Fuel Frustrations

[cc29_buckeye]

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As we were returning from a week long cruise, my engine (1977) started showing signs of fuel starvation (and of course a loss of power). Although it never died, it ran extremely rough only while under load (e.g. only in gear). I did have to be towed in the last hour of the trip.

I replace the in-line fuel filter prior to the trip and motored for more than 15-20 hours prior to this problem. I did notice (it is a clear filter) it runs seemly dry during most operation. I did not "bleed" the system after replacing the filter because I was told with gas engines, the fuel pump will pull what it needs (I have an electronic fuel pump).

I have been reading a bunch and am thinking it may be a blockage but before I pull the pick up tube and possibly the tank to inspect and clean it, I would like some suggestions...

I intend on replacing the fuel lines (incase I have an air leak) and adding a priming bulb to prime the system and see if this corrects the problem. Any other thoughts???

Thanks!

[Jim H]

How about your primary fuel filter? Have you replaced its cartridge lately?

As for your tank, I've heard of others temporarily running from a line into a different tank for pick-up, to see if the suction and inline filter stays filled. You can imagine the necessary safety precautions to do this, however.

Last question: how old is your electric pump? I'm thinking of replacing my mechanical with an elec from Moyer...

Jim H

[cc29_buckeye]

I have only changed the in-line fuel filter -- I guess I did not realize there was another one. Where is it?

I was planning on adding a primer ball to the system first to take out the air. If that doesn't work, I will try a temp tank to see if the flow is any better. If it is I will move to a blockage between the inline filter and the tank (including the pick-up tube which may still have the screen on it). I will swap out the electric fuel filter last as I think it was replaced within the last few years (I will check with the previous owner).

Thanks.

[Valdare]

I had an atomic 4 and for two years I fought the same problem you described. I finally had the carburetor pulled and cleaned (by a professional) and Walla power was back. Seems I had sucked up some dirt from the tank when I first purchased the boat and it would plug up the jets under power. Idled fine, ran fine when I revved the engine...just caused problems under power.

John

[Jim H]

Originally Posted by cc29_buckeye

I have only changed the in-line fuel filter -- I guess I did not realize there was another one. Where is it?

My boat didn't have a primary filter orginally, but the previous owner installed a Tempo Max Flow model in the early 90s and changed the cartridge every two years. I just changed mine yesterday. It's a unit that you mount between the tank and fuel pump-- Moyer has one like it listed here:

http://www.moyermarine.com/cgi-bin/s...rebuilder.html

(It's a Racor model that is nicer than mine.) I believe the other manuals I have for my Atomic 4 also recommend a primary filter like it as well.

John's point is also good that it may be the carburetor, but it would bother me if I had a clear inline fuel filter that appeared empty most of the time. That would suggest a flow/pump issue.

Jim H

[cc29_buckeye]

My inline filter is a Fram disposable (as opposed to the Racor style) and was just replaced. I know there has been a filter on the engine for at least 10 years so I am hoping it is either a blockage or the fuel pump.

Anyone have issues if their filter was not properly primed when installed? I thought the fuel pump will clear the air in the line when the filter is changed.

Thanks

[cc29_buckeye]

OK. I replaced the fuel line, in-line filter, and electric filter (and added a primer bulb). Started back up and everything seemed fine. I motored for just about an hour. Sailed for a few, and started back home under motor thinking I was in the clear... Then the same issue started. I have not yet pulled the pick-up tube and checked the tank. I hope to find a screen on the pick-up tube with some crap in it! If not, I have not ideas.

A friend made a comment he read on a C&C site, engines getting hot and causing the gas to vaporize (?) in the carborator. Problem is the issue was present when I first started up the engine so I am doubting its too hot.

Any one have any thoughts?

Thanks!

[cardiacpaul]

It's alright if the fuel filter doesn't seem to "fill up". If you have it on the suction side, there might be air trapped, but it shouldn't be a problem. If its on the pressure side, again, might be air trapped in it, but the pump shouldn't "push" more than a couple of lbs of pressure to the bowl anyway.
has the filter element discolored? like its dirty?

I'd take a gander at replacing the ignition coil and condenser.

[tenders]

Seems to me you have all the pieces here to rule out a fuel issue. If the problem stops when you squeeze the bulb then it's almost certainly fuel flow--bad electric pump, clogged intake or filter. (BTW I believe there is a filter on the bottom of the electric pumps). Have you used a tube to draw some fuel from the very bottom of the tank and look at it in a clear container? You'd be surprised how much water can be down there. You could have water in the carb bowl. Those would be the easiest to diagnose.

I agree with cardiacpaul that it could be coil or condenser. Sounds to me like a coil failing after it gets hot, or some other component of the ignition system like the rotor or cap having worn out or loosened. How about a break in the insulation of the wire that goes into the cap? If you've just completed a successful week of cruising you might as well replace these anyway. If that isn't it, having an extra coil around isn't the worst thing in the world.

My third guess would be schmutz in the carburetor. Do you have an adjustable jet, and does the problem change when you twist the jet a turn each way? The carb is really quite easy to remove and clean out. It is so simple that if you take it apart you will probably be surprised that it does anything at all.

Your friend's comment from the C&C site is about something called "vapor lock." This can happen with high performance engines running at very high temperatures but if your A4 is so hot that it's vaporizing fuel in the carburetor you're going to have a lot of other symptoms to worry about besides rough running and stalling.

[cc29_buckeye]

Coil and condenser... Interesting thought(s). On the advice of a mechanic, I pulled and checked the riser (thinking the engins is being back pressured). It was clean. So was the muffler and I the exhaust tube through the hull.

My next step was to pull the manifold and reseat it (new gasket) thinking is an air leak. I guess I will check out the carb while the manifold is off...

I am very frustrated without being able to sail...