90hp merc Idle problem (does not idle in neutral position)

[slyell]

I recently purchased a boat with a 90hp 2000 merc outboard. Took it to get service and they said it had great compression. Had the carbs cleaned, fuel pump replaced, all hoses and fuel lines replaced in the engine, and engine serviced.

1st trip the boat ran perfect until midmorning. then it would only idle for less than a minute.. i would have to push the neutral throttle up to get the rpms up for it to start and keep running before i can move it back to neutral to then engage into gear.

2nd trip i would have to push the throttle up to start and idle... then it would idle for about 20 seconds so i had time to move it into gear... by mid trip.. it would not even idle if kept in neutral. I would have to keep the neutral throttle pushed up for it to keep idling at 1100 rpm.. anything below and it would die.... it wouldnt idle long enough to allow me to engage into a gear.. it would just sputter out and die everytime i engaged... i finally would idle at high rpms and quickly move it into neutral to catch the gear.. once caught.. the engine ran strong....

engine starts very easily and as long as the throttle is pushed up in idle it would the engine would run fine..

any help would be greatly appreciated!

thanks. steve

 

[Laddies]

Re: 90hp merc Idle problem (does not idle in neutral position)

Either there is something left loose on the linkage or you sucked so crud into the carbs which means cleaning them again and installing a large spin on filter to prevent it from reoccurring. Probably the latter problem.

 

[slyell]

Re: 90hp merc Idle problem (does not idle in neutral position)

what do you mean by installing a spin on filter? Sorry, i am kind of new to this. thanks!

 

[Laddies]

Re: 90hp merc Idle problem (does not idle in neutral position)

For some reason iboats lists them separately but most kits come with the filter and base this link will show them just not assembled http://www.iboats.com/Mercury_Fuel_...2180107--**********.254614996--view_id.271592

 

[slyell]

Re: 90hp merc Idle problem (does not idle in neutral position)

I am going to take it back to the shop... hmm.. reading some of the other posts can i just adjust the idle screw that has a nut on it? when i seem to have it idling good.. i can see a gap from where the end of the screw usually rests against the wall...

 

[Laddies]

Re: 90hp merc Idle problem (does not idle in neutral position)

If your sure it's the idle stop scrw and not a pickup or other adjustment screw.

 

[achris]

Re: 90hp merc Idle problem (does not idle in neutral position)

Don't touch anything yourself.. Take it back to the dealer.. It should be covered under warranty... If they did the right thing and replaced the fuel filter (lives inside the engine and is between the fuel pump and the carbs) should have caught any rubbish...

Chris.......

 

[slyell]

Re: 90hp merc Idle problem (does not idle in neutral position)

thanks. I took it back to the shop and they said they would look into it but will charge me to look at it again... although they said they would try to keep the cost minimal

 

[mikeneal]

Re: 90hp merc Idle problem (does not idle in neutral position)

I saw you need new dealer. If I read your post right the 1st trip after they tuned it it would not idle? Did it operate normally prior to that? I would have issues with paying them to fix it if they caused it not to idle.

 

[achris]

Re: 90hp merc Idle problem (does not idle in neutral position)

I saw you need new dealer. If I read your post right the 1st trip after they tuned it it would not idle? Did it operate normally prior to that? I would have issues with paying them to fix it if they caused it not to idle.

I totally agree... The items you had looked at and the amount of work they did.... That's a warranty claim! NO WAY you should be paying anything!!!

Chris.........

 

[Irv964]

Re: 90hp merc Idle problem (does not idle in neutral position)

I agree and if they refuse to fix it for free ask them if they have ever heard of iboats.com? Tell them there are thousands of members on here who would love to know what dealer/marine wouldn't warranty their work!!........Irv964

 

[slyell]

Re: 90hp merc Idle problem (does not idle in neutral position)

i will let you guys know what happens when i get it back from the shop. thanks!

 

[slyell]

Re: 90hp merc Idle problem (does not idle in neutral position)

I picked up the boat from the boat shop and they did not charge me for it since the mgr said it should have been done already.. So i take it home and run the engine with the garden hose and it is idling at around 1,000 rpm. I was excited it was idling in netural but kind of weary the rpm was running a little low outta water. I put it into saltwater the next day and when it started it was idling in water at around 700. Hit the first spot and tried to start again, same problem... it quit idling in neutral, looked like it would try to idle around 500 and sputter out... when i do get it into gear, it runs fine... so i do not know what it is now... Idle problem still, going to take it into the shop but they said the engine was running perfect in their test tank... and they ran it hard....

When i flushed out the engine after the trip it quit idling outta water too.... starts easy and runs fine when i push up the netural to higher RPMS.. but cannot keep it in the neutral position.

 

[achris]

Re: 90hp merc Idle problem (does not idle in neutral position)

A couple of questions....

It this a 2 stroke or 4?

When the boat is sitting on the water, how far above the water line are the exhaust reliefs? They should be a minimum of about 4". If they are less, then there will be too much pressure on the exhaust and this could account for the poor idle.

Chris.........

 

[slyell]

Re: 90hp merc Idle problem (does not idle in neutral position)

The engine is a 2000 2 stroke and i believe the exhaust reliefs do get in water sometimes. But that does not explain why it wouldnt be idling outside of water when i try to flush it now. If i keep pushing the choke every couple seconds the engine will continue to idle @ 900 RMPs outside of water.

 

[achris]

Re: 90hp merc Idle problem (does not idle in neutral position)

The engine is a 2000 2 stroke and i believe the exhaust reliefs do get in water sometimes. But that does not explain why it wouldnt be idling outside of water when i try to flush it now. If i keep pushing the choke every couple seconds the engine will continue to idle @ 900 RMPs outside of water.

If you have to keep pressing the choke, that would indicate that the mixtures may be a little lean. The other thing to keep in mind, and this is why I asked if it was a 2 stroke, is that those engines have a really crappy idle... It's not smooth at all....

Chris...........

 

[slyell]

Re: 90hp merc Idle problem (does not idle in neutral position)

I took it back to the boat shop. They said they will look at it again. Would there be a problem with the fuel when the engine is running and the fuel prime bulb is not stiff? while it is running i can squeeze the bulb quite a bit.

 

[mikeneal]

Re: 90hp merc Idle problem (does not idle in neutral position)

No the primer bulb does not have to stay hard when running. Not to say there is not a fuel pump/fuel system problem, but the primer bulb is fine.

 

[road.ripper]

Re: 90hp merc Idle problem (does not idle in neutral position)

ok , hi all,
im not professing to know much on marine engines , but i do know alot about automotive carbs , heres my .02

assuming the carbs are set properly or reasonably close ie : low idle /high idle and fuel filters are clean
situation .
failing idle after engine gets to running temp,

vacumm leak or air leak (lean out ) on the intake side , when engine gets hot metals expand , the gasket in question wich ever one does not seal as intended. leans out your intake fuel ,flooding in extra air . thus choking the engine starts to help but only to a point then its overkill and engine stalls out. . here is where old school tricks can help .

first i would look for pre mentioned intake air leaks in my days of hot rodding and drag racing , as the engines running close to operating temp
CAREFULLY spray wd40 with short bursts (its safer then using the old propane type torch bottle we use to use) near the base of the carb and any connection hoses (NOT in the throat of the carb).. the sprayed product will get sucked into any leaking area and raise the RPM for just a few seconds .. this should be done with 2 people the other person can hit a kill switch or stop the engine as you need .

the next thing ( with a car ) i would look at is "boil off" the fuel in the carb float bowl is getting too hot and then it starts to "boil off" dropping the needles lower and lower into the seats causing no idle or stalling also hard restart after engine is at running temp. A quick fix here is a carb spacer ( back in the day we use to make them from oak plywood like a heat sheild ) this would stop 90% of heat transfer fixing the " boil off ".

last i would look at the exhaust for a restriction or carbon build up .

now as i said first im no mechanic , but i have had my share of engine and carb issues and rebuilt many too.

like i said just my .02 , good luck
Road.

go fast / drive it like ya stole it .