KillerRons - James Monroe
KillerRons - James Monroe





Congratulations on your acquisition of a Ron’s Fuel Injection system.  When calibrated, maintained and used properly these systems will provide you with great consistency and many years of trouble free performance.  We at KillerRONS.COM have put together a list of things all new users should know based upon the most common inquiries we receive.  We have done this in an effort to make your transition into the mechanical fuel injection world a little easier.  If after reading this you have any questions, please feel free to let us know, we are glad to help.

Far and away the biggest issue with mechanical fuel injection system installations is improper fuel cell design or utilization.  New users simply do not understand the importance of the fuel cell in the function of the system.  The fuel cell is much more than a place to store fuel before it is delivered to the engine.  With the design of these systems the pump pulls fuel very quickly out of the cell and delivers it to the barrel valve.  At the barrel valve a portion of the fuel (amount depending upon throttle position) is immediately forced to the engine under pressure.  The unneeded fuel is returned very quickly back into the fuel cell.  This cycle is repeated constantly at a high rate of speed so there is a lot of turbulence and pressure changes in the cell.  Due to this it is imperative that the cell construction and plumbing be scrutinized as much as a proper tune-up would be.  The first thing that needs to be done is to remove all media from the cell.  The mechanical pumps used in these systems have a very strong suction ability and when the fuel level gets too low there is a chance that the media will be sucked into the inlet of the feed hose causing a hard to find restriction.  In drag racing applications the fuel cell or surge tank needs to be mounted in front of the engine with the feed hose for the fuel pump facing the rear of the car.  This is done so that when the vehicle launches the fuel in the cell rushes towards the outlet and ultimately the fuel pump.  We have seen many instances where either the user had a rear mounted cell or, with a front mounted cell, the outlet for the feed hose was placed on the side of the cell and/or the feed hose went forward out of the fuel cell before it is directed towards the pump.  A simple way to think about this is to never ask the fuel to outrun the car as it is accelerating.  For most mechanical fuel injection units a minimum of three gallon capacity is recommended.  We at KillerRONS.COM prefer a four gallon capacity in most applications because we believe that at no time should the fuel level drop to much less than half-empty.  We are aware that many users may have fuel cells that are smaller than three gallon with no issues, this is a general rule of thumb.  The fuel cell must be vented and that vent working properly.  Although many use them we discourage roll-over valves, filters and hoses with loops or coils in them.  The best vent is a simple hose coming out of the top of the cell and directed down towards the bottom of the vehicle.  If a rollover valve is being used then a -8AN size should be used and monitored frequently. Otherwise, a -6AN OPEN fitting will suffice in most cases.  Non-vented or poorly vented fuel cells are the #1 cause of fuel injection system issues, period.  Other fuel injection technicians may disagree with this but KillerRONS.COM prefers all bypassed, low pressure fuel (main return, hi-speed return, idle bypass, etc.) have a dedicated return directly back into the top of the fuel cell.  Shared return hoses can create turbulence and resistance on one or both of the bypasses and not allow them to return fuel as efficiently as possible.  Also all returns should dump fuel back into the top of the fuel cell as far away from the outlet as possible.  Under no circumstances should a non-aeration tube be used within the fuel cell or return hoses be plumbed into the side of a fuel cell below the fuel level.


The stance at KillerRONS.COM is to only use fuel filters made by fuel injection companies. There are many high quality filters on the market but not all have the correct micron screen or element area to work correctly with mechanical injection.  As discussed above your fuel system moves a large amount of fuel in a short amount of time and any restriction from a filter used beyond its intended capacity can cause problems.  If you are unsure what filter you have then you should buy one that is meant to be used with mechanical injection.  In most cases we prefer that you utilize one filter in the suction hose between the fuel cell and fuel pump.  There are instances (with the use of a vane style pump) that a filter should also be used in the pressure hose between the pump and barrel valve.  Under no circumstances should you install a filter in a bypass hose.  This can cause a restriction in the returned fuel as mentioned above.  Check your filter before you go to the track the first time after you have had the engine running at home.  When new systems are built there can be many small pieces of loose debris that are pushed through the system the first time it is started and pressure is built up.


Clogged nozzle jets are rarely a problem with established systems although it can sometimes become an issue in newly installed systems.  The reason for this is that when new hoses are made even the most cautious assemblers leave behind residue and debris that is downstream from the filter.  It is highly recommended to check your nozzle jets for obstructions after the first couple start-ups and also after the first pass.  Often times the high pressure built up during initial use can dislodge a small piece of rubber and clog a nozzle jet.  If your system runs badly at the initial start-up or first outing this is the first thing a KillerRONS.COM technician is going to ask you to check.


If a system is stored for an extended amount of time it is good practice to lubricate the inner o-rings within your barrel valve.  This is done by removing the inlet hose and spraying a liberal amount of WD-40 into the barrel valve.  Once this is done work the shutoff and throttle levers open and closed several times and then spray more lubricant into the valve and give it as much time as possible to penetrate the o-ring material.  This will ensure that your sealing o-rings are lubricated and they seal properly when fuel pressure is introduced into the valve.  If you have a barrel valve that is already leaking you can still do the above procedure and let it sit for a few hours or overnight if possible.  Often times there is nothing wrong with o-rings short of needing this lubrication.  If this does not fix the problem you will need to call the manufacturer at 800-513-3835 and request an o-ring kit for your barrel valve.  They will need to know what make of barrel valve you have so that you receive the proper kit.  They are most easily differentiated by the color of valve (black, purple and gray).  Once you receive the kit click on to see detailed instructions for rebuilding your barrel valve.


If you purchased a used system or have been adjusting on the barrel valve turnbuckle without enough knowledge to make proper adjustments it is possible to get it set in a bad place. This can cause many problems ranging from excessive fuel usage, contaminated oil, harder than normal starting, a hesitation in throttle response and even poor full throttle performance. We get many calls from persons wanting to know what leakage to set their barrel valve to. That can be a potentially difficult question to answer because of so many different leak down testers being available.  With this in mind the KillerRONS technicians are reluctant to give a recommendation unless you have a Ron's Fuel Injection leak down tester. That said, every brand leak down tester is still a great tool for measuring the leak down AFTER the system is running correctly. A good starting point for the barrel valve can be achieved visually and with a feeler’s gauge. First thing is to check/set the throttle blade gaps. For a Flying Toilet set the blade gap at .010-.012” and for a single Terminator set the blade gaps to .008-.010”.  Once this is done look at the position of the screwdriver slot that is cut into the end of the barrel valve spool. If the barrel valve is a new style (gray #3014A) the slot should be perfectly straight up and down (vertical) or just very slightly left of that.  The #33 stamped next to the slot should be on the right side of the slot. If it is to the left the barrel valve spool is installed 180 degrees out.  If the barrel valve is an older model (black or purple) then screwdriver slot should be more noticeably left of vertical.  If you imagine the slot to be the hour hand of a clock the slot should be approximately 11:00-11:30 and, once again, the stamped number to the right of the slot.  It bears mentioning again, with the older model barrel valves (black or purple) the slot is noticeably left of 12:00 compared to the newer style barrel valves. From this point the engine should start, idle and RPM cleanly without hesitation. If the idle is a little low when first running the engine open your blade gap slightly.  Conversely, if the idle is a little too fast close your blade gap slightly. If more than a small blade gap adjustment is needed you may need to alter the position of your spool index mark to make the barrel valve (idle mixture) richer or leaner.  Lengthening the barrel valve turnbuckle (rotating the spool clockwise) will lean the mixture; raising the RPM.  Shortening the barrel valve turnbuckle (rotating the spool counter-clockwise) will richen the mixture; lowering RPM.  Only small changes will need to be made to the blade gap and/or idle mixture.  If you need to move the blade gap more than a couple thousandths or the idle mixture more than a few flats please contact a KillerRONS.COM technician for further guidance.  When making these adjustments shoot for around 1700-1800 RPM in park or neutral with a warm engine (150 degrees water temperature minimum).  Remember it will drop 300-500 RPM when put into gear with a torque converter equipped vehicle.  Mechanically injected cars don’t like to idle much below 1,000-1,100 RPM in gear.  Most users utilize 1,300-1,400 RPM for best results.

It is absolutely unacceptable to have or expect to have contaminated oil in your engine.  If you are experiencing this it needs to be addressed immediately.  There are two criteria to be met that will ensure your oil is as pure as possible at all times.  The first being the idle mixture set properly as discussed above (not too rich).  The second being proper use of the shutoff cable.  If your system did not come with a shutoff cable please call a KillerRONS.COM technician and order one.  It is extremely important in the proper use of your system every time you start the engine.  Of course the fuel should be fully ON when starting the engine but once the engine is running the cable needs to be manipulated.  The simplest way to state this is if the engine is running and you are not preparing for wide open throttle the cable should be pulled until you hear the engine RPM's tweaking up close to or above 2,000 RPM.  Many experienced users are adept at getting up to 2,200-2,500 RPM without stalling the engine.  This ensures that the engine is on the lean side and only getting the fuel it needs to run.  This should be done while you are warming the engine for the day as well as driving to and from the competition course.  In a drag racing application, agood policy after each pass is to see how much temperature you can gain before getting back to your pit area.  This will minimize the idle time building heat in preparation for the next pass.  It will also save fuel and your oil will look great.  If you can reach 170-180 degrees by the time you are back at your trailer most, if not all, of the moisture that is present will be eliminated from the oil.  It is also good practice at the end of each race day to remove your header evacuation assemblies from the valve covers or, with the use of a vacuum pump, remove the suction hose from the valve cover.  This will allow the trapped moisture to escape from the engine as it slowly cools down.  If you forget to do this it is a good idea during the week to remove your valve covers and wipe the “sludge” out of them with paper towels.  If you follow the shutoff cable recommendations your oil will last as long as it would in a gasoline burning engine.

If the above information does not help you achieve great results your system may not have the correct parts for your application or they may not be working properly.  If this is the case, you may need individualized help to sort it out.  If you purchased the system directly from KillerRONS.COM contact either James Monroe or Scott Offer
mann as they will already have your combination and fuel system information on file.  If you did not purchase from KillerRONS.COM directly please visit and fill out the questionnaire.  You will receive a response within hours in most cases.  It will never be more than 24 hours before a response.  If it is longer than that please call and make sure that we received it.


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KillerRons - James Monroe