spark or fuel ???

Joined
Jun 25, 2018
Messages
2
i have 1987 50hp johnson vro boats idles fine starts easy has new coil packs new plugs all new fuel lines rebuilt carbs sometimes it runs fine until it hits about 4000rpm then boggs down or fills like it runs out of fuel in the carbs if you back off a touch it runs good then if its really hot outside still cranks and idles fine but cant go any faster than 3mph just runs thens stop does the same thang goes and stop
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
Welcome aboard.

90% of ignition problems usually turn out to be mechanical. :smile:

Do a compression check, verify spark using an air-gap tester, make sure the carb is opening completely at WOT and check the float adjustment.
 

jakedaawg

Rear Admiral
Joined
Jun 26, 2012
Messages
4,275
I like to see ~120 on my guage. All guage read a little different though. Dont waste money on a harbor freight piece of chinesium. We have not had a single reliable number posted with such toys as they sell.
 

jakedaawg

Rear Admiral
Joined
Jun 26, 2012
Messages
4,275
You will need to do a compression check and post numbers.

Then you will need to do an open air gap spark check set to 7/16" with appropriate tester. Parts store sells them, key is open air gap not inline style. Post results.
 

WhatAdrag!

Recruit
Joined
Jun 25, 2018
Messages
2
I had a 60hp vro before, I read some where that the engine/fuel line or injectors get blamed for the "VRO" system not working properly as it presents similar symptoms. Its suggested that the VRO system requires a very detailed routine maintenance as it can clog and cause issues. Look into that if nothing else works.
 
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