im stuck. runs rough 1980 evinrude 35hp

[Maveric7383]

model # E35ECSM (1980 evinrude 35hp)

symptom > rough idle through mid rpm??. I dont have anyway to tell if the symptom is going through the entire rpm range. I have a garbage can that the engine is being run in. obviously if i open it up all the way all the water gets splashed out of the garbage can.

>top plug is very clean. lower plug is dark, If it way my guess (coming from an automotive background) I would say there is a small amount of water getting into the top cylinder and steam cleaning the plug or its very rich on the top cylinder which doesnt make sense since there is only one carb.

>while running I removed the top plug wire and grounded to block there was a smaller difference in idle compared to removed lower plug wire.

>So far I have cleaned the carburetor - checked float height & adjusted s/s needle to spec the best i could ( 1 1/4 turns ccw) , de-carbed the engine, link and sync'd, checked for vacuum leaks using brake parts cleaner and a propane torch (no lit) - found no vacuum leaks very hard to check top crank seal for leaks cant really get the brake clean up in that area, spark tested both cylinders - spark jumps 7/16" - 1/2" crisp blue spark. I replaced lower crank seal. performed compression test - 90 psi on each cylinder. inspected reeds while carb was off manifold - all looked good found no damage or partially opened reeds. found excessive amounts of oil on the top of the water in garbage can used to run the engine. this is telling me the top cylinder is not firing for one reason or another.

> Next step, going to wally world to buy muffs and run water through engine and look for water entering top cylinder. I would also like to try and rule out the top cylinder ignition system for problems. Isolate fuel pump, maybe its leaking so much the cylinder is not firing. who knows. Im not sure how to test the ignition system while its running. though, should I just put the spark gap tester at 3/8" and run it?

>Update - tried muffs didnt work, need to remove impeller for that test to work. Installed spark plug gap tester on top plug, set at 7/16" ran for 5 mins, found no problems engine ran the same. Isolated fuel pump from engine - no difference installed or isolated.

>Am I missing something? Either the top cylinder is way too rich which could possibly mean lower cylinder is lean (vacuum Leak) and carb is adjusted ideally for lower cylinder running which doesnt make sense since carb is set at factory specs and there is more of an idle difference when lower plug wire is removed and grounded.

 

[tashasdaddy]

Re: im stuck. runs rough 1980 evinrude 35hp

do a compression and spark check. 35 only has one carb so fuel mixture would be the same for both cylinders. http://forums.iboats.com/showthread.php?t=299680 also new hoses.

 

[Maveric7383]

Re: im stuck. runs rough 1980 evinrude 35hp

Alright my first response!
Compression is 95 psi both cylinders (pull start motor)
spark checked both cylinders, spark color blue jumping 7/16" gap while running. I also swapped coils between cylinders
installed new hoses on engine.
Im going to isolate the fuel pump again and run it much longer than i did previously. im wondering if its an intermittent fuel pump problem leaking into #1 cylinder.

 

[psteurer]

Re: im stuck. runs rough 1980 evinrude 35hp

Those fuel pumps are usually pretty reliable but you could have a problem there. If your problem is in the idle to mid range, try looking back over the carburetor. Did you remove the high and intermediate speed jets and clean the orifices they came out of? For the motor to idle, there are 2-3 small holes in the barrel right where the throttle plate meets the top of the carb. Make sure they are clear. Use a brass or copper wire to clear them. They are hard to see. The intermediate jet is located on the top of the carburetor. Check out the top secret file

 

[Maveric7383]

Re: im stuck. runs rough 1980 evinrude 35hp

i cleaned out the jet jet in the float bowl. I also clean out the small holes in the top of the barrel near the throttle plate. however I never cleaned out a second jet, is it located under that metal cap on the top of the carb? if i do remove that cap do i have to replace it with a new one? when i cleaned the carb out it was pretty clean to begin with. I hit it with compressed air and carb clean everything looked like it flowed pretty well. Jut to give you a reminder this is a twin cylinder single carb engine and im only having a flooding problem on the top cylinder which the fuel pump runs off of.

 

[psteurer]

Re: im stuck. runs rough 1980 evinrude 35hp

I looked at a schematic for that carburetor and it has a high speed jet on the bottom and the idle needle valve (no intermediate jet). Those metal caps you describe are called welch plugs. The top welch plug is over the low speed inlet that goes to barrel of the carburetor. Not really sure about the side plug and where it goes. If you bought a carburetor kit, you should have gotten some replacement plugs. Why don't you remove the plugs (especially the top one) and see if there is any crude in the cavities behind them. You may be surprised what you find. To remove them, take a small nail and hammer then puncture the center (don't go very deep). You can use an ice pick too. Then pry them out. See if there is any crude. The plugs are held in by friction. So to put in a new one, use a wood dowel or small socket (say 1/4 inch or so) put it over the new plug and tap it with a hammer. You can put some clear nail polish on the outside if you want to really ensure a seal.

The fuel pump provides fuel to one carburetor which feeds both cylinders. So if it is working for one cylinder it has to be working for the other. You can disassemble the pump if you want. There is a thin diaphragm in the pump that flutters back and forth based upon the compression in the top cylinder. Pretty simple design. If the diaphragm is okay (no holes, tears), you should be good to go with.