Continued Fuel pump Problem 1994 70 hp Force

Ok I have been through the fuel pump 3 times. 1st time thought I messed up. Ordered another kit. Went through it again. Everything looks good. When running she is spitting back through the carb hard and then eventually goes dead. Pulled the reeds out and found no problems there. Reading in Clymer I checked fuel pump operation according to the instructions. Pump the bulb and when I pump the bulb fuel spurts out in volume the size of the hose. When I spin the engine with the kill switch on so it dont start though I dont get any fuel. If I understand Clymer right this can possibly be caused by compression issues in the #2 cylinder or possible #3. I ordered a compression tester but will be about a week before I get it. I did hole my finger over that little hole on the port plate and had the old lady spin her over and not a lot of compression came through the little hole but some did. Dont know how much I should feel. Seems like I felt more from the hose that goes on the outside of the fuel pump. Anybody have any ideas? Hope I explained this where it is understandable. I have owned this boat since new in 94 and never had much trouble with it but let it setup for about 5 years. We got it running this year and took it to the lake and the water pump was not pump good at idle and it was idling really rough. Got her hot twice but shut it down as soon as the alarm came on. Brought it home put a new impellor in the water pump and fired it. Water pump ok now but idle was still rough. Decided after 17 years to rebuild the fuel pump after a lot of reading and 2 weeks later here I am. This hard spitting started after rebuilding the fuel pump. I have went through that thing a lot side beside with the prints, its not that complicated and feel comfortable that it is right but not sure. Debating buying a used pump off ebay and throwing it on there just to try something else. Compression test next weekend is my next stepping stone I guess. One item I left out I did have to make a gasket for the port plate on #2 cylinder it looked like one of my mechanics in the past had used some type gasket silicone or something on it and it was shot so I bought some gasket material and cut a gasket and repaired that. Anybody have any other ideas or am I heading in the right direction thinking check compression?

Re: Continued Fuel pump Problem 1994 70 hp Force

Did you clean or rebuild the carbs after that long 5 year sleep? I would clean/replace any fuel related components if the boat had sat that long. If you rebuilt the pump as per the manual then clean the carbs next, test compression and see what you get.

Re: Continued Fuel pump Problem 1994 70 hp Force

The fuel pump uses crankcase compression and vacuum alternately to move the diaphragm and pump fuel.
Checking compression through the sparkplug hole will tell you nothing unless the piston is so badly damaged that it will not pump air through the crankcase.

The crankcase compression is only about 2-6 PSI--not a lot. However, if you remove the impulse hose from #3 cylinder you should be able to feel air blowing out as the piston travels downward.

If that is the square Mercury pump, did you remember to install the gasket behind it oriented correctly? If it is the Force pump, the later ones had an X shaped gasket that went behind the pump and sealed it to the bypass cover.

Are you certain that the impulse hose is attached to the impulse nipple and not the pump outlet? It is possible. Are you certain that the inlet and outlet hoses are not reversed on the pump?

Re: Continued Fuel pump Problem 1994 70 hp Force

Your finger isin't a good indicator for compression.Even 30# will blow your finger away.The tester is needed.Get the guage and post your results.If you overheated the head gasket could be bad.
I have twin 88/85's and the port motor was acting up.I checked the comp and it was 150# all three cylinder.I checked the whole system and it was ok.So I pulled the head and sure enough there was a spot about the size of a pencil eraser.Gasket bad.Looking further I saw a small hole where the salt was eating the aluminum.Spot weld and new gasket,rund great.
Just turning it over won't pump any fuel.The motor needs to run to make the pump work.It's such a low volume pump they put the squeezie there to get the flow going.
Plugs burning ok??You align the arrow points on the pump?J

Re: Continued Fuel pump Problem 1994 70 hp Force

I held my finger over the hole behind the fuel pump on the port plate. Not much pressure at all coming out of there. Plugs are new. There is more air coming from the hose from number 3 than out the port behind the pump. It is that square mercury pump. Been over the hoses deligently and they are where they are supposed to be. I am betting on headgasket. I should have a compresson tester when I get back this coming weekend and test that and see what it tells me. I am fortunate enough to be one of Americas truckers and dont have much time to fish and hope I get this thing running soon. I have spent may last several one day at home a week working on it and nothing else. Mama is about ready to run me off if I dont get on the yard work.