Fuel consumtion mercruiser 3.0 on idle.

[guuben]

Hi there.
I would appreciate if somebody knows the real fuel consumtiion on idle. What do you think is reasonable for 10 minutes of idling?
I have a problem with my mercruiser 3.0 l year 2015. Its a built up from a new Barr base engine with new oem mercab 86007a2. i have spent 1,5 gallon on just testrunning the engine (not at sea).its not many minutes of tests....maybe 15 minutes., so something is really wrong.
And I wonder about the gasket between manifold 860235 and carburetor; The manifold has one big oval hole so lot of the gasket (with two round holes for the barrels) will "hang free in the air" - shall i cut off those unnecessary parts and just keep the parts of the gasket what is metal to metal?
For me its like some missing part - a metal brascket ? -adapter?- between manifold and carburetor, a adapter what is designed as the bottom of the carb with two round holes.
This gasket came along with the carburetor.
Regards Guuben
Little funny maybe but: when flame arrestor is off: Its sounds like an old steamtrain from the carb...zoff zoff zoff zoff... - maybe normal?

 

[alldodge]

Hi there.
I would appreciate if somebody knows the real fuel consumtiion on idle. What do you think is reasonable for 10 minutes of idling?
I have a problem with my mercruiser 3.0 l year 2015. Its a built up from a new Barr base engine with new oem mercab 86007a2. i have spent 1,5 gallon on just testrunning the engine (not at sea).its not many minutes of tests....maybe 15 minutes., so something is really wrong.
And I wonder about the gasket between manifold 860235 and carburetor; The manifold has one big oval hole so lot of the gasket (with two round holes for the barrels) will "hang free in the air" - shall i cut off those unnecessary parts and just keep the parts of the gasket what is metal to metal?
For me its like some missing part - a metal brascket ? -adapter?- between manifold and carburetor, a adapter what is designed as the bottom of the carb with two round holes.
This gasket came along with the carburetor.
Regards Guuben
Little funny maybe but: when flame arrestor is off: Its sounds like an old steamtrain from the carb...zoff zoff zoff zoff... - maybe normal?

:welcome: to iboats Guuben

Sorry it's taken so long to hear a response. Using 1.5 gallons or liters in 15 minutes is a lot of gas at idle. Not knowing your serial number I'll guess that your manifold is like item 1 in the link below.
http://www.mercruiserparts.com/Show...13603&bnbr=80&bdesc=Intake+/+Exhaust+Manifold

Your carb is in this link
http://www.mercruiserparts.com/Show...37190.png&inbr=13603&bnbr=70&bdesc=Carburetor

I don't understand what you mean by

shall i cut off those unnecessary parts and just keep the parts of the gasket what is metal to metal

Can you explain a bit further and maybe post a pic?

 

[guuben]

Thank You for reply and the welcomes.

My mainlanguage is, as you have for shure already realized not english, so i try to explain the "gasket matter" in other terms:
Imagine you have a mechanical fuelpump you gonna attach to the block (gm 3.0 L): The gasket is attaching all over its surface metal to metal (the engine block and surface of the fuelpump).
Now comes the more difficult part to explain about the gasket for the carb:
The bottom of the carb is not only two throttleholes and rest for attaching the carb.
The bottom of the carb is rather "complicated" with some hollows about 0,10 inch deep.
The gasket that came with the carb has the problem that lot of the gasket surface is not metal to metal......the upper side totally touching metal (the carbside) and the other side of the gasket is just against nothing at all except the outer parts, where it follows the manifolds iron casting.

So i cutted all this extra gasket away and I think it helped me into the right direction: i have now about 1,5 gallons/hour including some very very short high idling at about 1500 rpm,s. About 95 percent at 700 rpm,s. I hope that after 3-4 hours of cruising the engine will be smoother and runs more economically on idlespeed (I am gonna use that slowspeed a lot)
Mercruiser marine advertise that fuel comsumption is between 0,5 to 1,0 gallon per hour on idle....I am rather shure i read it somewhere on mercruisers homepages.

Summa summarum; now the gasket is cutted and there is only one big oval hole left on the gasket.
Maybe interesting for somebode else to know One single full pull at the throttle arm sprays 0,06 oz of gasoline into manifold....more than I thought. This is measured when i had the carb off.(i had 7 pulls total in a row) My engine starts at first ignition with one full pull and then back to 10-20 % gas.

I All items on my mercruiser is brand new and nothing is remanufactured either...as the carb 86007A2 (its "same carb" as your link...but older version)
But I must say - when I tried first time to crank the Mercruiser/GM 3.0 engine by hand (that time still unstarted) and with plugs unattached it was almost impossible to crank....I had a about 1,2 foot long ironbar to crank it from the waterpump boltheads - I put the bar between two bolts...I think the GM does not do so sophisticated engines...i get the feeling of an old tractorengine...haha. I am now comparing to carengines.

 

[alldodge]

Was hoping someone would come along with a bit more info to help. I'm a bit lost but from what I understand, you are using 1.5 gallons per hour and would like to get it more to the 1.0 gallons per hour or less.

The gasket was a bit restrictive so you cut away the inside which opened up the oval hole more and now your getting closer to where you want to be. That said you don't want to get the engine running to lean because it will destroy it self.

Why are you turning over the engine manually with a bar?

 

[guuben]

Thanks again for response.
I think I can make my first on sea trials in a couple of days - hopefully
I will be here after that again and maybe I have more specific to tell about fuel consumption.(on idle and cruising medium speed)
This engine will be mounted in a old 1934 built wooden boat with traditional finnish hull and midship mount for engine.
30 x 7 feet about. I think you call it fo a "double ender boat" - with this engine i hope to come iup to 16 knots and cruising at 13.
With a BMW 45 diesel it tops at 14 knot ....a very very solid engine but i om boored of the relatively hard diesel engine noise.
This experiment is to see if my theory is right: to use about only 60 hp from gm 3.0 and run rather "noiseless" and I think the fueleconomy
wont go up dramatically in cruising speed at about 13 knot. Time will show me

Ohhh, about to crank the engine by hand and why - it was just of curiosity.
I was stunned how hard it was.
I mean, lot of powers will of course go to press down the valve springs but i think most of the handpowers went to a very rough
mechanichal making of the engine, pistonrings to cylinder and some for bearings.
It felt like to roll an totally overheated engine what has "burnt" pistonrings....

About running on to lean ....no worry....the sparks are still too black.....all to black, but maybe this is to rough engine (new and hard to roll so more fuel is needed to roll it on idle).
But still I wonder why mercruiser gaskets are made (for intake/exhaust manifolds) with two holes when the ,manifolds always (?) have only one oval hole.! ! ? ?
Yes, there are gaskets with one hole only but mine carb had this 2 hole gasket in the retailbox and should be attached to manifold 860235.Crazy.

 

[Fun Times]

But still I wonder why mercruiser gaskets are made (for intake/exhaust manifolds) with two holes when the ,manifolds always (?) have only one oval hole.! ! ? ?
Yes, there are gaskets with one hole only but mine carb had this 2 hole gasket in the retailbox and should be attached to manifold 860235.Crazy.

Hi there, welcome to iboats!

?, In your first post you mentioned the engine was a new 2015 year model which would indicate you should have a TKS (Turn Key Start) Carburetor but you're describing the non TKS Merc carb gasket...... So what's the history with you obtaining the new engine?, or a new Carburetor? or a new carb bottom gasket?

Did the engine come assembled (< if so where) with the two hole gasket or did the gasket come in a gasket set for you to install?

Could you find and post the engine serial number please?

From what I'm gathering from your info, your gasket should have been Mercruiser part number 27-866027 and look like these gaskets, http://www.ebay.com/sch/i.html?_fro...1313.TR0.TRC0.H0.TRS0&_nkw=27-866027&_sacat=0

But you had, have or received this style gasket by mistake, see item number 26, http://www.mercruiserparts.com/Show...=4893&bnbr=100&bdesc=Fuel+Pump+and+Carburetor

Did you have a middle spacer that looks like item 15?, http://www.mercruiserparts.com/Show...bnbr=70&bdesc=Carburetor+and+Throttle+Linkage
http://forums.iboats.com/forum/engi...rottle-body-gasket-for-my-mercarb-3304-9565a1

 

[guuben]

Hi and thanks both of you.

Serialnumber on the block is 93441789 but notice there is no serialnumber label as on a new mercruiser ready to plug in engine have.
I bought this engine from a local dealer and it was Barr 3.0 GM engine where ready attached are the distributor,coil sparkplugs and oilfilter:
http://www.barrmarine.net/30l-base-engine.html ....... as that link.
Then I bought as extras the alternator, starter, manifold exhaust elbow, seawaterpumpo etc etc.
I dont have the TKS....maybe better to have oldfashioned style if some problem when starting .

The first carb the dealer supplied to me was a carb for a V8 engine (to big jets of course - luckely i checked the numbers on the carb)
So I ordered by myself this 860070a2. Here is one similar on ebay (I dont find any pics on that carb on mercruiser spare parts):
http://www.ebay.com/itm/MARINE-CARB...CARB-3310-860070A2-4CYL-2-5-3-0-/351360290356

But now is very interesting that you suggest (as i understand.) that i maybe should have a adapter between my carb and manifold. I do know they use adapters/risers to avoid on racingcars boiling fuel in carb ("coolers").but this is not the point here on a mercruiser...right?
In your lionk it was for a V8 engine....maybe more risk for hot carbs there?

I did ask the local dealer about a month ago if there shall be a riser/adapter....he said absolutely NO NEED and shall not be. But maybe he is totally wrong?
Mercruiser has used at least two different bolt patterns for the carbs and I have the "big one" with 3 3/4" x 2" - the small is 3 1/4 x 1 7/8 inches.
if i have to have one adapter i do must know its the right boltpattern on the adapter....i belive all the V8,s have the big boltpattern?

I think anyway you are right...hopefully anyway.....there MUST be a adapter. Maybe i get rid off the to grimy/sooty sparkplugs?
But i make a point here: ;Maybe the adapter is only there to avoid the trottlearm lower parts to touch the manifold. Nota bene; Most of the carbs what fits this 3 3/4 x 2" boltpattern has the throttlink lower than the bottom surface of the carb. And that will end that the trottlearm thouch the manifold - the full action for the trottlearm is hindered.
To this facts I have come by empirical studies

Only this oldstyle 860070a2 carb and the newest "TKS carbs" have a throttlearm what is more high up than the lowest part of the rest of the carb. This "carb with wrong outfit on throttlearm" occuers ONLY when you use the manifold 860235...this is NOT a problem for the older versions of manifolds which has a small "riser" for the carb ready casted.

If you still think I must have the adapter I will order it.

 

[guuben]

Anybody.....adapter or not....thats the question☺

 

[alldodge]

Anybody.....adapter or not....thats the question☺

I don't see the need for the adapter.

 

[Fun Times]

Serial number on the block is 93441789 but notice there is no serial number label as on a new mercruiser ready to plug in engine have.
I bought this engine from a local dealer and it was Barr 3.0 GM engine where ready attached are the distributor, coil spark plugs and oil filter:
http://www.barrmarine.net/30l-base-engine.html ....... as that link.
Then I bought as extras the alternator, starter, manifold exhaust elbow, seawater pumpo etc etc.
I don't have the TKS....maybe better to have oldfashioned style if some problem when starting .

Here's some basic info about your new engine model, 1996-2000 181 / 3.0 Liter, http://engineguy.com/other-makes-1/m...atkngm30m.html

Being a non TKS, the merc carb you have now used the gasket with two holes. I believe you mentioned you had one big hole gasket which would fit the TKS. (Or I might have what you said backwards now)
http://www.mercruiserparts.com/selec..._nbr=804862+99

The first carb the dealer supplied to me was a carb for a V8 engine (to big jets of course - luckily i checked the numbers on the carb)
So I ordered by myself this 860070a2. Here is one similar on eBay (I don't find any pics on that carb on mercruiser spare parts):
http://www.ebay.com/itm/MARINE-CARBU...-/351360290356

You may want to order the two hole gasket. here's a photo of your carb's bottom you have now. http://www.ebay.com/itm/3310-860070A...14f08c&vxp=mtr

But now is very interesting that you suggest (as i understand.) that i maybe should have a adapter between my carb and manifold. I do know they use adapters/risers to avoid on racing cars boiling fuel in carb ("coolers").but this is not the point here on a mercruiser...right?
In your link it was for a V8 engine....maybe more risk for hot carbs there?

The link with the adapter was more of an example to see if you had one already or not and the best I can tell, Merc didn't utilize that adaptor for the 3.0 as you'll notice in the below list of what that adaptor part number was recommended to fit.
This Mercury Marine part number 807726A2 ADAPTOR KIT-CARB is used on the below models

4.3L (GEN +) (2 BBL.) GM 262 V-6 1998 4.3L CARB ALPHA/BRAVO 4.3LH (GEN +) (4 BBL.) GM 262 V-6 1998 4.3LX (GEN +) (2 BBL.) GM 262 V-6 1996-1997 4.3LXH (GEN +) (4 BBL.) GM 262 V-6 1996-1997 5.0L (2 BBL.) GM 305 V-8 1998-2001 5.0L CARB ALPHA/BRAVO 5.7L (2 BBL.) GM 350 V-8 1998-2001 5.7L CARB ALPHA/BRAVO 5.7L CARB MI

But Merc did design an adaptor for the 3.0 to help keep the engine from dying it tight turns such as mentioned in the following link.
http://forums.iboats.com/forum/engin...ls#post9950680

I did ask the local dealer about a month ago if there shall be a riser/adapter....he said absolutely NO NEED and shall not be. But maybe he is totally wrong?
Mercruiser has used at least two different bolt patterns for the carbs and I have the "big one" with 3 3/4" x 2" - the small is 3 1/4 x 1 7/8 inches.
if i have to have one adapter i do must know its the right bolt pattern on the adapter....i believe all the V8,s have the big bolt pattern?

They made some adaptors but again I'm just not sure if it's for what you're wanting to accomplish.

If you still think I must have the adapter I will order it.

I don't think you should need one but it would seem best to order a matching gasket if at all possible. It must have helped your engine run a hole lot better when you received the correct carb for your 3.0 vs the original v8 carb you mentioned you had? If not than maybe still the wrong gasket?

Please know should you order and install the adaptor, it would be at your own risk....So please be careful.