140 vro power loss

[fiberformfloater]

Bought a used 1991 evinrude 140 vro. I checked compression before purchase all even and just under 140 cold.Installed on boat and replaced the impeller ran great for about 4 hours. The last time I took it out started ran great cruised for about 4 or 5 minutes at 4000 rpm, rpm dropped so I pulled it back to idle stayed running tried opening it up again came up to 4000 then almost immediatly lost power and died there was never a horn and the horn has been tested recently putted around on the kicker for a couple hours figured i would give it another try same thing. Kinda at a loss for a solution hope somebody can help

 

[kenmyfam]

Re: 140 vro power loss

Basic health check to begin with.
Compression (again)
Spark (with a spark tester)
Fuel delivery (to the carb's)
Spark plug condition (photos)

Post results and we can all go from there.
Welcome to iboats.

 

[fiberformfloater]

Re: 140 vro power loss

sorry to take so long to reply and i am afraid it is partial answer to your questions have not rechecked compression checked fuel to carbs no restriction no access to a spark tester but good blue spark at the plugs when cranking will take some pictures of the plugs soon but they look ok to me and i am going to replace them so that won't be a issue i am also going to try running off my portable tank to re confirm i don't have a fuel issue on that end any other steps for diagnostics would be appreciated

 

[kenmyfam]

Re: 140 vro power loss

sorry to take so long to reply and i am afraid it is partial answer to your questions have not rechecked compression checked fuel to carbs no restriction no access to a spark tester but good blue spark at the plugs when cranking will take some pictures of the plugs soon but they look ok to me and i am going to replace them so that won't be a issue i am also going to try running off my portable tank to re confirm i don't have a fuel issue on that end any other steps for diagnostics would be appreciated

OK,
Good blue spark grounded to the heads and good blue spark from the spark tester can be like night and day.
How did you check the fuel delivery ?? to test pump output you can crank the motor (with muffs on) after disconnecting the pump to carbs line into a container and watch the stream.
Strong regular spurts = pump working O.K.
Strong initial spurts tapering off = fuel pump beginning to fail
Trickles or dribbles = failed pump.

 

[ezeke]

Re: 140 vro power loss

S.L.O.W. is probably kicking in so troubleshoot the cooling system. It's probably the water control valve, but take the vernatherms out of the thermostats and test them first. Also inspect the thermostat seats while you have the units out.