I have been interested in Holley’s Sniper EFI kits for some time but have not had a project where they would apply until now.

I recently purchased a first generations Mitsubishi Montero and want to build it into an overlanding rig. After fixing some of the outstanding issues it was time to focus on making it more reliable by upgrading to EFI.

Installing a Holley Sniper 2300 has been done by a handful of people online but no guide has been written (there is an outline for a guide but it was never updated).

Overview

This is an install guide for a Holley Sniper 2300 onto a 2.6L first generation Mitsubishi Montero. My particular Montero was not completely stock as it already had a Weber carburetor installed and most of the emissions parts had been removed.

Parts

Below are the major parts I bought for the install but there were various things I had on hand that you will also need. (This includes wire, wire connectors, nuts, bolts, washers, tapes, etc.)

Parts	Price	Site
Holley Sniper EFI 2300 (self-tuning master kit)	$1,389.88	Amazon
Holley 350 / 500 to Weber Manifold Adapter Kit	$59.95	Iceperformance
Spectre Performance SPE-2435 Throttle Cable and Bracket Kit	$70.00	Amazon
(2x) EARL’S PERFORMANCE PLUMBING -6 90 Deg. To 3/8 Vapor Guard Hose End	$24.24 (total)	Amazon
Earl’s -6 45 Deg. To 3/8 Vapor Guard Hose End	$19.74	Amazon
(4x) M8-1.25x16mm Socket Cap Screws	$4.00 (total)	Ace Hardware
(2x) M8-1.25x? Bolts	$2.00 (total)	Ace Hardware
Aluminum Sheet (3’x2”x1/8”)	$12.00	Lowes
(2x) T-Bolt Clamps 1.75″	$9.99	Amazon

Guide/Steps

The install should be pretty straight forward but there are some decisions to make mostly about fuel lines. I am planning on running a new line to the EFI but will use one of the old hard lines as a return. The original line that went to the carb was a 5/16” hard line and an even smaller return line. Holley recommends using ⅜” line for both send and return. The send line will run around 60 psi whereas the return line is only about 9 psi. So I think a 5/16” return line should be fine (I guess we will see). I suspect that this size is based on the idea that larger displacement engines need at least that but I’m just using this on a 2.6L 4 cylinder.

Disassembly

Engine bay
1. Begin by disconnecting the battery
2. Then remove all of the fuel lines from the engine bay (including the old fuel filter)
3. Next remove the fuel pump
  1. Be ready with a towel to catch the oil that will spill out of the head
4. Disconnect the throttle cable from the carb
  1. From inside the cab pull the cable
  2. the n remove the remaining mounts and line
5. Finally remove the carburetor

(Note: My Montero had a Weber 38 installed and much of the emissions stuff already removed. My T V cable was also just hanging there without a mount, fun.)

Fuel system
1. Disconnect rubber lines between the tank and the hard lines
  1. You can cut them if you’d like as they wont be reused
2. Remove the fuel sending unit
  1. Be careful as the float likes to come out a specific way that requires some trial and error

Installation

Engine bay
1. Begin by installing the fuel pump block off plate
  1. I chose to make one but you can buy them, I don’t know where which is why I made one

(Note: If someone wanted to be cool they could design block off plates and then share those plans, people could then use those and just send them off to sendcutsend and have them made.)

Then Install the EGR block off plate
1. I also ~~had~~ chose to make one of these
2. Depending on your plate you may need shorter bolts, I know I sure did

Next install the adapter plate
1. Start by installing the 4 bolts to the plate to mount the carb
2. Like I said I had a Weber and it came with an adapter, if you have the original carb then it’s up to you but it still might be easier to buy a Weber adapter and then a Weber to Holley adapter (or make your own I guess).
3. My adapter was great but the mounting bolts were imperial so had to buy metric bolts

Install the Holley Sniper
1. Just set the thing on there for now

Install the throttle cable bracket
1. You’ll need to shorten the mounting screw to avoid it hitting the linkage
2. It’s held in place with the EFI nuts so now you can put all of those on

Finally install the throttle cable
1. Begin inside the cab by enlarging the hole in the sound deadening which will make it easier to install the washer and nut in a few steps
2. You need to be shorten the cable (you’ll only use a few inches) just follow the instructions with the cable
3. If you’re like me you will need to shorten it again, this is to accommodate the linkage and ensure it can open full throttle
4. Attach the cable to the linkage (this piece is not in the kit so you’ll need to get one

Install the return spring and bracket

Transmission cable – tbd
Fuel system

(This is up to you to decide if this is how you want to do it)

I started by modify the fuel sending unit
1. I cut the return hard line down flush with the unit
2. I then drilled it out to fit bulkhead fitting using a step bit
3. I then trimmed the gasket to make room for the bulkhead fitting
4. I had to grind down the internal washer and the nut some to make it all fit nicely
5. Then I installed the fittings
6. I realized I needed a 45 degree fitting for inside the tank to avoid hitting the float arm
7. I then installed the pickup line to that

Install fuel sending
1. Use a 90 degree fitting on the outer side
Install fuel pump
1. I didn’t like most of the mounting locations so I used an existing bolt on the frame rail
2. In the future I’ll be getting a different mount
Run fuel lines
1. Run the line included with the kit by mounting it using clamps to the existing fuel line mounting bolts
Install connect lines to the holley sniper
1. At least one (but two is better) 45 or 90 degree fittings should be used that are not included
2. I also repurposed the fuel filter mount and moved it up to hold the new filter

O2 sensor install
1. First I found a flat section of tub and marked where I’d place the O2 sensor (I held a socket in place while it was installed to ensure it would fit)
2. Then I removed the exhaust section
3. Then drilled out a hole
4. Then found out the clamps included were too big (another amazon order)
5. Then got new clamps installed and reinstalled everything
Temp sensor install
1. Drain some of the coolant from the radiator
2. Remove the thermo valve
3. Slowly install the temp sensor

Wiring
1. 7-Pin Harness
  1. Battery positive
  2. Battery negative
  3. Fuel pump
  4. Coil (-)

Keyed power
1. I used a wire from the old emissions harness (8-pin harness, black with white stripe)

10-Pin Harness
1. I did not install or use this (yet)
O2 Sensor connector
Temp Sensor Connector
Display Connector
1. I ran this through the main wiring harness grommet
First start
1. After connecting everything I turn the key (without starting the engine) and checked for fuel leaks
2. Then I went through the setup wizard (note engine size it cubic inches)
3. The I recycled the key
4. And…it fired but did not start (this issue was I had the coil wire on the positive terminal, should have been on the negative terminal)
5. Take two…it runs!
6. I had a super high idle and to resolve that you need to physically unscrew the idle screw on the EFI
  1. I also installed a throttle return spring (this came with the kit I ordered)

Learnings

If there had been a guide or more information I would have ordered some of the parts I mentioned in advance
1. 90/45 degree Earls fittings
2. An exhaust gasket in advance (this is hard to get quickly)
3. An air filter/housing (does not come with the kit)
4. Throttle bolt (I used the one off of my previous carb)
I would have planned on taking the exhaust section to a shop to have an O2 bung welded in (I will do this later)
The pedal is very linear
The fuel pump is noisy