merc 150 efi problems

this has been going on for awhile. we would go out for the day no problem then the next couple of time we would be humming along and it would just die. no warning just die. prime the bulb and off we go stop prime off we go....it would run longer in between each prime then the next time we would go out no problem then another time it would play up once..anyway finally had enough they said stator no good had that changed and one of the control modules had gone they said the whole problem was caused by a damaged wire. thought problem solved took it out worked okay running rough tach went crazy all over the shop. took it out again ran for 5 minutes died again same problem prime the bulb and off we go again...took it back after the money we have spent we throught problem solved.... they have now change fuel line even though they say all that checked before. they run for an hour and found no problems.. picking it up tomorrow and we shall see if this has finally fixed it..just wondering if anyone has this intermittant problem and finally had it sorted.

Re: merc 150 efi problems

I would install a fuel pump diaphram as it sound as if it cant supply the VST with fuel, the check valves are likely warped and not sealing due to ethanol.

Re: merc 150 efi problems

You may be developing a second issue with the tach becoming erratic.

When this occurs again, stop, disconnect the yellow wires connecting the stator to the voltage rectifier. Restart and run. If erratic running is now gone then begin testing rectifier(s).

Re: merc 150 efi problems

just so you know never used ethanol for boat. Re: Tacho being erratic mechanic said no problem yesterday. He has changed the fuel prime bulb and checked the line all seemed clear and running fine. He said lead connecting to battary were a bit loose that may have caused tacho being erratic. wired at ignation twisted straightened them and checked for to make sure all in good condition.
But it has done that to us before on the river running just fine one week then causing problems the next.
We have been told that the stator was pretty much fried. I am wondering if that was the case would the boat even start?? does anyone know the answer to that. If the problem occurs again may take our boat to another mechanic loosing faith in this one.

Re: merc 150 efi problems

If you pump up the bulb and it restarts and runs its not a electrical issue its a fuel issue. Still service the fuel pump diaphram as it needs replacing at least every 2 years. I myself think all fuels now have a ethanol trace due to cross comtamnation. Our bass club has tested several stations that claim no ethanol and all do have it in the 3 -5% range.

http://www.eaa.org/autofuel/autogas/test_kit.asp