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1988 120HP V4 VRO Problem

D

dame

New member
2 years ago my 1988 120hp v4 vro packed in with a busted power pack, I recently replaced this along with a set of spark plugs and ran the engine. The engine ran a little smokey but otherwise ok. I took it out onto the water and found I can only get 1/4 throttle around 8 knots max. I have checked all fuel lines, throttle linkages and wiring all ok, the only thing im not sure about is the oil I noticed dripping from the air intake box after switching engine off. Any ideas where I can start with my problem?
 
Re: 120HP V4 VRO Problem

Assuming that you have compression and proper spark on all cylinders.... have you checked?

Drain all four of the carburetor float chambers to see if a heavy "oil" concentration exists in any of them. If so, suspect a fuel restriction between the VRO pump and the fuel supply. A fuel restriction would of course result in a lack of gasoline reaching the VRO.... BUT.... the VRO would continue to pump oil which in a very short time would overcome the gasoline within the carburetors..... and raw oil does not flow well thru those carburetor passageways. This may not be your problem but it's an area that you do not want to overlook.

The most common fuel restriction follows:

(Fuel Anti Siphon Valve)
(J. Reeves)

Many of the later OMC V/6 engines incorporate a fuel restriction warning via a vacuum 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.
 
Re: 120HP V4 VRO Problem

Hi and thanks for the advice, compression and spark are both good. I removed the large screws and drained the float chambers into a cup, no heavy oil or any dirt. The fuel line does not have an anti siphon device and i have removed and cleaned all lines right down into the tank sender unti. Im thinking along the lines of a fault with the choke system... but not sure how it works properly.
 
Re: 120HP V4 VRO Problem

(Fuel Primer Solenoid Function)
(J. Reeves)

The RED lever...... The normal operating/running position is to have that red lever positioned over top of the solenoid and aimed at the other end of the solenoid, gently turned to its stop. This is the normal/automatic mode position. Pushing the key in opens the valve within the solenoid allowing fuel to pass thru it in order to prime and start the engine. Looking upon this solenoid as a electric choke results in a better understanding of it.

Having that red lever turned in the opposite direction, facing away from the solenoid, allows fuel to flow thru it to the crankcase area. One would only turn the red lever to this position in a case where the battery might go dead and the engine had to be started via the rope pull method. Look upon putting the red lever in this position as moving a choke lever on a choke equipped engine to the full closed position. Either one would supply fuel to the crankcase/engine for starting purposes BUT if left in that position while running would flood the engine.

The later model primer solenoids are equipped with a schrader valve, used for attaching a pressurized can of fogging oil etc, available at your local dealership with complete instructions.

Pumping the fuel primer bulb up hard fills the carburetor float chambers of course, but that process also applies fuel pressure to the primer solenoid.
The two small hoses leading from the primer solenoid branch off via tees to each fuel manifold section that would feed fuel to the individual cylinders.
Pushing the key in activates the primer solenoid to allow fuel to flow thru it to the intake manifold passageways. Cranking the engine over causes the fuel pump to engage which in turn sends fuel pulses to the primer solenoid via the 3/8" fuel hose.
Some engines incorporates the "Fast Start" feature which automatically advances the spark electronically so no advance of the throttle is required for starting.
Engines that do not have the "Fast Start" feature will be required to have the throttle advanced slightly.
Starting procedure: pump fuel bulb up hard, crank engine and push the key in at the same time. When the engine fires/starts, release the key so that it falls back to the run position.
Bottom line..... Look upon the primer solenoid as an electric choke.
 
Re: 120HP V4 VRO Problem

Run my 120 vro full throttle is fine then go back to just putting around, when I try to go to full throttle, bogs down and will not speed up. After waiting a bit will correct and run again. Checked wiring, no loose connections, pulled plugs, were wet and gap way wide so regapped them to .030 but have not had a chance to run it. Any ideas?
 
Your #1 post states that your powerpack went south 2 years ago and you just recently got around to replacing it, meaning that your engine has sat for 2 years. Sitting for that length of time, your carburetors, especially the high speed jets are most likely fouled, gummed, clogged.... needing a good cleaning/rebuilding.
 
Had a similar symptom happen to me today, seemed ok at low rpm then wouldn't get up and go. Turned out that when I removed the spark plugs to check them the coil in the boot of the spark plug lead had turned. This gave me a bad connection that only showed itself when I opened the throttle.
 
I have a 1990 120 hp Evinrude VRO outboard. New fuel lines, filter and fuel. Runs great, can get 5500 rpm top end until it has run for a while, then it falls on it's face. Can barely get 2500-3000 rpm. Spits, sputters, misses, whatever you want to call it. Let it cool off and it runs fine again. Suggestions please?
 
Some component in the electronics is more than likely breaking down from heating up,CDI electronics.com will have troubleshooting procedures
 
It runs great until it warms up then the rpms drop off to 3000 max but it comes and goes, the rpms will ramp from 3000 to maximum and back and forth. Guess it's going in the shop.
 
indian laker said:
It runs great until it warms up then the rpms drop off to 3000 max but it comes and goes, the rpms will ramp from 3000 to maximum and back and forth. Guess it's going in the shop.
Click to expand...

That sounds like a fuel restriction....

(Fuel Anti Siphon Valve)
(J. Reeves)

Many of the later OMC V/6 engines incorporate a fuel restriction warning via a vacuum 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.

NOTE: There has been cases when the output valve in the fuel primer bulb would come apart, and the inner portion of the valve would actually reverse itself and be drawn back into the primer bulb's output valve body. This in effect would create a shut off valve and result in a fuel restriction. If this is the case, you should be able to feel something laying in the bottom of the primer bulb when held horizontally.
 
indian laker said:
It runs great until it warms up then the rpms drop off to 3000 max but it comes and goes, the rpms will ramp from 3000 to maximum and back and forth. Guess it's going in the shop.
Click to expand...

I had same issue. I went through everything. Turned out bowls were warped. Rebuild and new bowls runs great.
 
Post is actually 11 years old (2010), revived somehow in 2017 temporarily..... Old Post !

Start a new post/thread Csummjr so that it'll be at the top of the stack under your own name and title for all to see. As it is... it's pretty well buried.
 
My 120 v4 vro has a buzzing coming from the control box. It's not constant mainly only does at low speed. Motor will run sweet for about 45mins to hr then just dies and cons out. Any advise or someone who has had this problem and know the fix would be appreciated.
 
Cheeby,
It's usually best to start your own thread. However, that buzzing is quite likely your warning horn that is just weak with age. You need to locate the horn and verify its operation. On these motors a constant horn is an overheat warning, so you need to verify the integrity of your water pump, check your thermostats, and possibly remove the heads to inspect your deflectors. A mother that just dies after 45 minutes means there is a significant problem and you should not run the engine until this is solved.

KJ
 
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