Need some advice

[rcb130]

Hello All,
Just purchased a 1992 Johnson 120 Hp V4.
Model J120TLAND, S/n G03002936
Motor starts and idles for approx 30 seconds and dies. Will immediately restart and idle for 25 seconds and dies.
I am looking toward a fuel delivery problem.
Previous owner claims to have rebuilt carbs, replaced coils and powerpack. Motor has a two year old VRO pump.
Does anyone agree with my preliminary diagnosis? If not, what are your thoughts?
I have not had the chance to do any further trouble shooting as of yet.
Thanks
rcb130

 

[racerone]

The VRO pump should last longer that 2 years.------But there is a chance that there are issues with crankcase compression.----That is what drives the VRO pump air motor.

 

[Joe Reeves]

Have someone pump the fuel primer bulb constantly, acting as a manual fuel pump. If that cures the problem, it proves that your suspicion is correct and most likely the fuel pump requires replacing or rebuilding.

Pertaining to your statement about your engine's model number:

"Just purchased a 1992 Johnson 120 Hp V4.
Model J120TLAND" <----- Shouldn't that "A" be an "E"?... EN stands for 92... AN stands for ?2

 

[rcb130]

Joe, Your are correct, typo on my end.
Racerone, would low crankcase pressure create a condition I described?
Thanks
rcb130

 

[racerone]

Well----The fuel pump would not operate properly.

 

[rcb130]

Racerone, How do I check crankcase pressure?
rcb130

 

[rcb130]

Joe,
Here is what I have found so far. Engine will crank, no start. Not even an attempt to start. Will jump spark plug gap but not a 7/16 gap. Carb for #2 clyinder is leaking, apparently at bowl.
I have found what looks like a ground wire with a bullet connector sticking out from behind the housing for the tilt/trim. I cannot find this wire on my factory schematic. any ideas where it goes?
Thanks
rcb130

 

[rcb130]

Joe Reeves, are you there?
rcb130

 

[Joe Reeves]

1 - Engine will crank, no start.... Not even an attempt to start.
2 - Will jump spark plug gap but not a 7/16 gap.
3 - Carb for #2 clyinder is leaking, apparently at bowl.
4 - I have found what looks like a ground wire with a bullet connector sticking out from behind the housing for the tilt/trim. I cannot find this wire on my factory schematic. any ideas where it goes?..

1 - Engine must crank over at least 300 rpm (fast)... a slow cranking engine will have erratic or no spark. Is this a fast cranking engine?
2 - Spark, with "all" spark plugs removed, must absolutely jump that 7/16" gap with a strong blue lightning like flame... a real SNAP!... Anything less will not do.
3 - Carburetor #2... faulty float needle valve, float set wrong, warped float chamber? You'll need to correct that problem.
4 - Sorry, I don't have a wiring diagram for that 1992 120hp either.

 

[oldboat1]

Maybe this: https://maxrules.com/graphics/omc/wiring/1992_V4.jpg