Puzzled boat owner needs engine guru's advice!

[liv2soar]

Allright....<br /><br />Today I took the spark plugs out, each and everyone of them was black as a chimney. The plugs were sooty, and had fuel on the threads of the plug. It met the description of "engine running very rich" in the maintenance manual.<br /><br />So I took apart the carburetor and dropped it in a carb chemical bucket to let it soak for 40 minutes in hopes to clean it. Then put it all back together. Just got back from the lake and still having the same problems. <br /><br />It runs beuatiful in nuetral from 600 rpm to 4500 rpms. But just as soon as I put it in drive and start turning the prop it wants to die. I'll give it alot of gas and then it backfire's and blows a a puff of unburned fuel and air mixture back out of the carburetor. It is a loud pop however, and it shakes the boat a little when it pops too. Any ideas?

 

[vinney]

Re: Puzzled boat owner needs engine guru's advice!

Need more information Cap. Black spark plugs are a sign of over fueling.

 

[hondon]

Re: Puzzled boat owner needs engine guru's advice!

What are your compression numbers? What is your state of tune?How old is that fuel you're trying to burn?Are you turning a huge prop on a huge boat with a little engine?Is dipping that carb the only thing you did to resolve this?

 

[Catchem]

Re: Puzzled boat owner needs engine guru's advice!

Check the timing.Check the choke.When you cleaned your carb did you happen to check the float,and needle valve.Shake the float.Any liquid in float throw out and get new one.Just a few easy things to check.

 

[achris]

Re: Puzzled boat owner needs engine guru's advice!

Let's start with - What engine are we talking about here? Is it 4, 6 or 8 cylinders? Hey, What color is it? (Merc, OMC, Volvo) Is it carbed or EFI? (OK, that one's already answered, but you get the idea).<br /><br />Then some of the advice with have merit.

 

[liv2soar]

Re: Puzzled boat owner needs engine guru's advice!

Here's the specs:<br /><br />1986 Bayliner 18 ft with a Volvo Penta 4 Cyliner inline AQ-131 inboard/outboard.<br /><br />The original prop and engine are on the boat. Nothing has been modified. I have used it several times and in the past it has driven wonderfully. <br /><br />The float was dry, no fuel inside it. The fuel is fine. This problem occured first at the end of last season. I used Stabil fuel additive to store it over the winter.<br /><br />Also I have shifted the timing by advancing it and retarding it a millimeter at a time and the position that it originally was in was where it ran the best out of all positions I moved it to. I set it back to where it was originally. <br /><br />I will check the compression, and also check the timing when my mechanic brother in law gets back into town tommorow. In the meantime...any ideas?

 

[liv2soar]

Re: Puzzled boat owner needs engine guru's advice!

Also, could the carburetor not be spraying the fuel into a fine spray and more just shooting the fuel like a water gun and that is why it is running so rich? It seems to me like this has got to be carburetor problems, such as an adjustment needed or more cleaning.

 

[Catchem]

Re: Puzzled boat owner needs engine guru's advice!

Scott,has this carb ever rebuilt?If it is original It's probably long over due,and being that a carb kit is relatively inexpensive and your brother in law is a mechanic I think i would redo it regardless of what else you might find.One other thing,How old are the spark plugs?

 

[liv2soar]

Re: Puzzled boat owner needs engine guru's advice!

The plugs that were black and sooty were very old. But I put new ones in last week and that did not fix the problem.

 

[fixin]

Re: Puzzled boat owner needs engine guru's advice!

Did you look under the disdribator cap?check the plug wires?all elec connections including grounds for corosion?I like to lay there and stare at it for a while,checking little things.

 

[akriverrat]

Re: Puzzled boat owner needs engine guru's advice!

if this is an overhead cam i would be checking cam belt.

 

[chadh]

Re: Puzzled boat owner needs engine guru's advice!

Check the float level in side the carb, or the needle and seat of the float.