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2001 mariner 115hp efi bogging down!!!

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Bobski

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Hi, new on here, i have a 2001 115hp efi mariner, starts great, revs up in neutral fine, even okay in gear out of water, but when in water it just boggs, still revs on warm up okay just problems under load! can anyone help please? no fault codes, service parts replaced, i'm ready to put a match to it!!!
 
Bogging under load means it's not getting enough gas.

So back to the start -

confirm:

the fuel pick-up in the tank is not obstructed

the pick-up tube is intact

the tank connections and anti-syphon valve are functioning properly

the tank vent is open and un-obstructed

the fuel hose and fitting are not leaking or sucking air

re-inspect all filters (inline, fuel, VST water separater etc)

If all that is fine try pumping the primer bulb on the fuel line when she bogs - if that helps rebuild the crankcase fuel pump

If it doesn't help get the electric fuel pump tested - if it's ok then have the injectors cleaned and have the throttle bodies checked out.

If the problem hasn't been found by that point then you could have a seal failure on the intake manifold or a crank seal failure (stuff you need to get the wrenches and pullers out for).....
 
Last edited:
Cheers for the advise galamb, checked most of the things you've said, i just fitted new injectors yesterday, havent had boat back in water yet but motor sounds a lot better on muffs with these fitted, thanks again and let ya know if it's cured once been in water
 
I have a 2001 90hp mariner that wouldn't idle. I cleaned all the carburators and flushed the fuel system back to the the tank.I noticed that only the upper iginition coil was firing two of the four plugs during the start sequence.I swapped the trigger wire for the coil and the problem follows. Is it normal during start to have only two cylinders fire? help...
 
Bobski ..Merc had a few problems with the harness into the ECU not making contact and causing cylinders to drop out,stalling ,missing so check to see if its tight...
 
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