newbie with a few questions on a Merc 7.5 outboard

[bluemonster1]

Hi all.This is my first thread on here and maybe I can get some info.I just bought a used 12 alum boat and 7.5 Merc outboard.This will be primarily used during the upcoming Flood situation we are facing in the next few weeks.Now the motor has been giving me static.First of all when I got everything home ..I wanted to try out the motor to see if it runs.Put motor in a barrel of water of course and proceded to start it.Now first of all the fitting from the tank hose to the motor was cracked(pissed off).I taped it up for the time being.knowing it will suck a little air probably.Got motor running, and it was not idling very good.I am still learning about these motors so bear with me.I found the fuel filter by removing the canister that sits over the top of the float bowl.It has some white crap in there,so cleaned it good and put back.It ran a little rough but ran.I since ordered a new complete fuel line with bulb and 2 new fittings now.I completely cleaned the carbs out twice already..today I made sure everything was clean.Mixed the gas 50:1 as required,choked it and it fired in like 5 pulls..runs good for a while,but after a bit I can't get it to idle smooth and sometimes it will just completely shut off.Once the motor has been running for like 5 minutes and then dies..it is really hard to start up again.Now if I put it in forward gear in order to open throttle more..it starts good,but I have to crank thottle down quick as the water in the barrel will fly everywhere..lol.Just can't get a consistant idle..sounds like it is sputtering and wants more fuel.,yet I can rev it up great and she sounds great.Overall there seems to be a slight up and down to the rpm's when running at 1/4 throttle.Anyways at idle for a bit and it will die.I adjusted the idle screw so the motor can keep a higher idle also,but sometimes still stalls out.Checked the fuel pump diaphram and it is good,the 2 valves inside move in and out,hoses aren't cracked anywhere or loose.SO...what the heck is going on here.I am so used to doing carb work on my 3 sleds that is doesn't bother me..but the carb is friggin clean now.What am I missing and need to try now.???The flood waters will be here soon and want to try and solve the issue.I mean I can still run her and just keep it above idle when I slow down or stop.HELP SOMEBODY PLEASE!!!!

Doug

thanks in advance.

PS: am thinking of finding another small motor just in case,but how do I know it won't do the same...

 

[bluemonster1]

Re: newbie with a few questions on a Merc 7.5 outboard

oh yeah..it is a 7.5 Merc..SN#2815100..should be a early 70's motor.

 

[Wingedwheel]

Re: newbie with a few questions on a Merc 7.5 outboard

You might want to check your bulb and if running off a remote tank, make sure the vent is open all the way. It sounds like your on the right track, but if it sat for awhile you may be sucking air around a bad gasket. In any case it sounds like your getting an air leak from somewhere.

 

[bluemonster1]

Re: newbie with a few questions on a Merc 7.5 outboard

I am going to order a rebuild kit for the fuel pump..doesn't cost much..but I noticed on a exploded view of the Tillotson carb that there is supposed to be a washer for the main jet as it is screwed in.When I took the carb apart..there was no washer ..NOW would this be causing something to happen..and aslo found out the idle mixture adjusting screw should be turned out 1/2 to 3/4 turn from seated as initial setting.Mine is set at 1 1/4 originally. Then one can adjust the idle mixture screw in or out to a point of smooth and steady idle. SOMEONE was playing around with this carb before....:facepalm:

 

[bluemonster1]

Re: newbie with a few questions on a Merc 7.5 outboard

You might want to check your bulb and if running off a remote tank, make sure the vent is open all the way. It sounds like your on the right track, but if it sat for awhile you may be sucking air around a bad gasket. In any case it sounds like your getting an air leak from somewhere.

I have a brand new hose,end fittings and bulb..totally new.Checked the filter in the gas tank and it is clean and tank is clean also. I have been checking all hoses and fittings to..no iisue I can see.

 

[Maxz695]

Re: newbie with a few questions on a Merc 7.5 outboard

as a rule i think 1 1/2 turns of the airmixture screw is the proper setting for the first initial adjust ment on starting on any carb that I know of and it does sound like you had crap in the carb. did you remove the jet in the bottom and run spay cleaner through it before replacing it also being a 2 stroke may be a hose that runs the side of some engines to take up extra fuel from the valve reed and this will in turn cause bad idol. check for it it is really small about 3 mm rebuild them carbs with full kits rebuild that fuel pump change all filters hoses. you should get a much better response than you are now

 

[bluemonster1]

Re: newbie with a few questions on a Merc 7.5 outboard

Max..actually the carbs were pretty clean upon first inspection.Jet was clear and I sprayed carb cleaner thruout every opening,removed all plugs and sprayed also.She is clean now.Checked needle and seating and all ok.Hoses all intact and good.I can't find a carb kit for my model.I already found a fuel pump kit..but want to order from 1 location..not 2.Found fuel kit at eastcoastmarineservice.com..I will check ou i boats.

 

[Wingedwheel]

Re: newbie with a few questions on a Merc 7.5 outboard

See if this is what you have. http://www.boats.net/parts/search/M...5 THRU 3274632/CARBURETOR ASSEMBLY/parts.html
Its not cheap, maybe your marine dealer could do better as mine always gives me a 20% discount and that normally offsets any online savings.

 

[bluemonster1]

Re: newbie with a few questions on a Merc 7.5 outboard

I have that diagram already anyways.I ordered a fuel pump rebuild kit..cheap really,but shipping was unreal to get it here fast.

 

[Maxz695]

Re: newbie with a few questions on a Merc 7.5 outboard

lol that would fit my carb (LINK) 40 HP 2 cyl 2 stroke 1979

 

[bluemonster1]

Re: newbie with a few questions on a Merc 7.5 outboard

Well I took the flywheel off and looks like one of the breaker gaps are not close to .20 gap,so re gapped it and made sure the other was good also.Now motor seems to smoother in the higher speed range and cruising range..nice steady running sound.STILL..as soon as I go dowm to near idle, or disengage shifter..it dies.So hoping a new fuel pump rebuild kit will help here,otherwise I don't have a clue waht is the cause...

 

[Maxz695]

Re: newbie with a few questions on a Merc 7.5 outboard

now sounds like a link and sinc and timming to be done after the fuel pump repair

 

[bluemonster1]

Re: newbie with a few questions on a Merc 7.5 outboard

lol yeah ..as if only I knew how.As long as it runs and pushs the boat around..I am happy,when I come to land..I'll just let it die and cruise on in.It is only going to be used during the Flood this Spring..and maybe not be used for 10 years later...

 

[Maxz695]

Re: newbie with a few questions on a Merc 7.5 outboard

link and sinc here ---> http://forums.iboats.com/showthread.php?t=168855

 

[bluemonster1]

Re: newbie with a few questions on a Merc 7.5 outboard

a little to complicated for me to do and don't have timing light anyways.I'll manage somehow,as when you are talking timing,advance and the such..I am completely lost with all that.I never touched or changed any timing on the motor anyways,so I'll just crank the idle scerw on the linkage to keep speed up instead.

 

[bluemonster1]

Re: newbie with a few questions on a Merc 7.5 outboard

downloaded a repair manual and did the link and sink procedure.Ran pretty good,yet at idle it would stop eventually.Like it wasn't getting fuel.Still waiting for the damn fuel pump repair kit..it has just arrived at the Postal Outlet this am..should be here tomorrow.I pulled the cover off that goes over the carb(with the filter in it) Now if I pump the bulb,gas will come flying out the end.Now if I pull start like 8 times..very little fuel wants to even come out..no steady stream.How much fuel would come out on every pull??Man I sure hope the repair kit fix's this or I will be pissed...

 

[Maxz695]

Re: newbie with a few questions on a Merc 7.5 outboard

Relax take a breath, and get the pump in. Dont fret over what you have no control over. It will be there and hopfully will be the end of this problem

 

[bluemonster1]

Re: newbie with a few questions on a Merc 7.5 outboard

well the rebuild kit was a waste of money..did nothing to help solve issues.Starts good cold...actually idles down right away.Then run it in the barrel for a while with prop engaged.Then bring it back down to idle and it will stop abruptly.Now there is still fuel in the carb because I tried squeezing the bulb and it is full.Seems like once the motor gets warmed up it starts to act up.Now I was thinking stator..but at nearly $500 for one shipped,I would thru this motor in the river and just save up for a 4 stroke eventually.Again I got ripped off by someone selling a boat and motor.We should never ever buy a boat motor unless we can hear it run.So many dis- honest people out there.If I was selling it..I would make sure it was running good at least..some people are just money hungry scum bags and will never change.Anyone got a good used stator kicking around for cheap???

 

[swamp-fox]

Re: newbie with a few questions on a Merc 7.5 outboard

What kind of remote fuel tank do you have? From some of your post you thought it might be sucking air. The new plastic tanks have a hard plastic pick up line on the inside. I have had two pick up lines crack at the top right where it meets the fitting on the inside.

This first time it happened I changed all the fuel lines like you did before I found it. If you can rev it up and it stays running that might not be the problem....Just a easy none costly check.

 

[bluemonster1]

Re: newbie with a few questions on a Merc 7.5 outboard

I have the original metal fuel tank.I checked the pick up on it and it seemed ok and clear of debris on filter.Now the stator on this motor looks a little funny.There is actually a chunk missing from it above where the 2 wires go into.Seems like maybe some of it melted or was ripped out,yet there is no debris anywhere...