1988 Evinrude VRO 140 HP help

NZmike

Cadet
Joined
Feb 23, 2010
Messages
11
Ok, where to begin?
I have a 1988 Evinrude VRO 140 HP that starts fine and will run up to about 4500RPM although seems a little week/slugish and takes a while to get the boat out of the hold. Then sometimes after about ten or fifteen minutes I will get a small kick/shudder and the engine will pop into full life. The revs will go up to around 5500rpm and she sounds absolutely perfect. From here if i stop for a fish and restart she will jump out of the hold and run perfectly for most of the day however sometimes after stopping it will go back to acting up and only get to the 4500 slugish RPM. I have tested the compression on all cylinders and these are all fine (within 5psi of each other). I am currently tracing all of the wiring and cleaning all the terminals. But where to go from here I am unsure. I have a manual and am currently working through that however I am waiting on the Flywheel removal tool which is still some weeks away. Any help would be greatly appreciated.
 

jonesg

Admiral
Joined
Feb 22, 2008
Messages
7,198
Re: 1988 Evinrude VRO 140 HP help

Flywheel removal?

I would first find out whether its fuel related or an ignition problem.
Could just be a sticking float in the carbs.

When it acts up punch the choke and see if it bogs down or picks up, the choke will bypass the carbs and inject raw fuel into the intake throats.

Get a spark gap tester and see if it has good spark to each cylinder, set spark gap ay 7/16th inch, you need a strong blue spark.( all plugs out).

My engine does the same and I know what it is but can't remember which carb it was so I'll be rebuilding all 6 carbs come spring.
The older hi-speed jet needles were rubber tipped , I think its sticking on me.
 

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: 1988 Evinrude VRO 140 HP help

You have what sounds like the beginning of an ignition problem. I would recommend that you run with an inductive timing light so that you can "read" each output through the RPM range. The ignition coils tend to fail under load so that initial bench testing may prove unreliable.

It's extremely important that the ignition coils be securely grounded, so it's worth the time to remove them so that you can clean the bases.

Check for arcing around your spark plugs.
 

NZmike

Cadet
Joined
Feb 23, 2010
Messages
11
Re: 1988 Evinrude VRO 140 HP help

Wow!! Thankyou so much for the rapid response.

I have only a few month ago rebuilt all four carbs and this has had nil effect on the problem but I will definately be giving the choke a punch next time I'm out too see if it bogs down or picks up. I take it it is safe to do this at these high revs?

I too am leaning in the direction of some type of electrical or ignition problem. I have during my fault finding thus far removed and cleaned up all four coils replacing one along with two of the leads that were excessively corroded. I have tested that the ignition coils are securely grounded and have installed correct new washers. The resistance on all four coils to ground is around 0.3 ohms with the resistance of the coils being 260 ohms each.

I have tested/checked the sensor coil Resistance with the results being approximately 42.6 ohms between the white and pink/purple/green and blue wires. Book states 40 plus or minus 10 ohms.

I have tested the Sensor coil for a Short to which there is not.

I have tested the Charge coil and the results that I got were 450 ohms where the book states the result should be 560 plus or minus 75 ohms meaning I am out of tolerance??? Could this be my problem???

The charge coil testing for short indicates no Short.

From here I will try and connect the power pack back up and carry out a few voltage checks. Problem is living down in this part of the world parts are so expensive and normally come with long lead times.

Once again thanks so much for your help so far as this problem is so frustrating to pin point as it is so intermitent as to when it occurs.
 

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,398
Re: 1988 Evinrude VRO 140 HP help

Compression
Spark
Fuel delivery
Spark plug condition

Does seem like an intermittent ignition issue from what you describe though.
 

NZmike

Cadet
Joined
Feb 23, 2010
Messages
11
Re: 1988 Evinrude VRO 140 HP help

Hmmmm!!!! Have just now noticed I am not firing on one cylinder.
 
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