Even stumped my mechanic (update)

[gss036]

Re: Even stumped my mechanic (update)

I would suspect that you are sucking air on the fuel line side and when you disconnect it, it stops sucking until it runs out of gas. I would be very careful doing this as I haled several pistons on 2 stroke motorcycles with lean conditions.<br />Try a different hose and tank.

 

[Fishallot]

Re: Even stumped my mechanic (update)

I have a 93 115 2+2. When I rebuilt my fuel pump 18 months ago I ran into the same question with the missing rubber valves in the kit that was straight from the local Merc dealer. The concensus of the board was that only the clear ones were used in these modern times. I put my pump back together with only the clear discs and its worked perfect ever since.

 

[Fishallot]

Re: Even stumped my mechanic (update)

Here's a pic of my fuel pump rebuild job. The old rubber valves that I took out are laying above the pump. Like I said I reinstalled it just as pictured and it's run great ever since.<br /><br />

 

[TenE307]

Re: Even stumped my mechanic (update)

thanks for the pics. that is the way my pump looks. now i have two fuel pump kits, one from napa with the rubber check valves and one from quicksiver without the rubber check valves.<br /><br />(update) - last night i took ALL of the fuel system off the motor to check out where and what was going on. i noticed a t-valve that was right before the fuel pump. this t-valve ran straight fuel to my #4 cylinder to a screwed in valve that was screwed into the back side of #4 cylinder. the accelerator pump which gets its fuel from between 2&3 cylinder is dispersed once it is actuated flows out to a valve screwed into the backside of #3 cylinder. when i had all the fuel system out i hooked it up to the fuel and pumped away. the check valve on #3 stopped as soon as i was done pumping, but the #4 cylinder kept shooting fuel out of the check valve. the springs in the check valves have to be equal in pressure. i stretched one spring then the other one wouldnt seat right. then i would strech the other one until i got both of the check valves to stop flowing fuel once i was done pumping. the only prob (finding a prob was good) was i finished at 10:30 last night, and i couldnt start the motor. the technical name for the check vavles and results will be posted as soon as possible.

 

[TenE307]

Re: Even stumped my mechanic (update)

The term taken out of the mercury manual is "cyinder check valve/ injector nozzle" they only mention it on the fuel flow diagram for the accelerator pump, and there is no picture of it.

 

[BikerBoater]

Re: Even stumped my mechanic (update)

I think all the symptoms you have are normal or at least explainable. I have the 1988 100HP 2+2. Last year I rebuilt my fuel pump and the Mercury instructions said to toss out the rubber disks and to only use the plastic ones. After the rebuild my engine runs great. Also about three weeks ago, I had checked the fuel line at the base of the engine connection and did not get it fully attached. I was crusing at about 5000 RPMs when all of a sudden the RPMs shot up to about 5800 RPMs for about 8-10 sec. Then the engine died. I thought the engine had blown. I checked the engine and the fuel line had popped off. Evidently it had sucked air during my 5800 RPM jump. I attached it and the engine ran fine. So I tried it again and had the same results. I'm not sure why it jumps up in RPMs but, I think it is normal when the fuel line is disconnected. Anyone else experience this?<br /><br />Are you sure this isn't a prop issue? Have you ran higher RPMs in the past with this same prop + load setup?

 

[TenE307]

Re: Even stumped my mechanic (update)

ITS FIXED!!!!!!!!!!!!!!!!!!!<br /><br />went camping all weekend and never even had to pull out the tools. it was the CYLINDER CHECK VALVE/INJECTOR NOZZLE. its amazing how it runs now. gets on plane in about three seconds and runs like a champ all day. plus i only went through about half of the 25 gal of gas all weekend. its amazing the difference all cylinders fireing at once can make.<br /><br />thanks to all for the input, couldnt have figured it out without the process of elimination. THANKS AGAIN!