OMC Cobra w/ 5.7 Holley 4010 using way too much gas

[ab59]

I installed this Holley marine rebuilt 4010 on this rebuilt 5.7 and it is really sucking up the fuel. Adjusted at 1 1/4 turns each side I can smell the raw gas . When I first started the engine and ran it off and on for about 30 to 40 minutes , no longer , I went through 3 gallons of gas. Thought it just had to seat the rings at first but this is crazy fuel usage. Got another 5 gal , ran for about half an hour off and on and again I used about 3 gallons again . This is at no more than about 2500 rpm and even at that it was varied from and idle to 2500 rpm. Starts and runs great , just sucks up so much fuel that I may get about and hour and a half use out of the boat to every ten gallons of gas.

 

[81manatee]

Check the floats.

 

[Scott Danforth]

verify you didnt have a backfire which can blow the power valve.

 

[ab59]

When we set the distributor the first time , we , of course , set it in 180* off . She did spit back through the carburetor a couple of times but not too radical. I will research how to check the power valve and check it tomorrow. I have seen the material but just don't remember the procedure .
Will it be obvious if the valve is damaged ? Not sure what I'm looking for.

 

[ab59]

81Manatee-- welcome to Iboats , this forum is undoubtedly the best and most active on the net . These guys now their stuff and there is a huge resource of knowledge here. What one dose not know it seems that another does so you came to the rite place for all around boat stuff.

 

[ab59]

Tested Holley 4010 carburetor by closing both adjustment screws only to have the engine continue to run , unaffected by closing them. Guess this means the power valve is no good , rite ? I just watched something on youtube put out by Holley and they said something about another small valve that is supposed to keep the power valve from damage when a backfire occurs , guess mine does not have this luxury .
looks like carburetor work tomorrow along with trying to figure out what I only have reverse and no forward when I shift into gear. Motor not running turning the prop by hand. Will chase that in another post.

 

[kenny nunez]

The "check ball" power valve protecter kit is available from Summit or Jegs. Very easy to install. Remove the front metering block and check if the valve is blown out by sucking on the diaphragm. Also if the idle stop screw has the throttle plates open too much you are taking fuel from the intermediate circuit and by passing the idle side. You should be able to have the idle stop screw only around 1 turn after it contacts the lever for correct idle. And 1.5 on the metering screws.

 

[ab59]

A thought just occurred to me , in my haste to get the engine going and back in the boat I did not hook up the positive wire to the electric choke . I would have to think that this would leave the choke in a constant choked position and would start and run fine but suck up the fuel . Would this be correct ? At rest the plate is only open about 3/8 s of an inch . Could this be why the engine continued to run with the idle jets closed or is it a definite power valve blown out or maybe even both ?
I don't think the Holley 4010 has a removable metering block , it looks like the body is one piece and the power valves screw in from the bottom , I think. I spent a good part of last night trying to find some good information on the 4010 but never found anything really clear on changing out the power valves.
I saw the power valve protectors last night in a couple of places and I think that would be 15 bucks well spent. One does not even include drilling anything out so maybe that one will get the nod.

 

[81manatee]

81Manatee-- welcome to Iboats , this forum is undoubtedly the best and most active on the net . These guys now their stuff and there is a huge resource of knowledge here. What one dose not know it seems that another does so you came to the rite place for all around boat stuff.

Thanks.

The bowl floats absolutely must be adjusted. Otherwise the carburetor will dump overflow fuel into the manifold as the engine runs. It is part of the process of elimination in this troubleshooting tree. All that's posted above is right, a blown powervalve will leak, even with the blowout protection check ball design. Test for blown powervalve is to close idle screws and if the engine still runs, it's being fed through the blown powervalve. The powervalve is behind the bowl and should be changed with one of the same variety.

 

[ab59]

I have been jumping back and fourth from making the new side panel on the operators side so I can mount my controls up solid and test my outdrive like it needs to be tested and the carburetor today. Upon further inspection I have found and corrected these overlooked problems as well as removed the carburetor and the power valve which is another story. As previously stated I forgot to hook up the electric choke and did so today. While hooking up the choke I looked down to find that my help did not return the vacuum plug on the carburetor base so I had a significant vacuum leak and so I plugged that as well. Hoping that these were my problems I fired up the engine once more and closed the idle mix screws and got the same result as before, the engine ran with no problem.
So , I let the engine cool and dropped the cables from the battery then removed the carburetor . An interesting find. After I got the carb out and on the bench i removed the front power valve. Once that was done I tried to remove the back power valve only to find that there was no valve there. It has been removed and plugged off by some one, maybe the rebuilder. The power valve has F 2 5 stamped on the face. I expected to find two 6.5 valves from what information I have been able to glean from the internet and Holley's website .



Why would some one block off the second Power valve and should I try to restore this carb to original configuration ? Is this the rite power valve for this configuration ? I bought a rebuilt carburetor so that I would not have these problems . To top it off when I emailed the company I bought this from they said that they knew nothing about them because they bought several from a rebuilder a few years ago and did not rebuild them their selves leaving me at another dead end.

 

[81manatee]

It's a hotrodding trick to plug the secondary power valve, sometimes compensated for by upping the secondary jet size. It's all theory or voodoo whether it works or doesn't depends on engine loadng and vacuum at various part throttle situations.

Some say plug it the carb will run better. Others say running a pv helps richen mixture in situations where secondaries are open at part throttle.

My suggestion is to try to get the carb back to stock with the holley spec jets and pv's, and tune from there.

 

[ab59]

Kenny N-- I did like you said and the power valve does not give when I draw on it. With the back valve plugged this just turned into another world of carburetor tweaking.
81- I don't want to rebuild this carb. If it comes down to it I may find a used 4150 or 60 and rebuild that. It would be nice if something that I bought " rebuilt " was actually what it was supposed to be .
Do I need to buy a gasket kit for this just to have a look at the floats ? Looks like the top has got to be separated from the main body to check out the floats on this model.

 

[kenny nunez]

The 4010 is similar to the Motorcraft Ford carburetor known as the "cracker box" since the top is removable. Are you sure that you have the marine version ? Most Holley's for marine only have 1 power valve and no rear metering block. Check with Summit or Jegs for what they have for marine use. They offer several. This may be the best way to get it right. If there are any marine shops in your area maybe they have a genuine marine used carburetor that is rebuildable by someone who knows what they are doing.

 

[ab59]

Kenny the carburetor is a R75008 with a date # stamped of 1637 and has the turned down tubes that Marine carburetors have so I reasonably sure that it is a Marine carburetor. This does only have one power valve with the secondary either plugged or blocked , maybe from the factory . Holley and Summit do not go back far enough to find true information on this particular carburetor, at least I have not been able to find numbers that are in the same general area most starting around 84000 and up. I will have a look at Jegs to see what they may have. Wish I would have just bought a quadrajet for the OMC.

 

[ab59]

My latest wrinkle . I had emailed Holley about the carb and they got back to me today with a rebuild kit number---37-1541. Interestingly enough this restore kt only has one power valve leading me to now believe that the plugged off secondary came like that from the factory , I guess specifically for Marine application.
I have been surfing the net looking for good information on disassembly of this carb and as of yet have not found much of anything useful . I would like to pop the top to check out the floats but there is the butterfly linkage to the choke there that I do not want to screw up. Hope I don't need to remove the electric choke just to have a look at the floats. Anyone familiar with this procedure ?

 

[ab59]

Ok , thanks to my old automotive Holley I figured out how to get inside this thing without tearing everything up. The floats are how I found them with one not even coming close to being level to the housing-right side pic. Found some gummy debris at the rear jets as well, odd for a rebuilt I would think. At least these are not the old plastic floats that were so much problem so guess all I need to do is bend both floats perpendicular to the body and re assemble . I think . Any advise before I button this up ?

 

[kenny nunez]

It looks like a later version of the cracker box . Easy to service. Give it another try it may work out.

 

[ab59]

Not to sure I like this float system and adjustment method. Somehow letting gas pour all over a running engine while you adjust the floats is contrary to good common sense. Unless this performs at a stellar level I don't think I will be using Holleys in the future.
Well 81 looks like you were rite all along about the floats needing the attention , could have saved myself some work by adjusting them first but since all the information from Holley said it was the power valve I went with that first . I guess I needed the experience with a Holley carburetor. Thanks anyway.
Got too dark to see what I was doing last night so will finish the carb work today, hopefully .

 

[ab59]

Everything is set up the way Holley says to do it. I haven't got a vacuum gauge and will have to order one to dial it in as to spec. Seems like it is still running rich at 1.25 and or 1.5 turns out on the idle mix. I still see a little white smoke that smells gassy so once I get a vacuum gauge the thought is that will go away after setting it to exact spec instead of by ear. At least my rpm gauge works on the boat so it was easy to set the idle at 650 rpm.
thanks to all who took an interest---a.b.

 

[ab59]

you know , I said something earlier in this post that was not what I did , so in case some one fighting the same battles in the future tries this it is wrong. I DID NOT BEND the float that was way out of adjustment , I adjusted it down into place with the adjustment screw. The only time you would bend the float is if you were out of adjustment and had no other option .In that case I would think that you may have another problem since the adjusting nut should be all you need .