Fuel problem - should my engine empty the glass fuel filter while idling?

[Gas Giant]

Engine is an Evinrude Lark III 40HP Model #35524

Been trying to get this engine running. Had some success, got it to fire up with the control lever at fast idle. However, while I was attempting to make adjustments on the low speed needle, it kept dying. Then, I noticed that while it was running, it would basically suck all the fuel out of the glass fuel filter on the fuel pump right before it sputtered out. (Also, its tough to turn that needle with the engine bucking around like a mechanical bull....)

Seems to me this is a problem. My Bel Air has one of these too, but I don't remember it ever emptying while the engine was running. But then again from where I sit in the driver's seat, I can't see it.

All my fuel lines are new. When I rebuilt the carburetor and replaced the fuel system, I took the fuel pump apart and cleaned it too. The diaphragm didn't appear to have anything wrong with it at the time. But it sure seems to me that the fuel pump isn't drawing any fuel from the tank....other than an air leak, what else could cause this? Would it be worthwhile to tear the fuel pump apart again?

 

[1946Zephyr]

Re: Fuel problem - should my engine empty the glass fuel filter while idling?

That fuel bowl should stay full while it's running. You may have a fuel issue. What I would do, is charge it up and unplug the fuel line from the carb. Put the end into a jar and see if it pumps gas into it. If not, then it's a pretty safe bet that your fuel pump is shot. If it seems to be hard to charge up, you may just have a blockage in the fuel flow. If it charges up easy, then I'm betting on a bad fuel pump.

 

[Gas Giant]

Re: Fuel problem - should my engine empty the glass fuel filter while idling?

Good idea, I feel kind of stupid that I didn't think to check that.

Of course, to complicate matters, I snapped the pull cord for the engine this afternoon. So I have no effective way of turning the engine right now. Guess I'll have to looking into getting a starter (and a new pull rope), but in the meantime I'll look into a fuel pump diaphragm also.

 

[1946Zephyr]

Re: Fuel problem - should my engine empty the glass fuel filter while idling?

Yea, I found that your model does have the rebuildable type of fuel pump. You should be able to get a kit at Sea-Way Marine. It nay be a bit dated to find here. Here is a good parts break down on your motor:

http://www.marineengine.com/parts/v...evinrude-johnson/ITEM_2516/ITEM_251600001.htm

 

[lindy46]

Re: Fuel problem - should my engine empty the glass fuel filter while idling?

I saw a starter for your motor on AOMCI.org yesterday for $65. Check the classifieds there.

 

[1946Zephyr]

Re: Fuel problem - should my engine empty the glass fuel filter while idling?

That's pretty reasonable. Having one rebuilt is over $200 these days.

 

[Robert R Ellis]

Re: Fuel problem - should my engine empty the glass fuel filter while idling?

I have a very similar engine so I'm interested in this thread. Someone wrote 'What I would do, is charge it up and unplug the fuel line from the carb. etc'.
I'm new to all this so can you explain what 'charge it up' means.

Robert

 

[lindy46]

Re: Fuel problem - should my engine empty the glass fuel filter while idling?

Just pump the fuel line bulb so there is plenty of fuel in the engine so she'll run. Then disconnect the fuel line at the carb, and put the end in a glass jar. Fire up the engine and see if fuel pulses out the line into the jar. BE CAREFUL! I usually cover the glass jar with aluminum foil to prevent fumes from circulating around the running motor.

 

[Robert R Ellis]

Re: Fuel problem - should my engine empty the glass fuel filter while idling?

Ahhh - very clever - I never would have thought of testing a fuel pump that way in a million years!

To the original poster - I have what I believe is a very similar engine - a 1963 40 hp Evinrude - I had a quick check this morning - at idle the glass sediment bowl at the side of the fuel pump is only about 1/3 full. This engine runs incredibly well at all speeds and starts reliably at the touch of the key so ... I don't know that it is anything you need to be too concerned about. On the other hand ... it could be that my fuel pump is on the way out - all I can say is that, at the moment, you couldn't ask for a smoother, better running engine. Don't give up on yours, they're really nice motors. Incidentally, I run it with a 40:1 ratio - is that about what you use? Also, is it true that Larks have no reverse gear?

 

[Gas Giant]

Re: Fuel problem - should my engine empty the glass fuel filter while idling?

Yes, I saw some starters for sale for about $65 a few days ago. I'll pick one up in a few weeks; for now I have to get the Bel Air back on the road since the weather is cooling off.

I don't want to give up on this motor, I have a feeling I am close to having it right. Once I repair one of the starting methods that is. I'm just going to rebuild the fuel pump; despite not being obviously broken or damaged I'm sure its on its way out - the rest of the fuel system on this motor was trashed from decades (yes, decades ) of sitting unused. At least that is what the previous owner told me, who knows.

Although mine would nearly entirely empty the fuel bowl and start to sputter as it got low, and then it would die.

I'm also planning to reseal the lower unit and put a new water pump in before this engine sees regular service. It does spit water out of the back of the engine while running, but who knows how long before the water pump goes.

I'm pretty sure the engine has a reverse gear though

For the ratio, I'm running 24:1 - I can't remember now where I got that figure now though.

 

[Robert R Ellis]

Re: Fuel problem - should my engine empty the glass fuel filter while idling?

Thinking of the cooling system, something I did that greatly improved the water flow rate was to remove the thermostat - not just the thermostat itself but the funny little ball thing below it. An amazing difference really - the engine doesn't seem to mind getting a good supply of cool Canadian water one bit - down your way in sunny Florida, there's probably even less of a reason to have a thermostat.

Not that I'm suggesting for a second that replacing the impeller isn't a damn good idea!

R.

 

[Gas Giant]

Re: Fuel problem - should my engine empty the glass fuel filter while idling?

Yeeeah, I decided to check the lower unit oil (again) after it had been sitting in a barrel of water - a bunch of water came out, and unnervingly little oil. I had filled it with fresh new oil before trying to start it.

So I pulled the lower, and it was full of milky gray-ish sludge. So, I guess I'm tearing the lower down before I do anything else to the upper portion of the motor!

I'm sure I'll have to start a new thread for that....