How to convert my 1993(?) 70 hp Johnson from oil injection to premix?

Wingeier

Cadet
Joined
Jun 24, 2007
Messages
16
I have a Johnson 70 hp model # J70TLER Serial # 03517453 I was wondering what is involved with bypassing the oil injection and just using premix? Thank you for your time! Any other info on this motor would be great also, is it a good motor, you know stuff like that. Thanks
 

JB

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Mar 25, 2001
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45,907
Re: How to convert my 1993(?) 70 hp Johnson from oil injection to premix?

Check the Engine FAQs for good info on keeping/removing auto-oiling systems, Wingeier.

Good luck. :)
 

noelm

Senior Chief Petty Officer
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Mar 8, 2005
Messages
761
Re: How to convert my 1993(?) 70 hp Johnson from oil injection to premix?

not too sure what you want to hear, but the old 3 cylinder 70HP was/is a very good motor, heaps of them around, had a pair of them on a boat once, they were neglected and never really serviced, but they went for years, and are still going on the boat today (I sold it about 12years ago) and if the oil system is OK why not keep it?? if it is broken, then fix it! simple
 

tashasdaddy

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Nov 11, 2005
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51,019
Re: How to convert my 1993(?) 70 hp Johnson from oil injection to premix?

i'm trying to find an excellant post by Joes Reeves on this subject. edit: here it is:


(VRO Pump Conversion To Straight Fuel Pump)
(J. Reeves)

You can convert the VRO pump into a straight fuel pump, eliminating the oil tank and VRO pump warning system, but retain the overheat warning setup by doing the following:

1 - Cut and plug the oil line at the engine so that the oil side of the VRO pump will not draw air into its system. Trace the wires from the back of the VRO to its rubber plug (electrical plug) and disconnect it.

2 - Trace the two wires from the oil tank to the engine, disconnect those two wires, then remove them and the oil tank.

3 - Mix the 50/1 oil in the proper amount with whatever quantity fuel you have. Disconnect the fuel line at the engine. Pump the fuel primer bulb until fuel exits that hose with the tint of whatever oil you used. Reconnect the fuel hose.

That's it. If you want to test the heat warning system to ease your mind, have the key in the on position, then ground out the tan heat sensor wire that you'll find protruding from the cylinder head. The warning horn should sound off
 

WillyBWright

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Dec 29, 2003
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8,200
Re: How to convert my 1993(?) 70 hp Johnson from oil injection to premix?

Why do you want to do that in the first place? Ary you buying into those absurd old-wives-tales about oil injection failures? After thirty years of doing this, I can tell you that far more motors fail from somebody improperly premixing gas/oil than ever failed from rumored oil injection failures. Even then, the vast majority of so-called oil injection failures had far more to do with water getting into the oil tank than actual mechanical failure of the pump. Without question, catastrophic failure is far more likely due to human factors than mechanical ones. 100:1 is probably a conservative estimate.
 

Wingeier

Cadet
Joined
Jun 24, 2007
Messages
16
Re: How to convert my 1993(?) 70 hp Johnson from oil injection to premix?

Wow, what great information! Thanks everybody. I guess I will keep the injection for now. I was just curious, and wanted to know for future reference if I ever wanted to mix it my-self. Keep up the good work everybody!
 

SawBum

Cadet
Joined
Jul 4, 2007
Messages
24
Re: How to convert my 1993(?) 70 hp Johnson from oil injection to premix?

Why do you want to do that in the first place? Ary you buying into those absurd old-wives-tales about oil injection failures? After thirty years of doing this, I can tell you that far more motors fail from somebody improperly premixing gas/oil than ever failed from rumored oil injection failures. Even then, the vast majority of so-called oil injection failures had far more to do with water getting into the oil tank than actual mechanical failure of the pump. Without question, catastrophic failure is far more likely due to human factors than mechanical ones. 100:1 is probably a conservative estimate.

I do not disagree willy, but, I bought my boat with a 1994 120 evinrude brand new, burned up 3 power heads within 1 year, all under warranty and ALL due to VRO failure. I supposedly have a good pump on there now (after the 3rd power head) but I immediately by passed it. I was tired of failures and was bitten 3 times. I have been having a top end problem for sometime now and posted on here for info on bypassing to make sure I did it right. Ended up finding an air leak which also could of caused a major failure. Do as you wish, I do wish I could trust my VRO and use it again.
Ron
 

mtriverfish

Recruit
Joined
Jun 2, 2007
Messages
3
Re: How to convert my 1993(?) 70 hp Johnson from oil injection to premix?

I have searched these forums and found alot of info on VRO pumps. There seems to be 2 trains of thought. 1 is they work great and you shouldn't mess w/ them. The other is they're faulty or unreliable.

I'm fed up w/ spending $300. to replace them and having the new one only last 10 to 20 hrs. I've checked everything else anyone has suggested and can't find another reason.

How can there be such a vast difference of opinion of these VRO's?

My service manual says the VRO can't lift over 24". All mechanics I've asked about this say that they should pick up much greater distance than that. Any thoughts?
 
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