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View Full Version : 90hp merc surging!



ericcs
31-07-2016, 10:13 PM
my 07 Mercury 90hp 2st has started to surge up to 500 rpm in about the 2500 to 5000 rpm range. by squeezing the primer bulb it seems to run fine, so I suspected air getting in the fuel line, or possibly the fuel pump or filters, but it runs fine from 5000 up to 5700rpm. it doesn't miss, so i'm ruling out an ignition problem, does anyone have any clues?

scottar
31-07-2016, 11:04 PM
Just be careful running a 2 stroke oil injected motor by pumping the fuel bulb. If it is the pump and the pump is also used to inject the oil, it may not be doing so properly. One of my uncle's seized a motor in such a manor attempting to get home one day. Went from new pump required to new engine required in a few kilometres. First thing I would try is a tote tank with a new fuel line to narrow down the possible faults.

ericcs
01-08-2016, 08:39 AM
Just be careful running a 2 stroke oil injected motor by pumping the fuel bulb. If it is the pump and the pump is also used to inject the oil, it may not be doing so properly. One of my uncle's seized a motor in such a manor attempting to get home one day. Went from new pump required to new engine required in a few kilometres. First thing I would try is a tote tank with a new fuel line to narrow down the possible faults.

good idea about the tote tank, i carry one on the boat as backup, cheers eric