1975 50hp evinrude problems!! Any advice, suggestions would be appreciated!

[sp4041]

I just bought this motor a few months ago and learned a valuable lesson! Always test a motor on the water!! It ran fine in the sellers yard and have not been able to even get on plane at lake since! It will idle ok doesnt sound too great but when I give it throttle nothing happens, I even manually gave it throttle and didnt do much just gurgled and bareley got me back to ramp last time.

I'm going to be taking carb off and cleaning as well as inspecting fuel pump and filter. This will be the first time I have done anything like this! Any advice or suggestions? I'm going to order the carb kit. Is their anything else I need to order that doesn't come in kit? Do I need to replace orifice plug/jet? This could turn bad I know, but I figure I might as well learn and save the $250 the mechanic told me it would cost to do carb.

Thanks for any advice or suggestions!!

 

[Pontoon24]

Re: 1975 50hp evinrude problems!! Any advice, suggestions would be appreciated!

Well, I'm sure you'll hear something to the contrary but I've cleaned plenty of carbs and have yet to replace anything on one so I would not even bother ordering the kit.
Go to boats.net and under parts you will find an exploded diagram of your carb. Study it. Remove the bowl and clean all jets and orifices.
Use a fine wire for the tiny holes in the jets. Soak everything in a gallon can of carburetor dip. (Avoid submerging plastic parts or rubber gaskets)
Use air to blow out and dry off everything including fuel lines.
Many on here I would guess could just about do it blindfolded. Reassemble and report back.
Also, you may be able to find a utube video to show you how to clean a carb even if it's not your exact part you will get the idea.

 

[sp4041]

Re: 1975 50hp evinrude problems!! Any advice, suggestions would be appreciated!

Thanks for the feedback! The previous owner and I put a carb kit in a month ago or sobut didn't really clean it. Do you think the gaskets would be ok and I can just take carb off, clean and put back on or would it be a good idea to put new gaskets? Also, he ordered the orifice plug last time becasue their was not one in the bottom jet. Again, thanks for any advice and suggestions!

 

[jtrom]

Re: 1975 50hp evinrude problems!! Any advice, suggestions would be appreciated!

I have a '74 Johnson 50 which is the same as your engine. I had the same problem and cleaned the carbs. It worked for a minute then one of the carbs got plugged up again. You really should rebuild them. Carb kits are only 25 bucks a piece for these motors and its easier than you think. Buy a manual on ebay (20 bucks) and do it right. Just my opinion. . One more thing....be sure to stop running it if indeed one carb is plugged: one cylinder is not getting gas which also means its not getting oil on a 2 stroke!

 

[jtrom]

Re: 1975 50hp evinrude problems!! Any advice, suggestions would be appreciated!

Oops...I didn't see the part where you installed new carb kits. Take off your intake air box so you can see straight into the carbs. Start it up and look and see if both carbs are spraying fuel.

 

[jere1972]

Re: 1975 50hp evinrude problems!! Any advice, suggestions would be appreciated!

is the timing advancing along with the carb? I have also seen things crawl up into the exhaust housing mid section and nest leaving partially to completly blocked exhaust path runs fair to medium on a trailer but not in the water causing a blow back into the engine ! sorry most likely a stretch!

 

[jtrom]

Re: 1975 50hp evinrude problems!! Any advice, suggestions would be appreciated!

Yeah that sounds like a stretch. First things first. Are both cylinders getting fuel?...are both getting spark? Do both have good compression?......if all that is good, then there is a process called "link and sync" for the carbs.

 

[eavega]

Re: 1975 50hp evinrude problems!! Any advice, suggestions would be appreciated!

Have you done the basic checks? Compression on each cylinder within 10% of each other, and a reasonable reading, Spark plugs correctly gapped an spark jumping 7/16" air gap with a good blue CRACK. Fuel pump moving fuel correctly?
If all that checks out correctly, then you are right to suspect the carbs, but before you simply clean out the carbs make sure your fuel lines (all of them from the tank, to the motor, to the fuel pump, to the carbs) are in good shape and are of the ethanol resistant variety.
Clean out the carbs by fully dissasembling them, removing the core plug, cleaning out all the passages and orifices, fully dry, check float level, etc. Reassemble and reinstall, performing a correct link-n-sync per the manual.


Rgds

 

[sp4041]

Re: 1975 50hp evinrude problems!! Any advice, suggestions would be appreciated!

Thank you for all the feedback and suggestions!! I had the mechanic come by and check the spark and compression a month or so ago. He said spark was ok and compression was decent, not identical, but within 10%. I will check all fuel lines, fuel pump, clean carbs and install kit. How can I tell if both carbs are spraying fuel? Is it obvious when I take air box off? How do I check if timing is advancing with carb?

One last thing. I don't know if this means anything or not but when I tilt the motor back up and get it back to house their is a black sludge dripping out of the motor?

Thanks again for all your help! Hopefully I can get this thing going. The kids are starting to lose interest!!

 

[jtrom]

Re: 1975 50hp evinrude problems!! Any advice, suggestions would be appreciated!

When I said air box I meant the rectangular cover...there are like 7 or so small bolts that hold it on. Once you remove that look through the choke butterfly valves (make sure they are all the way open). You should see fuel spraying from both carbs when motor is at idle . It should be obvious. Regarding the black sludge, did you ever check or change your lower unit gear oil?????

 

[eavega]

Re: 1975 50hp evinrude problems!! Any advice, suggestions would be appreciated!

Black sludge out of the lower unit is usually unburnt fuel oil. You may always get some, but you definitely get a lot more if you have a cylinder that is receiving fuel but not burning it completely for whatever reason.

Rgds

 

[sp4041]

Re: 1975 50hp evinrude problems!! Any advice, suggestions would be appreciated!

Again, Thank you for all the feedback!!! I will be doing all the maint. this weekend and will also check and see if both carbs are spraying fuel before I take apart. I have not changed or checked the the lower unit gear oil. I suppose I should do this as well? What would cause a cylinder to not burn the fuel completey? I assume if that cylinder doesnt have good spark or something along those lines. It definitely has had the occasion of running on one cylinder. Both mechanics I had to a quick check had to fiddle with a few things to get both firing correctly. Can the carb cause that problem? I know spark and other things can casue just trying to understand a little more before I jump into it this weekend. Thanks for you help!! I greatly appreciate it!!!

 

[jtrom]

Re: 1975 50hp evinrude problems!! Any advice, suggestions would be appreciated!

Yes change the gear oil. Take out both drain screws and drain old oil. Buy outboard gear oil and fill from BOTTOM hole till oil runs out top hole. (you will have to squeeze hard on the bottle). Quickly put drain screws in.

Do both spark plugs look the same? (is one oily?) Did you do a spark check on both cylinders?