'96 225 merc low speed stumble and stall

[mojo charmer]

my '96 225 merc runs fine at high and mid speed but when i accelerate slowly from a stop , it stalls like it's not getting fuel. if i accelerate quickly , it works ok.<br />i've done all the simple things like new filters,primer bulb & spark plugs.<br />i've taken it to the shop and the only thing they suggested was that the fuel i use has a high alcohol content and can cause vapor lock symptoms. i used hess gas almost exclusively before the mechanic warned me about it.<br />the only other idea i had was maybe the fuel pickup in the tank is partially clogged.<br />any ideas would be appreciated.

 

[achris]

Re: '96 225 merc low speed stumble and stall

Is it carbs or EFI?

 

[mojo charmer]

Re: '96 225 merc low speed stumble and stall

carbs , and the merc certified technician checked them out and said they're good.<br />he said i've got good spark ,compression,& fuel flow too.

 

[achris]

Re: '96 225 merc low speed stumble and stall

Mojo,<br /><br />You've thrown a really good one in here. Try taking the air box cover off and checking for 'blowback' out of the carbs. If you have any, particularly at the engine speed that causes the problem, then start thinking about reeds. Other than that, look for bleed hoses off or any point air could be leaking into the engine. Sorry if that's a bit vague, but that's all that's springing to mind at the moment.<br /><br />Chris.........

 

[mojo charmer]

Re: '96 225 merc low speed stumble and stall

i took it to the shop and the mechanic said that it could be something patially blocking the intermediate circuit of the carbs. he was hopeful that it was something minor.

 

[KCLOST]

Re: '96 225 merc low speed stumble and stall

Take the fuel out of the equation, run the engine off of a remote tank with fresh fuel...

 

[LubeDude]

Re: '96 225 merc low speed stumble and stall

Well, when you figure it out, let me know as I have been fighting this same thing all summer with my 150HP Merc. I too have done everything under the sun trying to figure it out to no avail. Im changing the reeds eventually, but like yours, it runs fine otherwise, so im just fishing.<br /><br />Weird thing about mine is that there are times when it is fine, but mostly not.<br /><br />List of things done:<br /><br />Carb rebuild, (twice)<br />Reset floats, (twice)<br />Rejetted the idle side, (helped some)<br />New fuel lines<br />New fuel pump<br />Checked timing<br />Checked fuel line preasure<br />Ran on another tank<br />Checked for air intrusion<br />New filters, (added water separating filter)<br />Synced carbs<br />On and On and ON!

 

[mojo charmer]

Re: '96 225 merc low speed stumble and stall

has anybody out there had similar problems which were fixed ?

 

[mojo charmer]

Re: '96 225 merc low speed stumble and stall

fantastic news ! the motor is fixed.<br />the mechanic was right about the intermediate fuel circuit and he opened the screws about a half turn each. he says that it runs like a bat out of hell and jumps right up out of the hole.<br />i can hardly wait to take it out. it goes 44mph @ 5200 rpm and is faster than it's ever run for me.<br />could the previous 3 mechanics been so bad or so lazy to have not tried a simple carb adjustment?<br />i'm so happy that it's fixed i feel like it's a new boat again.

 

[LubeDude]

Re: '96 225 merc low speed stumble and stall

Thats interesting, my engine has NO Carb adjustments at all, (other than float level), and I wasnt aware that there are any on the 225s either, sure might be though, not familiar with the 225s.

 

[lund17]

Re: '96 225 merc low speed stumble and stall

Mojo-<br />I'm just curious as I run a Hess station and use the gas almost exclusively. What were the problems with the gas that he warned you about? I'm not defensive I just want the best fuel for my motor regardles of brand.

 

[gss036]

Re: '96 225 merc low speed stumble and stall

I am not familiar with "Hess stations", but would suspect it is like our AM/PM selling ARCO gas. They have a lot of alcohol in it and my old 89 Merc 200 owners manual specifically says not to use gas with alcohol in it.

 

[mojo charmer]

Re: '96 225 merc low speed stumble and stall

i think that the sevice mgr( from marinemax) was grasping at straws when he said that about hess gas. his mechanic could not find the problem nor diagnose the causes from my description so they came up with the hess story. i don't think that the gas was ever a problem. for anybody that has a similar engine problem, call this dealer and ask for andrew. he's the owner and mechanic and was able to properly diagnose the problem from my description over the phone. all he had to do was to run it in the water and turn the carb adjustment screws until the stalling was fixed.<br />i'm taking it out on saturday and can hardly wait to see how it does. he says that it hauls *** now. you push down on the throttle and it screams.<br /><br />Dealer Name RIVERSIDE MARINE INC <br />Address 8100 N FLORIDA AVE<br />TAMPA, FL 33604 View Map <br /> <br />Phone 813-254-7630 <br />Fax 813-254-4927 <br />Products Outboards, Racing Outboards, MerCruiser, Jet Drives, Inflatable Boats