I can't get her running smoothly "98 90SPL rough and lots of thick oil from exhaust

[toddschubert]

I can't get her running smoothly "98 90SPL rough and lots of thick oil from exhaust

I should start from beginning of problem.
Went fishing w wife running great. Stopped to fish then would not start. After playing with throttle positions got it running but sounded like missing cyl or two. I found no apparent issues with head e.g. compression is normal and spark is good. I removed carburetors and cleaned all orafaces and replaced. I cranked her up with no cables attached and it ran pretty smooth. Thinkinf I nipped the problem I replaced all cables back to original positions. Throttle and timing and shift. Tried to crank it and had the same original problem. If I got it running it was at a high idle and it ran rough. Also important to note is the thick oil from exhaust. This would appear to me as a timing issue. Unburnt fuel somewhere.

I'm no expert on these motors but know something about how it works and I'm stumped hoping someone could lend some advice to help out.
Please let me know what other info would help in giving me some ideas.
Link and sync from this crazy SELOC manual is not helping.
Please remember it was running fine then suddenly wouldn't start after 20 min of fishing.

Thanks
Todd

 

[racerone]

Exact answers are required in order to help you.-----What are the compression test readings as " normal " means very little.----Will spark jump a gap of 7/16" or more on all 4 leads..----And have you checked the diaphragm on the fuel pump ?-----Does primer bulb go hard when you operate it?

 

[toddschubert]

UPDATE
I took her out to see if running higher RPM would smooth it out. Well, it did in a way. Once I get it started and can get her in gear it does smooth out but I feel like its not hitting on all 4. I was running w hood off and carb cover off and noticed that when it starts to die fuel runs out of carbs. I did have motor tilted up a bit but this can't be right. When I throttle down it dies. I also changed spark plugs.

 

[racerone]

Questions have not been answered !

 

[toddschubert]

Just saw post. It didn't show when I posted last comments
Thanks. I need to check for spark power. I only checked that it was present.
Pump looks good
Primer bulb working fine. It never did get hard which I can't figure out but it works just as it did when motor ran fine
Your help is much needed and appreciated but I reiterated please keep in mind it ran fine, I stoped it to fish for 20. Min then had problem. This to me would seem to rule out things like primer bulb and what it affects. I will double check the other areas

 

[toddschubert]

Oh, compression is at 60 psi +- 2 on all 4 which is low but I think this reading is incorrect bc of gauge. However they all are about the same and the same as last tested when running fine.

 

[racerone]

When you are starting a motor the primer bulb MUST go hard.----If it does not there is a problem.----Could be a leaking float valve or a hole in the fuel pump diaphragm.......You have to check these things out .

 

[toddschubert]

I have had two of these Johnny 88 and 90SPL and the primer never got hard on either. They ran great for years. Could it be something different in these mods?
There is a difference in pressure from first pumping to after 10 -12 pumps but never gets hard like I have found on other motors and what you are talking about.

What causes thick black oil in exhaust??? This answer might get me to the problem quicker. Timing?, carbs?, piston rings? (compression good though), What about a valve problem? I have never dealt with that before?

 

[racerone]

The bulb must go HARD !!------And what valves would you like to know about ?

 

[ondarvr]

As stated, the primer bulb must get hard if everything is working correctly, if it doesn't get hard you either have a float needle problem or defective check valve in the squeeze bulb. Actually a ruptured fuel pump could act like this too.

 

[toddschubert]

So would a float or needle valve cause thick oil spewing from exhaust? If so we might be getting somewhere.
I think I must have had cheap primer bulbs then cuz they have never gotten hard. By the way, I rarely had to use primer bulb in past. I used the boat frequently enough and it always started right up...first crank.
PLEASE remember it was running fine then NOT suddenly. Could I be dealing with electronic issue that suddenly went bad? You see my point is I can't imagine some of the issues being brought up suddenly going bad. I have serviced the carbs fully and I still had identical problem when put back on.
Thanks again, Please bare with me. I will be checking spark power in the morning.

 

[durban]

you have a separate oil tank ? observe the oil pressure switch any changes there will result more oil being pump into motor & coning out the exhaust ive seen this happen before .

 

[racerone]

Most SPL models did not come with oil injection system !

 

[toddschubert]

Right. It's my understanding that that was the purpose of the "SPL" for commercial users who demanded a mix system rather than oil inj that would fail and ruin engine.

So the oil is mixed in fuel. Inj system ruled out

 

[steelespike]

Yes the needle/float valves could cause excessive unburned fuel discharge.
A defective primer (choke) valve could introduce too much fuel.Not sure how the 90 is
laid out but There is
usually a red manual choke lever on the primer valve. is it in the off position?
A leaky fuel pump diaphram could dump fuel into the cylinders involved.
Its normal for a heathy motor to have some unburned fuel discharge.
If you unhook the fuel line at the motor and squeeze the primer bulb it should get hard.
if it doesn't then the bulb is bad or the fuel pump diaphram is leaking.

 

[toddschubert]

You have something there Spike. The guys above have stated about the bulb. The bulb is bad (backflows) however it does its job well enough. Other problem is fuel runs out of carbs when squeezing it. I just noticed this and will take a closer look at pump.
BTW spark dances all over gap tester beyond 7/16 on all 4

 

[ondarvr]

It's not uncommon for bulbs to have leaky check valves, it really only needs to work well enough to pump fuel to the carb.

 

[toddschubert]

Finally got somewhere after working on and of
The primer pump had melted the plastic valve allowing fuel to flow into carbs. I sealed the primer out of system as I rarely use it and it runs but now have another problem and will start new thread
Thanks for the comments