Motor wont restart once warm

[BringOutAnother1000]

I have a 96' mercury 90hp 2-stroke that starts fine the first time it is fired up. It runs fine and will run WOT no problem. What I am having an issue with is the restart once out on the water. After the initial start if I turn the motor off to troll or just relax on the water, it wont restart again till it has been sitting for long enough to have cooled down again.

Couple of things I am seeing:
- I replaced the inline filer that is inside the engine hood with a clear one. After the motor is warm and I pump the primer bulb it only fills the inline filter up about half way and then the gas slowly drains back out of the filter.
- While running the inline filter is only about half full and bubbles.
- I have replaced the primer bulb but that doesn't seem to have changed anything.
- My fuel system is an aluminum tank with a fuel line run to a filter/water separator, then a primer bulb, then hits the motor.


Any advice on what to try or ideas of what the problem might be would be very helpful.

Cheers,

 

[MH Hawker]

you are having a heat soak problem, not fuel, one of the electrical components is breaking down once it heats up, get out the ohm meter and write down the values when cold then take it for a run and after it quits test it again and see what readings have changed and you will find the problem

 

[racerone]

Outline your starting procedure cold.---Outline the procedure when warm.----Perhaps an error can be spotted.

 

[roscoe]

Or possibly a flooding condition when the warm engine sits.

If you run it and turn it off, will it start if you try to restart it within a minute or 2 after shutdown?

 

[Texasmark]

Outline your starting procedure cold.---Outline the procedure when warm.----Perhaps an error can be spotted.

+1. Process may be flooding the engine.

On the inline fuel filter not appearing full, that is not necessarily a gauge that fuel is flowing properly. BTDT on numerous types of engines. The air bubble can remain even though fuel is flowing. That's probably why they make OEMs opaque. Can't see the bubble and worry about it.

I had the '02 version of that engine and first start of the day exhibited lean fuel supply and we won't get into that. After first start, all I needed was to touch the key, shifter in N, no fast start, no bulb squeeze and it would light off faster than I could get my finger off the key, unless it sat for a half hour or so. For that, bringing up the fast idle would do the trick. No fuel enhancement (pushing in of the key) required.

Dropping a cylinder on that engine wouldn't keep it from starting unless you were having a thermal problem with the stator....which I find unlikely considering there is nothing but ignition coils under the flywheel and they work otherwise. Each cylinder had a completely separate trigger, high voltage generation circuitry and the engine would start on 2 and probably stumble on with one.

Vapor lock could be a problem due to engine heat and fuel line routing but a better source on that old of an engine would be cracks in the fuel lines somewhere allowing air in which would allow the fuel to siphon back to the tank when you shut the engine off and would require a "cold engine" start sequence.

 

[BringOutAnother1000]

Cold Start - Pump primer till hard, turn key to on, push in and hold for 5-8 sec, turn key to start.

Warm start - Pump primer then turn key to start

I will try this weekend in my driveway to start it and then restart with just turning the key. I will also take the Ohms reading to check any possible electrical issues off the list.

Thanks for help guys!

 

[MH Hawker]

the quick test is to see if you have spark when it wont start

 

[Texasmark]

the quick test is to see if you have spark when it wont start

+1 and quickest way to do that is to pop the cowl, clip on a battery operated timing light, clip the power leads, clip the lead on a spark plug wire and hit the switch. Test all 3 and you can eliminate spark as an issue. Ignition coils have a history of failing (when they fail) like your problem but if your engine is setup like my 2002 90, each cylinder has it's own coil in the CDI per cylinder so normally you would only loose the cylinder associated with the temperature sensitive coil.

I had one of my CDIs that wouldn't fire when cold. The engine had to warm up somewhat. I attributed that to an electronic component (not an electro-magnetic component)....didn't bother trying to figure which one. Had a spare, popped it in and that was that.

 

[racerone]

The way to start it is prime the bulb till hard.-----Push key in while cranking it over.-----Push key in as needed till motor warms a bit.-----When warm you may try pushing key in too while cranling.

 

[roscoe]

So you never advance the throttle to start this motor?

Every Merc I have owned seems to need the throttle advanced to start when cold along with the choke.
Some of them need the throttle advanced when warm also.

 

[racerone]

Yes, advance throttle as required too.

 

[Texasmark]

So you never advance the throttle to start this motor?

Every Merc I have owned seems to need the throttle advanced to start when cold along with the choke.
Some of them need the throttle advanced when warm also.

I use full fast idle always on first crank. If on the water, I first attempt a no nothings, turn the key, no push. I that fails, I up the fast idle to max. If that fails I leave it up and use some fuel enhancement. All in that sequence all in the matter of a minute. Depending on the sitting time, usually key only lights her off faster than you can say hey she's lit turn loose of the key.

 

[Silvertip]

Every engine has it's "likes & needs". The fast idle lever is the most overlooked feature on outboards (as well as carbed I/O's). People simply fail to "experiment" using the features available on these motors. There should be no reason to squeeze the primer bulb after the first start of the day unless: 1) there is a leaky carburetor or 2) leaky/weak fuel pump, or bad primer bulb. Once the engine has been running and then shut off for a bit, to restart simply set the fast idle lever 1/2 up and hit the key. Only on a very chilly day would you need to push the key in during cranking. Full up on the fast idle lever is the way to clear a flooded engine. Over use of the primer is a good way to actually flood the engine, especially if the float level is wrong and/or inlet needle is not seating properly.

 

[Alumarine]

If you don't have a fast idle lever you have a throttle control with a button on the side that you push or pull so you can advance the throttle without it going into gear.

 

[Texasmark]

If you don't have a fast idle lever you have a throttle control with a button on the side that you push or pull so you can advance the throttle without it going into gear.

That's the Quicksilver Commander 3000. It and the cables and electrical cable are behind the bulkhead. The 2000 is mounted on the bulkhead and the cables are exposed. It has the very convenient lift lever. Always press the lever down or on the 3000 return the control to N prior to putting in gear....course on the 3000 you have to get to N to get back to the dual function lever.

 

[BringOutAnother1000]

Thanks for everyone's help. Turns out I was just flooding the motor. Glad it was nothing expensive.

 

[Texasmark]

Life is sweet sometimes isn't it!