Fire comes out of carb

[victorc1]

Okay I rebuilt my 1995 Mercruiser 3.0 LX, changed piston rings, crankshaft and piston bearings, rebuilt the head, new gaskets and hoses. I did not touch the camshaft bearings because the owner before me did it already. Okay, so when I try to start the motor flames come out of the carb and the motor does not start. Can someone help me Please?
Also I used 5 cans of black motor paint...

 

[JustJason]

Re: Fire comes out of carb

start with a compression test and come back with the results.

 

[Bt Doctur]

Re: Fire comes out of carb

Assuming you lined up the cam to the crank correctly, then suspect the timing is off. Did you install it with #1 at TDC compression stroke?, firing order 1,3,4,2.

 

[victorc1]

Re: Fire comes out of carb

Before I started it I checked the compression on the 4 cylinders, 120. I aligned the crankshaft with the camshaft gears and set the damper to 0 TDC, the rotor points to the the number 1 spark plug wire.

 

[Don S]

Re: Fire comes out of carb

I aligned the crankshaft with the camshaft gears and set the damper to 0 TDC

You are 180 out when the cam and crank marks are aligned.

 

[victorc1]

Re: Fire comes out of carb

What does that mean? I did exactly as the manual describes.

 

[Don S]

Re: Fire comes out of carb

It means you are not on #1 TDC on the compression stroke when you installed your distributor.
It takes 2 complete revolutions of the crankshaft to accomplish all 4 strokes of a 4 stroke engine.
Look at page 4B-10 of manual #13. It explains how to find #1 TDC on the compression stroke.

 

[victorc1]

Re: Fire comes out of carb

I aligned the timing marks on both gears exactly as described in the manual page 3a-39.

 

[Don S]

Re: Fire comes out of carb

I know you said that, but that is not #1 TDC on the compression stroke. That is just the cam and crankshaft timing.

 

[victorc1]

Re: Fire comes out of carb

Okay I'm going to the boat now with page 4B-10, I'll try it and get back to you. Thanks.

 

[a70eliminator]

Re: Fire comes out of carb

Your valve timing is correctly set as you describe lining up the crank and cam keys.
Distributor position effects ignition timing and although you rotor is pointed to #1 the piston may be on it's exhaust stroke and not compression stroke.

 

[Don S]

Re: Fire comes out of carb

Your valve timing is correctly set as you describe lining up the crank and cam keys.

You don't line up the keys, you line up the marks on the cam gear and the crankshaft gear.

 

[Ridemywideglide]

Re: Fire comes out of carb

Easiest way to check for being 180 out.. Turn the distributor 180 off and try to start it.

 

[a70eliminator]

Re: Fire comes out of carb

You don't line up the keys, you line up the marks on the cam gear and the crankshaft gear.

Pip marks, not keyways ok, my point was valve timing and ignition timing are two totally different things.

 

[Bondo]

Re: Fire comes out of carb

Ayuh,... I agree with the current diagnosis,... Timing out by 180?...

About the only other thing I can think of that'll do that is,.. The Valves are way Too Tight...

 

[FreeBeeTony]

Re: Fire comes out of carb

i don't even think it takes 180* to get a flame outa the carb......it happened to me during the initial start-up after I replaced my heads.......thought the timing was close enough for the 1st start up but not quite. I had about a 4' flame come out of the carb......just about took my son's eyebrows off........ just needed a little adjustment for the initial start up after that.

 

[JustJason]

Re: Fire comes out of carb

or you could just do a compression test, and you'd know that your having a power stroke wanting to happen while the intake valve is still open.

 

[Alpheus]

Re: Fire comes out of carb

K.I.S.S. method. put your finger over the # one sparkplug hole, turn the engine over by hand until you feel the pressure under your finger building up. Then you know its on the compression stroke...

 

[victorc1]

Re: Fire comes out of carb

Thanks Don, I did exactly as described on the page and it started perfectly. Only the motor sucks air in through the carb gasket that goes between the carb and manifold. I am using the old original gasket because it is like a spacer type gasket and the gasket that came with the kit is not. I am afraid that if I use the new gasket because it is thinner, the heat from the manifold will heat up the carb. Could I use the new gasket or will I need to find the spacer type?

 

[Don S]

Re: Fire comes out of carb

Yes, using old gaskets will cause leaks. Get a new one. Merc still sells them.

The Merc part number is 8079821.
'
Just use the new thin gasket you have to get things going until you get the correct one.