Troubleshooting Fuel Issue 90HP EFI (2012)

Hello,

Serial Number 1B948812Model Number 1F90413ED

I've read quite a bit here and what folks have shared has been very helpful. I replaced a faulty float switch in my FSM based on troubleshooting steps provided here, so thank you! Unfortunately, it seems like I have run into problem after problem over the last year or so with this engine.

The first mechanic I took the boat to replaced the IAC and the boat DID idle better afterwards. Though it was still dying out after longer runs. This is when I took the FSM apart, tested and replaced the float switch. I also replaced the inline fuel filters. The boat ran better, but was losing power and stalling out. I was able to idle back to the dock. I ended up replacing the float switch with the Mercury part since I was worried the knockoff might be part of the problem (even though it tested fine). I took it out again and again it ran rough, but would idle decently. I took the boat to another mechanic that quickly diagnosed one of the inline filters as being defective. Supposedly an internal piece of the filter broke off and was clogging the fuel flow. Took the boat out again continued to have issues after running at high speed. Now after idling a while, the engine finally stopped even starting.

It did not appear that fuel was getting pulled into the FSM, though fuel was visible in the high-side inline fuel filter side and this side was under some pressure since it sprayed everywhere when I disconnected it to check it. Fuel seems to be flowing freely from the main tank, but there didn't appear to be much in the FSM when I removed it yesterday (though again, fuel was in the high pressure line). I ordered a new seal kit figuring it would make sense to replace it, but I am not sure where to go next. I do have vessel view, but it is not throwing any alarms related to the fuel system (it has on occasion when I repeatedly try to start it, thrown both a neutral switch error (110-Legacy) and an oil pressure (85-legacy), but these faults seem to clear on their own.

Apologies for the long post, but I am not sure where to go next. Was thinking of replacing the fuel lift pump, but I am not sure that is 100% logical. Also wondered if the pressure regulator could be preventing flow after fuel gets into the high side, like at some point, could a vacuum prevent the flow of any more fuel?

Thanks,
Alex

Replaced the lift pump today with a new one and now I am getting the "Electric Lift Fuel Pump Timeout" error. Despite never getting that with the old pump. Wonder if the new pump can't keep up or if I need to replace all seals, etc. (those are on the way).

Well, I filled the FSM about half-way and then ran a line from the lift pump input on the FSM to a jar of clean gas. The engine started right up, but didn't really need to pull any gas since some was already in the FSM. Almost the whole time, I could see bubbles coming out the end of the hose that was in the glass jar. Eventually the FSM ran low on gas and the lift pump pulled a decent about of gas into the FSM, but the engine died out and then the gas was returned to the jar.

I am wondering if the air bubbles coming out of the lift pump line indicates that the pressure regulator isn't working properly. I can't think of any reason why air would be escaping there. Then once the lift pump start pulling gas, the air had no way to go, then pressure built up and then the engine died and the pressure pushed the gas back in the jar? This makes me think the pressure regulator might not be working? Does this make sense to anyone?

I was pretty sure the pressure regulator wasn't regulating the pressure so I took it into a shop expecting them to hook it up to the computer and see what the ECM was telling them. I am not sure what they did, but they came back saying the lift pump was bad and asking for $1000 to replace the lift pump, the fuel filters and to "clean up" the VST. I replaced the lift pump (and cleaned the "VST") three days prior to bringing it to them and it is lifting fuel. It is throwing an error, but I think that is because the pressure build up is preventing fuel from reaching the proper levels in the tank. In any case, I told them to forget it. I would expect to pay $1000 or close if they replaced the whole FSM, but I have no confidence they even know what is wrong. They actually replaced the fuel filters themselves two weeks ago and that was after I completely emptied the tank and replaced it with new fuel. I have a new pressure regulator on the way and will close things out here if it fixes my issue.

alhud said:

Estaba bastante seguro de que el regulador de presión no estaba regulando la presión, así que lo llevé a un taller esperando que lo conectaran a la computadora y vieran qué les decía el ECM. No estoy seguro de lo que hicieron, pero regresaron diciendo que la bomba de elevación estaba defectuosa y pidiendo $1000 para reemplazar la bomba de elevación, los filtros de combustible y "limpiar" el VST. Reemplacé la bomba de elevación (y limpié el "VST") tres días antes de entregársela y está elevando combustible. Está arrojando un error, pero creo que se debe a que el aumento de presión impide que el combustible alcance los niveles adecuados en el tanque. En cualquier caso, les dije que lo olvidaran. Esperaría pagar $1000 o cerca si reemplazaran todo el FSM, pero no tengo confianza en que sepan qué está mal. De hecho, ellos mismos reemplazaron los filtros de combustible hace dos semanas y eso fue después de que vacié completamente el tanque y lo reemplacé con combustible nuevo. Tengo un nuevo regulador de presión en camino y cerraré todo aquí si soluciona mi problema.

Click to expand...

hello alhud, Could it solve your problem? I have the same symptom, bubbles in the bottle.

alhud said:

Estaba bastante seguro de que el regulador de presión no estaba regulando la presión, así que lo llevé a un taller esperando que lo conectaran a la computadora y vieran qué les decía el ECM. No estoy seguro de lo que hicieron, pero regresaron diciendo que la bomba de elevación estaba defectuosa y pidiendo $1000 para reemplazar la bomba de elevación, los filtros de combustible y "limpiar" el VST. Reemplacé la bomba de elevación (y limpié el "VST") tres días antes de entregársela y está elevando combustible. Está arrojando un error, pero creo que se debe a que el aumento de presión impide que el combustible alcance los niveles adecuados en el tanque. En cualquier caso, les dije que lo olvidaran. Esperaría pagar $1000 o cerca si reemplazaran todo el FSM, pero no tengo confianza en que sepan qué está mal. De hecho, ellos mismos reemplazaron los filtros de combustible hace dos semanas y eso fue después de que vacié completamente el tanque y lo reemplacé con combustible nuevo. Tengo un nuevo regulador de presión en camino y cerraré todo aquí si soluciona mi problema.

Click to expand...

hello alhud, were you able to solve your problem whit the new pressure regulator? I have the same symptom, bubbles in the glass jar.