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Mercruiser 37 please help

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stevejay

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can anyone help i have a mercr

can anyone help i have a mercruiser 3.7 1989 approx can not get it to idle have striped and cleaned carb (2pot) new points condenser plugs rotor and coil etc fresh petrol etc etc it revs up fine just will not tickover can anyone help before i shoot myself thanks
 
Hi Steve.
Are the idle screws

Hi Steve.
Are the idle screws set/open? They should be 1 1/2 to three turns open I think. if it idles turn them in or out till smoothest idle(or highest vacuum if you have a gauge) then set idle speed 650rpm on throttle idle stop. Is your choke open all the way?
 
hiya ken
yep the idle screws

hiya ken
yep the idle screws are open and set you can fully open or close them it makes no difference to how the engine runs when you open the throttle it revs up and is smooth it just wont idle
 
"I had the saem problem with a

"I had the saem problem with a 4 stroke outboard.
Ethanol in the gas had dumped lots of junk in the carb. I did the usual carb clean to no avail.
In the end I had to snake a 30 ga wire thru the idle circuit to get it clean (its quite small on a 7.5HP). Your carb is bigger. But the point here, is that the crap that ethanol can deposit in fine passages can be very difficult to get out. I had my carb apart 4 times."
 
stevejay:

Can you turn the

stevejay:

Can you turn the idle speed screw to reduce the RPMs to 650?

Get a thicker base gasket so it will atomize fuel at idle and allow you to adjust the mixture screws; 1/4" or 6.35 mm from Merc.
 
guy it wont idle no matter wha

guy it wont idle no matter what i do.when you rev it up its sweet no miss fire i will get a thick spacer made at work clean the carb again and try again cheers mate
 
"Your idle circuit is likely p

"Your idle circuit is likely plugged up with crud. If so, there is no way it will want to idle no matter what you do with the idle adjuster screws.

There was a topic no long ago about the same thing. Do a search in the last 3-4 months and you should find it. That carb was a Q'jet 4 bbl, but the same basic info and procedures hold true for all carbs.

Rod"
 
"steve jay
Check for a vacuum

"steve jay
Check for a vacuum leak on the intake gaskets, seals,bushings etc.
Bert"
 
"Steve...

I know that you s

"Steve...

I know that you said the carb was just rebuilt... but who did it? Something went together wrong inside? As Rod said your idle circuit is plugged. The float is set to high or it sank (did you use a new float or the old one over?) it may be spilling fuel down the carb all the time its running because of the float. It certainly won't idle if its doing that. Look down the throat as you're slowing it down to it's lowest speed before it dies and see if fuel is spilling out of the jets.... Set the idle speed screw ,(not the idle mixture screws), to open the throttle more and get it idleing, thats what Guy was talking about.

Wrench"
 
"You said you cleaned the carb

"You said you cleaned the carb (2pot). Not sure what you mean. When you clean a carb you need to take it apart and soak the parts and the bowl in a good carb soak cleaner for several hours; overnight if possible and then rinse in clean water and blow it out and dry it with compressed air. Replace all gaskets, fuel inlet needle and seat and all other wear parts. If there is some stubborn grime in it use some laquer thinner on metal parts only and it will clean out hardened crud."
 
2 pot = 2 bbl

Sounds like a

2 pot = 2 bbl

Sounds like a vacuum leak to me...........

OH WELLLLLL..........
 
thanks guys made a spacer for

thanks guys made a spacer for the carb at work 6.5mm thick out of tuffnal fitted it and music to my ears it runs like a dream and can even set the mixture no probs
 
tufnall is a resin fibre block

tufnall is a resin fibre block that we use on helicopters at work you can do anything with the stuff drill tap turn and even grind it its used on helicopters as a heat shield and by the way guys it keeps the carb cool as well
again many thanks to everyone
 
In the end it was probably a v

In the end it was probably a vacuum leak between the carb and intake. Replacing the spacer didn't hurt though.
 
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