Mercury 4hp wont start, fuel problem

[allymoss]

I just bought a 1998 merc 4hp s/s. I was shown it running by seller but it took him a while. He said it was because it was on its side in the van. He cleaned the spark plug as it was covered in petrol, and it started first pull after that. 30mins after arriving! It ran for 20mins then I turned it off. I could restart easily.

Now, I cannot start it. I pull the cord a few times and then take the spark plug out only to find it covered in petrol. I clean it and replace it. It starts for about 1/2 a second and dies. I have tried fiddling with a screw that has a spring round it. On the end of this screw is a needle, I beleive the fuel valve, setting how much fuel goes in. If it tighten it in so it is closed, and clean the spark plug, it runs for about 5 seconds. Then dies and will not restart.

Am I fiddling with the correct screw? What do I do! Help meeeeeee! Please.

 

[Laddies]

Re: Mercury 4hp wont start, fuel problem

Start by cleaning the carb

 

[JUSTINTIME]

Re: Mercury 4hp wont start, fuel problem

do what laddies says
and buy a manual also

 

[allymoss]

Re: Mercury 4hp wont start, fuel problem

Have bought manual. Cleaning carbs is pro work isnt it. I am used to British Seagulls, wipe them with your thumb! Do I need to remove it and take it somewhere? excuse my noviceness!

 

[allymoss]

Re: Mercury 4hp wont start, fuel problem

Manual on its way and just bought a can of carb cleaner.

You say to clean my carb but will that solve the amount of fuel getting to the cylinder?

My carb has the air intake at the front. I take a cover off and I can see right down the carb. The choke is a round piece of metal on a stick, that rotates like a chicken on a rotisarie. Do I spray down there? Also, on top of the carb, there is a metal plate, I take it off and inside are 2 rubber caps. I take them off (they are loose) and one is just a small cavity, the other is a larger cavity with 2 brass holes. I think these are jets. Shall I spray them as well?

 

[allymoss]

Re: Mercury 4hp wont start, fuel problem

I took the carb off and sprayed it with cleaner. Put it back on and it ran dream for 30mins then I turned it off as I had to go. I went back out a couple of hours later and it wouldn't start, not even one fire.

What should I do?

 

[JB]

Re: Mercury 4hp wont start, fuel problem

Go to Engine FAQs, allymoss.

Do the troubleshooting in "Outboard won't start".

Let us know what you find.

 

[allymoss]

Re: Mercury 4hp wont start, fuel problem

Hi,

looked at FAQ but have checked all that, there is plenty of compression and a spark. I had it running for 30mins no problem yesterday. stopped it started it ok but when left for a couple of hours it wont start!
Is there a tickler for the float on these modern carbs, I haven't noticed one but it would be useful to know.
My email is allymoss(at)gmail.com if anone has any ideas.

 

[allymoss]

Re: Mercury 4hp wont start, fuel problem

Hi, Went out today. Tried to start, it wouldn't. I cleaned the plug off a few times then, I turned the throttle up a bit and sprayed some cleaner in the carb, it started first pull! Will try again tommorow.

 

[Plainsman]

Re: Mercury 4hp wont start, fuel problem

Don't spray the cleaner in the carb to start it. You need to have oil in there as well. Use a premix of gas and oil to try and start it.

Just taking the carb off and spraying cleaner in there will help some, but you need to soak them in cleaner, then use compressed air to clean it out.

I'd wait for your manual and do it correct or you may cause yourself more headaches.

What is your starting procedure?

 

[allymoss]

Re: Mercury 4hp wont start, fuel problem

Hi,

Starting procedure.
TUrn fuel on, undo air filler cap ontop of tank
Put throttle in indicated position (i have tried others)
Pull the cable.
I do not use the choke as it seems the cylinder gets too much fuel anyway. I have tried it before but to no success.

I have manual now and had a look through. It just tells me how to dissasemble it which I have already done!

 

[allymoss]

Re: Mercury 4hp wont start, fuel problem

Any help would be appreciated!

 

[steelespike]

Re: Mercury 4hp wont start, fuel problem

It sure sounds like it is flooding.Possibly too much choke
but more likely carb needs a rebuild with special attention to cleaning.If the float doesn't work properly it lets in too much gas and floods the motor.you can check by trying to start then thourghly dry the plugs when it fails to start.Unhook the fuel line and try again without choke then choke..It may start if it does reconnect the fuel line.
If it starts without fuel line it is a sure indication it is flooding.Sometimes when the plugs are repeatedly wet they may fail though for both to fail would be rare.
If you suspect the motor has been sitting alot you may have to go through the fuel system from tank to carb with specual attention to cleaning.If the motor has a kill switch or safety lanyard be sure it is working properly.

 

[allymoss]

Re: Mercury 4hp wont start, fuel problem

Hi,

I have tried unhooking the fuel line and have cleaned it with cleaner. Float works, I have had it running but after 2 hours, it wont fire up again!

I will check the kill switch again as it is the obvious cause!

 

[allymoss]

Re: Mercury 4hp wont start, fuel problem

Took the carb off, soaked in cleaner and repaced, started straight away. 2 hours later I went out and it woudln't start! Spark lpug gets coated in fuel! I drain the float bowl and turn fuel off but it still happens. I left the plug out for a bit and let the carb dry out a bit, re clelaned it but no luck. I really dont know what to do!

 

[jimlad]

Re: Mercury 4hp wont start, fuel problem

just a guess but have a check to see if the float is damaged or split if it is it will let fuel into it thus making the float stay down cause of the weight of fuel in it or the float it self may need adjusting to stop it overfilling

jimlad

 

[jimlad]

Re: Mercury 4hp wont start, fuel problem

also you cant beat really taking the carb apart and cleaning it manually as i just had to do this myself and the amount of stuff on the jets and other things was unbelieveable now mine looks like new

 

[allymoss]

Re: Mercury 4hp wont start, fuel problem

Hi, float works fine. I will try cleaning manually although I will need to borrow a compressor!