1994 120 force o/b won't start

brian66r1

Seaman
Joined
Aug 18, 2011
Messages
54
Hi all.

I have a 1994 120hp outboard and whilst out last weekend for a slow trip up the river with the family, we came across a spot of trouble.

Going out, I decided I wanted to use a plastic fuel can (25 litres) to check our economy so I filled it with fresh fuel and oil, put the boat in the water, it started fine, ran well at all speeds, then we entered the river and ran it for about 30 - 40 minutes at about 2500-3000 revs (speed limit in the river is 10Kts).

Ran out of fuel in the reserve tank, no problem, switch to the main tank, prime up the bulb, start the motor again, off we go again.

Not that easy. The engine wouldn't start. Tried and tried and tried again, no good. Good thing we were in the river and within drifting distance of a pretty big and pretty expensive private marina.

Got over to a berth and checked: Plugs (looked fine), fuel (cracked the fuel line off from between the 2 carbs and petrol sprayed all over the place), spark (looked really weak but it was there, at least I think it was), checked spark again and nope, No spark.

Looked around everywhere, coils, plug leads, CDI. Tried starting several more time using a jump pack and even a completely new battery. Actually did get it started, after about 2 or 3 hours, don't know how, but it stalled the moment I put the throttle in gear. Where do we go from here? I've tried cranking it at home with the muffs on and and after a couple of 15 or 20 second attempts, it actually fires but it won't start.

Going to try pull the flywheel off in the morning to check the magnets underneath it and the stator. What should I be looking for at the coils and the CDI?


Brian
 

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,909
Re: 1994 120 force o/b won't start

The fact that it tries to fires but wouldn't start indicates it's starving of fuel. Since the only thing that changed when it was properly running was ran out of fuel and changed over to the main tank, a leak could have developed in the fuel system or it could just be coincidence that the needle valve on one of the carbs got stuck in the up position. I'll say clean both carbs first by spraying the ports (specifically the idle ports) with carb cleaners and then install a see-through fuel filter and watch for bubbles. If bubbles are present it's an indication of leaks in the system.
 

jerryjerry05

Supreme Mariner
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18,049
Re: 1994 120 force o/b won't start

Start with a compression test.Then spark.Then fuel.
Then the flywheel key.J
 

brian66r1

Seaman
Joined
Aug 18, 2011
Messages
54
Re: 1994 120 force o/b won't start

Compression is good. 120, 140, 120 and 120 roughly. Just dropped a bowl off the top carb and found it full of crud. Water especially. Before I filled the plastic tank with fresh fuel, I dumped the half a tank of fuel that was in it into my main tank (plus another 50 litres of new fuel also) and the half a tank of fuel that was in it must have been 3/4 water.

Anyway. We emptied out the main tank. Dropped the crappy fuel out of the carbies refilled the plastic tank with more fresh fuel. Mixed it up. And tried it hoping that with weak spark and all it might still fire. No.

What next. The spark is blue but not what I would call very strong. Now the main tank is completely empty. The plastic tank has good fuel in it the bilge is sparkling clean. I replaced the fuel filter and the fuel line inside the engine cowl. The motor. She still not go. If water got sucked into the carbs and into the engine. What would have happened.

My batteries are strong and they crank good. Do I start looking for a new CDI pack? Is it just a coincidence that something happened to the coils or the CDI at the same time I connected the engine to a crappy fuel supply?

Brian
 

jerryjerry05

Supreme Mariner
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May 7, 2008
Messages
18,049
Re: 1994 120 force o/b won't start

No the CDI is probably still good.Did it backfire?Backfire makes it jump time.
The carbs probably need to come off and cleaned.Check the filters on the motor.
Once you suck up crud it gets in the needle/seat.One piece of crud the size of a grain of coffee or smaller can stop you from running.
Install an inline water/fuel seperator.J
 

chrome dome

Petty Officer 1st Class
Joined
Sep 24, 2010
Messages
303
Re: 1994 120 force o/b won't start

does sound like crap in the carbies problem,

mind you, it could also be a hooning problem though...speed limit upstream of the bridge is 5 kts
:p
 

brian66r1

Seaman
Joined
Aug 18, 2011
Messages
54
Re: 1994 120 force o/b won't start

Good point chrome.

I was only doing 6-8Kts up from the bridge but with all the weight on board (6 pob) I had to push it pretty hard even to get that (hence 3000RPM). I hope the extra bodies on board are the reason for getting such crappy economy too (not that a 15 plus year old big 4 cylinder 2 stroke outboard is going to be very economical to run anyway). But I put it in at Altona, went out past Gellibrand and then up the river and I only made it into Docklands. 25 litres (almost) and 11 nautical miles????

I took out the plastic screw in covers over the idle jets and had a look just now but it's dark now and my jaw hurts from holding the little torch in my mouth. Both jets were clean as a whistle. The main jets in the top carb were good too. Haven't taken them off yet. The other interest in the boat is a bit hesitant in me doing this. The spark on the plugs is blue but looks very weak. I'm wanting to break a golden rule and spray some Nulon Aero Start into them just to see if it will kick, that's all. Maybe on Friday morning?

Brian.
 

jerryjerry05

Supreme Mariner
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18,049
Re: 1994 120 force o/b won't start

What the heck is a HOONING Problem??????????
Thay's a new one.:)
 

brian66r1

Seaman
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Aug 18, 2011
Messages
54
Re: 1994 120 force o/b won't start

What the heck is a HOONING Problem??????????
Thay's a new one.:)


He is implying that I was a bit of a lead foot, or a Hoon. Tearing around at some great rate of Knots in a speed restricted zone.

We live in a bit of a Nanny state me and Chrome. The police enforce a zero tolerance to speeding in cars, doing burnouts, drifting sideways around corners, doing wheelies on bikes and more than likely speeding in boats. In fact, if we get caught doing any of the aforementioned activities, they will remove our cars or bikes (and possibly even boats) and impound them for a period of time. Repeat offenders risk losing their pride and joy permanently. The state government calls it "The Hoon Legislation".

Brian.
 

brian66r1

Seaman
Joined
Aug 18, 2011
Messages
54
Re: 1994 120 force o/b won't start

Jerry,

What do you mean, "Did it backfire?Backfire makes it jump time.". How can the timing adjust or jump? I see it has a sort of mechanical advance. You can work that out without removing the flywheel but how can it adjust? And if it does, what do I have to do to set the timing again? I can't remember it backfiring before it broke but it has once a while ago that I remember.

Brian.
 

chrome dome

Petty Officer 1st Class
Joined
Sep 24, 2010
Messages
303
Re: 1994 120 force o/b won't start

yeh, we do live in a nanny state,
:facepalm:
just a bit of leg pulling..

anywho, along with the good advice already given this may come in handy if the carb cleaning doesn't fix the problem and you want to trouble shoot the electrics,

http://issuu.com/cdielectronics/doc...t.xml&backgroundColor=000000&showFlipBtn=true

just a question re the size of the boat..it's not going to fix your problem though,

it must be a reasonable size to have 6 pob.. which means that it certainly isn't going to plane at the speeds that you were doing in the river..what size is the boat and what size donk is the boat rated for?

too small can be much the same as too big...donk has to work just as hard,specially at sub planning speeds,

11NM = 18 k's ( l think ) doesn't sound a lot admittedly..l count on 1.5 k's per litre ( 36k's per 24 lt tank X 2 ) for a 70 hp,

son has a 120 hp Chrysler that has weak spark on 3 & 4 but still fires on them


that is a nice cruise along there..did that ( just to the mouth though ) on a party boat two saturday nights ago...LOTS of nice "sights" walking around too
:cool:

might do it new years with our boat then,
 

Jiggz

Captain
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Oct 23, 2009
Messages
3,909
Re: 1994 120 force o/b won't start

I know this almost sound ridiculous but while cranking, can you smell fuel coming out of the exhaust? If not, get a spray bottle with fuel-oil mix and spray it directly into the carb's throat while cranking. If it kicks or coughs, can you open or unscrew the idle mixture about one full turn counter clockwise? As soon as she starts running then re-set the idle mixture screw. If it still would not go hold on the tie bar to open the throttle half way while cranking, still now go? Clean the plugs or replace with new ones.
 

brian66r1

Seaman
Joined
Aug 18, 2011
Messages
54
Re: 1994 120 force o/b won't start

Thanks Jiggz.

I can't say for sure if there is any petrol fumes around the exhaust. I am a smoker and my sense of smell is all up the creek. It is also a terrible hayfever season here and I am suffering from it pretty bad.
We did try what you said "If it still would not go hold on the tie bar to open the throttle half way while cranking, still now go?" Sunday week ago and it did start and run but it died the moment I shifted it into gear. It also ran like crap doing this too because the engine wasn't under any load and the timing wasn't advancing. It also made a horrible knock sound when we revved the engine this way.
I haven't tried a spray bottle yet but I did try spray a short burst of Aerostart into each sparkplug hole and it made no attempt to kick. Also tried to spray a short puff into the carbs too and nothing.
I'm sure there is fuel getting in, I use the choke button every time I try to start it and that puts the fuel straight into the inlet manifold. Although, the plugs dont appear to be too wet when I pull them out after each starting attempt.
Maybe I have to pull the carbs off and spray the crap out of them with carby cleaner. That way I can have a good look at the reed valves at the same time.

And Chrome, the boat is a oldish 18 foot Pride Montego half cabin.

Brian
 

chrome dome

Petty Officer 1st Class
Joined
Sep 24, 2010
Messages
303
Re: 1994 120 force o/b won't start

well, there goes that "theory" then LOL,
l had wondered if it was a pretty flash big boat..or even just a flash, pretty boat..like those docked in the river,
 

jason32038

Chief Petty Officer
Joined
May 25, 2009
Messages
555
Re: 1994 120 force o/b won't start

Your problem must be fuel related. Disassemble and completely clean the carbs and the reserve tank. Replace all hoses and add a filter from the tank to the pump and another from the pump to the carbs. Check fuel pump.
 

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,909
Re: 1994 120 force o/b won't start

The plugs should have been super wet if there's fuel getting into the cylinders and not starting especially if you are using the choke during starting. If the plugs are not really that wet, I still believe it's a fuel problem and it could also be the fuel pump. the fuel pump can easily be tested by disconnecting the outlet hose and see if fuel mix is being pump out. And then, you can check the carbs if it's taking on fuel by emptying both fully and then crank. Open the carb's bowl again and if it's still empty they are not taking on fuel. If they're both full then the last thing to check are the jets. If she's still won't start it's time to check the electrical side. As for the timing advance, it's purely mechanical and doesn't have anything to do with or without load. The timing advance system is mechanically linked with the throttle linkage. Check make sure the linkage is still properly connected for a disconnected linkage will mess up your timing.
 

brian66r1

Seaman
Joined
Aug 18, 2011
Messages
54
Re: 1994 120 force o/b won't start

Still no good. It has new spark plugs and they are the correct ones now too. The ones in it were NGK BUHW and the ones in it now are BUZHW. Now the spark is like a camera flash. There is fuel going into the carbs. The fuel pump diaphragm is fine. The fine stainless mesh filter in the fuel pump had a heap of crud underneath it. That's gone now. The carbs have been off, sprayed, blown out, re-fitted. Tried spraying pre-mixed fuel into the carbs whilst cranking. Tried more of that "Start ya Bastard" Ether spray straight into the carbs whilst cranking and except on 2 occasions, it doesn't even make the slightest attempt to even backfire. On the weekend after a whole day of trying with the lower leg in a big tub and the throttle wide open it fired up for only a second or so and because the throttle was wide open and the engine cowl was off it screamed, we crapped ourselves and killed it. When I hold my hand over the carb opening whilst someone cranks the motor, I can feel my hand being sucked by the vacuum, when I pull my hand away, it is saturated with fuel and the insides of the carbs are wet through. Fuel comes dripping out of the front of the carbs. Still when I pull out the plugs after cranking the engine over, they are not all that wet, they only have the slightest residue of fuel on them. I would have thought that they would be saturated with the amount of fuel we were puting into it? The sticker on the front of the motor says "This engine has passed a factory test run by tester Marv Brehmer". Where are you now Marv? I could use a little help here.
 

Frank Acampora

Supreme Mariner
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Jan 19, 2007
Messages
12,004
Re: 1994 120 force o/b won't start

It still seems like a fuel problem. Try this: Remove all four plugs and squirt about 2-5 cc of premixed fuel (50-1) into each cylinder. Replace the plugs. Now, with the control handle in the fast idle/start position (you are trying to start it correctly, aren't you) crank the engine without choking it. The premix you squirted in will flood the engine and as it clears itself out, it should fire and run for a second or two.

If it does this, then for sure you have a fuel problem and need to re-clean the carbs, rebuild the fuel pump, and clean out the fuel lines and filter (if any).

If it does not clear itself or does not fire, then you need to check the electrical.

Note that it is relatively easy to flood these engines and holding your hand over the carb will do that. Then, unless you let it sit a while, or crank excessively she will not start.

Also note that your contol box has a neutral lock-out. You must either pull out the handle or press the center button in and advance the control handle as far as it will go. This cracks open the throttle and advances the timing a couple of degrees to start the engine while leaving the lower unit in neutral. Some engines are fussy and will not start unless in this position.

You also need to check cranking speed. The ignition is self enegising but if the engine turns over too slowly, not enough voltage is delivered to the coils to fire the plugs. This is not apparent when cranking with the plugs out since there is no load and they will fire.

Hey---I've never been down under. Pay my airfare and I'll come down there and start it for you--LOL
 

brian66r1

Seaman
Joined
Aug 18, 2011
Messages
54
Re: 1994 120 force o/b won't start

Thanks for such a fast reply Frank.

I did do that on Saturday but I put more like 30 or 40 cc in each hole. I was thinking there must still be a fair amount of water in the crank cases from the bad fuel I put in there and I wanted to try and rinse it out. I'll do it again but before I do this, should I blow some air through each spark plug hole as I turn the flywheel to vent out each cylinder. How much past TDC on each cylinder would I need to turn it to just open up the inlet port? I think this is what I did last weekend just before it actually kicked one time.

I might try and do another quick compression check again tomorrow before I squirt the fuel in. No real reason. Just to do it.

Brian.
 

Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
Messages
12,004
Re: 1994 120 force o/b won't start

102_6650.jpg102_6651.jpg102_6652.jpg102_6653.jpg102_6654.jpgIf you crank it over for 30 seconds with the plugs out, anything that is in the crankcase will be blown out the plug holes. You do not need to turn the engine to squirt in the pre-mix. You don't need that much. Just squirt it in and any excess will simply run out the exhaust ports when you try to start it. The engine will still be flooded but should clear itself out and fire.

Oh, by the way: Do not crank the engine using the key without grounding the plugs. This can damage ignition components. You either ground all the plugs OR jump the solenoid with the key off

Unless you submerge the engine, even with a carb full of water,not that much gets into the crankcases. It would have all blown out by now--especially if the engine did start and scream as you said.

From top dead center, the exhaust ports start to open at about 120 degrees and the bypass about 30 degrees later. It varies from engine to engine and these are rough guidelines.

Now, I remember you mentioning plastic covers on the carbs. These screw-in plugs cover the air bleed jets of the idle system. Both fuel and air pass these jets. The main fuel jets are down below the floats. SO: Remove the plastic plugs and using the correct sized flat blade screwdriver remove the air bleed jets. Remove the brass needle and now squirt some WD 40 OR the Aus. equivalent through the passages. Run a pipe cleaner through there too. At the bottom of the carb, run a pipe cleaner through the main jet. Then squirt WD up the small brass tube. It should come out the back of the carb on top of the buttefly. If it does not, run a fine wire up the brass tube to clear it.

The photos show the screwdriver removing the air bleed jet, the air bleed hole in the top of the carb, in front of the brass tube, the brass low speed tube and a fine wire clearing it, and finally, the back of the carb with the low speed fuel delivery port above the butterfly.

Note that I have used a fine nail ONLY for demonstration purposes--it is what was handy. You really need a length of fine copper wire or welding rod that will reach all the way up to the top of the carb.
 
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