engine needs full choke to run - but brand new carb

[fixxxer0]

so ill get right to it... my late model A4 engine was stalling out when giving it throttle, and wouldnt bring my 1973 C&C 30 above 3 or 3.5 knots. so i started by checking the fuel filter and it was disgusting. ended up getting rid of it completely because it was so bad.

i removed the copper tubing and put in all new fuel line, a new racor filter, cleaned the sediment bowl and screen on the manual pump (diaphragm appeared okay since it could hold pressure against my finger for 30sec or so), replaced the carb with a new one (old one looked like it had polyeurthane in it lol),
, installed the polishing filter between the pump and carb, i also stuck a hose in the fill spot and sucked out some crud and water from the bottom of the fuel tank. it does seem kinda dirty and golden yellow (not the clear with a hint when i put it in). I also installed new electronic ignition and lubed the distributor advance weights, new coil with new wire end connections now mounted on a bulkhead, and new spark plug wires (the plugs were only a few hours old).


the engine started right up and sounded better than ever, revved up with no hesitation at all in neutral. i was excited to test it out, expecting to go shoot up to 5.5 knots no problem.

well it didnt work that way, as always. it ran fine for 10 minutes to get me out of the fleet and moving along, but still only 3.0-3.5 knots at top speed... i was about to go down below to adjust the timing under load when the engine died. it was somewhat quick, and knowing the trouble shooting methods and signs i tried to start it again with the choke on. and it came right back to life, trying to close the choke it shut off on me again. i was able to make it back to my mooring by running with full choke only, anything less it wouldnt run.

i know this usually means the carbs main jet is messed up but this is brand new and has 2 fuel filters before it! i was concerned about water in the tank so i drained the RACORs bowl and the fuel that came out looked very clear (although still golden) and with no water.


i am going to pull the main jet just because i know thats what i should check first, but i just wanted to know what else could cause you to need full choke to run?

also, i still cant get above 3 - 3.5 knots at full throttle, i dont know if its an engine problem, (folding) prop fouling, dirty bottom, exhaust back pressure, or something i cant even think of... but that seems like a big drop from the 5.5 knots it used to do.

[Steve Lomas]

You're probably not as stupid as I am, but I had the same symptom once after replacing the carb- eventually found I'd linked the choke cable back on incorrectly-
So you could try setting the choke directly at the carb to eliminate bad linkage.

Also had experience with a corroded fuel tank that cause a lot of grief-
might be wise to replace the tank/ or at least try running the engine from a temp tank- so you can eliminate contaminated fuel also?

and check the fuel filters again- they can clog very quickly if the tank is bad- I use clear ones so I can check easily

Steve

[fixxxer0]

i was manually checking the choke because on the install the cable was sticking so when i was opening and closing the choke it was by hand at the carb itself.


if i am having a fuel restriction because of a dirty tank that plugged my filters, would closing the choke help this and allow the engine to run???

[Kurt]

I don't think running with full choke would help you if your filters were clogged. I'd also check the main jet. In terms of exhaust back pressure, the test for that is simple. First off, if you have back pressure issues, you won't have full acceleration in neutral or in gear. So, first check to see if you have that explosive, full acceleration in neutral. That being said, I don't think elevated exhaust back pressure would explain your ability to keep the engine running with full choke. Sounds fuel related to me. Let us know what you discover.

[fixxxer0]

First off, if you have back pressure issues, you won't have full acceleration in neutral or in gear. So, first check to see if you have that explosive, full acceleration in neutral.

Thats good to know, I thought it would only be in gear because you burned more fuel or something.

The throttle (before this issue yesterday) responded instantly when flicked forward and could rev very high in neutral.

[roadnsky]

I think you could possibly have more than one issue going on here.
Certainly appears to be a question of fuel quality at minimum.

Have you double checked your firing order on the spark plug wires and distributor?

[Marian Claire]

Any time I hear “only runs with choke on”. I think lean condition. Too little gas for the amount of air. Problem is this can be caused by blocked jets, plugged filters; poorly operating fuel pumps etc that limit the fuel flow. Or too much air for the amount of fuel. Caused by air leaks in the carb, carb/manifold connection etc. Follow advice by others on fuel quality and exhaust back pressure and slowly eliminate each possible cause one at a time. I know easier said than done. Good luck. Dan S/V Marian Claire

[fixxxer0]

just thought i would update everyone on the cause incase someone is having similar issues.


it was the fuel filter(s). my brand new racor filter, was plugged up in all of 15 minutes of running with a dirty fuel tank.

i have replaced the old tank (steel tank w/aluminum lining mfg. ~1994) with a moeller inboard polyethylene tank. the old tank was visible rusty on about 50% of the interior surface, from what i could see through the fill hole.

when i removed the racor filter and turned it upside down the gas that came out was a dark red/brown and there was tons of crud in it. barely smelled like gas.


the bowl was all full of rust particles as well, and even fuel pump sediment bowl was dirty again.



how would i know in the future when the fuel filters are getting dirty/clogged, short of having engine problems? would a vacuum gauge do this?

[Don Moyer]

Several of my friends with diesel engines have actually already installed vacuum gauges between their filters and their fuel pumps. I don't mean to sound critical, but if we made the same effort to take care of our fuel systems as our diesel powered colleagues, we'd have a lot less fuel related issues.

[fixxxer0]

oh i agree completely don. Thats why i replaced everything - tank, vales, lines, filter/seperators, and took apart the pump.

i just bought this bought in July so i have been fixing and maintaining all the things the previous owner neglected.


he had a vacuum gauge installed to a T-fitting on copper scavenge tube (which broke when i moved it), it had a braided fiber hose to the gauge and i never had a baseline reading for it so i didnt know what it meant really.


is this another appropriate place to install a vacuum gauge to check the fuel filters? or should it be where you mentioned, between the pump and the filter?


I heard you were considering offering a vacuum gauge package on your site... is this true/happening?

[dvd]

Fixxxer

Where did you get the new gas tank. Is a plastic tank recommended and do they have all the various sizes

Thanks

DVD

[sastanley]

I got my 18 gal. Moeller poly tank from Amazon for about $165.

lots of sizes available from Moeller..I happened to find one I needed for my C-30 at Amazon.

[Mark S]

Shawn,

Any adverse effects from ethanol on the poly tank?

Mark

[sastanley]

Mark, I haven't seen any yet, but on the other hand, the ethanol blend fuel was added just a few days before our most recent trip. I'll admit unfortunately, that I haven't used the boat since then (3 weeks).
I seem to recall doing some research on the Moeller tanks and the report was they were safe for ethanol blends...and I am by no means a plastic expert, but I do know my fuel tank is polyethylene and my holding tank is polypropylene

I am attempting not to have any ethanol in my poly fuel tank. A little has snuck in there, when I don't have time to drive the extra 15 minutes (of course in the opposite direction of the boat!!) to the nearby Shell filling station (and lug the jerry cans in the truck) to get ethanol free fuel. I learned about the local ethanol free Shell from a powerboat buddy, also attempting to keep the ethanol out of his marine tank.

I'll dig around and see if I find anything next time my wife allows me to be home for a weekend and I can get to the boat (won't be this weekend either)..it may be time to drain the Racor and pop the bowl off the fuel pump to see if any water is in there. I can't blame it on my wife 100% though, the rotator cuff surgery has really inhibited me from doing even 'remedial' tasks like opening the fuel tank petcock without help.

If I had to guess, I probably have about a 5% concentration in there now as roughly half the fuel was ethanol free, and the other half was 10% ethanol. My goal is to burn as much of that fuel out as I can this season, and then fill it with ethanol free fuel and stabilizer when it is time to store the boat for winter.

[MikeB.330]

just an FYI but filling stations in MD are not required by law to post that they are selling E10. having said that , every gas pump I've seen around the annapolis & calvert county area have been posted E10.

Mike