1995 90HP Johnson dies hot

[Rambler]

During 1st run in spring, died at idle speed and would not restart - had run it 20 mins. at 3500 rpm. Marina suspected water in gas - changed gas, gas filter, plugs then retarted (barely) and ran rough back across lake to take out. Took it to a mechanic and the mechanic spotted a primer unit crack and replaced, replaced carb o-rings, and a loose BB from carb that was causing fuel leak. Got it back and ran it as different speeds for about 20 mins and it died suddenly while at 3000 rpm. Recranked and ran rough. The motor did same after about 20 mins when returned to mechanic for test. Mechanic referred me to OMC shop but still thinking fuel problem. Shop wanted to rebuild engine because of some relatively minor wear evident in one cylinder. He said it was a compression problem without testing anything. I took boat home and replaced thermostats and seals from salt water corrosion I noticed while the head was off, replaced cylinder O rings and remounted heads, compression OK at 135-145 PSI. I had suspected water contamination in cylinder when I saw the thermostat seals were shot. On lake, boat ran great at all speeds for about 40 mins. Got trailer in water and boat would not start. Spotted minor fuel leak from another carb BB - fixed and retested. Hard to start again - died in 5 mins and would not restart. Checked spark and found to be erratic. Replaced power pack. Boat started great and ran great at all speeds, great idle, great out of hole and trottled up to about 5500 rpm - then died while at idle speed about 1 hr into test. Restarted and ran on a couple of cylinders to take out. Boat would not restart after it was cut off. Would not restart while hot, pumping bulb, choke, nothing. Let it cool on way home and it restarted immediately at house. Just checked compression hot and cold and that is OK. Seems that the original problem has not been solved, and the other fixes may have been coincedental. So far it has been diagnosed as fuel, compression and spark. Any ideas. Thanks

 

[ob]

Re: 1995 90HP Johnson dies hot

have you checked pick-up in fuel tank? this motor equipped with vro oiling system ?Insure fuel connectors are sealing .Possible failing fuel pump

 

[hondon]

Re: 1995 90HP Johnson dies hot

Since you have stated that you have o rings for head gaskets we can assume this is a looper 90 and not a CF.They made both in this time frame you know and a model # would help us.OB is correct in you isolating fuel delivery problems,but these loopers can have problems with the seal between the carb and throttle body that could give you your symptoms.

 

[Rambler]

Re: 1995 90HP Johnson dies hot

Thanks for the quick responses. It is a loop version - J90SLEOC Oceanrunner version. The fuel primer bulb does not stay firm but never has (this is the only problem(s) I have had in the 3.5 years I have owned it). This is the first boat I've owned so I may be a little slow on common knowledge but my Clymer's manual is starting to get a good workout. I primed the bulb on the occasions that the engine would not restart and it did not help. The first mechanic said the carbs were full of fuel when it died on him... I didn't know the significance of that but maybe he was ruling out fuel starvation. Lack of fuel would be suspect for dying while under way but I can't see it causing poor or no restart since I prime the bulb if it doesn't start right up since it's warmed at the time. Is the soft priming bulb always a problem causer?? I checked for line leaks and found nothing obvious, tighened the fuel filter a little but made no difference on bulb. Maybe two different problems still. Any chance this is a timing sensor problem brought on by heating up some component?

 

[ob]

Re: 1995 90HP Johnson dies hot

Sounds like the only thing you haven't been into is the carbs.I still feel you have pickup restriction in carbs .Bowls would stay full anyway.Just can't figure how mechanic dtermined carbs were full when it died on him .Oh well.Almost all performance problems are attributable to fuel flow and or carb sinc.I would remove and clean all carb components before I looked any further.If your mechanic has diagnosed the above things you mention to no avail then it seems he's playing guessing game as am I .The only difference is that he has visual and operational access to motor in question.Hope this helps some.Still would help diagnosing if I knew the motor was using VRO or fuel mix at 50:1

 

[Rambler]

Re: 1995 90HP Johnson dies hot

It has a VRO 50:1 oil system. There have been no warning horns or lights for any of these failures. Thanks

 

[ob]

Re: 1995 90HP Johnson dies hot

The only time you will get an alarm is in the advent of no oil pressure,low oil level in remote tank ,and a combination alarm of fuel restriction through vro pump and overheat.Fuel restriction through vro pump gets its signal from within vro pump assy. The S.L.O.W.is activated when overheat is detected which electronically limits rpms to 2500 or there abouts.If your motor is a 95 model I'm pretty sure it has this feature.However ,fuel restrictions within carbs have no alarms to notify operator.