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1999 35Hp - Fuel Tank in the Bow?

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brw0513

Member
Hi All.

I have a 4m side console aluminium boat powered by a 1999 35Hp Johnson outboard. It struggles to get on the plane with 2x batteries, fuel tank and me at the back of the boat. At 120kg, I cast a rather large shadow :(

I'm thinking of moving the fuel tank from the stern to the bow. The fuel line would end up being around 4.5m long. Would this be too far away?

The previous owner removed the oil mixing system, so I use pre-mixed fuel. The J35TEL3EEM outboard has dual fuel pumps.

Good advice appreciated.

Thanks.
 
Well----That motor should have no trouble with a 4 meter boat.-----Perhaps motor has issues.----Post your compression test numbers.-----What pitch is your prop ?-----Sounds like it is running on 2 cylinders.----Check spark.
 
I agree with racerone, something isn’t right. I had a 5m aluminum with a 40hp Mercury and could take kids waterskiing with 2 adults and have power to spare.
 
Well I agree, that is a lot of weight in the rear of a small boat. It should fly once up on plane, right? Anything you can do to shift or eliminate some weight should help. Length of the fuel line is no problem at all.
 
The outboard runs well (for a 22 year old 2-stroke) and once up onto the plane the boat certainly does then scoot along fast enough for me. But it takes a while to get out of the hole.

The boat has front and rear casting decks (carpeted plywood) and weighbridge results put the boat and motor at around 450kg. So it's not light for a 35Hp outboard. The Build Plate states 40Hp maximum, but I've had the boat re-surveyed to 50Hp and may go that way. But the boat is also 22 years old so still undecided if it is wise to put a $10k new outboard on a $1500 hull.

I'll try the tank up front.

Thanks all.
 
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???----No answers yet.------That motor should take off like a rocket.----Have you changed trim angle on the motor ?-----What pitch is the prop ?----What are the compression results on this 22 year old motor ?---Some 50 year old 2 strokes run like new.------Do you have good spark on all leads?
 
racerone said:
???----No answers yet.------That motor should take off like a rocket.----Have you changed trim angle on the motor ?-----What pitch is the prop ?----What are the compression results on this 22 year old motor ?---Some 50 year old 2 strokes run like new.------Do you have good spark on all leads?
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I'll get these things after work today. But I do know the engine is in VGC.

The 35Hp 3-cyl is a very nicely made engine. The manufacturing effort would have been considerable. But these 2-strokes definitely are a dated technology. I understand why they have been banned in many jurisdictions.
 
I have a number of these motors for parts / rebuilding.------Yes they are well made with some bearings the same size as the 3 cylinder 70 HP.----And on more than one occasion have I talked to folks who thought their motor was running fine.----But in fact it was not.
 
racerone said:
I have a number of these motors for parts / rebuilding.------Yes they are well made with some bearings the same size as the 3 cylinder 70 HP.----And on more than one occasion have I talked to folks who thought their motor was running fine.----But in fact it was not.
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The motor is running well. It starts well from cold or hot. It idles well at around 1000rpm - and on all three cylinders (under the right atmoshperic conditions, the plastic idle circuit cover on each of the 3 carbies gets covered with moisture as it condenses out of the air). And it was pulling 6100rpm until I got the 4-blade prop cupped and it now does 5900rpm. I can't see a poor running engine doing these things.
 
Just for the sake of wondering, why two batteries? Trolling motor, I suppose. That's ok, but it's also a box of lead, so to speak.
 
All 3 cylinders are in the 145 - 148 psi range (warm engine, good battery). The 4 blade prop is 10 1/2" x 12" but is a little worn on diameter. Idle speed is around 1000rpm in neutral; 850rpm in gear. All good.

I've tried to find a new OEM prop, but no luck. Went to purchase a new 3 blade prop but was told mine was still good to use.
 
fdrgator said:
Just for the sake of wondering, why two batteries? Trolling motor, I suppose. That's ok, but it's also a box of lead, so to speak.
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The two batteries at the stern are for starting (580MCA at around 17kg) and house (38Ah AGM at around 9kg for nav lights, dash lights, sounder) duties. Both are relatively small but it is a small boat.
 
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