Logo
FULL SITE MENU

Evinrude 90

S

stevenz

New member
"I have a Evinrude 1987, 90hp

"I have a Evinrude 1987, 90hp
Been having problems with it dying, mechanic replaced power pack,stator,checked carb,new fuel line, now has a miss at around 3500 that we can,t find.
any ideas
Just bought boat and motor a month ago and going mad."
 
"Basics.... Compression should

"Basics.... Compression should be 100+ psi and even on all cylinders. What do you have? Name all cyls and psi.

Spark plugs removed... Spark should jump a 7/16" gap with a strong blue lightning like flame, a real SNAP! Does it?

Be more specific in describing this missing problem. Is it a sharp breakup such as an instant cut in, cut out type miss (ignition), or is it a somewhat slow up and down surge (fuel)? Does it seem like a cylinder stops firing altogether resilting in a drop of rpms, at which it stays, or do the rpms alternate back and forth? Or does the engine have a tendency to die out as the throttle is increased?"
 
"Started off with engine just

"Started off with engine just dying down to rough idle, would sometimes stop but would restart with idle up. Replaced fuel line to tote tank,breather ok, still the same.Mechnic #1 replaced power pack,compression 112 all round, motor run fine for a wee while then rough as guts. Took to Mechanic #2 only running on one bank, fit new stator, old one cracked and bit of melting, just about running fine, then back to rough. Checked carb ok,sometimes starts fine other times needs idle lever up, just keeps alternating good / bad.Sorry if a bit unspecific but on my first outboard engine,diesel engines ok but these i have learn,t more about in a month than i ever knew. Miss occurs as you increase revs,can idle fine, then happen when power on.unsure as to sharp or slow miss but once it losses power it stays off and when you ease off it runs rough, very erratic, the only persistant thing is the problem."
 
"The overheat warning horn sho

"The overheat warning horn should sound when you turn the key on. If it does, fine. If it does not, have the key ON but engine not running. Find the heat sensor TAN wires that protrude out of both cylinder heads. Ground one or both of those TAN wires to the block, at which time the horn should sound immediately. If it does not, find out why as that's the only warning you'll receive if the engine starts to overheat, run low on oil, or have the VRO pump fail.

I'm having a hard time undrstanding exactly what the engine is doing except that you have a power problem when the throttle is increased.

Check the timer base under the flywheel to make sure that it moves smoothly from its idle position to its full throttle full spark position as you increase the throttle. Do this with the engine NOT running. If it sticks at any point, correct that problem.

You may have a restricted/sticking Anti Siphon Valve. See the following:

(Fuel Anti Siphon Valve)
(J. Reeves)

Many of the later OMC V/6 engines incorporate a fuel restriction warning via a vaccum device attached to the powerhead. If the engine overheats, or if you have a fuel restriction, the warning is the same.... a steady constant beep.

NOTE... Only the V/6 & V/8 engines have the above "Fuel Restriction Warning". The warning horn will not sound on the other models.

The fact that a engine is not overheating, but the warning horn sounds off with a constant steady beep, and that the rpms drop drastically would indicate that the engine is starving for fuel due to a fuel restriction. Check the built in fuel tank where the rubber fuel line attaches to the tank fitting. That fitting is in all probability a "Anti Siphon" valve which is notorious for sticking in a semi closed position. It will be aluminum, about 2" long, and the insides of it will consist of a spring, a ball, and a ball seat. If this valve exists, remove it, knock out those inner components which will convert it to a straight through fitting, then re-install it. Hopefully that cures the problem.

The above procedure will cure a restriction problem with the anti siphon valve as stated. BUT, it may also allow fuel to drain backwards to the fuel tank when the engine is not running (siphoning backwards) due to the fact that the carburetors/fuel pump etc are higher than the fuel tank. This condition is not an absolute as the valves in the fuel primer bulb usually prevent this backwards siphoning problem. However.... if this does take place, the cure would be to install a new anti siphon valve.

Also, if you're using any other spark plugs except the following, change them.

Use Champion QL77JC4 plugs, gapped at .040 ."
 
"Thanks,will recheck plugs,mec

"Thanks,will recheck plugs,mechanic checked timing - ok,Should have mentioned engine is V4 VRO
Does this model have alarm,Mech#1 said it was,nt working and Mech #2 said this model doesn,t have one.A mate tried to gorund wire but no noise, where is alarm sited?"
 
"Fire Mech #2 as that engine a

"Fire Mech #2 as that engine absolutely is equipped with an alarm system. If you have a console type control, the horn should be under the dash.

There would be a purple wire from the "A" terminal of the ignition switch to the horn which supplies 12 volts to the horn when the key is in the ON or START position. A TAN wire would connect to a second terminal on the horn which leads to the wiring harness going to the engine. Note that the TAN wire connects to the terminal closest to the built in black ground wire.

If on the other hand, you have a OMC control box whereas the ignition switch, warm up lever, and single throttle/shift lever are incorporated, the horn is also inside that control box.

I strongly suggest that you do not run that engine until you're absolutely sure that the warning system is operating properly."
 
"Yep....

(VRO Horn Warn

"Yep....

(VRO Horn Warnings)
(J. Reeves)

1 - A steady constant beep = Overheating - The V/6 engines, possibly some others, have a fuel restriction warning which is also a steady constant beep.
2 - A beep every 20 or 40 seconds = oil level has dropped to 1/4 tank. (Late model engine = Every 40 seconds)
3 - A beep every other second = VRO failure, air leak in oil line, oil restriction, (anything that would result in a lack of oil being supplied to the engine).

NOTE - If the warning horn is the black plastic (overpriced) three wire type horn, the warning horn should beep once when the ignition key is turned to the ON position. If it does not, it is either faulty or someone has disconnected it (a stupid move!). At any rate, if it does not beep which indicates that the horn is non functional, find out why and do not run the engine until the problem is corrected."
 
Back
Top