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Evinrude 8 HP 1991 Stalls on low RPM

M

Mike_swe

New member
Hello everyone.

I recently purchased an older evinrude engine. When i went to try it at the dealer we started the engine in ran it in a waterbarrel and from what i could see and hear it all sounded ok.

I mounted the engine on my boat and the motor was running fine the 3 first times i used it. Then the problem started.

All the sudden the engine became very hard to start. I had to pull the cord for about 20 times. Choke or no, same result. As a result of this and bad luck the starter spring broke and i had to replace it with a new one.
The startingproblem continued so i took apart the carburator and cleaned it. I reinstalled everything and while i were at it i also replaced the sparkplugs. I went to the dealer and through the service manual he picked the right ones for my model. I started it up in my barrel and on the 4 pull it started. Runned like a sharm.

Back in the boat the engine runs fine. Fairly easy to start and i went for a longer run. On full throttle it runs absolutly perfect. But now to my problem. When i run the engine at fishing speed i can hear that it sound like the engine doesnt get any fuel. The engine rpm does quick dips and all the sudden it complety dies. When this accour, i can pump the primer and then start to pull. It takes about 20 pulls then its running again. But not for long. It all starts over again until i run the engine at full speed. Then its running fine.

What could cause this? Could it still be the carb thats not working properly? I havent replaced any gaskets. I took it apart and put it in a bucket of petrol then blowed it dry with air.

Fuelpump?

Thanks in advance
/Mike
 
The oil iam using is an outboard 2 stroke oil. I think it rather old. It has been sitting in my storage room for a couple of years. The mixture ratio iam using is 2%.

I have replaced the old metal tank with a new plastic one so it should be completly clean.
 
Ive tried to run it today again and it really feels like its getting low on fuel but when i look at the plugs they are wet.
I really appreciate any kind of tip here.

/Mike
 
Fuel pump would a cheap thing to do. Compared to other things. Engine is old enough for a pump job. If you do the fuel pump rebuild . Folllow the instruction about OILING the tiny rubber check valves BEFORE trying to pull them thru the holes............DO 1 at a time. They do go onto the plate from opposite directions. USE ALL the parts to replace ALL the parts in your pump.

I am assuming the 8 hp use the same pump as almost all other Evinrudes.
 
Old mind forgot.

Do the rebuild on a table in the house. Caution.. The pump HAS A SPRING under the center of the diaphram & a disc / button . There is another small spring & plastic part ............BOTH can fall off as you loosen the screws & lift the pump off the engine. GONE. Not supplied with the kit. I put a LARGE WHITE bath towel tucked under the fuel pump & extended it around the engine to catch parts. I tip the engines fully up in the boat.

Use the towel AGAIN when putting the rebuilt pump back on the engine. I had fun trying to keep the center spring & plastic disc centered in the diaphram. 4 tries until all the mounting screw holes lined up perfectly with the pump pressed into place. If you are a person not good with keeping all the spring parts balanced & in place. Have a GOOD mechanic do the Job.
 
Thank for all your advices. I really appreciate it.


Sorry for not clarify the oil mix ratio. Iam using 50:1 mix and the oil is for 2 stroke outboard specific.
I do not own a compression test tool or a spark gap tester but the first 3 long runs with the motor was problem free. As i recall it, this all started when i for some reason used the primerbulb one morning to start the engine. When i tested to start the cold engine at the previous owner before i bought it i newer used the primer at all. Second pull and then it was running fine. Should i still invest some money in these instruments? Could something got broken when i used the primer perhaps?

I ordered the rebuild kit for the fuel pump and will do the pump rebuild in the weekend. The pricetag for this was cheap =) compared to the starterspring i broke =). By doing this at least one thing could be eliminated.
I will also check the plugs for water and report back of my progress.

/Mike
 
cyclops2 said:
Fuel pump would a cheap thing to do. Compared to other things. Engine is old enough for a pump job. If you do the fuel pump rebuild . Folllow the instruction about OILING the tiny rubber check valves BEFORE trying to pull them thru the holes............DO 1 at a time. They do go onto the plate from opposite directions. USE ALL the parts to replace ALL the parts in your pump.

I am assuming the 8 hp use the same pump as almost all other Evinrudes.
Click to expand...

If there's liquid on the plugs, I'd look at the ignition, too, whether it's a mag or electronic.
 
Hello again. Thanks for all suggestions and help.

I rebuild the fuelpump yesterday and it seems like it did the trick. No hickups at all and it runs smooth on all rpms. I did a longer run for an hour yesterday at different speeds and it didnt die once.
No water on the sparks. Tested with a lighter =).

But one problem remains. It is still hard to start. I think i have to pull the cord 10-15 times before i got it running and i think this could be a tuning issue. Even when the engine is warm ill have the starting problem. After running for 30 minutes yesterday i stopped the engine, enjoyed the wether och had a coffee. Five minutes later i tried to start it and had to pull 10-15 times again. Once running it idles just fine.

It seems like when the grip handle is in the startarea, its to little gas? If i just give it a little more gas it starts easier. The idle is alright so i guess it could not be the screw on the right side of the carborator. When i look at the throttlehandle, from the lowest rpm to a bit over the startermark, i can see that the throttle roller on the carborator is in the air. It isnt pressed agains the engine until i turn the throttle handle just below half throttle. So my guess is that the lower rpm speeds are only handled by ignition?

If i look at the throttlewire, there is a adjustment screw at the end which i can turn shorter o longer which gives me more or less rpm. Could this be the right one to adjust?
 
I took the boat out for a new trip today and it still works except for some minor issue =). The hard starting and now when the engine was tilted up against the boat for an hour when i stopped for fishing, the engine has no form of idle rpm. If i put the gas handle with no gas the idle rpm is now to low. But if i just start with some more throttle then its no problem. Not at high rpm and not at low.

If anyone has any more suggestions on what to do i will more than happy try them. It feels like i solve one problem and create a new one =)

/Mike
 
A manual is a really good investment. It will show you how to properly synchronize your linkage . I purchased on off ebay for maybe 40 bucks . Covers motors from 3hp -70. Lots of good info. No more guessing
 
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