Engine won't start-No fuel in bottom of carb

[SvenTheGoose]

New to me engine that I have seen run before we pulled it and moved it to a new boat. Good compression on all cylinders (70 psi), good spark from coil, OK spark on all spark plugs but I am not 100% sure what that should look like. The plugs are new as of a couple months ago. Proper gap is set on the plugs. Electronic ignition but that is from the "old" engine, not the new to me one. I could change out the distributor to the new one but it has points...

Fuel filling the bowl on the carb but the bottom of the carb is dry after turning over way to many times. This has been the case with both carbs (old and new engine). I torn down one of the carbs per the Moyer Manuel, cleaned everything and reassembled. Turned the engine over and still no fuel in the carb. Choke it closed and throttle wide open, middle of the road, etc... Tried turning it over with the spark arrestor off and felt suction. Tried spraying starter fluid into the carb and tried to start it, nothing. Put a tablespoon or so of gas in the bottom of the carb, put the spark arrestor back on, closed the choke and got a backfire but then nothing.

Drained the carb from the carb drain (older 4 bolt carb) and the fuel looked good, nothing in it, clean, etc..

Mechanical fuel pump but when we start from an empty carb it only takes 1-2 second before the bowl fill up. I can tell the fuel flow through a clear fuel filter.

Pull the carb today again (it went in this morning after the rebuild last night) and the main jet looks clean.

Can my issues be anyplace but the carb?
The three things I can think of that would stop fuel from being in the bottom of the carb would be:
1) No suction, which I have
2) Plugged main jet, which I have cleaned
3) Plugged carb nozzle, I cleaned this last night but maybe not as well as the main jet.
Anything else? I guess a clog between the main jet and the carb nozzle maybe but I sprayed the crap out of it with carb cleaner.

Other things I checked today, did these one at a time.
Confirmed timing was good, swapped distributor caps, but neither is new.
Swapped rotor, one is new on it older.

Open to anything else I should try here. I am on the hard the the boat is tilted about 5 degrees to starboard.

[Al Schober]

If fuel supply is good and the bowl is dry, I'd check the float valve. Could be stuck shut. Recommend replacing the needle valve and seat.

[SvenTheGoose]

Al,
Wouldn't a stuck float valve stop the bowl from filling? After installing the 2nd carb the pump filled the bowl in seconds and I confirmed it was full by draining it via the drain plug and got about 1/4 cup of fuel out. Just confirmed on my other carb that is in pieces that the bowl hold about 1/4 cup.

Does the carb need pressure from the fuel pump to operate? I thought it would just work on gravity from the bottom of the bowl putting fuel in front of the main jet and then the suction from the engine would pull the fuel through the main jet and then into the nozzle.

Guess I should just order the rebuild kit but something isn't feeling right about that being the problem.

[TimBSmith]

Carb pressure thread from our host...

https://www.moyermarineforum.com/forums/showthread.php?t=242

https://www.moyermarineforum.com/forums/showthread.php?t=242

[SvenTheGoose]

Tim,
Thanks for the post, it is indeed a 4 bolt carb I have in there right now. I had already flattened the body when I reassembled it. I had a 5 bolt in Thursday that was exhibiting the same issues but it did need a good cleaning so maybe I should head back to the 5 bolt version. I originally had double gaskets when I started and only 1 survived disassembly so I used that in the rebuild of the 4 bolt version.

I am thinking my best course of action if going to be to rebuild the 5 bolt one.

Thanks,
Brant

[Dave Neptune]

Double check that the choke is closing all the way. If there is fuel in the carb during cranking and the choke is closed seeing a bit of fuel in the throat is normal if the carb is functioning properly.

Did you poke out the two idle ports in the throat of the carb? And are you sure the carb bowl gasket is sealing around the emulsion well in the center of the bowl? If it leaks a bit of air it will be very hard to start and run poorly if it does.

Also are you sure that the wires are in the correct order (double-check)? How did you check the timing?

Dave Neptune

[SvenTheGoose]

Dave,
I did use a wire bristle to poke out the two idle ports. I am not getting fuel around the choke.

I just lapped the top of a 5 bolt carb I have and the fit is really good compared to the one on my engine right now so I am going to see if I pull the gasket off the 4 bolt one (it is a 5 bolt gasket) and put it on and see what happens. I think you are onto something with the air getting in between the halves.

I'll order a rebuild kit Monday no matter what but would like to see her start at least once.

I did double check the wire order with someone looking over my shoulder and that is correct.

For the timing I set to top dead center using a pencil to see the valve closing then turning until the roll pin was vertical. I then used static timing light to adjust the distributor. Basically I followed Don's video here:

https://www.youtube.com/watch?v=2ysFGcm8oNo

Thanks,
Brant

[Dave Neptune]

Simple TDC test

Watching a valve close is OK if it is on the right stroke. Remember that the exhaust stroke at TDC has the exhaust closing as the intake is opening, this is called "over-lap" as both valves are barely open at the same time.

When on the compression stroke the exhaust is already closed and the intake is closing and at TDC both valves should be closed.

Now I have seen a lot of ideas on how to determine if you are actually on the compression stroke on this site. Just place a piece of hose over the spark plug hole when the pin is vertical and hold firmly in place. While holding it just blow through the other end. If you have resistance when trying to blow into the cylinder you are on the compression stroke if you are on the exhaust stroke you will be able to blow past the valves into the intake manifold and the exhaust IE no resistance. This test is best done with the throttle open.

Brant, are you sure you were on the compression stroke absolutely?

Another point is I see you have played with the distributor, cap and wires. If all was well when shut off last time nothing should of changed with the timing. I did not see that you checked for spark, did you?

You are now in a classic case of you should only trouble shoot one thing at a time. I would not be surprised if your start issue "was" the carb and now it is timing. It should try to start with starter fluid and if not it is timing or spark. If the carb has fuel in the bowl it should at least kick a few times unless no spark, bad timing and/or plug wires out of sinc.

Take a very slow look at what you have changed and played with, especially the timing and spark.

Dave Neptune

[SvenTheGoose]

Thanks everyone. I swapped out the carb with my "new" 5 bolt one and moved the gasket over. Felt good suction on the air intake but still would not start. Decided to swap to the points based distributor I had because that was what had been on the engine when I saw it work. Doing that ment redoing timing but that is easy enough but we rewatched Don's video again just to make sure. Pressed the start button and she just started right up. Not sure if the timing was off or the distributor but I have a running engine!