Evenrude 4hp outboard, only runs on choke

[kieronriley]

I have an Evenrude 4 hp outboard that will only run on about 3/4 Choke , could it just need the mixture adjusting. I took the jet out today and cleaned it ( though it did look ok on removal) on past experience I have found that this usually stops the problem , but not this time , are there any other common problems that I might try, thanks. Kieron

 

[VicS]

You don't say the age or the model number, which would identify it exactly.
Does it have two mixture adjustment screws or just a slow running adjustment.?
Try adjusting the mixture screw(s) as described in the workshop manual or as described by Joe Reeves on the iBoats forums engine FAQs
Carb Needle Adjustments For Asorted Carb Variations by Joe Reeves

If you cannot get it to run properly by adjustment of the mixture screw(s) it almost certainly needs a full carb clean.

 

[Slowboat35]

My virtually unused Mariner has done this repeatedly. Traced to a deteriorating fuel line between tank and carb shedding tiny pieces of rubber flakes that obstruct the main jet. Caused almost certainly by etahnol in petrol. Cure, dismantle, blow jets with airline, fit new fuel hose and small inline filter.

 

[kieronriley]

You don't say the age or the model number, which would identify it exactly.
Does it have two mixture adjustment screws or just a slow running adjustment.?
Try adjusting the mixture screw(s) as described in the workshop manual or as described by Joe Reeves on the iBoats forums engine FAQs
Carb Needle Adjustments For Asorted Carb Variations by Joe Reeves

If you cannot get it to run properly by adjustment of the mixture screw(s) it almost certainly needs a full carb clean.

You don't say the age or the model number, which would identify it exactly.
Does it have two mixture adjustment screws or just a slow running adjustment.?
Try adjusting the mixture screw(s) as described in the workshop manual or as described by Joe Reeves on the iBoats forums engine FAQs
Carb Needle Adjustments For Asorted Carb Variations by Joe Reeves

If you cannot get it to run properly by adjustment of the mixture screw(s) it almost certainly needs a full carb clean.

It has as far as I can see have only one and that is a slow running ( lean rich ) adjuster. Thanks

 

[Slowboat35]

Leave needle adjustments well alone unless you've already messed them about. It almost certainly isn't that. An engine that only runs on choke simply isn't getting fuel from the main jet as you've already discovered in the past simply by cleaning it out thereby restoring the engine to running. It won't suddenly stop running due to needle adjustments unless someone's just buggered about with - the needle adjustment! It can't bugger itself out of adjustment! Equally it would take a pretty major messing about with the adjustment to prevent it running at all without ¾ choke - it'd almost certainly still run but not happily.
What you've described is classic symptoms of intermittent lack of fuel flow due to blockage to/at the main jet. Find source of blockage, clean, fix source and you're done!The feed pipe from the tank isn't blocked because the choke is getting sufficient fuel, but it may be the source of the particles. A small filter - looks like two tiny funnels back to back close to the carb is advised for the future. You have removed the float bowl and cleaned it out punctiliously, and ensured the needle isn't sticking, haven't you? Crap left behind after ineffective cleaning is a frequent cause of this sort of problem reoccuring, usually thirty seconds or so after it restarted apparently fine following the previous clean-out and you were just congratulating yourself...
An airline to blow the carb's passages through is invaluable. It only takes the tiniest crumb to block the tiny jet and passages on one of thee engines. For heaven's sake doen't even think of riddling the jet out with a bit of wire/needle etc. If yo have done so - go and get a new one, cos the old one will be ph'ed...

 

[VicS]

It has as far as I can see have only one and that is a slow running ( lean rich ) adjuster. Thanks

If that is out of adjustment it will only affect slow running.
It's almost certainly in need of a carb clean.
Check the float height setting as you reassembleit but dont mess with it unless obviously incorrect .
Before you tear into it check the flow if it's from an internal tank . Also check the fuel filter
Is the carb one with a bladder that acts as a sort of fuel pump when drawing from an internal tank.

You indicate that this is arecurring problem therefore check and clean the fuel tank and the fuel hoses for deterioration

Post the model number as that will answer some of the questions I am asking.

 

[kieronriley]

If that is out of adjustment it will only affect slow running.
It's almost certainly in need of a carb clean.
Check the float height setting as you reassembleit but dont mess with it unless obviously incorrect .
Before you tear into it check the flow if it's from an internal tank . Also check the fuel filter
Is the carb one with a bladder that acts as a sort of fuel pump when drawing from an internal tank.

You indicate that this is arecurring problem therefore check and clean the fuel tank and the fuel hoses for deterioration

Post the model number as that will answer some of the questions I am asking.

Model number 45B66A serial number B5054, thanks for your time.Kieron

 

[kieronriley]

and sorry should probably give you the full story,i have only just come by this engine ,so cant be sure if anyone has played with the mixture screw, i am the yard and berthing master at my sailing club and a young lad (18) came to the yard looking for a trailer and an outboard for a mirror dinghy he had got hold of . the lad wanted to put it in the sea and tow it around to various places to ,just mess about in the water. we had an abandoned boat in the yard in relatively good condition,so we have given him the boat and i am now trying to get him on the water as cheaply as possible, hence this outboard, so thanks for your time and advice. Kieron

 

[fushion julz]

Yours is a 1975 4hp motor

I have newer (1985/87) versions, but I believe they are similar. Mine was doing something similar and I traced it to the coil(s). That was after a full carb clean and service, check of the float level and replacement of condensers and points.
I also replaced one of the spark plug leads as it was looking a little crusty!