Page 1 of 4 1 2 3 4 LastLast
Results 1 to 15 of 59

Thread: Oil injection fuel pump

  1. #1
    Registered User
    Join Date
    Apr 2015
    Location
    Canada
    Posts
    315
    Likes (Given)
    0
    Likes (Received)
    65

    Oil injection fuel pump

    Is this such a thing? If not, why not? How hard would it be to design a fuel pump (either vacuum or electric) to pump a ratio of oil and fuel? We mix fuel and oil by volume, right? Wouldn't a fuel pump that had a two draws, one for fuel (normal sized) and one for oil (50 times smaller) draw a ratio of 50:1 therefore negating the need for a more complicated carb injection system? Obviously the carb injection system is the way to go if your engine has that option, but since mine doesn't, I'm trying to come up with a solution.

    One of the unknowns is; will the ratio stay the same at different power settings (more likely a problem for the vacuum driven pump since the electric would probably just put out a constant 3 psi or whatever)

    Anyway, just a thought that hit me last night. Please discuss.

  2. #2
    Registered User
    Join Date
    Apr 2010
    Location
    Memphis, TN
    Posts
    10,749
    Likes (Given)
    26
    Likes (Received)
    2857

    Re: Oil injection fuel pump

    Rotax uses them on some engines. The question comes on reliability. Some don't like the possibility of the pump malfunctioning so they rather mix. Tons of mopeds have used it to.

  3. #3
    Registered User
    Join Date
    Apr 2015
    Location
    Canada
    Posts
    315
    Likes (Given)
    0
    Likes (Received)
    65

    Re: Oil injection fuel pump

    I don't mean an oil injection kit, but a fuel pump that also pumps oil at the same time, but at a reduced ratio via a smaller port.... or is this really a thing? If so... links?!? I'd love to put one on my plane since the engine on it is not set up for an oil injection kit. (old Bosch ignition 503)

  4. #4
    Registered User
    Join Date
    Sep 2011
    Location
    AMES, IA USA
    Posts
    2,791
    Likes (Given)
    80
    Likes (Received)
    213

    Re: Oil injection fuel pump

    Fuel Pumps also fail. Oil Injection Pumps Fail. People Fail to PreMix right ratio needed, or Fail to even Add the Oil. Easy to solve, use dual Fuel Pumps. Figure out Why the Oil Punmps Fail and make the Upgrade. If you PreMix, have a Check List and pay Attention to what your doing! The Oil Pump failure is the Plastic Gear used, Center Hub.

  5. #5
    Registered User
    Join Date
    Oct 2015
    Location
    Lincolnton, NC USA
    Posts
    117
    Likes (Given)
    80
    Likes (Received)
    15

    Re: Oil injection fuel pump

    I'll happily stick with my pre-mix! That way, I'm the only thing to fail.

  6. #6
    Registered User
    Join Date
    Mar 2008
    Location
    Upper midwest in a house
    Posts
    4,466
    Likes (Given)
    637
    Likes (Received)
    1518

    Re: Oil injection fuel pump

    If you are trying to avoid mixing fuel and oil in a container then pouring it in the fuel tank, perhaps you can come up with a system than injects oil into the fuel tank anytime you refuel?
    Say a manually operated PD pump that draws oil from a reservoir and dispenses ~5oz of oil per actuation of crank or handle?

  7. #7
    Registered User
    Join Date
    Apr 2015
    Location
    Canada
    Posts
    315
    Likes (Given)
    0
    Likes (Received)
    65

    Re: Oil injection fuel pump

    Quote Originally Posted by Armilite View Post
    Fuel Pumps also fail. Oil Injection Pumps Fail. People Fail to PreMix right ratio needed, or Fail to even Add the Oil. Easy to solve, use dual Fuel Pumps. Figure out Why the Oil Punmps Fail and make the Upgrade. If you PreMix, have a Check List and pay Attention to what your doing! The Oil Pump failure is the Plastic Gear used, Center Hub.
    Yes, I get all that. I'm not trying to make a better product, I'm trying to come up with a solution for people who don't have the option for an oil injection system on their engine.

    I understand that a proper oil injection system will regulate the the ratio differently at different RPMs. The solution I'm thinking of won't do this. It will simply mix the gas/oil at 50:1 right at the fuel pump before it hits the carbs. No, this is not an ideal set-up, just one that will allow people who don't have the option of proper oil injection for their engine.

    The benefits of this system will be less than the benefits of a proper oil injection system but there will be benefits nonetheless:
    - pre-mixed gas lasts only 10 or so days before it must be burned (unmixed is easily good for a month)
    - easier to re-fuel away from your home airport
    - any 2-stroke engine will be able to use it

    So, back to the original question; what do you think would be the best way to design a fuel pump that also pumps oil at a pre-set ratio for 2-stroke engines that don't have the option of a proper oil injection kit?

  8. #8
    Registered User
    Join Date
    Apr 2015
    Location
    Canada
    Posts
    315
    Likes (Given)
    0
    Likes (Received)
    65

    Re: Oil injection fuel pump

    Quote Originally Posted by Turd Ferguson View Post
    If you are trying to avoid mixing fuel and oil in a container then pouring it in the fuel tank, perhaps you can come up with a system than injects oil into the fuel tank anytime you refuel?
    Say a manually operated PD pump that draws oil from a reservoir and dispenses ~5oz of oil per actuation of crank or handle?
    That would also make things a bit easier. But if I'm going that far, why not just attach it to the aircraft have it do that for me while I fly? The benefits of the system I have in mind that I'm most concerned with is the fact that the unmixed gas lasts longer (the weather where I live is very volatile and I have wasted many a tank of gas when I simply couldn't get out in time to fly) and the ease of re-fueling away from home where I might not have my mixing apparatus.

  9. #9
    Registered User
    Join Date
    Mar 2008
    Location
    Upper midwest in a house
    Posts
    4,466
    Likes (Given)
    637
    Likes (Received)
    1518

    Re: Oil injection fuel pump

    I see you plan to "T" the fuel and oil line together prior to entering the carb(s) and I think that will be a problem. They won't mix together at that point as you desire. Would ruin your day if a slug of oil blocked or restricted fuel flow. It's just too easy to foul the carbs by mixing at that point that I wouldn't attempt it.

    I think you are underestimating the shelf life of gas and gas/oil mixture. Not a bad thing but if you're going to dispose of pre-mixed fuel because it's >10 days old, just need a system of containers for fresh fuel and old fuel and some transfer pumps.

    Back in another lifetime when I rode pre-mix two-stroke road bikes, they were always refueled at a gas station. Simply carried a container of measured oil in the storage compartment. Pull into a gas station, dump the oil in the gas tank, add the desired amount of gasoline and it was good to go.

  10. #10
    Registered User
    Join Date
    Sep 2011
    Location
    AMES, IA USA
    Posts
    2,791
    Likes (Given)
    80
    Likes (Received)
    213

    Re: Oil injection fuel pump

    Many Multi Millions of 2 Strokes use Oil Injection today successfully, but only a Small Amount are subjected to the Endurance factor of being used on an Airplane. Make that White Plastic Gear, and the White Shaft on the Oil Injection out of a better material and you solve 99.9% of the Oil Injection Failures. Around me when I canvased Airports in 50 mile Radius Circles, only 1 out of 21 even carried Mo Gas. So burn 100LL which has a 5 year shelve life and you don't have to worry about Detonation. Oil Injection Failure on Skidoo/Rotax Sleds is almost unheard of, Why, they Speed up, Slow down, Stop, Speed up, Slow Down, Stop, etc. They are not run at Continious Rpms for hours like on Planes. It's the Center Hub failing on the Gear, shaped like a D.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	s-l1600.jpg 
Views:	48 
Size:	65.2 KB 
ID:	56167   Click image for larger version. 

Name:	ROTAX OIL INJECTION 1.jpg 
Views:	23 
Size:	6.1 KB 
ID:	56168  
    Attached Images Attached Images    

  11. #11
    Registered User
    Join Date
    Sep 2011
    Location
    AMES, IA USA
    Posts
    2,791
    Likes (Given)
    80
    Likes (Received)
    213

    Re: Oil injection fuel pump

    Quote Originally Posted by mmatt View Post
    Yes, I get all that. I'm not trying to make a better product, I'm trying to come up with a solution for people who don't have the option for an oil injection system on their engine.

    I understand that a proper oil injection system will regulate the the ratio differently at different RPMs. The solution I'm thinking of won't do this. It will simply mix the gas/oil at 50:1 right at the fuel pump before it hits the carbs. No, this is not an ideal set-up, just one that will allow people who don't have the option of proper oil injection for their engine.

    The benefits of this system will be less than the benefits of a proper oil injection system but there will be benefits nonetheless:
    - pre-mixed gas lasts only 10 or so days before it must be burned (unmixed is easily good for a month)
    - easier to re-fuel away from your home airport
    - any 2-stroke engine will be able to use it

    So, back to the original question; what do you think would be the best way to design a fuel pump that also pumps oil at a pre-set ratio for 2-stroke engines that don't have the option of a proper oil injection kit?
    A Plastic that can handle more Heat also.

    ================================================== ===============

    Almost all 2 Strokes made today use Oil Injection, and older ones can have it upgraded. Only Weed Wackers have held out. To do what your talking about would take a Computer Controled Electronic Oil Injection. Remember the KISS principle, "Keep it Simple Stupid" lees thing to fail. A Mechanical Oil Injection is the most reliable way. Make the Center part of the gear thicker, or add a Metal Stamped D Hub, or use better Material, or combination of all three. Like the Blue one would be my choice.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	ROTAX OIL INJECTION 5.jpg 
Views:	45 
Size:	64.6 KB 
ID:	56171   Click image for larger version. 

Name:	ROTAX OIL INJECTION 6.jpg 
Views:	17 
Size:	98.2 KB 
ID:	56172   Click image for larger version. 

Name:	ROTAX OIL INJECTION 7.jpg 
Views:	20 
Size:	17.2 KB 
ID:	56173  


  12. #12
    Registered User StarJar's Avatar
    Join Date
    Sep 2011
    Location
    El Centro, California, USA
    Posts
    1,738
    Likes (Given)
    931
    Likes (Received)
    414

    Re: Oil injection fuel pump

    You could put the T or Y near the tank and oil container to give it a couple feet to mix.
    The biggest problem is that it might decide sometime to draw just fuel. The slightest impedance to oil flow would just stop it possibly.

  13. #13
    Registered User
    Join Date
    Sep 2011
    Location
    AMES, IA USA
    Posts
    2,791
    Likes (Given)
    80
    Likes (Received)
    213

    Re: Oil injection fuel pump

    Quote Originally Posted by Turd Ferguson View Post
    I see you plan to "T" the fuel and oil line together prior to entering the carb(s) and I think that will be a problem. They won't mix together at that point as you desire. Would ruin your day if a slug of oil blocked or restricted fuel flow. It's just too easy to foul the carbs by mixing at that point that I wouldn't attempt it.

    I think you are underestimating the shelf life of gas and gas/oil mixture. Not a bad thing but if you're going to dispose of pre-mixed fuel because it's >10 days old, just need a system of containers for fresh fuel and old fuel and some transfer pumps.

    Back in another lifetime when I rode pre-mix two-stroke road bikes, they were always refueled at a gas station. Simply carried a container of measured oil in the storage compartment. Pull into a gas station, dump the oil in the gas tank, add the desired amount of gasoline and it was good to go.
    ================================================== ===========================
    Pump Gas has a 6 month shelf life. But it can loose 2 points in Octane in as little as 2 Weeks. So if you fueled up with 91, and you come back say a week or two later, your not burning 91 Octane now, but 90, maybe 89, and that's Why People have Detonation problems with their Rotax 2 Strokes used in planes. The few engines using lower Compression like 9.6cr, may not suffer from it as soon as the guy using 10.8 to 11.8cr. People who use lower rpm's will have less problems also. That's Why, some Pistons seem to get slowly eaten away, little pits in the Top, and others suffer Piston/Ring Failure all at once!

    Put your favorite Pump gas in a Gas Jar with a lid and set it aside for 6-12 months and watch it slowly change.

  14. #14
    Registered User
    Join Date
    Mar 2008
    Location
    Upper midwest in a house
    Posts
    4,466
    Likes (Given)
    637
    Likes (Received)
    1518

    Re: Oil injection fuel pump

    Quote Originally Posted by Armilite View Post
    Many Multi Millions of 2 Strokes use Oil Injection today successfully, but only a Small Amount are subjected to the Endurance factor of being used on an Airplane. D.
    My Polaris watercraft have a PD gear pump that varies oil delivery with engine speed and throttle position, anywhere between 20:1 to 80:1. None of the parts are plastic and I've never heard of the system failing. Have some pumps that were run ~500 hrs, reinstalled when the engines were rebuilt so are well past that mark now.

  15. #15
    Registered User
    Join Date
    Mar 2008
    Location
    Upper midwest in a house
    Posts
    4,466
    Likes (Given)
    637
    Likes (Received)
    1518

    Re: Oil injection fuel pump

    Quote Originally Posted by StarJar View Post
    You could put the T or Y near the tank and oil container to give it a couple feet to mix.
    The biggest problem is that it might decide sometime to draw just fuel. The slightest impedance to oil flow would just stop it possibly.
    Ya, there's a reason why 2 stroke powerplant companies never did it that way.

Similar Threads

  1. EGT's and fuel injection
    By BobbyZ in forum Volkswagen
    Replies: 4
    Last Post: March 8th, 2016, 12:54 PM
  2. FUEL INJECTION?
    By Armilite in forum General Experimental Aviation Questions
    Replies: 17
    Last Post: October 30th, 2015, 07:55 AM
  3. IO-470VO Injection Fuel Pump
    By Eduardo Fadul in forum Firewall Forward / Props / Fuel system
    Replies: 2
    Last Post: December 28th, 2014, 02:34 PM
  4. Mikuni Fuel Pump: Problems with fuel running up the line
    By bholabhala in forum Firewall Forward / Props / Fuel system
    Replies: 23
    Last Post: September 22nd, 2014, 09:31 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •