Engine stalls when flame arrestor is on

ok i just replaces the gaskets

ok i just replaces the gaskets on the intake and exhaust manifold as well as the head gasket(blown head gasket)...there was water everywhere prior to changing the gaskets..now the boat runs then stalls...when i take the spark arrestor off it runs fine...but there is steam coming from the hole where the arrestor connects to the crank case...any ideas? what is supposed to flow from the engine into the arrestor? should it be pressurized?

Have you cleaned the arrestor?

Have you cleaned the arrestor? Did you change the oil when you did the other work? What does the oil look like? Is there a buildup of creamy tan stuff on the arrestor?

"SG: give us a little more in

"SG: give us a little more info. Engine model, year, when does it stall? did you use a torque wrench on the bolts? use marine gaskets? did you change the oil & filter? clean the arrestor? reset the timing to specs? Does the engine idle and accellerate smoothly? Did you pull the spark plugs and inspect them? Water vapor or steam is a byproduct of combustion and a small amount is supposed to vent to the arrestor thru the hoses attached to the valve covers. The amount of vapor should diminish as the engine reaches operating temperature."

Was the head & block deck

Was the head & block deck checked for warping before being reassembled? Compression check of cylinders & pressure check of cooling system?

everything was checked and was

everything was checked and was fine...i cleaned the arrestor ..the engine idles ok but when i try to accelerate i get a couple of loud putts and then stalls...all new(marine) gaskets...oil was canged...filter was changed...the motor is an 1986 mercruiser 170

"It still sounds like bad gas

"It still sounds like bad gas or the accellerator pump needs replaced if you are 100% sure the timing is set at what the engine label states and the ignition SPARK IS STRONG. Old plug wires will cross fire under a load. With the engine idling, take a spray bottle filled with water and spray each wire along its entire length; also spray the the top of the dist. cap to see if the engine stumbles. If it does, you found one problem.

In the dark, you will also see the spark jump across the bad wire to another one when its cylinder is on its intake stoke which would make the pop sound.

What was the timing reading? What is the vacuum reading @ idle? What is the idle RPM? How old are the plug wires, cap & rotor? You can check the accellerator pump ON A COLD ENGINE & IGNITION OFF by removing the flame arrestor and looking down the barrel of the carb. It should squirt a pair of steady straight streams of fuel when you give the throttle a quick pull to wide open throttle position. It will look like a rattle snake spitting venom. Replace the pump if it doesn't."

"Ok, a sort of similar problem

"Ok, a sort of similar problem, opposite throttle setting. I have a 1997 3.0l LX aplha 1 gen 2 mercruiser. It will only run in neutral at a high throttle setting, 3000rpm or greater, when the throttle is brought down it stalls immediately. The distributor cap, rotor, and plugs are all new, wires show no sign of corrosion. I pulled the gas hose off the fuelpump, from the line that runs between the gas tank and the fuel pump, and no gas poured out, is this normal? I have not checked to see if the arrester squirts fuel from idle to wide open, I am assuming it does since the engine would run at high throttle settings. Any help would be appecitated."

"Timing could be off due to ch

"Timing could be off due to chain wear and parts replacement although the latter should be a minimal effect. Change the fuel filter? Do you have fuel in the tank; gauge work? You won't get fuel out of the hose when there's no place for fuel to go if the filter is plugged. It is starving for fuel when it dies at idle and/or engine timing off can cause it to die or backfire on accelleration?

You need to rule out TIMING OFF, FUEL FILTER PLUGGED, VACUUM LEAKS, ELECTRIC CHOKE WORK? Choke should open quickly in warm weather and be warm to touch around the housing."

"Guy,
I checked the fuel filt

"Guy,
I checked the fuel filter on the carburetor line, no clogging, is there one on the fule pump line from the gas tank to the fuel pump? Timing is good, and no vacuum leaks, choke seems good, the boat actually ran great the week before, only had a slight hesitation on big throttle movements."

"If it has a mech. fuel pump,

"If it has a mech. fuel pump, there is a filter in the cone of it. You need to see if the accel. pump spits fuel like a rattle snake when throttle is pulled quickly (IGNITIOn OFF ON A COLD ENGINE) or it could flash in your face. If it's not there replace the accel. pump or rebuild the 9 year old carb.

Any OLD boat or OLD auto mech. can rebuild it with the right kit. Boat dealers tend to just replace it with a new or reman. for $500-$1000. A two barrell is not hard to rebuild with a manual & digital camera to photo each part and step you take--I did it and it had been 25 yrs. since the last one. Replace the float. A complete kit is less than $100 w/float and needles. Remans from MERC are avail. for under $400 frt. included in North Carolina. http://bpi.ebasicpower.com/mm5/merchant.mvc?"

"SG, Steam coming from the cra

"SG, Steam coming from the crankcasr hose means there is water in the crankcase.
I would suspect that a gasket is cracked/broken/kincked where the water jacket passage is crossing over to an oil passageway.
I don't know your motor, but doesn't the valve cover hose connect to the arrestor?"

yes it connects to the arresto

yes it connects to the arrestor but the steam is gone but oil is now spitting from it