Nw carb wont start

[Fstued]

I rebuilt my engine last yr and have maybe 20 hrs on it. I was having trouble running at low RPM had to feather choke then it just quit and won't start I was back in the slip so no worries. I needed gas so figured I finally ran out. Added gas still won't go no doubt a clog in a jet so I go to rebuild the carb and one of my mechanic friends says this carb is shot. So i order a new carb install it and the engine still wont go there is 1/2 tank of fuel now and an oil change. I check for spark looks fine on all 4, check gas to carb I have it. The spark plugs are dry and the engine fires with a shot of ether but then dies quick. So fuel to the chamber seems like the problem. What am I missing
Why won't it go This is beginning to frustrate me Thanks

[ndutton]

Sounds to me like you're on the right path. What type of fuel pump do you have, mechanical or electric? The answer to that question will open up a specific fuel supply diagnosis strategy. I believe you are very close to success.

one of my mechanic friends says this carb is shot

Based on WHAT? Isn't it interesting that following his advice has resulted in zero improvement and a lighter wallet.

[Sam]

Say hello to a fuel pressure gauge - your new best friend.

[Fstued]

It is a manual fuel pump but there was fuel coming out of the bowl So gas is getting to the carb I didn't have the line from the fuel pump to the carb tight and fuel was screaming out of it. I gave it a twist and that solved the problem. I still feel a liittle lost on this one. Maybe not enough fuel pressure?

[ndutton]

If there is fuel in the bowl the problem is inside the carburetor. Are you sure the choke is closing completely? Is the mixture screw set at the default 1½ turns off the seat? Is the main jet clogged?

[nyvoyager]

After cranking are the spark plugs wet with fuel?

[Fstued]

no the spark plugs are not wet All things point to the new carb. There is fuel in the bowl. Do I have to take the new carb out take it apart and blow it out?

[ndutton]

Based on your reports, the typical issue is a clogged jet so yes, a dismantling and cleaning is in order. However, how does a new carburetor get clogged? The go-to answer is feeding it rancid fuel. Without resolving the suspected contaminated fuel issue, a newly cleaned carburetor will clog up in short order and the cycle repeats.

[Fstued]

Well I took the old new carb off and cleaned it, replaced the fuel water separator, pumped fuel through the fuel pump and then reassembled everything and again failed to make it run. I guess the next task is to repeat the process drain the fuel from the tanks and reassemble. Still not getting gas to the cylinders. Here is the old gas after settling. I am getting good at it. Will I have to remove the fuel pump and clean that too? I did install an in line filter between the pump and the carb. At least the engine cranks fine just no gas in the cylinders.

[ndutton]

Well, there's your problem. A proper repair is to clean the entire fuel system from tank to carb and everything between. Even more important is to determine the source of the contamination so it doesn't happen again. The usual culprits are bad gas pumped in from the fuel dock and a damaged fill plate O ring, could be both too.

[tenders]

What is that sediment - water, or some kind of salt or metal corrosion? Hard to tell from the photo. What's your fuel tank made out of? If aluminum, and that stuff is aluminum corrosion, I think you're going to need a new tank. I guess the good news is that if the tank is steel, that sediment definitely isn't rust.

Also keep in mind that the little "polishing" filter between the pump and the carb will quickly get overwhelmed by this degree of gunk. You might think about buying a dozen or so plastic ones on Amazon for $10 while you're sorting this out. They're terribly cheap, and not legal for marine use, but you can see through them.

[Fstued]

Think I am getting to the root cause. Ran the engine for a while today off another tank of clean gas. A least that is a plus, plugged it back into the boat fuel tank and the engine stopped. So its the fuel tank full of something that doesn't agree with the engine. I guess that might mean a new tank. I am not quite sure how to deal with it right now but at least the problem has been found. MIght just put a plastic tank in and by pass the tank that is there. I'll try to clean it first.

[zellerj]

Some tanks are monel, that will last forever - just clean it out.

Some tanks are aluminum - they develop pin hole leaks after a while - best to replace them.

Some tanks are stainless - clean them out and they should be good.

If your tank is bad, try Moller plastic tanks - cheap and usually you can find a model that drops right in for a replacement.

http://www.moellermarine.com/product-category/fuel-containment/permanent-fuel-tanks/

[JOHN COOKSON]

Water in the tank will most assuredly cause engine problems. A common way for water to get into the tank is by way of the fill cap.
So, check the fill cap to be sure it is sealing properly.

TRUE GRIT

Also: can you blow into the tank (with your lungs) using the fuel line and hear bubbles? Maybe there is some sort of blockage at the end of the pick up tube in the tank.

[Dave Neptune]

Advise

Get a Fuel pressure gage mounted in front of the carb and the guessing will stop.

Contaminated fuel is a BIGGIE! If you have good access sometimes you can access the "BOTTOM" of the tank via a cover plate, pick up tube, vent or even the filler. If you can get to the bottom pump out all of the fuel and try again.

Often the tank contamination accumulates below the pick up tube and goes unnoticed until either rough seas or the KRAP has accumulated enough to now be sucked up the tube to cause big issues.

Dave Neptune