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1998 Mercury 175 EFI - Starts and Dies

ploof340

New member
Mechanic told me the compression was low and that is why it would not start - had the power head rebuilt - still will not start - took it back to the Mercury dealer and he now says that the ECU was bad and not turning on my fuel pump - was going to buy a new one and a guy from another bass club gave me his old one and told me to try it - now I can here the pump and it starts foe a few seconds and then dies - has anyone ever heard of this or can steer me in the right direction. Thanks
 
If Merc (or one of their certified tech's) rebuilt the powerhead they should have returned the motor in running order.

You have a computer, sensors, injectors etc, fuel pumps (plural) any of which cold be the issue.

What caused the low compression in the first place?????

If whatever toasted the cylinders or rings was not addressed you still have the same issue and your "rebuild" is headed for an early grave.

Too many questions to ask before troubleshooting can begin.

What all was done in the "rebuild" - slapped in some new rings or really rebuilt it - new pistons, rings, bearings, gaskets etc, etc.
 
If Merc (or one of their certified tech's) rebuilt the powerhead they should have returned the motor in running order.

You have a computer, sensors, injectors etc, fuel pumps (plural) any of which cold be the issue.

What caused the low compression in the first place?????

If whatever toasted the cylinders or rings was not addressed you still have the same issue and your "rebuild" is headed for an early grave.

Too many questions to ask before troubleshooting can begin.

What all was done in the "rebuild" - slapped in some new rings or really rebuilt it - new pistons, rings, bearings, gaskets etc, etc.


It was taken apart sent to machine shop - hone cleaned - block deck cut and heads cleaned and cut - new rings, bearings and gaskets - customer did not want to replace reeds - some of them were beyond spec - cylinders were washed down from running lean
 
"running lean" =

clogged injectors, under spec high pressure fuel pump, perf in low pressure pump - those out of spec reeds that you note, leaky gasket, bad crank seal.

Any of those could cause the lean condition and again, if that was never addressed an has now become worse it could well explain why it won't start at all now.

You have to address the "initial" issue that caused the lean running that resulted in the rebuild...
 
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