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Evinrude 70 HP VRO: Removal of the Oil Reservoir a Good Strategy
|Author||Topic: Evinrude 70 HP VRO: Removal of the Oil Reservoir a Good Strategy|
posted 03-29-2006 10:00 PM ET (US)
I have a seemingly tempermental 1991 Evinrude 70-HP on a Super Sport 15. I use it on weekends from June to September, sometimes skipping a weekend. I have had this rig since 1994. The first few years it ran spotty at low speed. Then I had the VRO pump replaced and it ran reasonably well for about 5 years. Then, last year, the engine started a few times and then wouldn't start. I took it to the same mechanic and he did two things:
--removed the oil reservoir, plugging up the oil intake and had me pre-mix the oil. The logic being with the limited amount of use, the oil would build up in the pump and cylinder walls making for hard starts and poor idling.
--rebuilt the carburetors.
It didn't run right the rest of summer, in that it started with an incredible amount of smoke and it fairly predictably would conk out at low speed when idling while setting up to pull a tuber. It has however, run consistently very well at WOT. I just took it back to the same mechanic so he could straighten it out before the season.
Does anyone have any advice with this particular engine in general?
Does the removal of oil reservoir sound like a good strategy with this particular Evinrude given its use pattern? Thanks - Lou
posted 03-30-2006 09:07 AM ET (US)
The Evinrude 70-HP motor has a very good reputation. It is a classic three-cylinder outboard. There is no reason why it should not be providing good performance for you.
Your frequency of use on a once a week basis is not unusual, and I don't think it should contribute any problems to the motor.
Your motor was probably delivered with the VRO2 oiling system. I do not see any particular advantage to be gained by disconnecting it. I don't recall if that engine used a remote oil reservoir or an under-cowling reservoir. If you had a remote tank, there may be some advantage to eliminating it; it would save some space at the transom of a small boat. And if you run the motor from small 6-gallon or 12-gallon tanks, pre-mixing the fuel is not a terrible chore.
Let's set aside the question of the VRO2 oil system and whether it was a good idea to remove it or not. It is gone. The motor will run without it.
It sounds like your engine needs a good tune up, and maybe a good mechanic. Check the fuel system for any restrictions. Install new spark plugs of the proper type and set them to the specified spark gap. Check the carburetors for proper operation. After 15 years, they made need an overhaul.
posted 03-30-2006 11:49 AM ET (US)
My 1986 70hp three cylinder had similar symptoms: ran fine at speed but just would not idle. After doing all the obvious maintenance items including replacing all the fuel lines under the cowling, rebuilding the fuel pump, electrical tune-up, etc, I finally removed the carbs and brought them into a trusted mechanic to have them rebuilt. It turned out that two of the three carbs had cracked emulsion tubes (these are the tubes that extend down into the carb bowl and actually get the fuel out of the carb and into the business end of the motor). As a result the motor was quite leaned out and would not run properly at low speeds. The mechanic and I tried for several weeks to obtain some replacement carbs (the tubes on that year motor were NOT serviceable items) but to no avail; I finally told him to just reassemble the carbs with the rebuild kits and put it all back together and went off to purchase my 90etec.
Note1: The motor ran better than it had for several years on it's final run to drop off the boat where I had purchased the new motor, and I ALMOST said the heck with the new motor.
Note2: I scrapped the VRO system early in the life of that motor and always ran the gas/oil mix a bit on the rich side; doing that likely prevented the motor from totally self-destructing due to the lean fuel/air ratio.
posted 03-30-2006 12:53 PM ET (US)
As they say in the business .... huh!
posted 03-30-2006 01:02 PM ET (US)
I did not wear a raincoat to work today, and this likely prevented it from raining. You can use that same type of logic to explain all sorts of things that did not happen.
posted 03-30-2006 01:22 PM ET (US)
I would say it is your mechanic. When you rebuild those 70's carbs you can bench set them up but in order to set the idle it needs to be in the water running. This is called a synch & link. Reason is unlike many motors these do NOT have an idle circuit and the only way they idle is the butterflies are almost closed which in a sense is choking the engine to make it idle. Primitive but effective.
posted 03-30-2006 02:24 PM ET (US)
I don't know how long I was running with broken carbs but I WAS having difficulties at low rpm's that were getting to the point that I was considering a new motor almost a year prior to actually purchasing the one I have now. My mech told me the cracked emulsion tubes could definitely cause the low speed problems and as he figured it was creating a lean run condition I figure the extra oil was a plus.
Keep yer raincoat on and carry an umbrella, too; it's making for great early season boating here on LI! Oh, and don't go washing windows or trucks either!
BTW, nnylip, it is very easy to check those carbs for cracked tubes; just drop the bowls (and it is not so hard to pull the carbs or replace and set them back up again). If you need a sanity check I picked up a spare set of carbs (from the forsale forum here) you could borrow if you are in the LI area. (I'll need them back as I intend to put that old 70 back in operation one of these days)
posted 03-31-2006 08:48 AM ET (US)
Thanks Crabby, I am going to take pieces of this discussion to my mechanic and have him check out the carbs. I'm in NYC while the boat is in NJ, so who knows, maybe I'll take you up on your offer!
posted 03-31-2006 08:52 AM ET (US)
BTW, "the Judge", I didn't put all the detail in the story, but my mechanic had the boat between his yard and the lake 1 or 2 times, which, I suppose, is a good sign. That is why I had to bring it back to him, because he said that there was something further he had to do in his shop which couldn't be done on the water. - Lou
posted 04-04-2006 02:32 PM ET (US)
I think Nick "The Judge" has hit the nail on the head again. Your problem is similiar to what I have been experiencing lately. I have an 88 70 Johnson that is having a similar problem as yours. I've had the carbs off and apart several times in the last 3 months. After reading Nick's advise, I rechecked my linkage and found that the center carb linkage was wrong. Corrected idle stalls and stalling when backing down.
posted 04-05-2006 02:58 PM ET (US)
I have a 89 70hp Johnson and I was told by my mechanic the oil pump (VRO) was not working as it should and that it would cost $300 to replace it. I am now mixing my gas. Something he told me about the VRO I found interesting was it is a diaphragm that pumps the oil over time will soon or later get weak. So when do you know it is not working 100%? One thing I know about my motor is it's getting the oil it needs. New to the continuous wave, good stuff. Zimboy
posted 04-05-2006 05:18 PM ET (US)
I wound up showing this thread to my mechanic. He knew about both the carberator tubes and the linkage. He didn't seemed particularly moved by the tube discussion, but he was in heated agreement with getting the linkage right and expounded on several examples. Regarding my boat, he said it was idling fine in the shop and he had to get it back out to the lake. We shall see.
posted 04-05-2006 05:58 PM ET (US)
Good for you on the adjustments. When my mechanic found the broken tubes in my carbs it was the end of July and I was going crazy when we were almost at Labor Day and a set of carbs still had not been located by either of us. I might still have that motor on my rig if I could have gotten it straightened out.
It is not difficult to rebuild the fuel/vro pump, there is an article here in the ref section about it (I believe). I rebuilt the whole gizmo prior to discovering the bum carbs on my motor (not for the vro which I had already bypassed but wondering if the fuel pump was flaky) and start to finish it only took a few hours (including running back and forth to the dealer for odds and ends). But as you know it is easier to just premix and never worry about too little (unless it is YOUR goof!).
posted 06-12-2008 09:22 PM ET (US)
I own a 1988 70 hp vro Evinrude boat motor. I am having problems with fuel pump. [Intend to] convert to regular fuel pump. Will pre mix my own oil.
What is the proper PSI of fuel pump needed to operate [a 1988 Evinrude 70-HP] motor properly?
Information needed ASAP.
posted 06-13-2008 06:51 AM ET (US)
Use an OEM pump and it will deliver the correct fuel pressure. Your 70 will already have the bosses on the block for the pump to mount to.
posted 06-13-2008 09:37 AM ET (US)
The fuel pump in a carburetor motor just lifts fuel from the fuel tank to the carburetor bowls. You only need enough pressure to overcome any suction in the fuel hose and to over come gravity to lift the fuel from the tank.
posted 06-13-2008 04:07 PM ET (US)
[T]hank you for the info[rmation,] but I am loking for the exact PSI required from pump to operate motor proper Evinrude 1988 70 VRO.
posted 06-13-2008 08:08 PM ET (US)
The service manual for my Evinrude motor which has a VRO2 pump specifies that on the hose connection between the output of the pump and the carburetors the pressure of the fuel in PSI should be not less than 3-PSI when the pressure gauge is held level with the VRO hose fitting.
posted 06-13-2008 08:26 PM ET (US)
This old discussion was revived. It has been moved to REPAIRS/MODS.
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