88 Johnson GT 175 stalls under load

[Bjd102984]

88 Johnson Gt 175 model # J175STLCCM serial # R 7819867.

Motor has not been run in 5 years, prepped the motor and performed the following:
new spark plugs
new primer solenoid
new thermostats
new water pump and lower unit oil
rebuilt all three carbs
cleaned fuel tanks
new primer ball and fuel lines
mixed gas 50:1 in both tanks to verify the vro pump is working correctly
new oil filter and gaskets in vro tank.

PROBLEM: motor runs perfect on muffs, took the boat to the lake today and the engine stalls in forward, motor will only make 1800 rpms. The motor revs good in neutral and reverse but falls dead in forward.

I brought it home and checked for spark on all six plugs (good spark) spark advance is not stuck and moves with the throttle, couldn't find any fuel or vacuum leaks, all three carb had fuel in the bowls.

I took it to a local mechanic who unplugged all the warning sensors telling me he thought it may be in safe mode, (I checked the oil alarm and high water temp alarms and seem to work) I took the boat back to the lake and still have the same issue.

any input would be greatly appreciate, also I did a compression test prior to start up and all 6 cylinder's had 80-85 psi ( I am will to test again).

[ChampioNman]

All 6 high speed orifices full seated in the float bowls? Throttle plates all opening fully at WOT? Throttle roller contacting the short embossed mark on the cam follower in neutral and no throttle applied? Idle timing spot on?

[Bjd102984]

All orifices are seated, throttle plates are all in sync and the cam follow roller is correct per the manual. I have not touched the timing.

[316jughead]

Do have the OMC manual? Timing advancing 8 degree's before the carbs open? Best if spark plugs are Champion QL77JC4 gaped at .030. You may want to check for air in the fuel lines, it will make the VRO pump to much oil, air will be sucked in and fuel will not leak, at the fittings. By the way, you do not have a safe mode.

[omcforever]

88 Johnson Gt 175 model # J175STLCCM serial # R 7819867.

Motor has not been run in 5 years, prepped the motor and performed the following:
new spark plugs
new primer solenoid
new thermostats
new water pump and lower unit oil
rebuilt all three carbs
cleaned fuel tanks
new primer ball and fuel lines
mixed gas 50:1 in both tanks to verify the vro pump is working correctly
new oil filter and gaskets in vro tank.

PROBLEM: motor runs perfect on muffs, took the boat to the lake today and the engine stalls in forward, motor will only make 1800 rpms. The motor revs good in neutral and reverse but falls dead in forward.

I brought it home and checked for spark on all six plugs (good spark) spark advance is not stuck and moves with the throttle, couldn't find any fuel or vacuum leaks, all three carb had fuel in the bowls.

I took it to a local mechanic who unplugged all the warning sensors telling me he thought it may be in safe mode, (I checked the oil alarm and high water temp alarms and seem to work) I took the boat back to the lake and still have the same issue.

any input would be greatly appreciate, also I did a compression test prior to start up and all 6 cylinder's had 80-85 psi ( I am will to test again).

Did you use (OMC) new gaskets and seals and needle and seat and new floats in rebuild of carbs? Where all orifices removed and passages cleaned? Where carb welch plugs removed and cavities cleaned and new plugs installed per the OMC service manual? Float height and drop set per OMC manual?
(sat for 5 years)

[omcforever]

Mid and main jets in right orifice? main-61C/mid-36.....

[Bjd102984]

Yes oem kits, new bowls with new orifices as well and I did build per the OMC manual. I will add that the boat jumped up on pad and ran well for about five minutes before the problem started.

[316jughead]

Yes oem kits, new bowls with new orifices as well and I did build per the OMC manual. I will add that the boat jumped up on pad and ran well for about five minutes before the problem started.

I will add, that was some important info left out, good luck.

[Bjd102984]

I apologize and I do appreciate your input. Thank you

[Bjd102984]

Also left out that the boat jumped up on pad and ran good for five minutes before the problem started, I apologize for not including that.

[Bjd102984]

Update !

rans new fuel hose’s For the VRO pump and the boats running pretty good, my problem now is it won’t make above 4800-4900 rpms, runs good on plane and cruises at 55mph, tach quit working while running it, the voltage regulator is working fine so it may be a bad tach or loose wire. I’m thinking I may have a coil or power pac issue, going to replace both power pacs and the coils since they are cheap.

any other ideas ?

[omcforever]

So you concluded the stator is not the issue????? Throwing parts at a guess can get $$$$$$$ Your OEM repair manual sure does have some funny troubleshootings ways,,,,