1998 150 Merc OFFSHORE, FUEL / CARB QUESTION .. Please help.

[Ant-Knee]

Good Morning All,

I just bought a new boat which is a 1988 19ft Bonito center console with a 150 V-6 offshore merc. Boat sat for a year to a year and a half without running at all.

The motor turns over fine but will not start. engine has 3 carbs on it. it has good fire and if I spray starting fluid in the carbs it will run for a second then die.. I noticed that the top carb does not seem to be getting any fuel at all, the middle and bottom carbs seem to get fuel. Should the top carb be getting fuel for start up? I would think all the carbs should get fuel but kind of new to marine so I am just not sure. This is my first boat. I am an auto mechanic but know very little about an outboard marine engine.

Any help is appreciated ..

Thanks,

Ant...

 

[Texasmark]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

You answered your own question. All the carbs should be fueled equally and by spraying fuel into the carbs and getting what you got you got your answer of inadequate fuel delivery, i.e. varnished carbs...for starters.

I'd do a carb(s) kit repair and ensure that you get all the passages cleaned out good. Soaking in a suitable can with full strength Berryman's Chem tool (available in most all auto parts stores as is Sea Foam mentioned later) can chemically clean the carbs for you then a little tooth brushing for areas really thick and a good air blowing out when finished. The Berryman's is great because it has the right solvents to break down the varnish and evaporates when finished.

Obviously you want fresh fuel so before you reinstall your carbs, with fresh fuel ( and Sea Foam gas additive....directions on the can) in your tank, I'd spin the engine over for a couple of 30 second, rest and cool, 30 second spins and ensure that your fuel pump is pumping and is pumping fresh fuel. What you didn't get the Sea Foam will and it will also clean up your cylinders and loosen any carbon and stuck rings that may have been part of the "deal".

HTH,

Mark

 

[Ant-Knee]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Thanks a bunch, Got all carbs off this morning and waiting on carb kits, I will soak them once I get the kits and put them back together and I think I should be good to go after that..

I have like a full tank of rotten fuel that I need to get rid of, and refill with fresh fuel...

This should be fun..

Thanks,

Ant..

Ill update post more once carbs are done and have fresh fuel in tank...

 

[CharlieB]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

That old fuel may run fine in a car or lawn-mower.

Lots of us drain our tanks every fall/spring and tank up the car.

 

[Ant-Knee]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

That old fuel may run fine in a car or lawn-mower.

Lots of us drain our tanks every fall/spring and tank up the car.

Yes, I read that in the manual that the old fuel would be fine for a car or other vehicle..

Couple questions.

What is the best and safest way to drain this tank?
Once tank is drained what grade of fuel should I use, 87, 89, 92?

Thanks for the help guys..

Ant...

 

[j_martin]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Yes, I read that in the manual that the old fuel would be fine for a car or other vehicle..

Couple questions.

What is the best and safest way to drain this tank?
Once tank is drained what grade of fuel should I use, 87, 89, 92?

Thanks for the help guys..

Ant...

I Usually:
1. Park the boat on a high spot, with the tail hanging over a lower spot.
2. Disconnect the fuel line at the engine, and add a splice and a length of hose sufficient to reach the ground.
2. Stick said extension into a fuel can.
4. Pump the primer bulb a few times to start the siphon. You may have to twist it around so the arrow is up to get it to work.
5. Twiddle my thumbs till it's time to move the hose to the next can.
6. Because I've pulled all the fuel through the filter/water separator, It's ready for the family bus or lawn mower.

BTW, throw in a fuel pump kit while yer into the engine. Also, quit spraying bearing dryer er starting fluid into the engine. Use 2 cycle fuel in a spray bottle.

 

[Ant-Knee]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Awesome, Sounds easy enough...

I ordered a fuel pump already, Waiting for that in the mail..
I am also done with the starting fluid as I now have all the carbs apart and off the engine..( Waiting for Carb Kits )

When I am done with draining the tank I will also replace the fuel filter, Is there anything else I will need to change out?
And what Grade fuel should I use in this motor?

Thanks ,

Ant...

 

[j_martin]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

If you find rubber particles in the carbs, change out the fuel hoses.

Any pump gas will run. Non-oxy will keep longer in the tank, and not instantly skunk out if you get a bit of water in it like the gasohol will. The extra octane isn't beneficial, but won't hurt. On the other hand, you could up your compression a bit, gain a few ponies and use the extra octane.

 

[Ant-Knee]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

If you find rubber particles in the carbs, change out the fuel hoses.

Any pump gas will run. Non-oxy will keep longer in the tank, and not instantly skunk out if you get a bit of water in it like the gasohol will. The extra octane isn't beneficial, but won't hurt. On the other hand, you could up your compression a bit, gain a few ponies and use the extra octane.

I did not see any rubber particles in the carbs but I am going to change out the fuel lines anyways. When I pulled apart carb #1 (Top Carb) I saw why this carb was not getting fuel, The needle that is connected to the float was not connected and berried under the float which was not allowing fuel to enter.. Who ever did the last carb rebuild on the carbs must have overlooked that .. Can't wait to fire her up and do some fishing...

Thanks again for the help!!!

Ant...

 

[Ant-Knee]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Hello All,

Got all carbs back together and installed , drained the old fuel out of the tank, Filled her up with new
fuel and boat fired right up today, Motor sounds real good and strong.. It is realy crappy out so I will wait for the next nice day to take her on the water for my first ride..

Drained lower unit gear oil and refilled with fresh oil.. I am wanting to change the water pump so I just ordered one of the kits for that.. The motor is spitting out water fine but would feel better with a new pump there so I will change that out once the kit gets here..

Thank you guys for all your help!!!

Thanks,

Ant...

 

[j_martin]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Yer on it man. Take good care of your baby and it'll give you a lot of good times.

 

[Ant-Knee]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Hello All,

Ok, Ran the boat some more it seems once the motor warms up it develops a miss, I am not sure if it is in the ignition system or the fuel system just yet. I am going to play with her some more today. I will post a video of what is going on.. Also I notice that when I try to goose the throttle she realy stuumbles which makes me think the fuel system but just not sure ( I am thinking something to do with the choke), I just rebuilt the carbs and they are super clean and free of any debri, I adjusted the air screws 1-1/2 turns out from seated position on all carbs. Like I said I will post a vieo of motor running in a little while as it is early here and don't want to **** off my neighbors and would like to hear what you guys think it could be..

Thank you,

Ant...

 

[CharlieB]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

when I try to goose the throttle she realy stuumbles .......................... I just rebuilt the carbs ............ I adjusted the air screws 1-1/2 turns out from seated position on all carbs....

Those are idle FUEL screws, that is the starting point, now adjust each one to 'Best' idle speed. PLUS almost 1/4 turn more fuel (CCW).

This should get you close enough to get started and in gear once the boat is in the water. Final adjustment MUST BE done whole in the water as exhaust back-pressure caused by the water AND load on the motor being IN gear, will increase the demand for idle fuel.

Once IN the water and IN Forward gear, again adjust idle mixture screws to 'Best' idle PLUS almost 1/8 turn out to provide the additional fuel necessary for crisp acceleration.

Test acceleration by rapidly opening the throttle and see how the holeshot is. ANY bog, lean cough, hesitation, in the slightest, shows a need for additional fuel. Open each idle screw just the wideth of the screwdriver blade slot then retest acceleration.

Repeat to perfection.

 

[Ant-Knee]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Those are idle FUEL screws, that is the starting point, now adjust each one to 'Best' idle speed. PLUS almost 1/4 turn more fuel (CCW).

This should get you close enough to get started and in gear once the boat is in the water. Final adjustment MUST BE done whole in the water as exhaust back-pressure caused by the water AND load on the motor being IN gear, will increase the demand for idle fuel.

Once IN the water and IN Forward gear, again adjust idle mixture screws to 'Best' idle PLUS almost 1/8 turn out to provide the additional fuel necessary for crisp acceleration.

Test acceleration by rapidly opening the throttle and see how the holeshot is. ANY bog, lean cough, hesitation, in the slightest, shows a need for additional fuel. Open each idle screw just the wideth of the screwdriver blade slot then retest acceleration.

Repeat to perfection.

Ok, Sounds easy enough.
First I will try to get it running better out of the water maybe the miss / lean cough will go away after adjusting the idle screws better.
I will try to get it on the water today if weather is half way descent..
I do believe this is the problem as it seems to be starving for fuel upon exceleration..

Thank you,

Ant...

 

[Texasmark]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Those are idle FUEL screws, that is the starting point, now adjust each one to 'Best' idle speed. PLUS almost 1/4 turn more fuel (CCW).

This should get you close enough to get started and in gear once the boat is in the water. Final adjustment MUST BE done whole in the water as exhaust back-pressure caused by the water AND load on the motor being IN gear, will increase the demand for idle fuel.

Once IN the water and IN Forward gear, again adjust idle mixture screws to 'Best' idle PLUS almost 1/8 turn out to provide the additional fuel necessary for crisp acceleration.

Test acceleration by rapidly opening the throttle and see how the holeshot is. ANY bog, lean cough, hesitation, in the slightest, shows a need for additional fuel. Open each idle screw just the wideth of the screwdriver blade slot then retest acceleration.

Repeat to perfection.

I had a real problem with my idle mixture (self inflicted) and upon Charlie mentoring me as he did/is you, I was able to solve my problem and am happy with the results.

He suggested that I leave the boat on the trailer to get the final tweak rather than hang off the transom and attempt an on the water tweak. I undid the stern clamps and left the winch rope connected and it is below the bow chock so the boat can't climb the chock, backing the boat into the water just as if I were going to launch. I did the muffs test initially at home, best it wanted and upon water testing I found out that it didn't want to take the throttle like you need in your hole shot.

The other thing that he and others mentioned was that on my 90 triple, tweaks can be as small as the width of the screwdriver. So, It took 2 screwdriver width tweaks to get where it wanted to push the trailer up the ramp and when I took it out the first punch outta-da-hole was perfect and I let it be. I spent a couple of hours water testing all senario's and I am a happy camper and thanks ever so much, Charlie!

HTH,

Mark

 

[Ant-Knee]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

WOW WOW ,

What a difference already..
I am in the driveway and just did some adjusting and can now goose the throttle with no stumble at all..
I am gonna try to take it to the water for final adjustments.. I have a couple holes that are in the back of the boat to patch real quick ( Where a ladder use to be).. Once this is done I am off to the water..

Yippeeeeee... Thank you so much for the greatly appreciated input Charlie... Your the best man..

Thanks,

Ant....

 

[Ant-Knee]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Tried to run boat in water but did not go well..
I think the main problem is plug wires / or it has a bad power pack,

It seemed to be backfiring when under load in water..
I tried to adjust the carbs on the water but it made no change..

I have new wires on the way, They will be here bye next friday..
But in the meantime I will test the coils.

Thank you,

Ant...

 

[j_martin]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

 

[CharlieB]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

That is the PERFECT tool for checking spark.

Mine is soo old the top two screws are used to keep the center ground attached, and the clear plastic is (?) faded (?) needs to be buffed out clear again so I can see the gap!

 

[Sunfish12]

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Re: 1998 Merc, OFFSHORE, FUEL / CARB QUESTION .. Please help.

Where do you find a spark tester like that?