Outboard Blues

[blackrose]

36 minutes ago, Alan de Enfield said:

I was always told to tilt the outboard out of the water and let the cooling water drain out.

 

Reason : To stop the water freezing up and 'bursting something' in the engine or leg.

 

Ok but it's not a closed cooling system so surely as the water starts to freeze and expand it will be forced out and won't burst anything? I suppose if it froze at one point and trapped unfrozen water inside it could happen.

 

Anyway, I've never had a problem over many freezing winters.

Edited July 16, 2023 by blackrose

[Alan de Enfield]

6 minutes ago, blackrose said:

Anyway, I've never had a problem over many freezing winters.

 

 

Neither have I, but I've always either removed the OB (up to 50hp) if they will be unsuded for some months, or, left them 'up' on the trim-lock (50+ HP)

[Guest]

Are these older outboards OK with E10 fuel?

 

I know some older garden machinery isnt

It can harm fuel systems/lines.

[Alan de Enfield]

4 minutes ago, M_JG said:

Are these older outboards OK with E10 fuel?

 

I know some older garden machinery isnt

It can harm fuel systems/lines.

 

Yamaha outboard motors are not designed to operate on Ethanol Blended Fuels at any percentage1. Using SP95-E10 fuel in a Yamaha 4-stroke marine engine is not recommended2. Yamaha outboard motors built after 2003 can run on E10 petrol, but those built before 2003 cannot3. The newer Yamaha outboards and their components have been designed to withstand the corrosive properties of ethanol fuels, but it is still recommended to run the manufacturer’s stated octane fuel, and also subscribe to the major brand-name fuel suppliers that add detergents and lubricants like Techroline to their fuels

Edited July 16, 2023 by Alan de Enfield

[Tony Brooks]

Such fuel certainly wrecks the fuel pump diaphragm cum valves in my mower over a couple of years. They twist, soften and distort.

[Guest]

Just now, Tony Brooks said:

Such fuel certainly wrecks the fuel pump diaphragm cum valves in my mower over a couple of years. They twist, soften and distort.

 

My Webb mower has started behaving erratically this season (symptoms similar to the OP's outboard as it happens). Im suspecting the use of E10 fuel, despite Webb claiming it is OK to use.

[blackrose]

I use Briggs & Stratton fuel additive in the fuel for my outboard and generator as it tends to get left in there for long periods between uses. 

 

https://amzn.eu/d/5eDoCzN

 

The other thing I do after I've finished using them is always switch off the fuel tap while the engine is running and let the carb run dry until the engine conks out. Because there's no fuel left in there I think it's less likely for it to gum up the carb. 

[Mad Harold]

A couple of things come to mind.

The auto choke is I think that solenoid?on top of the carb.

Put your ear close when you switch the ignition on, and you should hear it click.If it clicks on, keep the throttle in the tickover position, while starting or it will over fuel.If it doesn't click, give it a bit of throttle when starting.

The other thing it could be as I think it may keep running if you keep squeezing the primer bulb, is a perished fuel pump diaphragm.

This is operated by vacuum pulses from the manifold, and if E10 petrol has been used it will perish quicker than normal.

[bigfatmatt]

I’m using Super Unleaded which I believe is E5.

 

I don’t know if the previous owners used E10.

Edited July 16, 2023 by bigfatmatt

[Guest]

1 minute ago, bigfatmatt said:

I’m using Super Unleaded which I believe is E5.

 

Yes, it is.

 

 

 

That should be OK.

[Tony Brooks]

9 minutes ago, M_JG said:

 

Yes, it is.

 

 

 

That should be OK.

 

It still has ethanol in it, so will just take longer for the ethanol to affect the diaphragm. My mower has lost maybe two years life on E10 for the diaphragm compared with E5.

[Guest]

2 minutes ago, Tony Brooks said:

 

It still has ethanol in it, so will just take longer for the ethanol to affect the diaphragm. My mower has lost maybe two years life on E10 for the diaphragm compared with E5.

 

Fair point.

[Bod]

Does this outboard have a Kill Switch?

If so is it set to Run?

 

Bod.

[bigfatmatt]

16 hours ago, Bod said:

Does this outboard have a Kill Switch?

If so is it set to Run?

 

Bod.

 

The kill switch is a clip below the ignition, if the clip comes off it will kill the engine. There’s not one on the outboard itself.

[jonathanA]

I think the kill switch would let the engine turnover on the starter but not fire. As the OB fires and runs seems unlikely its anything to do with the kill switch or dodgy electrics.  

 

on the one i'm familiar with (looks very similar) the wiring at the O/B end had a dodgy fuse holder and that caused some intermittent engine stopping/not starting problems until we replaced the knackered fuse holder and silver papered fuse....   the pics in this thread seem to show pretty tidy electrics at the engine end.  We also had a problem with the 'neutral' switch on the OB - it needed a slight adjustment as it wasn't operating properly.  in the first video it looks as though the engine might be in gear ?  - hard to tell but that could be  a problem ?

[bigfatmatt]

38 minutes ago, jonathanA said:

I think the kill switch would let the engine turnover on the starter but not fire. As the OB fires and runs seems unlikely its anything to do with the kill switch or dodgy electrics.  

 

on the one i'm familiar with (looks very similar) the wiring at the O/B end had a dodgy fuse holder and that caused some intermittent engine stopping/not starting problems until we replaced the knackered fuse holder and silver papered fuse....   the pics in this thread seem to show pretty tidy electrics at the engine end.  We also had a problem with the 'neutral' switch on the OB - it needed a slight adjustment as it wasn't operating properly.  in the first video it looks as though the engine might be in gear ?  - hard to tell but that could be  a problem ?

 

The engine wont start in gear, I did put it in gear in one of the videos to show that it’s happy to fire on gear while fuel is being pushed into it.

[Tacet]

In days of old, the fuel tank was pressurised to lift the petrol to the carburettor

 

If it runs when being primed with the bulb - but not otherwise - could it be the filler opening is not sealing, for example?   

 

PS I now note the OP refers to the fuel tank vent as being open!

Edited July 17, 2023 by Tacet
add the PS

[Dockeroo]

- Are you making sure the cap of the fuel tank has its air vent open? Its like the lid on top of the lid that you open to let air get in the tank as the fuel drains, if you dont then the engine will cut out as the fuel can't leave the tank as the lid is sealed shut completely.

 

- Other thing is the fuel line and or filter from the tank to the motor can get clogged and need to replace.

 

 It really sound like one of those if you haven't yet checked.

Edited July 17, 2023 by Dockeroo

[bigfatmatt]

17 hours ago, Dockeroo said:

- Are you making sure the cap of the fuel tank has its air vent open? Its like the lid on top of the lid that you open to let air get in the tank as the fuel drains, if you dont then the engine will cut out as the fuel can't leave the tank as the lid is sealed shut completely.

 

- Other thing is the fuel line and or filter from the tank to the motor can get clogged and need to replace.

 

 It really sound like one of those if you haven't yet checked.

Cap of the fuel tank has the air vent open, confirming.

 

I’m going to take another look tomorrow with a mate who knows what he’s doing. Seems like the most likely culprits are fuel line/primer bulb, spark plugs, and jets.

[Tacet]

8 hours ago, bigfatmatt said:

Cap of the fuel tank has the air vent open, confirming.

 

I’m going to take another look tomorrow with a mate who knows what he’s doing. Seems like the most likely culprits are fuel line/primer bulb, spark plugs, and jets.

I still think you may need to have the vent closed! In some outboards, pressure is developed in the tank to push the petrol into the carburettor.  And an open vent on a petrol tank that may (even if not in your case) typically sit in the bilges is hardly a good design.

 

The best idea would be to check the outboard manual.   If not, post the model on here and someone may know.

[Tony Brooks]

All our Mercury and the odd Evenrude and Chrysler in the 1970s has a SINGLE (not twin) fuel line and had to have the tank vent open.

 

If it is to work as Tacet says, then you need two "fuel" lines, so the motor can pressurise the tank as far as I can see.

[Tacet]

12 hours ago, Tony Brooks said:

All our Mercury and the odd Evenrude and Chrysler in the 1970s has a SINGLE (not twin) fuel line and had to have the tank vent open.

 

If it is to work as Tacet says, then you need two "fuel" lines, so the motor can pressurise the tank as far as I can see.

On some Hondas, at least, both lines were incorporated into one flexible pipe.

[rusty69]

Our small Honda outboard was playing up yesterday. It would start and run and almost immediately cut out. I took the bowl off the bottom of the carb,which had bits of rust in it, took the jet out, blew it through, new o ring (the old one had swelled). It started first pull. 

[bigfatmatt]

Update:

 

- Replaced spark plugs

- Replaced fuel filter

- Replaced the fuel and added some Redex, emptied all the sediment out of the fuel can

- Cleaned the carb & jets with carb cleaner

- Cleaned the fuel line out thoroughly

 

Engine will now start and run in neutral or in low revs, if I try to push her to higher revs even warm she cuts out. Thinking I need to find a Yamaha outboard specialist at this point. Thanks for suggestions.

 

Also trying to start with the vent closed she chokes out instantly, there is safe ventilation out of the compartment the tank sits in so fume buildup isn’t a major concern.

Edited July 20, 2023 by bigfatmatt

[Tony Brooks]

Have you blown through the jets or just soaked them with cleaner.

 

This is not in any way a diagnosis, but it is sounding more and more like a failing ignition module. I know some OBs have had a problem maintaining a good earth (negative) connection between module and metal parts of the engine, so see if anything is corroded, loose or dirty.

 

FWIW, I also understand that for some OB the ignition module sold for the same brand's motorcycles work and are cheaper.

 

As I said, this is not a diagnosis and is only intended to give you something else you can check.