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blue band mercury 4hp

T

tom horner

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hi there i have just bought a 4hp blue band mercury immaculate condition has had
very low use looks mint bought for a good price i got remotes and tank with it.
I had to replace the fuel primer bulb as it was leaking i have done this and it
get pressure fine, however it will only fire for a second of so then die and
wont start for a while i tried a new plug started stright away but died after a
second. I had full throttle on and it didnt seem to rev very high just like
starting a engine at full throttle then turning it off if that makes sense i have got the carb off but cant appear to get the jets out anyone got any ideas?

160820111378.jpg

160820111374.jpgregards tom
 
...cant appear to get the jets out anyone got any ideas?
Click to expand...

Unless they are corroded don't take them out. Do as racerone stated. "The carburetor needs a good cleaning." Soak it overnight and blow it out w/compressed air. Check the point on the needle screws for damage; replace if necessary. Good luck.
 
thanks for the help i will let it soak in some stuff, how come the impeller needs replacing? when it briefly fired it pump quite a bit of water out of the tell tail..
 
Tom,When an engine is new to you it is good practice to replace the impeller even if the seller tells you he/she replaced it yesterday,unless you were standing watching them.Then replace every two years .Rubber tends to perish and the less use an engine gets the bigger the chance of perishing.
 
...immaculate condition has had very low use looks mint...
Click to expand...

Haventaclue is right about the impeller. Time is the rubber impeller's enemy; it takes a set (curled) sleeping in the Wpump hsg. and doesn't do well when being awkened after a long rest. You purchased a real gem; replacing the impeller will keep it that way.
 
The massey 35 (1960) is the diesel just bhiend the engine her the grey fergy is petrol paraffin 1950, i let the carb soak in brake cleaner today says it was safe for carbs and then blown everything out with compressed air i can blow through various places now with my mouth and all seams clear i am going to put it back together tonight and try again, how do you replace the impeller? Has anyone got any guides?

regards tom
 
still the same no joy, anyone got any ideas? what are the original carb settings and which are the screws to do it? there appears to be a bit of petrol coming from near where the air goes into the carb, only a little bit though, getting a bit frustraed :/
 
mine seems to have the same symptoms as this but mine is only single cylinder, it will start rev up then die plenty of fuel appears to be getting there all the carb was like new when i taken it apart but i cleaned it all anyway and it all free :/
 
...original carb settings and which are the screws to do it?
Click to expand...

The needle valve screw w/the spring around it is the mixture adjustment. Start by gently turning the screw CW (in) until it barely makes contact w/the seat. Next, turn the screw CCW (out) about 1 & 1/2 turns. Start the engine in a drum of cold water and let it warm up. Turn the idle mix. screw CW slowly until the engine begins to stumble then turn it CCW until the idle smooths out. Continue turning CCW 1/4 turn.

"how do you replace the impeller?" There are many videos on here.

http://www.youtube.com/watch?v=7B7ZQ_VTjr0

find you engine here:
http://www.mercruiserparts.com/selectSerailRange.asp?doc_nbr=4+HP+2%2DStroke
 
guyjg said:
The needle valve screw w/the spring around it is the mixture adjustment. Start by gently turning the screw CW (in) until it barely makes contact w/the seat. Next, turn the screw CCW (out) about 1 & 1/2 turns. Start the engine in a drum of cold water and let it warm up. Turn the idle mix. screw CW slowly until the engine begins to stumble then turn it CCW until the idle smooths out. Continue turning CCW 1/4 turn.

"how do you replace the impeller?" There are many videos on here.

http://www.youtube.com/watch?v=7B7ZQ_VTjr0

find you engine here:
http://www.mercruiserparts.com/selectSerailRange.asp?doc_nbr=4+HP+2-Stroke
Click to expand...

thanks for the advice its one and half turns out as if is but it wont run for more than couple of seconds with out dieing and will only start with full throttle i have same symptons as the thread above i found :/
 
It was the TVO I was looking at,lol.From the little I can see they look good.
If you have the screw out 1 1/2 turns,back it on out to see if it picks up.
Has that engine a fuel pump?I see it has the tilston carb on it. If it has maybe check the pump diaphragm for pin holes, perhaps a rebuild there.
 
i presume it has a fuel pump as it wouldnt be able to suck the fuel through with out it, again i have never taken one apart to look at, are they quite simple?
 
I have once again taken it apart and everything looks fine i am certain it must be electrical. I have checked the fuel diaphragm and its fine evan sucked and blown through the little hole on the casing and it moves fine i pumped fuel through it all once put back together and no problem there and the carb is clean as a whistle, what can go on the electrics on them? i know its a different engine but this has the same symptoms http://forums.iboats.com/showthread.php?t=341728



Regards Tom
 
I read the iboats forum thread. Please post the engine's serial number for reference. Also explain in detail how you are starting the engine especially how you are using the choke. Do you have a timing light? It can be attached to a plug wire to see if the engine is loosing spart when it quits.
 
i spoke to a bike mechanic as the electrics look simular and he said after if had started and stopped pull the plug out and check it which i did and it was wet he said the sparks dissapearing and i am not getting a spark. So how can i check the coil pack and the igniton system? I appear to be getting a spark when i take the plug out and have got a brand new spark plug but still the same, is there a way of checking the coils?

regards tom
 
Thank you. Based upon the diagram below I am taking a WAG at it.

Try to ohm #2 & #8. They are coils and should have some resistance; don't know how much but should not be open circuits. #10 ignition coil should be OK. It should have high resistance between the spark plug cap to ground but not open. Temporarily disconnect #34; if it runs correctly and won't shut off then just disconnect the fuel line (that would be the problem).

http://www.mercruiserparts.com/Show...bnbr=30&bdesc=Magneto+and+Ignition+Components
 
I have got the engine back today and it runs sweet as a nut, they have put a new coil on it and they said there was a blockage between the fuel connector and the fuel pump. They charged me £60 which is enough but i didnt think it was to bad.
 
i had a 3hp evinrude before and speed wise on the boat they seem pretty much the same, is it possible to get a smaller propeller? it has a the original 2 blade prop on it not sure of the pitch.
 
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