mercury efi failure problem?? please help suggestions needed

[Gerry Zagorski]

If they are thinking it's a fuel issue easiest way to find out is to hook your motor up directly to a portable tank.... If that does not resolve your issue you know everything on the boat is likley OK. If it does resolve the issue then keep on working backwards from the motor introducing more of your fuel delivery system inline with the portable tank. Put it just before the primer ball, then the filter, then the line coming out of your boat fuel tank until you get the same issue and you have found your culprit.

If it turns out the issue is in the tank, the check valve PA Fire mentioned is a usual suspect. One other thing to before that would be your fuel vent line. If it's clogged it can also restrick the flow of fuel. Easiest way to check if the vent is clogged is to simply open your fuel cap which allows your tank to vent and try and run the boat...

Good luck. Frustrating stuff but using the protable tank will help you from replacing uneeded parts.

[Bass_Appeal]

Mercury is thinking diaphrams on fuel pump maybe worn also , so at this point waiting on saturday to even start to crack into what why when and how !

[Bass_Appeal]

Well , rebuilt my fuel pump diaphrams , cleaned regulator , changed filters , emptied vst , check fuel lines , and still the same problem ......then pulled the plugs and they seemed fouled out , so i glass beaded them put em back in and seemed to be slightly better but still rough......im assuming new plugs and i should be ok .....go figure !

[Bass_Appeal]

I forgot that , i put some seafoam in and never changed plugs after ....doi !!!

[hammer4reel]

when the neutral selector switch starts to stick you can get that same issue, But it will usually throw a code.
it wont let it go over 2500 while it says its in neutral.( just changed my second one )

I also had a piece of aluminum slag stick in my check valve on the tank and it did the exact same thing.

SO different things totally can cause the same symtoms

[Bass_Appeal]

After i cleaned the plugs it ran ruff from 2000 -3000 then ramped up fast to 5000 rpm backed down to prevent over rev......and it kinda stalled out ....so ....what ever the problem i dont think check valve because it only gives me problems between 2-3k rpm ....i was running ngk plugs bought , champions marine plugs and need to install see what happens ....i can tell u it is frustrating to say the least.......but i do think seafoam may be part of my problem ....i wanna get out and run every ounce of fuel out of it ...and go fresh ....