1898 Evinrude 120 HP Shakes violently above 2500 RPM's HELP PLEASE

capsnumber1 · #1 June 18th, 2006, 02:14 PM

Hey everyone, Happy Fathers Day to all you fathers out there!!! I have a 1989 120 HP Evinrude 4 cylinder 2 stroke. The engine idles fine and runs fine in both forward and reverse up to about 2500 RPMs As soon as you hit 2500 RPM's the engine starts to violently shake and sputter. It does not stall out but it shakes REALLY Hard so much so that you can feel it through the whole boat. Water pump was replaced earlier this year. Once again the engine runs great until it hits 2500 RPM. It has NGK BPZ8HS-10 spark plugs in it which were replaced earlier this year. I have not run the motor above idle until today so I don't know if it was an issue before the plugs were replaced. I bought it last November. Any suggestions!?!? Thanks in advance everyone!

Walker · #2 June 18th, 2006, 04:49 PM

No alarms sounding?? You motor is going or staying in SLOW mode. And you have the wrong plugs in it. Should be Champion QL77JC4, or QL78C

Does it do this as soon as you put it in the water or only after the motor has warmed up. You need to make sure your motor is not overheating and make sure your heat sensors and alarm is working.

capsnumber1 · #3 June 18th, 2006, 05:02 PM

No, it does this immediately. There is a constant alarm sound that sounds as soon as the key is turned. The engine does not have to even be started before the alarm goes off. It is a solid alarm. The water pump has been replaced and the VRO pump is working because I can see oil in the water when the engine is running in my driveway. At this point I think that the engine went into limp home mode with the previous owners because of the water pump issue. Unfortunately, it seems that it is stuck in this mode. I have been reading on the internet and it seems like the power pack needs to be replaced when this happens. Would a bad power pack leaving the engine in limp home mode continue to make the alarm sound?? Is there a way to test to see if the power pack is the issue?? Thanks!!

Walker · #4 June 18th, 2006, 05:08 PM

Okay, on the port side cylinder head there are 2 wires coming out. A tan one and a white with black stripe. They come out of the heat sensor. Turn the key on and unplug the tan one and see if the alarm stops. If it stops then your heat sensor is bad and if you unplug the other wire the motor should run right. If that fixes your problem please replace the heat senson and don't just run the motor with the wires unplugged.

capsnumber1 · #5 June 18th, 2006, 05:42 PM

Alarm does not stop

capsnumber1 · #6 June 18th, 2006, 05:45 PM

I just went outside and revved the engine up outside of water. The alarm was still sounding. I got it up to over 3000 RPMs with no issue out of water. However, this seemed to be a lower throttle setting than that which it was in the water. I have no idea what is going on!

Walker · #7 June 18th, 2006, 05:50 PM

Unplug the tan wire on the other head. Unplug the wires to the oil tank, unplug the wires to the VRO pump. That should be all the alarm sensors you have. If the alarm still sounds then I suspect the alarm buzzer itself is bad, but that should not affect the SLOW mode. That whitl/bk wire is the sensor wire to the SLOW.

capsnumber1 · #8 June 18th, 2006, 06:08 PM

I have already been through all of that with the alarm. I think that the alarm is bad as well. I was reading elsewhere on the net and people that have had similar problems to mine have been replacing their power pack. If I disconnect the white/black wire from the port side (I don't think there is on on starboard) then the engine should go out of SLOW mode correct??? There are no other wires that would be sending it a signal to go into slow mode are there??

I will disconnect this wire and put the boat in the water tomorrow morning, if it runs without going into slow mode then the temp sensor is the problem. If it still goes into SLOW mode then the powerpack should be the problem. Am I correct in this statement???

Walker · #9 June 18th, 2006, 07:25 PM

I looked it up in my manual and the test for the SLOW system is to run the engine on a test prop or underway in the water and disconnect the tan wire from the temp sensors and ground the harness end to the engine block. The SLOW mode should kick in. Both sensor's tan wires should do it. The wiring schematic does indeed show the tan wires going to a junction and to the powerpack So I guess I was wrong and the tan wires "DO" control the SLOW system.

Tommorow on the water to do it safely, disconnect one tan wire at a time and run your boat. If you find one side disconnected lets your motor run then that side sensor is bad.

Walker · #10 June 18th, 2006, 07:36 PM

After studying the wiring the schematic some more I'd say that a shorted out buzzer will indeed send a ground signal thru the tan wires to the power pack. So you need to disconnect to tan wire from the powerpack bypass that fault.

I'm sorry I steered you wrong in my first post.

cougar1985 · #11 June 19th, 2006, 02:26 AM

dont rev engine up outside of water,disaster awaits!

capsnumber1 · #12 June 19th, 2006, 05:01 AM

I will be out on the water this morning and run the test. If that does not bring the engine out of SLOW mode then I will assume the problem is a defective power pack. I'll let you know how it goes!

capsnumber1 · #13 June 19th, 2006, 07:26 AM

Now the engine shakes and sputters at neutral. When you put it into gear it jolts. The engine then sounds like it is going to stall. It kicks and jolts continuously. Sounds to me like it is starved of fuel or something. Maybe my fuel pump needs replaced?? I am at a loss here and I think it is time for her to go see the doctor.

tashasdaddy · #14 June 19th, 2006, 07:32 AM

make sure your plug wires are in the right place.

capsnumber1 · #15 June 20th, 2006, 09:57 AM

changed the plugs to champion QL16V which is what the local mechanic recommended and put in a new fuel filter. The engine still shakes and sputters a bit while idling and just of idle but it runs like a champ going fast now. Gas was put in last November - with a new tank of fuel the engine will hopefully run better while going slow! Thanks for the help and it looks like problem solved!

Walker · #16 June 20th, 2006, 12:40 PM

So the only thing you actually changed was the plugs?? You might test the reicrculation valves. One or 2 bad ones will give you a rough idle. Could be the idle circuits in the carbs too.

wilde1j · #17 June 20th, 2006, 05:27 PM

Quote:

Originally posted by tashasdaddy:

make sure your plug wires are in the right place.

Have you done this???

capsnumber1 · #18 June 20th, 2006, 06:25 PM

I don't have an owners manual - I assume the wires are supposed to match up by location. The portside upper wire goes to the portside upper plug, portside lower wire goes to portside lower plug - same for starboard side. How do I go about testing those valves and where are they located? Thanks!

wilde1j · #19 June 20th, 2006, 07:34 PM

Find a shop manual to look at. Your motor is running like you have wires crossed plus I assume it ran OK before you changed the plugs.

capsnumber1 · #20 June 21st, 2006, 05:53 AM

I don't know if it ran ok or not because it was the first time I ran the engine since I bought the boat. I left the wires the way they were when I bought it. I will try to find a shop manual so I can make sure.