90 hp 1984 Evinrude low power at WOT.

[pegs11]

I've been working on this motor for several months trying to get it to run.

Here is what I know. It used to run pretty good. Rough and not very dependable but it would get the boat up and plane at WOT.


This is what its doing today. It starts really hard, and very cold blooded. Needs lots of choke and seems to lack either the power or rpms or both to get the boat to plane. Yesterday I had it out testing it and went through some weeds. It caused the prop to cavitate and I'm pretty sure the motor went to WOT. I let it run like that for just a couple of seconds to make sure it would stay that way and it did. As soon as I let off the throttle and ran it back up...... same thing. Just acts like it doesn't have enough power to run back up to a high rpm.

I have checked the cylinder pressures and they are all between 105 and 115.

Checked the spark plugs with a gap tester and could jump a good 1/2 inch but not sure about how hot it was.

Checked each spark plug wire with an induction timing light and had spark on all 4

Rebuilt the carbs and replaced all of the jets, gaskets and cleaned them.

I've also replaced the spark plugs and one coil. Its got fresh gas some sea foam and some octane booster in the gas.

Pumping the primer bulb at WOT has little or no effect nor does hitting the choke pump.

I'm going back out today to pull all of the plugs and see what they look like and to double check the cylinder pressures. I'll post back with the latest.

My grandson and I really like this boat so I'm hoping I can get this motor running before the lake freezes.

 

[phillnjack2]

Re: 90 hp 1984 Evinrude low power at WOT.

Have you checked the timing at all ?
and have you got a manual for the engine to show how to do the timing for that particular model engine ?

it could simply be timing if youve never had it run real good and smooth.
and have you cleaned out the fuel pump and pipes from fuel pump to carbs ?these can get messed up.
also take notice of the inside diameter of the fuel tubing everywhere, its common that when people change these they
dont get the correct sizes of pipes and the engine just dont get enough fuel delivery

just a few ideas spring to mind.

phill

 

[pegs11]

Re: 90 hp 1984 Evinrude low power at WOT.

Have you checked the timing at all ?
and have you got a manual for the engine to show how to do the timing for that particular model engine ?

it could simply be timing if youve never had it run real good and smooth.
and have you cleaned out the fuel pump and pipes from fuel pump to carbs ?these can get messed up.
also take notice of the inside diameter of the fuel tubing everywhere, its common that when people change these they
dont get the correct sizes of pipes and the engine just dont get enough fuel delivery

just a few ideas spring to mind.

phill

I just came back in front checking the compression again. If it let it turn over just a little longer the pressures are more like 120 -125.

I double checked the throttle travel too Its maxed out full forward on the throttle lever but the travel on the throttle linkage is full WOT too. Quite a bit of "dead" travel in the beginning, but its still moving the linkage all the way.

I'm going back out now to check the timing. I hadn't done that before, but I do have a Seloc repair manual so we'll see what happens.

 

[pegs11]

Re: 90 hp 1984 Evinrude low power at WOT.

Went out to check the timing with the boat in the lake. Apparently the timing information was on a sticker/decal on the front of the carburetor intake cover but its half gone. I can see a 28 oon the first line and on the second line looks like 3 to 5 BTDC but for what I don't

Also. Started trying to adjust the low speed idle which right now is off the rubber stop a good 3/8 - 1/2

What I'm finding is that if I try to reduce the idle adjustment the motor doesn't seem to want to idle. The lower the rpms go the rougher it runs until it just dies which doesn't take very long.
Seems like the rpms have to be pretty high to keep it running. Makes sense since its so cold blooded too.

It appears the last owner had fudged the throttle using the cable adjustment thats what is holding the idle stop off the bumper. Once I backed that off the cable until the bumper hit the block the engine won't even start.

Going to town to see if the boat shop has a new impeller and some kind of rpm guage

 

[pegs11]

Re: 90 hp 1984 Evinrude low power at WOT.

Anyone have specs and instructions for timing a 90 hp evinrude? I have a Selco manual but its pretty vague and references things this motor doesn't have.

Any information that pertains to electrical checks would be great thanks.

 

[pegs11]

Re: 90 hp 1984 Evinrude low power at WOT.

rotated all the cylinders to TDC and marked the fly wheel. #1 was 180 degrees opposite the timing marks and the other wires didn't match up with the right cylinders. Anyone got any idea what I should do next?

 

[Bosunsmate]

Re: 90 hp 1984 Evinrude low power at WOT.

which cylinder did you mark as cylinder one? Starboard or port, top or bottom?

 

[pegs11]

Re: 90 hp 1984 Evinrude low power at WOT.

which cylinder did you mark as cylinder one? Starboard or port, top or bottom?

standing behind the engine looking forward, the top right.

 

[Bosunsmate]

Re: 90 hp 1984 Evinrude low power at WOT.

Hows the cylinder below it go on timing?

 

[pegs11]

Re: 90 hp 1984 Evinrude low power at WOT.

Hows the cylinder below it go on timing?

none of the cylinders are really close to the timing mark. The closest place is BTDC quite a bit. The next closest place is about a 1/4 of the way past the timing mark

 

[Bosunsmate]

Re: 90 hp 1984 Evinrude low power at WOT.

You could pull the flywheel an check the woodruff key isnt sheared

 

[Bosunsmate]

Re: 90 hp 1984 Evinrude low power at WOT.

Check your timing base magnet on the flywheel and also check the timing base output using this link
I did one the other day its pretty straight forward
ISSUU - CDI Electronics Practical Outboard Ignition Troubleshooting by CDI Electronics

 

[pegs11]

Re: 90 hp 1984 Evinrude low power at WOT.

Thanks I really appreciate the help and links. I won't be able to work on it anymore until tomorrow after noon. I'll pull the fly wheel off and post what I find out.

 

[emdsapmgr]

Re: 90 hp 1984 Evinrude low power at WOT.

You may want to double check the current sync and link setup. If it's off, it won't run right. That procedure is detailed in the factory service manual. You may want to get one-checkout this website: outboardbooks.com

 

[pegs11]

Re: 90 hp 1984 Evinrude low power at WOT.

I'll look into the book emdsapmgr thanks.

 

[pegs11]

Re: 90 hp 1984 Evinrude low power at WOT.

Ok, Pulled the flywheel off this AM. Woodruff key looked good. wiring and stator looked ok. No cracks, no magnets cracked or missing.

What should I check next?

 

[Bosunsmate]

Re: 90 hp 1984 Evinrude low power at WOT.

Check the timing base ohmns
Check the powerpacks are the right serial number

 

[Bosunsmate]

Re: 90 hp 1984 Evinrude low power at WOT.

Your #1 cylinder is 180 off
So closest you have is one quite a bit before BTDC?
and the next is 1/4 way around flywheel ATDC?
So the other must be very far out too?

Are they consistent spark there?

 

[pegs11]

Re: 90 hp 1984 Evinrude low power at WOT.

I will go check the serial numbers . Which wire do I check the ohms on and what should they be?

 

[pegs11]

Re: 90 hp 1984 Evinrude low power at WOT.

As near as I can tell. Yes #1. {The upper right cylinder standing in the back looking forward} fires straight across the fly wheel from where the timing mark is on the pointer. And aside from an intermittent miss I haven't tracked down all 4 are firing. Just not when and where they are supposed to.