1990 Will Not Start

[winnard]

Symptoms
- Spark – Yes
- Compression – Yes, All 3 cylinders within 3 psi of 105, but engine seems to turn over too rapidly
- Gas – No
Problem
Gas enters through jet upstream of b- valve in carburetor during normal operation of venturi at operational speeds. Therefore, since vacuum within carb with b-valve shut excludes the jet, the choke must put gas into engine other than thru jet on start. Attached to center carb (see pic) is a solenoid. After removal and testing, it energized but did not function to retract the plunger. I am assuming that this solenoid allows for gas to enter carb somewhere on vacuum side of b-valve during startup.


Question
Obviously, my knowledge is limited. Please comment on anything that may be helpful.

[winnard]

Note - engine is 90 HP - thank you

[99yam40]

there are main jets and pilot(idle)jets and air jets in the carbs. The solinoid you spoke of is probably the Prime Start heater that shuts of the extra fuel flow as the motor warms up.

You probably need to pull and clean carbs if everything else is good.
A repair/service manual will hell you out and save you lots of money and time if you plan on working on this motor yourself

[winnard]

Thank you - See attached pic of solenoid - my son and I removed / inspected carbs yesterday - looked pretty clean except bottom carb - cleaned (but not soaked) , re-assembled and tested but still no smell of gas with or without spark plugs inserted - also, tested fuel pump and have gas flow at intake to carb – worrisome is the seeming lack of compression during engine turning - seems to spin effortlessly

[winnard]

Perhaps there is a port with a nozzel available on the vacuum side of the intake where the existence of low presure can be detected with a small hose and one's finger?

[jb123]

is there gas in the bowls ??
with carbs on intake, remove drain screws and pump ball
with a bad lp pump you still would smell gas and have on plugs

[winnard]

Sorry - yes, the bulbs were full of gas - we drained them before removing carbs. Also, I was able. after cleaning carbs, to obtain a very small air flow by blowing on gas intake nozzel through carbs and out large (~1/8" diameter) visable brass jet (sticks up about 1/8") on the base of the up stream side of b-valve.

[winnard]

Ok - this am we were able to get engine started - with throttle in choke position (all 3 B-valves closed), engine turned over but no ignition. However, when we placed red emergency fuel enrichment switch (3 position; normal, open, closed) from normal to open, with throttle in choke position, the engine fired off almost immediately. We would appreciate an explanation, since we do not know what happened and would like to understand how this engine functions. One more piece of information, the boat, Hewes flats, has a choke switch on the center console - I cannot figure out what it does since the throttle appears to completely control B-valve position, and I could not find a solenoid that operates to change B-valve position. Yesterday, a kind person explained the function of the prime start heater which I had mistaken as a solenoid.

[99yam40]

sounds like your pilot(idle) jet/ passages are still plugged. The emergency lever bypasses the carbs and injects fuel directly into the intake behind the carbs. There is no choke on a prime start motor, and the throttle controls the RPM of the motor by opening the throttle plates.
The choke switch on that boat does not do anything if the motor is prime start motor. Do a forum search for prime Start and read up on it.
better yet, get a manual for your motor and read it

[winnard]

Thank you thank you thank you - will do

[winnard]

Ok - we took your advice and went back into the carbs - this time with carb cleaner - sure enough there were all those holes and channels throughout the device that were drenched and purged with carb cleaner – buttoned back up – placed throttle in the choke position, and voila the engine started right up –spent about $25 so far – this engine is twenty years old – you guys are money – next step is to take to lake and test under load – still have concerns about the auto oil injection system but so far exhaust looks fairly blue