All the orifices, and there are several, have to be cleaned and check individually.

However, if you think revving one up and slamming it in gear is ok, I have serious doubts about you having the mechanical knowledge to clean and adjust the carburetors.  

 

I'm not trying to be ugly or sarcastic, but that's about one of the dumbest things I've heard.

Even if you get it going down the lake with dirty carbs, it can lean the motor out and melt a piston.

 

[galyonj]

3 minutes ago, Way2slow said:

Unless you have a good, spare lower unit laying around, DO NOT be slapping in gear at high rpm.

 

Yeah, you really don't want to do that. Neutral drops create expensive problems.

 

@livemusic, I agree that you have a fuel delivery issue. The gas itself may or may not be a problem (I can't speak to octane ratings as they apply to marine engines), but I'd bet dollars to donuts that, if you inspect the fuel lines, you'll find them clogged.

 

Replace each section of fuel line that you can't easily blow through.

 

Then see if it runs without choking down the airflow.

 

If it still needs to be choked down, or won't idle correctly, your carburetor needs cleaning and/or tuning.

[livemusic]

36 minutes ago, Way2slow said:

Unless you have a good, spare lower unit laying around, DO NOT be slapping in gear at high rpm.

If you don't know what you are doing or how to trouble shoot the problem, taking it to a shop for repair is going to be cheaper than replacing the lower unit.

It seems very obvious you have a fuel delivery problem.

If you want to shotgun the problem (do something and hope it works) the most logical place to start it doing a proper cleaning and rebuilding the carburetors.  That only works if you know how, just taking one apart and cleaning it out is not how.  All the orifices, and there are several, have to be cleaned and check individually.

However, if you think revving one up and slamming it in gear is ok, I have serious doubts about you having the mechanical knowledge to clean and adjust the carburetors.  

 

I'm not trying to be ugly or sarcastic, but that's about one of the dumbest things I've heard.

Even if you get it going down the lake with dirty carbs, it can lean the motor out and melt a piston.

 

 

As for it being dumb, I'm certainly capable, it won't be the first time, but to get it in gear, I have to pull the throttle back to idle position and then put it in gear. It might have been put in gear above idle throttle but not at the high rpms it was at, as that is impossible when you return the throttle to the idle/neutral position and then put it in gear. Slam it in gear meant after pulling it back to neutral, get it in gear quickly before it dies and give it the gas.

[Sir Shamsalot]

I'm not familiar with that make and model, but I would think your carb needle valves need cleaned. On smaller motors, i practice disconnecting the fuel line, and allowing the motor idle out the gas between uses.

[Michigander]

If your bulb isn't firming then the little valve inside it might be trash.

[Smokinal]

I agree with most of the above;

---clogged carb port

---bad fuel pump

---bad primer bulb

 

You mentioned it has sat for a while with not much use. I'd throw a fuel pump at it as it never hurts to have a fresh pump; most engines are cheap and easy.   I'd do the primer bulb while you're at it.

Then reassess

[Way2slow]

OK, that's sound a little better, but you still don't won't to be slamming it in gear if the rpm's are above 800 rpm, even at that you get a pretty good clunk.

 

Take one of the fuel line off a carburetor, pump the primer bulb and see if you are getting a good, unrestricted flow out of the line.  If so, leave the line off and crank the motor over some and see if you get a good fuel pulse.  It will be in pulses because it only pumps fuel when the piston the fuel pump is connected to is on the down stroke.  It should make pretty good squirt and not just a mere trickle. 

If you are getting just a trickle or no fuel at all, the fuel pump is not working or not getting fuel to it.  So, you need to chase that rabbit and find out why it's not giving a pulse of fuel.  

If you are getting a good pulse of fuel, it's time to take the carburetors off.   

[GaryH]

Livemusic if you have a trust worthy marine mechanic near you it would be worth it to have him look at it and give you a diagnosis on the issues your having. Sometimes you can throw a lot of money at a problem before you find the problem. 
If your set on doing it yourself then I would follow the good advice you’ve been giving. Good luck I hope it works out for you.

[livemusic]

I had a mechanic tell me one time that these fuel line/bulbs that you buy at Walmart, Academy, Basspro, etc. are crap. He was REALLY against them, adamantly so. He advised letting him 'build' me one. Mine was brand new, so, I didn't do that, lol. Anyone know how one could build one superior? I was wondering if he makes it such that there is no clamp to the motor but it's a direct line. Meaning that instead of having the clamp gizmo on the end, it would just directly, permanently attach to the motor with no clamp like bigger motors do. Other than that, only other thing I can think of is him using, supposedly, superior line or bulb.

 

I tried the boat again in my yard with the ears that you put on the bottom for the garden hose and worked with it and it's running better now but not perfect. It seems to be cleaning up some but I'd rather take it the lake and have it in the water.

 

Am suspicious of this gas line/bulb since it won't firm up much.

3 minutes ago, Way2slow said:

OK, that's sound a little better, but you still don't won't to be slamming it in gear if the rpm's are above 800 rpm, even at that you get a pretty good clunk.

 

Take one of the fuel line off a carburetor, pump the primer bulb and see if you are getting a good, unrestricted flow out of the line.  If so, leave the line off and crank the motor over some and see if you get a good fuel pulse.  It will be in pulses because it only pumps fuel when the piston the fuel pump is connected to is on the down stroke.  It should make pretty good squirt and not just a mere trickle. 

If you are getting just a trickle or no fuel at all, the fuel pump is not working or not getting fuel to it.  So, you need to chase that rabbit and find out why it's not giving a pulse of fuel.  

If you are getting a good pulse of fuel, it's time to take the carburetors off.   

 

Ok, will do that. I am awaiting a fuel filter, I want to change that. I also see that the fuel pump is readily accessible if I have/need to change that.

 

I put new spark plugs in it and that didn't do anything even though the old ones looked HORRIBLE.

 

It sure is hard to find a good and trustworthy boat mechanic. I have a phone call into a guy who told me about a good one. I want to find out if my friend still feels that way, lol, as this was years ago. If I could fix it myself, I'd rather, as I'd bet money he is weeks behind and it's fishing time!

[Way2slow]

Can't really blame you there.  It would give me cold chills to even think about having to trust a mechanic, of any kind.  

I've been doing this stuff for over 60 years and in that, I can just about count on one hand those I've come across that I would consider a "good" mechanic.  The only way so many of the know how to diagnose a problem is to stick a new part in and see if that fixes it.  If that doesn't then another part goes until the find the one that fixes it.  However, you still get stuck with the bill for all the other parts, because it was a chain reaction situation that caused all the other parts to be bad also.

Not even going to mention finding an honest mechanic, they are almost an extinct breed in todays economy.  There is no such thing as a five minute simple fix replacing a blown fuse, fixing a broken wire, or tightening something loose, unless it was a warranty repair.  

 

However, at the same time, I've seen soooo many people turn a simple fix into a major repair, trying to fix it them self 

[livemusic]

10 minutes ago, Way2slow said:

Can't really blame you there.  It would give me cold chills to even think about having to trust a mechanic, of any kind.  

I've been doing this stuff for over 60 years and in that, I can just about count on one hand those I've come across that I would consider a "good" mechanic.  The only way so many of the know how to diagnose a problem is to stick a new part in and see if that fixes it.  If that doesn't then another part goes until the find the one that fixes it.  However, you still get stuck with the bill for all the other parts, because it was a chain reaction situation that caused all the other parts to be bad also.

Not even going to mention finding an honest mechanic, they are almost an extinct breed in todays economy.  There is no such thing as a five minute simple fix replacing a blown fuse, fixing a broken wire, or tightening something loose, unless it was a warranty repair.  

 

I just complained to my brother about this very thing... not trusting a mechanic... take this fuel line/bulb issue... let's say that this is the problem... I could take it to an untrustworthy mechanic and instead of it being a cheap fix, the fuel line/bulb, he could charge me the standard $400-anytime-you-let-hime-touch-it deal. Problem is, I am, obviously, not a good mechanic, so, if I can't fix it, I have to take it to somebody.

 

BTW, I thought I would add... one time I did take this boat to a recommended mechanic and he told me that this particular motor is notorious for this starting problem. (This is not the first time it has acted up.) At that time, for some reason, I could not leave it with him for a complete tuneup. He got it running well with some fairly simple fix and I don't recall what the fix was. It wasn't major and it was pretty fast. But anyway, he was adamant about him being able to tune this particular motor. He was very confident about it. It was one of those deals where he said that too many people don't know the 'trick' to tune them. That is what I recall the essence of the conversation was... his confidence that he could make it purr like a kitten if he could do his magic on it. I'm getting fired up about seeing him again, lol. If he's still in business, that was a few years ago.

[J Francho]

So, you don't have the skills and don't want to pay someone that does?  Sounds like you're on an island.  Living near the Great Lakes, there are literally a ton decent boat mechanics within an hour that all do good work and have good reputations.   The dudes that can't do good work are weeded out pretty quick.

[Way2slow]

Like J Francho said, if you don't have the skill set to fix it yourself.  Your only option is a mechanic.  Also remember, if they are a whole lot cheaper than most of the others, there is a reason.  A good mechanic, that has to do it for a living is not going to work nothing.  I've been retired since 2011 and still have some of my old customers call me sob stories about how they have done paid a fortune to get a piece of equipment fixed, and it's still not working, and if I would come a fix it for them.  A couple I do, because I still depend on them of certain favors from time to time, but most, I tell them, "sorry".  I have this thing, I consider a favor owed by the right person is a whole lot more valuable than money.

Without being able to diagnose other fuel delivery problems, carbs are the most common cause of the problem you have having.  Next would be the fuel pump and other associated items. 

With that said, I do not advocate anyone that does not have a good understanding of how a carburetor works, what to look for and how to clean one to even think about trying.  Carbs control the fuel air mixture, if it's not right, they either don't let it run, flood it out, or lean it out and melt pistons. 

[TnRiver46]

2 hours ago, Way2slow said:

Like J Francho said, if you don't have the skill set to fix it yourself.  Your only option is a mechanic.  Also remember, if they are a whole lot cheaper than most of the others, there is a reason.  A good mechanic, that has to do it for a living is not going to work nothing.  I've been retired since 2011 and still have some of my old customers call me sob stories about how they have done paid a fortune to get a piece of equipment fixed, and it's still not working, and if I would come a fix it for them.  A couple I do, because I still depend on them of certain favors from time to time, but most, I tell them, "sorry".  I have this thing, I consider a favor owed by the right person is a whole lot more valuable than money.

Without being able to diagnose other fuel delivery problems, carbs are the most common cause of the problem you have having.  Next would be the fuel pump and other associated items. 

With that said, I do not advocate anyone that does not have a good understanding of how a carburetor works, what to look for and how to clean one to even think about trying.  Carbs control the fuel air mixture, if it's not right, they either don't let it run, flood it out, or lean it out and melt pistons. 

But How can you learn how to take apart a carb without taking apart a carb? I say practice on a cheap lawn mower first haha. 

[Way2slow]

Some lawn more carbs are the hardest.  A lot of carbs have small dome disk in them that have to be penned in, covering joints were they had to make holes from two directions.  The only way to properly clean them is to take that disk out, that can be a challenge, and getting the new one back in so it doesn't leak can be a bigger challenge.  Some carbs have the intermediate orifices in another removeable jet behind the main jet or in another passage off to the side, that has to come out.  Do that one wrong, or somebody else didn't do it right, I might not come out, making it impossible to clean.  That means getting a replacement carb.  You have to know where and what orifices you are looking for and what they do.  For what a boat motor cost these day, and how temperamental they can be, that's not where I would suggest getting into carburetor 101.   Then with a multi-carb setup, you've got to know how to balance them.

 

I will say, it's not uncommon for the fuel to evaporate out and leave that lacquer build up in the bowl, and since a lot of time the main jet is at the bottom of the bowl on a lot of them, it get plugged also.  If the bowls have large headed brass screws, you can take out, those are usually access plugs for the mains, so all it have to do is screw the main out, clean it and put it back in.  Might even be able to use a tooth pick or sharpened wooden skewer and spin around in the jet and clean it.   However if the layer of crud is deep enough, it's going to plug more than just the main.    

[Log Catcher]

I had my boat at the dealer a few years ago to get a water pump put in it. While they had it they called and said I need new fuel lines and primer bulb. The reason the ones I had could be damaged by ethanol and cause a lot of problems later on. They replaced them some that ethanol is not supposed to cause problems with.

[E-rude dude]

Since the boat was sitting for 2 years. I would start by eliminating the fuel tank as the problem.

Buy a cheap plastic tank with a primer bulb and hook it up to the engine. If the engine runs the problem is in the tank fuel lines or bulb. If it still stalls the problem is in the motor. 
A good service manual will tell you how to test the fuel pump pressure. 
Replace the fuel filters. Replace the plugs

If those check out. My guess would be carbs/injectors are dirty. Sea foam was a good idea. 
While your looking at the manual look at compression testing. It would also be a good idea. Motors can run on a dead cylinder. They are usually hard to start though.

[Way2slow]

E-rude dude, you commented on something, I made an assumption on he had already done. making sure it was running on both cylinders, but I'm sure you have heard what assumptions do.  

Livemusic, I hope you have done that, but if you haven't, That's the very first thing you need to do.  You mentioned you replaced the plugs because they looked bad.  When it starts up and dies, have you pulled the plugs and made sure it was running on both cylinders.  If one is wet or has no color it's not running on that cylinder.  You always start with the basics, Ignition Fuel, and Air.  Start with making sure both cylinders have good compression, then make sure they both have good ignition, at the proper time. Without those, fuel delivery does nothing.

[HenryPF]

This guy explains the reason why you should replace the fuel lines:

 

 

 

 

[Way2slow]

OK, my last post.  Enough other experts in hear to take care of the problems.

Like I said, you can shotgun it all day long and hope you finally find that magic fix, or you can go through a logical sequence of trouble shooting procedures and find what the problem is.  If you are not mechanical enough to know what or how to go through that logical sequence, then you need to find a professional mechanic that is, but just doing stuff or swapping out stuff in some random order is not the way to trouble shoot the problem.  

As for just swapping out fuel hose, unless you are buying a high quality, major brand, to replace what you have with, you could be putting on new hose that's worse than the old stuff you took off, and if you use that grey stuff you get in a kit from walmart, that's is about the worse stuff you can buy, unless you want to replace it every couple of years.

The very first thing is the check the compression, 10% or more difference between cylinders is considered a motor on the verge of needing rebuilt.  Sometimes a good decarb will help that.

Then you want to read the plugs and see what they tell you.  They are a key indicator of many problems.  If you have thrown the old plugs away, the new plugs my not have colored up yet.

Understanding the basics and following those is the key.  Running is easy if you know how to walk, but first you have to learn how to walk,

Good Luck.

 

[J Francho]

13 hours ago, Way2slow said:

Some lawn more carbs are the hardest.

I can testify to this.  My current rider needed carb work.  I opted for a new carb since it was a little more than the parts and easier to replace the whole thing.  I am not much of a 2-cycle guy, but my son is and I haven't bought any new lawn equipment in well over decade.  My boat outboards usually go to a Merc technician, though I've changed a starter, and always winterize myself.  I look at this way: my lawnmower poops out, the grass gets long.  My outboard poops out, and I might be stuck out on Lake Ontario floating to Canada.

[bulldog1935]

My dad's Johnson 115 smoker behaves with much the same symptom - it loses the ability to idle. It wants to die when you drop the throttle and are trying to shift.  He chased the fuel question for a couple of years and replaced everything.  

 

In his case, we traced it to the throttle cable housing sliding in its boss on the motor frame - when it slides, it has the effect of lengthening the throttle cable so that you need more throttle to hold idle.  Have to loosen the bolt, push the housing shorter and re-tighten.  It will run fine for awhile and slide to the same bad spot from motor vibration.