I’m really considering deleting the injection system on my 98 EFI. My only concern is most of my fishing is done at no wake lakes. Is there a good way to prevent carbon buildup if I delete the system? Don’t want to buy a new engine for awhile if I don’t need to.
1995 Ranger 487VS / 1998 Mercury 200 EFI
Go with a full synthetic oil.
if mostly idling around, and very seldom at WOT, & if you eliminate the oil injection system, go synthetic & mix it 70:1.
most outboards can run 100:1 mix at all speeds, but outboard manufacturers protect themselves, and say to run 50:1.
Quick Clean. We did this on my Dad's 96 150 EFI.
Bryan McDonough
2023 Nitro Z21 XL
Nitro Team
I would recommend switching to Penzoil XLF which is a great oil for older efi's. It will burn much cleaner than mercury premium plus (if thats what your're using), and leave less carbon buildup. I'd personally be hesitant to mix less than 50:1 because of the hassle if you want to ever get up and run. I'd still mix 50:1 and then make sure you get to run it at a high throttle occasionally.
Colorado State University Bass Team
2000 Viper Cobra 201D, 200 merc efi
Why do you want to delete the oil injection? Read through the Mercury boards...it's a common misconception that failures in the oil injection system are common or that oil injection leads to problems. It's far more common for people to make mistakes in mixing it themselves.
2011 Skeeter ZX225
225 Yamaha HPDI Series 2
Minn Kota Ultrex 112 52"
Console: HDS 16 Carbon
Bow: HDS 12 Carbon, Solix 12 G2, Mega 360, Garmin 106 SV, LVS 34
Best if you leave it alone and just run a fuel additive such as seafoam or some others.
Main thing is to install a new impeller each spring. The drive gear for the oil injection is a nylon gear. If it overheats it will warp the gear, thus no oil is injected.
Last edited by brushsjigs; 02-20-2018 at 05:37 PM.
In the '90's, oil injection was notorious for failure and killed thousands of Mercs because of it. It is NOT a misconception. The last 10 years might be different, but an oil injection system of the '80's and '90's are ticking time bombs, not if, but when it'll fail.Originally Posted by DrewFlu33
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Bullet 20XD w/ 225 ProMax
After a certain point those nylon gears spun at 5500 RPM's are like Russian Roulette. If you're not going to break it down to be able to replace, this is smart. Personally, I too have been considering switching over to the XLF after seeing a few other articles this past Fall. Other than that, let it cough on 50:1 and run it open here and there to let it burn it up.
How long could a person idle before having to run wide open? Then how long would a person have to run wide open? I have about one lake within 30-45 minutes of me that a person can run wide open and it isn’t a very good bass lake so I would like to minimize trips tonit if possible.
1995 Ranger 487VS / 1998 Mercury 200 EFI
Yet somehow there are still thousands and thousands and thousands of the 80s and 90s motors with the original oil injection systems that are beyond old enough to drink plugging along without issue, and the resident Mercury expert on these boards who works on these engines every day and answers questions about them during his spare time says it's best to leave the oil injection alone on them. All it takes to grenade one is to look at a measuring device wrong when mixing it yourself. Personally I'll go ahead with the injection system that's done it flawlessly for 20+ years.
2011 Skeeter ZX225
225 Yamaha HPDI Series 2
Minn Kota Ultrex 112 52"
Console: HDS 16 Carbon
Bow: HDS 12 Carbon, Solix 12 G2, Mega 360, Garmin 106 SV, LVS 34
Do not delete the oil injection!!! Send the fuel injectors out to be cleaned and calibrated every 100-150 hours and the motor will last as long as you need it.
Especially because you intend to idle almost all of the time I would also be inclined to leave your oil injection on, and maintain the system. The only reason I removed my oil injection is because my engine is getting really high on hours now, and I spend a lot of time at very high rpms fishing tournaments and such. It was also recommended to me that I mix xlf at 40:1 for my purposes by a race engine guy. With the way you use your engine, failure of the pump would be extremely rare in my opinion.
Colorado State University Bass Team
2000 Viper Cobra 201D, 200 merc efi
Had an older merc that I had to mix with. Hated and I mean hated doing it. Was always afraid that I'd mix wrongbor forget to.
Dont run full synthetic oil in it's a engine killer for Mercury steel sleeve motor's.
I run Pennzoil Premuim or XLF oil in my motor at 50:1 and Mercury Quickleen product's in every tank's......no problem .
In the summer when i plan on running it hard .I mix and run it @40:1 with know problem . At 6000 rpm, has the oiler removed . Motor is a 1991 2.5 200 carb.
As mentioned by DrewFlu the expert on mercury motors does not recommend deleting the oil injection system on EFI motors. It is a hassle to mix your measured amount of oil to the gas tank when you fill up.
I ran my 1996 Mercury 150hp for 14 years without a problem with oil injection. I did run quickclean and quickcare in every tank of gas.
If your going take oil system out try klotz lubricant technIplate it's what we run in our mercury racing engines out of our shop never had any problems
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