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90hp v4 Johnson barb ports on intake manifold

F

fishhawk90

Member
Hey guys I was just wondering if someone can tell me what’s the purpous of these ports. It only lets air out & not in. Two of them under the top carb connects to a tee that goes to a port on the side of crankcase that feeds cylinder 3. One goes higher up to cylinder 1 closer to where the 3 intake holes r in the cylinder .

As for the port side 1 goes to the exactly the same location to cylinder 2 as cylinder 1. & cylinder 4 has none going to it except the 1/4 vlave that goes to the vro pump which draws vac when the piston goes up.

are these valves to release pressure against the reeds & redirect it back into the cylinders? & if that’s the case why won’t cylinder 4 have one to release its pressure as well?
 
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How it works when you push the key in to start at the same time it opens the choke solenoid valve petrol is pumped to the choke solenoid valve and in turn it gets pumped to the intake manifold through those pipes you see and referring to the vacuum then sucks the fuel in through the reed valves and turns it into vapor. Now you can also use the manual side of the system without pushing the key in to use the choke system designed with this system by turning the little red lever you are then opening the choke valve manually without using the solenoid buy opening it with the little red lever the fuel still gets pumped into the intake manifold to start it .So there are 2 ways to use this choke system. Those pipes go onto little brass nipples sometime on some motors they are plastic nipples on some motors .they also have a very very fine mesh in and they do get dirty and the fuel doesn't come through and it makes starting with the choke used difficult .
 
Tegweni.------The check valves mentioned in post # 1 and pictured in post # 2 are not part of the primer valve starting system !!!-----And are you sure you understand how the electric primer valve works ??
 
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Iam very confidant in how the choke primer system works .If he uploaded a model number i would know where iam on the map ,later models may have come out with a different priming system that you may be referring too.thanks raceone
 
The primer valve is not a pump !-------They have worked the same from about 1980 to 2007 models !-----They do not use the check valves as posted in #1 and pictured in # 2 post.
 
I don't want to be the captain on the ship. All i know since they have stopped using the butterfly system on carbs they have switched over to a solenoid valve system some only work with key pushed in or manually by turning the little red knob and fuel is pumped to it the same way its pumped to the float bowl and and whether he has got a priming system or not the solenoid valve still has to open to get the fuel to the inlet manifold.
 
So the solenoid valve does not produce its own pressure? I guess its pressure comes just from pumping the squeeze bulb to get the system pressurized......then the solenoid acts as the valve only. Simple.
 
The primer valve has NOTHING to do with the hoses in the OPs question. Those hoses recirculate the excess oil in the crankcase. The primer solenoid is NOTHING more than a valve that opens and closes. The fuel pressure is provided from the fuel pump while the motor is cranking. The red lever is a manual bypass if the electric part fails. As racerone said used from about 1983 to 2007.
 
Tegweni said:
You understand it timguy:)
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Post # 10 explains how the primer system works. The fuel line primer does NOT provide the pressure. The only way the primer bulb on the fuel line lines works with the primer, is when the red lever is in the manual position and ONLY then.
 
Thats why it has 3hose nippels one feeds fuel when the red lever is turned for the manual priming the other is when the key switch is pushed in the bigger nippel is the fuel supply.
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No , both small hoses feed fuel when the key is pushed in and the motor is cranking.------And both small hoses feed fuel when the red lever is turned and the manual pump is operated.
 
then explain why is it that when you close the red knob in the closed position and you blow air into the bigger nipel and you connect 12v to the soleniod the air only comes out one small nipel and when you disconnect the 12v and blow air with the red lever still closed no air comes out and when you turn the red knob to the open position and the soleniod still disconected air comes out the other small nipel . i understand wot they mean by the word manual that is on the sticker stuckto to the unit.:eek:
 
Tegweni said:
then explain why is it that when you close the red knob in the closed position and you blow air into the bigger nipel and you connect 12v to the soleniod the air only comes out one small nipel and when you disconnect the 12v and blow air with the red lever still closed no air comes out and when you turn the red knob to the open position and the soleniod still disconected air comes out the other small nipel . i understand wot they mean by the word manual that is on the sticker stuckto to the unit.:eek:
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What you are describing cannot physically happen unless something in the valve itself is broke. Try this disconnect the primer lines from the motor. Now try to start the motor with the key pushed in Watch where the fuel comes out. That valve is only an open and close valve it does not switch between the lines.
 
In that case why did,nt they just make it with only 2 nipples fuel in and fuel out and wot happens when you have a flat battery and you have to rope start it. this is why they made it with 3 nipples one is for fuel in from the pump the 2 small nipples one for using the solenoid valve . the other one is for switching over to the manual mode by turning the red knob if your battery is flat you can then still prime it using the primer bulb , makes sense to me.and this is how it works.Ive experimented with this thing before using air.
 
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-Well on the small 3 cylinder 25 / 35 HP and other small motors there is only one wee nipple.---And it works in the manual mode and electric mode using just one small nipple.-----Same solenoid valve with a different cover !!--So yes there are some with that feature.-----I think you should do some more testing.
 
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