evinrude Lark 6 - 40hp, Surging. (MFG gypsy)

[areoseek]

I've looked around for hours on the forum and google and I can't find the exact same issue that i'm having. I have a suspicion its the fuel pump but wanted a second opinion before I tore into it.

Just bought a 1983 mfg gypsy, with came with a 40hp evinrude lark VI. Put fresh ethanol free gas in her, 50:1 oil mix, primed it, and she instantly fired. idles great. as soon as I put it in gear and give it any throttle, it starts surging. I went out on presque isle (Erie PA,) to see if I could get it to go away, and I had my passenger squeeze the prime bulb while I applied about 80% throttle. IF he squeezed it, it would run at full throttle for about 5 seconds without surging. I had him squeeze every second, I could maintain almost 100% throttle with very little surging. This tells me its something in the fuel delivery. I would assume fuel pump, but could this be anything else? The fuel bowl (glass) looks CRYSTAL clear baby blue. everything on this motor looks like it's been replaced. new starter, new fuel line, spark plug wires, fuel lines, ect.

also on a separate note, it's not generating power. do these engines have a generator or am I crazy? I believe it's the black cylindrical object opposite the starter (port side)with the belt around it.

Thanks, Devin
(long time lurker, first time poster).

 

[emckelvy]

Looks like your motor is 'circa 1964. It certainly could be a weak fuel pump; there are diaphragm kits available and it's probably a good idea to do a rebuild.

If it turns out to not be an issue with the fuel pump, you'll probably need to pull the carburetor for teardown/inspection/cleaning . You'll want a carb repair kit which should include a float bowl gasket, carb-to-intake gasket, maybe the rubber main jet emulsion tube-to-float-bowl gasket. If the carb has a cork float, and there's ever a possiblity that you would run Gasohol, you'll want to renew the float to an ethanol-resistant one. Alcohol fuels will dissolve the old varnish on cork floats.

It sure sounds like you have a generator; I've attached a drawing that shows the generator wiring. Pay no heed if yours isn't an electric-shift model, the generator wiring would be the same regardless. The important pieces in the system are the generator itself and the voltage regulator. You may have to pull the generator to a specialty shop and have it tested. They may be able to test the V. Reg as well. Check all the associated wiring for damage and corrosion. Make sure any connecting plugs are cleaned.

If your electrical components box (mounted inside the boat, typically) has fuses, be sure to check for a burnt-out fuse and check the fuse holders for tightness/cleanliness. Might be simple as a bad fuse, that would be easy!

Hope that helps, let us know what you find...................ed

 

[areoseek]

ed, thank you for that diagram. you wouldnt happen to have a part number on that kit woud you? there are tons on ebay and i dont trust what they say things fit.

it is indeed electric shift. ill have to look in that small grey electrical box and see if i can identify the regulator. is there a resistance check i can preform?


sorry for all of the questions, devin.

 

[emckelvy]

Try a Sierra Marine 18-7801. I checked the iboats store and they have it in stock for $17.57 plus shipping. Just click on "Boats Motors Parts" at the top of the page and search for the part #, it should come right up.

You'll need to pick up a manual for testing info, or search the postings here.

Or, if you have access to a basic Motors automotive manual, go to any of the old vehicles from the 50's and early 60's that had generators, the testing of generators/regulators is pretty basic and you can apply the principles laid out in the Motors manual to test your components.

If you can't find a suitable manual for sale at iBoats, try these guys, selling both factory and aftermarket manuals:

http://www.marine engine. com/parts/johnson-evinrude-manuals.php?Year=1964&HP=40&Model=

Just remove the spaces after you copy/past into your browser's address bar. This site parses certain web addresses and there's no other way to post them.

Here's a link to the Sierra Marine aftermarket parts catalog, an invaluable reference for finding parts for your "classic" outboard:

http://www.sierramarine.com/pdfcatalog/2014sierra/2014searchmain.html

That particular link is for the fuel pump repair kits. If you go to the next page, you'll find the application chart, where I found the part # for your kit.

Knowledge is power! Make yourself more powerful by utilizing the fantastic resources of the 'Net.

Back in the Dark Ages (pre-Internet), I had to scour the library and have subscriptions to all sorts of magazines; sitting at a keyboard is so much easier!

In fact, here's a 1964 40hp service manual, found on eBay with a simple keyword search:

http://www.ebay.com/itm/271909146408

Amazing the resources that are out there, including this great site!

BTW that's what we're all here for, to help out. No apologies necessary, you're keeping a classic outboard alive and that's a very cool thing!

It doesn't matter how much or how little you know, there's always something to be learned when the Collective Brain Trust shares its knowledge!

HTH & G'luck...........ed

 

[areoseek]

ed, you've been an amazing help. it finally stopped raining up here in erie so im going to try and take the old pump off and take a look. ill post pictures. should that clear fuel bowl stay full while the boat is running in gear? it never really empties.

 

[emckelvy]

should that clear fuel bowl stay full while the boat is running in gear? it never really empties.

As long as the fuel pump can keep up with the engine's demands, the sediment bowl will likely remain filled.

 

[areoseek]

As long as the fuel pump can keep up with the engine's demands, the sediment bowl will likely remain filled.

i took the fuel pump off and apart and did not see any tears in the diaphragm. i re assembled but tightened the screws significantly. i ran the engine in a barell before and after. before it would struggle to idle and go from high rpm to low. after it started right up and idled like a champ. ill take her out on tuesday to confirm that the issue is gone for now, but i have a feeling it will return. ill order a kit for it if so.

as for the generator: i opened the fuse panel, and low and behold, the green wire had a missing fuse . i replaced it and cranked the motor up, but it is still not charging. wires all look good and the belt is new. i should note that there is also another fuse slot above the one for the green wire that was missing a fuse. i added a 20 amp fuse there but it did not seem to change anything. not sure what its for... any idea where to go from here? im worried about the lights eating the batteries when i come in at night and would be much more comfortable if i could charge at peast one battery. (using three). thanks again, devin.

 

[emckelvy]

I found an old thread here with tips for testing the generator, maybe you'll find that useful:

http://forums.iboats.com/forum/engi...s/220428-1964-evinrude-75hp-testing-generator

 

[emckelvy]

I found something even better, an online service manual with a comprehensive section on generators:

http://www.boatinfo.no/lib/evinrude/manuals/1956-1970johnsonevinrude.html#/180

That oughta do the trick!!

 

[areoseek]

thank you ed, ill keep you updated!

 

[areoseek]

As long as the fuel pump can keep up with the engine's demands, the sediment bowl will likely remain filled.

Ed, I just ordered 18-7820 my motor appears to be a 78. that is the only kit that matched the shape of the diaphram and mounting gasket.

I took it out on the water tonight and the surging was still very bad. it kept stalling. had to use the trolling motor to get it back to the dock. When i turn the choke to "manual off" instead of "automatic" it shudders and dies.


Maybe this is a carb issue. the fuel pump rebuild can't hurt though at least not for 18$.

 

[racerone]

May need to polarize the generator.

 

[emckelvy]

Sounds like the carb needs work. BTW they didn't make a 40hp in 1978, so maybe someone down-the-line has installed a later-style pump.

 

[areoseek]

May need to polarize the generator.

How would I go about doing this?



And Ed, I took the pump apart again after a tip from my buddy, He told me to stretch out the spring inside that the diaphram pumps up and down. I did this, and Alas! I have a little bit of throttle to play with, I never knew this boat was so fast! It still struggles to do anything over half throttle, but I got her up to almost 10 knots without surging. (may not seem like a lot to you but i've never used anything but idle speed !)

I get the new diaphram in the mail tomorrow, so hopefully the spring wont cause any more problems. my diaphram is very stretched and i believe that explains why stretching the spring helps it pump more. I'm so happy that it's not carb trouble! Really didn't want to replace all of those tiny parts! Everyone, you have helped me so much, i never realized that the boating community was so helpful!

-Devin, Erie Pa.

 

[areoseek]

new diaphram instaled, still no dice. i cant blow through it, wich is good. i am going to proceed to remove the carb and adjust the float, as this is what i believe it may be. i can run it just fine if i squeeze the bulb ever once and a while, but then it starves out. a jet is probably clogged and the float is probably off / very dirty. will update...

 

[areoseek]

Giving up. putting the motor on craigslist and getting a newer one. thanks for the help guys.