Premix vs Oil Injection

[labguy]

Hey guys,

I just bought a boat with a 91 Mercury Blackmax 135 and wanted to get you all's input on premix vs oil injection. I have read on here where people have said that my motor has a plastic gear that runs the oil injection system and can fail. I also just read that bypassing the oil injection and premixing can damage the engine in the long run. What do you guys recommend? If oil injection is the best, what type of preventative maintenance can I perform to ensure everything stays in working order? How do I test the alarm system works in the event of a failure? I know I have asked a lot of questions, but this is my first outboard and want to get everything just right before the weather gets hot down here (Alabama) and start skiing and tubing. Thanks again.

Don

 

[j_martin]

Re: Premix vs Oil Injection

If you get 4 or 5 beeps when you turn on the ignition key, and the wires to the reserve oil tank (on the engine) haven't been disconnected, you're covered in the alarm area.

The drive gear on the crank is plastic. Overheat or over rev and time can take them out.

If you run at part throttle, you'll run a lot cleaner and use less oil with the VRO. If the only two throttle positions you know are at the extreme ends of the throw, it won't make much difference.

For the record, I use the VRO on my XR4, and I tend to run it pretty hard. I add about an ounce per gallon of oil to the main fuel tank, and carry two quarts in the spare locker to add to the 27 gallon tank if the alarm should go off when underway. Happened once, turned out to be the oil alert module. (false alarm) Ran a little smokey till I burned off the extra oil. No big deal, repaired with used parts. Missed about 3 casts in the fishing while I dumped the extra oil into the gas tank.

hope it helps
john

 

[labguy]

Re: Premix vs Oil Injection

Yeah, it gives me two beeps when I turn the ignition on. Thats the alarm sounding? Good idea on the extra oil. As obvious as that is, I didn't think of that. Do the shop/service manuals pretty much cover every maintanence/repair on the engine?

 

[Faztbullet]

Re: Premix vs Oil Injection

This is a good oiling system and really not as failure prone as lead to believe, most failures occur after an engine has overheated and gear was softened and damaged. This can fail within day to months later down the road, anytime a customer has had a overheat ,I pull pump and inspect gear with a borescope...

 

[labguy]

Re: Premix vs Oil Injection

Okay, cool. So, if it does fail while out on the water and I add some oil to the fuel tank (even if a little too much), I won't damage the engine (other than maybe fouling a plug or two)?

 

[Faztbullet]

Re: Premix vs Oil Injection

That is correct....

 

[tx1961whaler]

Re: Premix vs Oil Injection

A buddy of mine is paranoid enough that he always mixes his tank at 100:1, even though he has a VRO. He's never had a problem with that engine...

 

[sschefer]

Re: Premix vs Oil Injection

If the pump is set to the marks as described in the manual then yes, the VRO does use less oil at idle. It is thought to be a very reliable system.

Your engine also has a rotational sensor that should trigger the alarm if the pump stops turning. Test your alarm cicuits regularly and you should be able to rely on them in case of pump failure.

I remove my VRO's and all the reasons can be argued so I won't go into them. I will tell you that it makes me feel better not having to worry about it. I run 92 octane fuel at 40:1 and my engine does not load up on me any more than it did with the pump.

 

[grandpaclint]

Re: Premix vs Oil Injection

in 1989 i bought a brand new Bass buggy with a 75 hp Merc. with oil
injection,,,,the oil reservoir was full.

launched the boat, let it idle for awhile, even put oil in the gas as per
instructions,,,,went out cruising,,went to full speed , then 1/2 speed
just for small amounts of time.

went back to full speed,after about 1 minute it slowed down and stopped. finally started, idled back to the dock, loaded the boat, took it to the dealer, left it there,,he said the plastic oil pump had failed, and had to replace the whole top end of the motor.

under warranty,---good

ohhh by the way it took almost a month and 1/2 for the dealer to
repair the motor, this was a major merc dealer in las vegas

i will never own another oil injected outboard.

just my 2 cents

 

[labguy]

Re: Premix vs Oil Injection

in 1989 i bought a brand new Bass buggy with a 75 hp Merc. with oil
injection,,,,the oil reservoir was full.

launched the boat, let it idle for awhile, even put oil in the gas as per
instructions,,,,went out cruising,,went to full speed , then 1/2 speed
just for small amounts of time.

went back to full speed,after about 1 minute it slowed down and stopped. finally started, idled back to the dock, loaded the boat, took it to the dealer, left it there,,he said the plastic oil pump had failed, and had to replace the whole top end of the motor.

under warranty,---good

ohhh by the way it took almost a month and 1/2 for the dealer to
repair the motor, this was a major merc dealer in las vegas

i will never own another oil injected outboard.

just my 2 cents

The alarm didn't sound? Sounds like you had a faulty system to begin with. Man, Im still on the fence on this one...... One school of thought is mine is a 1991 model and still works, which says that its reliable. Another school of thought is mine is a 1991 model and knowing my luck, is on the verge of failure.

 

[j_martin]

Re: Premix vs Oil Injection

The alarm didn't sound? Sounds like you had a faulty system to begin with. Man, Im still on the fence on this one...... One school of thought is mine is a 1991 model and still works, which says that its reliable. Another school of thought is mine is a 1991 model and knowing my luck, is on the verge of failure.

Rigger didn't hook up the buzzer. Test beeps not heard. probably not primed right and pump froze up and sheared the gear.

You can't fix stupid.

 

[achris]

Re: Premix vs Oil Injection

...i will never own another oil injected outboard...

Then I guess you'll never own a new engine.... and very soon you won't have a choice, as ALL newer engines are oil injected. And with each year that passes, those engine become the second hand engines that other people buy....

The right oil injection system is a good one, but like everything else, they need to be looked after....

Chris.........

 

[Dukedog]

Re: Premix vs Oil Injection

This is a good oiling system and really not as failure prone as lead to believe, most failures occur after an engine has overheated and gear was softened and damaged. This can fail within day to months later down the road, anytime a customer has had a overheat ,I pull pump and inspect gear with a borescope...

Got ta agree with Fb on this one and something else they get a bad rap on is tha rpm. Just how many PMax motors ya think are out there (that belong ta tha NORMAL boater) from '94 up still turning up ta 6800 and still going strong. Tha only thing you here is if one craters and tha (performance) rebuilders start hollerin' WOLF. Feel tha same 'bout TOP pinning for NO good reason in a lake motor. Hell, anything can fail on these things for no good reason. If it ain't broke take care of if and it will probably stay that way.....................JMO

Oh, Did I mention tha rebuilders recomend and SELL that stuff.............

 

[Faztbullet]

Re: Premix vs Oil Injection

and very soon you won't have a choice, as ALL newer engines are oil injected. And with each year that passes, those engine become the second hand engines that other people buy....

Thats true and even the late model second hand engines wont allow the customer to do much repair unless the have the CDS or MEDS software to test them. From the rumor I am hearing, the newer engines that are comming out have a extra harness(21 pin if I remember) to allow reprogamming engine for updates and area of usage, A California motor program will be different than Ohio one due to the EPA regluations, and the CDS upgrade is around $1600. Also heard a rumor of more "western lakes" that want to ban 2 stokes and only 4 strokes or electrics.

 

[sschefer]

Re: Premix vs Oil Injection

Also heard a rumor of more "western lakes" that want to ban 2 stokes and only 4 strokes or electrics.

That's very true. In California the law leaves the restriction up to local govt. Remote lakes that are often best for fishing will be the last to go since the local communities rely on the tourism.

With the present economy it's unlikely that anyone willing to travel and spend a buck will be turned away. I don't feel completely safe from the inevitable restrictions but I don't think it will come as soon as it would have if the economy had stayed strong.

 

[labguy]

Re: Premix vs Oil Injection

Also heard a rumor of more "western lakes" that want to ban 2 stokes and only 4 strokes or electrics.

Yet another reason why Im glad I live in the Southeast United States.