1983 25hp merc. wont hold pressure (Picture)

[SkeeterDuke15]

I have been messing around with my 83' 25hp 2 stroke motor, electric start. I have had the carb replaced but the engine will not suck the gas out of the tank. i know it all has to be air tight and i have replaced all of the hoses and connectors from the tank to the carb, it has a new filter so i know there is no blockage. when i prime the the tank it will put enough gas in the engine to start it and the only way to keep the motor running (idle or WOT) is to pump the bulb, pretty much pumping the gas in the engine manually is the only to to make it run. Im not sure what else i can try. since i dont have much experience with this kind of stuff what is the average cost of a repair shop for something like this, i know it could be anything, but any ideas on a repair cost would be helpful. Thanks! Nick

 

[SkeeterDuke15]

Re: 1983 25hp merc. wont hold pressure

Re: 1983 25hp merc. wont hold pressure

also the fuel pump has been rebuilt and the diaphram is not backwards or torn, the Spark Plugs were replaced 2 years ago, but could the spark plugs have gone bad? would that cause the problem or could it be Cylinder compression? I think one cylinder works the fuel pump. Correct?

 

[Texasmark]

Re: 1983 25hp merc. wont hold pressure

Re: 1983 25hp merc. wont hold pressure

I'm going to say that if your compression were that bad your engine wouldn't run. Disconnect your fuel line and stick it in a fresh gallon jug of fuel mix with only the engine, the squeeze bulb and the line involved. What happens with that. If it works, you have tank problems clogged filter (in the tank) or tank/cap air inlet clogged (slight possibility...completely removing the cap would test that).

Mark

Mark

 

[SkeeterDuke15]

Re: 1983 25hp merc. wont hold pressure

Re: 1983 25hp merc. wont hold pressure

I'm going to say that if your compression were that bad your engine wouldn't run. Disconnect your fuel line and stick it in a fresh gallon jug of fuel mix with only the engine, the squeeze bulb and the line involved. What happens with that. If it works, you have tank problems clogged filter (in the tank) or tank/cap air inlet clogged (slight possibility...completely removing the cap would test that).

Mark

Mark

Still no suction. filter is clean

 

[Texasmark]

Re: 1983 25hp merc. wont hold pressure

Re: 1983 25hp merc. wont hold pressure

Well, maybe you didn't redo the fuel pump diaphragm per spec. If you can't suck and the engine runs (adequate compression) the fuel system is sucking air somewhere or not sucking at all. Might readdress the fuel pump diaphragm/seals,

Mark

 

[ufm82]

Re: 1983 25hp merc. wont hold pressure

Re: 1983 25hp merc. wont hold pressure

Can you place the tank above the engine and see if it will gravity feed? That will pinpoint the pump issue. If it runs properly that way you'll know you have no restrictions or air leaks.

 

[SkeeterDuke15]

Re: 1983 25hp merc. wont hold pressure

Re: 1983 25hp merc. wont hold pressure

well im waiting on a few gaskets before i can fire it up. but i was just tinkering with the carb and noticed that the idle pin looks like it may be missing an o ring. could this be an issue?

 

[Texasmark]

Re: 1983 25hp merc. wont hold pressure

Re: 1983 25hp merc. wont hold pressure

the idle pin looks like it may be missing an o ring. could this be an issue?

Where do you think it would be? Not aware of one, just the screw and a spring to hold the setting.

Mark

 

[SkeeterDuke15]

Re: 1983 25hp merc. wont hold pressure

Re: 1983 25hp merc. wont hold pressure

corrected there is not supposed to be an Oring, on the other hand i got to taking to carb off again and inspected the fuel pump, diaphram ect. and its dummy proof, basically you cant put it on backwards, upside down ect. so i know im in good shape there. on the other hand the gasket in between the carb and the cylinder block, in front of the reed valve, there was a small opening from the carb that lined up with an opening around to the cylinder block that was not cut out of the gasket. Anyway so i cut a new gasket for the carb and put it back together. Could that have been an issue? hopefully i can start it up later and see if that gasket was my problem. im gonna try and load a picture. the gasket has in the picture has the hole on the bottom, mine looked like it was upside down so the hole was on top, i made the gasket look like this on ein the picture.

 

[FLATHEAD MAC]

Re: 1983 25hp merc. wont hold pressure

Re: 1983 25hp merc. wont hold pressure

Just a thought is the tank vent opened or closed

 

[Texasmark]

Re: 1983 25hp merc. wont hold pressure

Re: 1983 25hp merc. wont hold pressure

well im waiting on a few gaskets before i can fire it up. but i was just tinkering with the carb and noticed that the idle pin looks like it may be missing an o ring. could this be an issue?

On the oring, checked the IPB for my engine and my carbs only use a spring and screw as I mentioned.

On the hole not being in the gasket, can't help with that. If you have 2 holes that line up and the gasket blocks them you may be onto your problem....course, remembering head gaskets on auto engines years ago, the gasket has some holes plugged that were cast into the block and head. Apparently they knew what they were doing as the all had it and all worked.

Mark

 

[SkeeterDuke15]

Re: 1983 25hp merc. wont hold pressure (Picture)

The tank is vented, and as for right now ive got the motor all back together and waiting to test it out one day after work, ill let you know how it goes!

 

[SkeeterDuke15]

Re: 1983 25hp merc. wont hold pressure (Picture)...fixed!

Re: 1983 25hp merc. wont hold pressure (Picture)...fixed!

a big thanks goes out everyone who had some input, allthough the problem was the gasket! i took it home lastnight to test, and it ran great! im still not sure what the hole actually does, but it def. has to do with the motor pulling gas from the engine. thanks again!