4.3 excessive fuel consumption??-gctid388961

[Guest]

Yesterday I ran my 18.5 98 that is new to me. It seems to run great once running but I dare not "set" the electric choke because then for sure... it will not start. Have to then hold the flapper open to get started! But once running it runs great eccept that I burned up 17 gals (imperial) in 40 miles running around 3500 RPM with a 23 pitch prop and 4 men on board. Seems a bit much right???

I have been told that that is twice what it should use.

[Guest]

ivbinconned wrote:
Yesterday I ran my 18.5 98 that is new to me. It seems to run great once running but I dare not "set" the electric choke because then for sure... it will not start. Have to then hold the flapper open to get started! But once running it runs great eccept that I burned up 17 gals (imperial) in 40 miles running around 3500 RPM with a 23 pitch prop and 4 men on board. Seems a bit much right???

I have been told that that is twice what it should use.

On average I use around 12 litres/ hr skiing at around the same rpm.

Not sure if that helps??

[bhawes]

While the fuel usage seems a bit high, I burn 6.8 [email protected] mph, with 2 of us on board. With your the extra load, and depending on what speed you were running, sea conditions, stops and starts, you're not far off the mark. You might also be running a bit rich with your choke setting.

[Guest]

Well then some thing is quite amiss with mine as I burnt about 35 to 40 ltrs per hour!! What should I do??? Help!!

[Chief_Alen]

Seems everywhere i go and i am near the water there are boats not starting and i just can't help but get involved. Was waiting for my brother to bring in his sailboat to load on the trailer and a guy had a no start condition at the public boat ramp in miami a few short weeks ago.

But the owner told me he had problems as yours he wired the choke plate open. Was burning fuel like crazy and now the boat won't start.

If this was my boat i would first see what the fuel pump was giving me, carbed engine 4-7 psi no more. His problem was he installed a fuel pump that was overpowering the float and needle was like 12 psi or alot more i forget. He also had a 4.3l.

His oil smelled like fuel was the first thing i always do is check the oil, i smelled the fuel right off and his oil was way overfilled. Then i asked him what was the last thing he did to the boat before this problem started.

At first he was curt saying i didn't know what i was talking about why should he check the oil had nothing to do with the engine not starting.

When all was said and done he couldn't thank me enough said he was sorry maybe 20 times.

[Guest]

You should get that choke working properly. The choke flap should be open completely when the engine is at operating temp.

Once set, the engine will fire easily when cold.

[Guest]

I have wondered about the fuel pump because at one point here in my shop I shut the engine down, but then turned the key on again to check if there was electrical current at the choke. The fuel pump kept running...even though the engine was not. Can I hot wire the fuel pump in order to check its pressure?

Thanks for your replies.

[Guest]

Was just thinking (some day I'll get good at it) ...could it be that the needle and seat is not sealing and there for consuming more fuel?

[Guest]

If the needle and seat assembly weren't operating correctly (staying open) there would be fuel coming out of the vent at the top of the carb.

[Chief_Alen]

Am i right 3.8 liters to a gallon. Old geezer like me it tough to convert. I'll look it up latter.

When you turn the key the fuel pump should run for a few seconds, with a electric fuel pump. If the switch does not sense oil pressure shuts down the fuel pump.

Yes you can put steady dc power to the fuel pump to test it.

You need for a carbed engine 4-7 psi no less, and no more. Where the fuel will go if the fuel pump is overpowering the needle and seat would be a real long thread.

Check the oil and smell it.

Maybe someone already bypassed the switch and maybe someone has wired the electric fuel pump to the ignition key. Some people i know have wired a toggle switch to the fuel pump. Maybe even hid the toggle switch, so the boat can't be stolen.

I wired my sisters chevy to start with the lights on.

[Guest]

Ok

After being on the lake the other day there was a bit of water in the bildge and I just descoverd perhaps why. The water pump intermitedly dribbles water out a drain hole!!

Wecome your thoughts

[Guest]

Is it electric or heated spring? Once, when my alternator died, my choke closed partially and I burned a lot of gas. It turns out that the electric choke was hooked to the auxiliary connection on the alternator, which wasn't working. Another common thing is that the float in the carb has gotten heavy. This will make the gas level high in the carb body. This is hard to determin until you hold both floats and can feel the difference in weight.

[Guest]

It is electric and it does pull wide open in a few minuets. I did turn it clockwise to weaken it a bit. Just started it again this morning and it starts right up with out setting the choke.

[Guest]

ivbinconned wrote:


I have been told that that is twice what it should use.

no.

32L/hour at cruise would be typical for a 200HP V6 i/o, and it can use 60L per hour at WOT.

I doubt you'll find a problem. 4 adult men in a boat is a full load for sure.

a fuel flow meter is a real eye opener on a boat.

also bhawes is in Canada where 6.8gph = 31 l/hour

Imperial gallon = 4.54L

[Guest]

ivbinconned,

You are right you are using twice what you should.

But it does depend on your boat attitude in the water and weight distribution, trim adjust, fuel quality etc.

If my math is right ? -

40 miles @ 17 imperial gallons = 64km @ 77 litres = 0.83 km/l

You should be getting around 1.6 km/l

I run 92-95 RON with upper cylinder lube in the fuel and moly in the oil, makes a noticable difference.

I run a 4.3 mpi 220hp in a Discovery 19.2 and get > 1.8 km/l between 2500 and 4000 rpm (best efficiency km/l range)

This was measured at 20 l/hr @ 2500, 30 l/hr @ 3500 and 37 l/hr @ 4000 rpm

Does not change much with water sking or cruising with a bit of gear and 200kg of people.

Though better a little rich than too lean.

Hope this helps