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first sailed january 2008
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Discussion Starter · #1 · (Edited)
Four stroke outboard died. Fuel?

1. New 1990's honda 7.5hp dinghy outboard. Short shaft. Ran it today for the first time since test run and it was beautiful. Then I got back to the harbor and throttled down all the way and it shut off. I tried a various combination of pulling, the choke, and various throttle positions and it wouldn't start again.

The primer bulb wouldn't stay as tight as I'm used to and I may have heard a hissing sound from the attachment where the fuel line connector connects. I had also messed with the two bolts under the hood that adjust the throttle. When I bought it it was so tight it started at mid throttle and couldn't be turned down. The throttle doesn't turn much. From idea to full you only have to tuen the throttle about 50 degrees.

Those are your clues. Please let me know where to begin.
 

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north, not knowing what two screws you turned makes answering your question rather difficult. I'm guessing you messed with the mixture? On many small engines, there is often a procedure to tighten it all the way down and back it off a defined amount, then fine tune. Do you have the repair or workshop manual for your outboard. Even those of us with more mechanical experience than you would have all of these aboard for every major system. My Grandmother used to say, "if you can read, you can cook". A tad more to it, for sure, but it was good advice to anyone that thought they couldn't. Close to the same for many repairs.

Since you already own the boat, you may want to be on an accelerated curve. Are there adult technical ed resources in CA? There must be. I'm familiar with them in other places of the country. Everything from diesel mechanic to electrician to woodwork to refrigeration are usually available.
 

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first sailed january 2008
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1,409 Posts
Discussion Starter · #3 ·
I turned two nuts. The cable that goes from the throttle handle has two small nuts that attach the cable inside the housing. I think they are for adjusting the throttle.

This may not be the problem. I was just throwing out there all info that I did. When I bought the engine the seller had the throttle really high so when all the way backed off, it sill started at high rpm's and couldn't go lower until I adjusted the nuts.

I'm thinking it's more to do with not getting a steady fuel flow. Just because I hear that air sucking sound from the hose connector. Perhaps that one is just old and it needs a new one.

It was running really nice on my test run until I throttled down all the way and it shut off. So maybe it is that I adjusted the idle too low so it dies, but why then not restart with more throttle?

Another thought is that the carb is partially clogged. Someone mentioned when I was first testing the engine and told them how fast the throttle was set, that maybe the seller set it like that so it would get lots of fuel and would start for selling purposes.
 

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If you dont know what scews you are stuffing around with then read the f'ing book... Available free on the internet :)

Then go back and do what your first reply suggested :) bit I prefer JimRaffords idea... Take it back... But thats difficult with Craigslist etc.
 

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first sailed january 2008
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1,409 Posts
Discussion Starter · #7 ·
You may be better at this than you know.
Thanks! :).

I didn't know the manuals were available as downloads these days. I remember them being plastic wrapped and stores having like 100 different ones. Manuals huh, I guess.

Even if I hadnt gotten it from Craigslist, I don't think I would return it yet. I think it's going to be a small issue. To me it says "fuel issue". Might be wrong.
 

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Tank vent open??
 

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I assume this engine has an external fuel tank, most engines of that size do.

The fuel line is a consumable item and may be leaking at the bulb. This could have killed the fuel prime when the engine speed dropped and the fuel pump couldn't overcome the air leak. When you tried to restart it you may have just flooded the engine trying to reprime it.

When I had an outboard powered sailboat I always carried a spare fuel line assembly as a backup. It is a cheap bit of insurance.

I think you misunderstood our comments on chat about setting up threads. A single boat buying thread provides a lot of context and would have helped people follow along. A single thread that changes between questions on Honda outboards, adjusting the steering on your inboard powered sailboat, and proper sail trim could be confusing (I picked the latter two topics at random). Additionally I'd encourage you to put proper titles on your threads. You have a few words to provide all of the context necessary for someone to know "Should I click on this?" A good title for this thread would have been "My Honda outboard is dying at low idle and hard to restart".
 

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Bombay Explorer 44
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If the engine has sat for a while then there is a very good chance that you have gummy goop in the carb. Remove the bowl clean everything out and blow through the jets paying particular attention to the slow running system and the float needle valve. I usually pump some fuel through the system with the carb bowl off. Anything to shift the goop. It is pretty easy which is the good news, the bad news is you may need to do it more than once.

This is a very common problem with 2 st engines that have not been run dry before storage.
 

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If the "hissing" sound is in fact a sucking sound then that is your most likely problem. So locate the air leak and if it is on any component of the fuel line - tank connector, bulb connector, bulb, bulb connector, engine connector - replace it as recommended above. Also inspects closely the engine and tank connectors to insure they are in good condition.
It really sounds like the PO adjusted the throttle to keep it running and ignored the low speed problem. Running at high speed would indicate the tank vent was open, unless the tank connector is where the leak is located.
I would call him and ask him directly about this. He could demure, even lie to you, but you will have placed the seed in his conscience, if he has one.
John
 

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A new hose doesn't cost much, & is quick to change. If it runs OK at speed there are two possibilities:

1. The low speed fuel mixture may need to be adjusted. On my motors it is a small screw
near the mouth of the carb. I back it out until the engine starts to stumble, then just back until it runs smooth. Some screws adjust air flow, some fuel. If it starts to cough or spit it is too lean. If it just starts to run rough, probably too rich. The screw may have a plastic cap over it which you have to remove.

2. Next & final adjustment is idle speed by adjusting the throttle linkage adjusters, which sounds like what you have been doing.

If neither of these work, as mentioned, the carb may have debris in it from evaporated gas. Suggest you try the mixture & speed adjustments first. "Hissing" is not good & likely the problem.

A shop manual would be a big help.

Paul T
 

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A plugged jet can give you that 'groan' on a start attempt...
 

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first sailed january 2008
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1,409 Posts
Discussion Starter · #15 ·
Thanks. To clarify. It's a four stroke, not empty of fuel, and the vent is open. I will look up petcocks.

I started it today, and I think yesterday I flooded it, as mentioned, because to day it would start every time, and if I left the throttle wide open, it would run, but when I lowered the throttle it would die. So that's what it is, something to do with with not getting enough fuel at low throttle. But I have had outboard before, I know what the throttle should sound like at idle, and at the speed it dies, it should be running.

I'm going to get a new connector piece or whole new hose today, in about an hour..
 

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Dying at idle speeds in all conditions usually means that the idle jet in the carb is clogged with debris or varnish. A new hose won't fix that. A new hose will fix an air leak in the hoe.
 

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I will start with trying to clean it out with seafoam. I've had good luck with that in the past. If not I'll take the carb apart. Probably another of those things I should know how to do.
Forgot this, after you get it dialed in/fixed, suggest you drain the carb if you are not going to run it again within a week or so.

Paul T
 
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