Force 120hp won't start

[Maus01]

Have you checked the compression by your self or it is information from pre owner?
Have you checked the timing by your self ?
How have you stated you have spark at all three cylinders?
Do as topgun3690 and racerone says.
Clean the carbs and put a clear inline filter between the fuel pump and the carbs.
Check the flywheel key as back fire is one indication of a shared flywheel key.
The flywheel keys purpose is to set the flywheel to a fixed point to the crank shaft and it is for ignition/timing purpose.
You can check the flywheel key in two ways.
1. Set the throttle in lowest position (idle). Set the top piston in TDC (top dead center) by using a screw driver or a another bar to locate it. The zero mark on the flywheel should line up with zero mark at the timing plate.
2. Pull the flywheel and check the flywheel key.

The flywheel and key are looking like New. And they are absolutly fixed on the crankshaft no movemend. at all.

 

[Maus01]

By back you mean the throat (front) ?
Has the float been set-up properly on the lower one?

Iam sorry what do you mean with the float on bottem carb?? I followd the manual from frank

 

[The Force power]

Iam sorry what do you mean with the float on bottem carb?? I followd the manual from frank

The float inside the bottom carb.
Has this been set properly/letting fuel in the bowl

 

[The Force power]

No Just visual. Spark on all 4 cylinders. Not with a tester I ordered one yesterday. How do they (tester) work??

They test/ measure the jump of the spark
Also make sure you are working with a; tested good battery to ensure enough RPM's while cranking the engine ( this is needed to generate enough voltage to charge-up the coils for ignition
marineengine.com/parts/cdi-electronics-outboard-parts/outboard-ignition-troubleshooting/10/

 

[Maus01]

The float inside the bottom carb.
Has this been set properly/letting fuel in the bowl

Pump it up with the primer bulb.when ibtake the Bowl of. It is filt with fuel

 

[Maus01]

They test/ measure the jump of the spark
Also make sure you are working with a; tested good battery to ensure enough RPM's while cranking the engine ( this is needed to generate enough voltage to charge-up the coils for ignition
marineengine.com/parts/cdi-electronics-outboard-parts/outboard-ignition-troubleshooting/10/

Almost New battery normal for a mercedes 800ah test past with a tester

 

[Maus01]

So yesterday i mounted clear fuel lines. From the fuel pomp to the carb the is no fuel running.. ONLY when i put my hand on the air inlet of the top carb fuel is floating. The spark gap tester cones in afew days. But tomorrow iam going on vacation so i Will have to wait for 2 week 's before posting results. I Will clean the carbs again today.

 

[beepx2]

Are you sure the little passages in the brass bolts which hold the float bowls on are not clogged?

 

[Maus01]

I really dont know. On vacation now. Will look at it when i am back

 

[Maus01]

Nr 20??

 

[Jiggz]

So yesterday i mounted clear fuel lines. From the fuel pomp to the carb the is no fuel running.. ONLY when i put my hand on the air inlet of the top carb fuel is floating. The spark gap tester cones in afew days. But tomorrow iam going on vacation so i Will have to wait for 2 week 's before posting results. I Will clean the carbs again today.

Understand you are on vacation now. When you dismount the both carbs check the following:
1. Using a flashlight, look through the intake manifold adapters and check the reed valves. Even better if you have spare gaskets, dismount the reed blocks. All reeds must sit flat on the block. If not you need to replace the reeds.
2. Check the floats on both carbs. Remove the fuel bowl. Place a short plastic hose (properly fitted on the fuel inlet line) on the fuel line connection and try blowing into the hose and listening for air entering the fuel bowl section. There should be air entering or air hissing to the fuel bowl section. If no air is entering, then need to adjust the float hinge so it allows the inlet valve to drop and allow air or fuel to enter. If there is then go to next step. Invert the carb so the fuel bowl section is on top. Watch the float make sure it is on full horizontal with the body of the carb. If not adjust the hinge so it stays only on horizontal when inverted. Now blow again into the small hose and you should not hear any air entering the bowl section. If there is air entering then need to adjust the hinge section again to make sure the inlet valve is close when inverted.

Most likely you have broken reeds which doesn't affect the compression of the engine but doesn't allow fresh fuel-air mixture to get into the cylinders. And since it wouldn't run at all, most likely multiple reeds are broken. Another multiple cause probably a ruptured fuel pump diaphragm. Since you already installed clear fuel hoses, do you see fuel coming out of the fuel pump and getting into the carbs when you squeeze the primer bulb? If not then the primer bulb maybe bad, fuel filter clogged, leaky fuel hose from the tank to primer bulb and finally a ruptured fuel pump diaphragm.

 

[Maus01]

Understand you are on vacation now. When you dismount the both carbs check the following:
1. Using a flashlight, look through the intake manifold adapters and check the reed valves. Even better if you have spare gaskets, dismount the reed blocks. All reeds must sit flat on the block. If not you need to replace the reeds.
2. Check the floats on both carbs. Remove the fuel bowl. Place a short plastic hose (properly fitted on the fuel inlet line) on the fuel line connection and try blowing into the hose and listening for air entering the fuel bowl section. There should be air entering or air hissing to the fuel bowl section. If no air is entering, then need to adjust the float hinge so it allows the inlet valve to drop and allow air or fuel to enter. If there is then go to next step. Invert the carb so the fuel bowl section is on top. Watch the float make sure it is on full horizontal with the body of the carb. If not adjust the hinge so it stays only on horizontal when inverted. Now blow again into the small hose and you should not hear any air entering the bowl section. If there is air entering then need to adjust the hinge section again to make sure the inlet valve is close when inverted.

Most likely you have broken reeds which doesn't affect the compression of the engine but doesn't allow fresh fuel-air mixture to get into the cylinders. And since it wouldn't run at all, most likely multiple reeds are broken. Another multiple cause probably a ruptured fuel pump diaphragm. Since you already installed clear fuel hoses, do you see fuel coming out of the fuel pump and getting into the carbs when you squeeze the primer bulb? If not then the primer bulb maybe bad, fuel filter clogged, leaky fuel hose from the tank to primer bulb and finally a ruptured fuel pump diaphragm.

Tnx for your answer.. The fuel pomp is rebuild. Fuel is getting to the carbs. The reeds are intact. They close Almost completly., when i put a flashlight on the reeds i See a tiny bit of Light. Or should it Be completly closed( like 100%). When iam back from vacation i will rebuild the carbs. Last Day before vacation i cleant them(again) ultrasonic. I will check everything you said then

 

[jerryjerry05]

The reeds can have a small gap.

 

[Jiggz]

Tnx for your answer.. The fuel pomp is rebuild. Fuel is getting to the carbs. The reeds are intact. They close Almost completly., when i put a flashlight on the reeds i See a tiny bit of Light. Or should it Be completly closed( like 100%). When iam back from vacation i will rebuild the carbs. Last Day before vacation i cleant them(again) ultrasonic. I will check everything you said then

Great. Hairline gaps on the reeds is acceptable. After rebuilding the carbs and it still would not run, have a small spray bottle filled with fuel-oil mixture. Remove the air covers from the front of the carbs and if possible have a 2nd person doing the cranking. Place the throttle on fast idle (usually this is by pulling the throttle outward and pushing it forward. Others uses a center push button and pushing the throttle control forward).Make sure cooling water is hooked up, while cranking spray fuel-oil mixture into each carb alternately. If the engine coughs or try to start, then you have carburetion or fuel related problem. If it did not sputter or cough at all it is a spark problem or even a timing problem. Check timing with a conventional inductive timing light. One that has two battery wires and a simple inductive wire that connects to #1 plug wire. This is with the assumption you have good compression on all cylinders.

 

[Maus01]

Great. Hairline gaps on the reeds is acceptable. After rebuilding the carbs and it still would not run, have a small spray bottle filled with fuel-oil mixture. Remove the air covers from the front of the carbs and if possible have a 2nd person doing the cranking. Place the throttle on fast idle (usually this is by pulling the throttle outward and pushing it forward. Others uses a center push button and pushing the throttle control forward).Make sure cooling water is hooked up, while cranking spray fuel-oil mixture into each carb alternately. If the engine coughs or try to start, then you have carburetion or fuel related problem. If it did not sputter or cough at all it is a spark problem or even a timing problem. Check timing with a conventional inductive timing light. One that has two battery wires and a simple inductive wire that connects to #1 plug wire. This is with the assumption you have good compression on all cylinders.

Timing is set at 28/30 WOT. With a simple timing light. Compression is 120 at all 4 cilinders. Withe a spraycan i already Tried that. It starts to sputter a bit... I hope for a little more.

 

[Jiggz]

Timing is set at 28/30 WOT. With a simple timing light. Compression is 120 at all 4 cilinders. Withe a spraycan i already Tried that. It starts to sputter a bit... I hope for a little more.

If it sputter then it is most likely a fuel delivery or carburetion problem. But can also be spark timing problem. Let us focus on these two problems for now. Check all plug wires with the switchbox to make sure it is all in correct orientation according to wiring diagram. 1991 120HP Wiring Diagram .

When you said fuel is getting into the carbs is this when you squeeze the priming bulb? Or only after manually choking the carbs as you described earlier . . . when you put your hand at the front of the top carb you see fuel flowing.

Ensure the priming bulb is firm if not squeeze it until it is firm. This should prime the fuel suction hose up to the fuel pump. Disconnect the clear fuel hose from the fuel pump outlet. Drain it empty to a small container. Reconnect. Now have someone crank or start the motor for about 2-3 seconds while you are watching the fuel pump outlet and the clear hose. Do you see fuel coming out of the fuel pump. If not there's something wrong with the rebuild of the fuel pump. If there is then fuel delivery is good and you can check this off the problem list.

Next check carburetion. Check the position of the choke shutter (butterfly) located at the very front of each carb. It should be on full horizontal. Test the choke by having someone push in the key ignition. DO NOT START! The shutter should move down to almost close, 80-90% close. Release the key ignition and shutters should return to horizontal position.

Next check the throttle shutters (also called butterfly) located at the very end or base of the each carb using a flashlight. You will need to remove the air covers (if equipped) from the front of the carb to do this. The shutters should be almost close with about 5-10% open. If there is no sign of being opened, adjust the idle screw at the bottom of the timing tower to open it a bit.

If there's no movement on the throttle shutters after two turns from the timing tower, then you need to adjust the linkage between the timing tower and the cam.

Lastly, check the setting of the idle mixture screw (fuel air mixture screw) #29 on carb diagram. Make sure it is 1 1/2 turn out from slightly seated on each carb. This action means you would screw in the mixture screw all the way in (slowly to avoid damaging the tip) lightly. Then turn it back out 1.5 turns out and leave it set it there.

Try again and let us know. If it still would not run, have someone do the starting while you hold on the carbs' tie bar (flat bar that connects between the two carbs throttle shutters) in half way up position. This action opens the throttle shutter about half way and see if it'll run. Goodluck.

 

[Maus01]

If it sputter then it is most likely a fuel delivery or carburetion problem. But can also be spark timing problem. Let us focus on these two problems for now. Check all plug wires with the switchbox to make sure it is all in correct orientation according to wiring diagram. 1991 120HP Wiring Diagram .

When you said fuel is getting into the carbs is this when you squeeze the priming bulb? Or only after manually choking the carbs as you described earlier . . . when you put your hand at the front of the top carb you see fuel flowing.

Ensure the priming bulb is firm if not squeeze it until it is firm. This should prime the fuel suction hose up to the fuel pump. Disconnect the clear fuel hose from the fuel pump outlet. Drain it empty to a small container. Reconnect. Now have someone crank or start the motor for about 2-3 seconds while you are watching the fuel pump outlet and the clear hose. Do you see fuel coming out of the fuel pump. If not there's something wrong with the rebuild of the fuel pump. If there is then fuel delivery is good and you can check this off the problem list.

Next check carburetion. Check the position of the choke shutter (butterfly) located at the very front of each carb. It should be on full horizontal. Test the choke by having someone push in the key ignition. DO NOT START! The shutter should move down to almost close, 80-90% close. Release the key ignition and shutters should return to horizontal position.

Next check the throttle shutters (also called butterfly) located at the very end or base of the each carb using a flashlight. You will need to remove the air covers (if equipped) from the front of the carb to do this. The shutters should be almost close with about 5-10% open. If there is no sign of being opened, adjust the idle screw at the bottom of the timing tower to open it a bit.

If there's no movement on the throttle shutters after two turns from the timing tower, then you need to adjust the linkage between the timing tower and the cam.

Lastly, check the setting of the idle mixture screw (fuel air mixture screw) #29 on carb diagram. Make sure it is 1 1/2 turn out from slightly seated on each carb. This action means you would screw in the mixture screw all the way in (slowly to avoid damaging the tip) lightly. Then turn it back out 1.5 turns out and leave it set it there.

Try again and let us know. If it still would not run, have someone do the starting while you hold on the carbs' tie bar (flat bar that connects between the two carbs throttle shutters) in half way up position. This action opens the throttle shutter about half way and see if it'll run. Goodluck.

Tnx for all the Good thinking every one. Iam back from vacation.
The bottum carb was stock. it didnt get any fuel. Clean it again. Now it look okay. I checked every thing you mentioned. ONLY thing is checking how strong the spark is. Spark gap tester is comming today... I hope. At my surprise the engine started. It ran for a few seconds. But now same story..it Almost wants to start. The starter stops starting when that happens.

What should the timing Be with no trottle at idle.. Or doesnt that make a difference?

 

[racerone]

Saw a fairly new Suzuki 25 HP 4 stroke abandoned at a dealer.----Issues with power head.----Lower unit was sold.----Just a parts motor.----Know of a Yamaha 90 4 stroke with severe internal corrosion at head gasket area.----Dealer said he was not going to fix it.----Have a 50 Yamaha 4 stroke here with same corrosion issue.----Yes they run nice and dealers will do service work.-----Many dealers will not do MAJOR work on them.

 

[Jiggz]

Tnx for all the Good thinking every one. Iam back from vacation.
The bottum carb was stock. it didnt get any fuel. Clean it again. Now it look okay. I checked every thing you mentioned. ONLY thing is checking how strong the spark is. Spark gap tester is comming today... I hope. At my surprise the engine started. It ran for a few seconds. But now same story..it Almost wants to start. The starter stops starting when that happens.

What should the timing Be with no trottle at idle.. Or doesnt that make a difference?

The timing should be set at 30 BTDC (+/- 2 degrees). This is done at WOT in static mode. Static means the engine is not running or firing at all. There's a sticky in this forum on how to do it or on Youtube. Anyways, if it started and then died, did you try having someone do the starting while you are holding up on the carb's tie bar (flat tie bar that connects the two carbs throttle shutter) about half way up? It sounds like fuel delivery is the problem but then of course, it can also be the timing. So get the timing out of the way first and try again.

As for the starter disengaging when engine sputters or coughs, that is natural. All you need to do is to reset the ignition switch and try again.

 

[Maus01]

The timing should be set at 30 BTDC (+/- 2 degrees). This is done at WOT in static mode. Static means the engine is not running or firing at all. There's a sticky in this forum on how to do it or on Youtube. Anyways, if it started and then died, did you try having someone do the starting while you are holding up on the carb's tie bar (flat tie bar that connects the two carbs throttle shutter) about half way up? It sounds like fuel delivery is the problem but then of course, it can also be the timing. So get the timing out of the way first and try again.

As for the starter disengaging when engine sputters or coughs, that is natural. All you need to do is to reset the ignition switch and try again.

Okay.. The spark gap tester goes over 30kv. I think that is okay..... Timing is set at arround 28 30 WOT static..... Fuel pomp works. The clear fuel line is getting full with fuel..... Primerbulb is staying hard...... Choking lets it sputter en sometimes it starts. Also manual open the butterflies... Sometimes it wants to start.