Holley Sniper EFI for BBD Carbs

[ag4ever]

Good news / bad news. I jumpered the connector to the ignition module, and I am getting crank signal. So good that it is working, bad that the harness connectors are bad. I had to bend the spades that go into the harness connector to get a firm connection.



Next issue is no fuel in the surge tank. I think the in line filter is blocking flow from the mechanical pump. I’m gonna remake the hose without the filter to see if that fixes it.

 

[sxer]

while waiting for the kit to arrive, I did some research and thinking about how to feed fuel to the throttle body. I ended up buying one of these:

View attachment 83629

I like this type of fuel feed since it keeps the pump submerged, the return line to the tank will be adequate since it is returning low pressure fuel from the mechanical pump, and the mechanical pump is pulling fuel from the stank like the stock setup.

I figured this would be a good way to go since it is similar to the fuel feed on my ski boat. Pleasure Craft Marine has utilized what they call the Fuel Control Center “FCC” since they converted to EFI. Mine is an ‘02 version on a Chevy 350 type engine. I’ve never had a lick of trouble from it since new. The FCC also integrates a fuel filter. I had though about buying a FCC and using that, but the FiTech unit looks to be more easily serviced with more standardized parts. The PCM parts are much more expensive since they are intended for a marine environment.

Unless it has changed recently Marine stern drive engines have not had an in tank pump or return line. They have two pumps, a low pressure to pull fuel from the tank and a high pressure in the vapor separator to feed the injectors. Excess fuel is returned to the line from the tank at the engine.

 

[ag4ever]

Unless it has changed recently Marine stern drive engines have not had an in tank pump or return line. They have two pumps, a low pressure to pull fuel from the tank and a high pressure in the vapor separator to feed the injectors. Excess fuel is returned to the line from the tank at the engine.

That is exactly how my ‘02 Nautique is done. Has a low pressure pump to the “fuel control cell” where there is a filter and high pressure pump. In hindsight, I probably should have bought one of those for an all-in-one solution of pump/filter. Plus it is slightly smaller than the FI Tech one.

I might need to eat some crow though. My mechanical pump is not supplying fuel to the surge tank. I tried pulling a vacuum on the line and no fuel. Pulled the supply line to the mechanical pump and pulled a vacuum there and I have fuel. I plan to swap the mechanical pump for a known good one. Sad thing is the mechanical pump was working fine before I started the swap.

 

[sxer]

That is exactly how my ‘02 Nautique is done. Has a low pressure pump to the “fuel control cell” where there is a filter and high pressure pump. In hindsight, I probably should have bought one of those for an all-in-one solution of pump/filter. Plus it is slightly smaller than the FI Tech one.

I might need to eat some crow though. My mechanical pump is not supplying fuel to the surge tank. I tried pulling a vacuum on the line and no fuel. Pulled the supply line to the mechanical pump and pulled a vacuum there and I have fuel. I plan to swap the mechanical pump for a known good one. Sad thing is the mechanical pump was working fine before I started the swap.

Is the vacuum high like a
restriction? Maybe you could find a used Marine low pressure electric pump.

 

[ag4ever]

Is the vacuum high like a
restriction? Maybe you could find a used Marine low pressure electric pump.

No, vacuum did not register on the gauge when I pulled on the feed to the mechanical pump. I was able to pull a pint or two out of the tank using a catch can with a small vacuum pump.

 

[sxer]

That is exactly how my ‘02 Nautique is done. Has a low pressure pump to the “fuel control cell” where there is a filter and high pressure pump. In hindsight, I probably should have bought one of those for an all-in-one solution of pump/filter. Plus it is slightly smaller than the FI Tech one.

I might need to eat some crow though. My mechanical pump is not supplying fuel to the surge tank. I tried pulling a vacuum on the line and no fuel. Pulled the supply line to the mechanical pump and pulled a vacuum there and I have fuel. I plan to swap the mechanical pump for a known good one. Sad thing is the mechanical pump was working fine before I started the swap.

A Marine system would be pretty easy. All electronics are on the engine. All you have to provide is switched power and start signal to the solenoid. And a fuel supply. Senders for for oil pressure and water temp are part of the harness between dash and engine.

 

[sxer]

No, vacuum did not register on the gauge when I pulled on the feed to the mechanical pump. I was able to pull a pint or two out of the tank using a catch

No, vacuum did not register on the gauge when I pulled on the feed to the mechanical pump. I was able to pull a pint or two out of the tank using a catch can with a small vacuum pump.

How about when you pull on the pressure side of the pump?

 

[ag4ever]

How about when you pull on the pressure side of the pump?

No flow, don’t remember if it held vacuum. The line from the pump to the surge tank is clear. I need to verify the return to the tank.

Before I started the swap, the fuel pump worked and flowed a couple pints into a catch can when I pulled the line from the carb. Also, the engine was running when I drove it into the garage just before starting the swap.

 

[ag4ever]

Replaced the mechanical fuel pump.



Primed the fuel system and ...



But, now I have a seeping fitting on the surge tank.



The power feed pass thru is seeping fuel. Gotta pull the top off the surge tank to see what the issue is. I fear I tightened it too much and cracked the seal.

 

[ag4ever]

I will say it is amazing how good it runs. Neither of my Jeeps have ever run that smooth and with this much throttle response. It is impressively responsive.

Now I need to fix the transmission. I have a feeling it needs a complete rebuild, but before I do that I plan to diagnose it with this:





My Father’s Day present this year. Funny thing is I never asked for it. Guess my family just knew what was needed next. I have the best family (for a bunch of reasons)!

 

[ag4ever]

To do list for completing the install:

Replace the harness connectors to the ignition module.

Fix the seeping fuel pump power feed.

Reinstall ignition module and coolant overflow.

Check vacuum hoses and determine why I am at 1,700 rpm idle with a 0% iac setting. (Have a feeling I am getting too much vacuum flow on a “manifold” line.)

Top off engine coolant.

 

[ag4ever]

Fuel leak fixed. Opened the surge tank, tightened the terminal, closed it up. Took about 5 minutes. Much easier than dropping a tank.

 

[ag4ever]

Small update, I have not had a chance to actually drive it yet. Mainly due to the faulty ignition module wiring. I ordered new ignition module plugs, and got these in the mail today.



Hopefully these will fix my wiring issue when I splice them into the harness. Not thrilled to be cutting the factory ends off, but they are not working, so I guess it is not a huge loss.

One issue is the gauge of the new wires don’t match the harness wire gauges for some.

That, and the two wire plug has 4 wires coming from it. 2 in one spot and an extra 3rd that is not used in this application.

 

[zdatjeep]

Hi, thank you for your post.
Does the Holley allow you to look up fuel and ignition tables that are stored in the system (rpm vs load etc)?
I was wondering what kind of AFR you are seeing ? at idle , cruise and wide open throttle.
I am in the middle of tuning a standalone system, its a tbi set up and fully programmable ignition (Megasquirt2). I have been working on in my free time for a couple of years and finally getting around to fine tuning. I think I built a good ignition advance curve for it, now I have been working on target AFRs. After a couple of days of experimenting I just figured the manifold is so inefficient I started thinking like a carburetor, It seems to like rich afrs all around, more so than a more modern system. So after a couple of runs today targeting a 12.5 AFR I am starting to get somewhere. When I tried to set leaner cruise AFR she did not respond well so I am still experimenting.
You have benefited from the Holley Sniper setup having all that preprogrammed for you.

 

[tower210]

Hi, thank you for your post.
Does the Holley allow you to look up fuel and ignition tables that are stored in the system (rpm vs load etc)?
I was wondering what kind of AFR you are seeing ? at idle , cruise and wide open throttle.
I am in the middle of tuning a standalone system, its a tbi set up and fully programmable ignition (Megasquirt2). I have been working on in my free time for a couple of years and finally getting around to fine tuning. I think I built a good ignition advance curve for it, now I have been working on target AFRs. After a couple of days of experimenting I just figured the manifold is so inefficient I started thinking like a carburetor, It seems to like rich afrs all around, more so than a more modern system. So after a couple of runs today targeting a 12.5 AFR I am starting to get somewhere. When I tried to set leaner cruise AFR she did not respond well so I am still experimenting.
You have benefited from the Holley Sniper setup having all that preprogrammed for you.

By "didn't respond so well"; what do you mean?

 

[GreatCJ8]

What is the general consensus on intake manifolds for the sniper kits? I can choose since I currently don't have one. I sold it and my mc2100 together when I was about to go fi, years ago. Then we moved and have been without a garage ever since

 

[ag4ever]

Hi, thank you for your post.
Does the Holley allow you to look up fuel and ignition tables that are stored in the system (rpm vs load etc)?
I was wondering what kind of AFR you are seeing ? at idle , cruise and wide open throttle.
I am in the middle of tuning a standalone system, its a tbi set up and fully programmable ignition (Megasquirt2). I have been working on in my free time for a couple of years and finally getting around to fine tuning. I think I built a good ignition advance curve for it, now I have been working on target AFRs. After a couple of days of experimenting I just figured the manifold is so inefficient I started thinking like a carburetor, It seems to like rich afrs all around, more so than a more modern system. So after a couple of runs today targeting a 12.5 AFR I am starting to get somewhere. When I tried to set leaner cruise AFR she did not respond well so I am still experimenting.
You have benefited from the Holley Sniper setup having all that preprogrammed for you.

The sniper does allow you to go into the tables and make modifications. It also “self” tunes based on target AFR.

I have not had a chance to drive it around due to my ignition issues. The replacement plugs are still not working.

I also have been having a very lean AFR at idle, I think I have a vacuum leak that needs to be fixed preventing the throttle body from accurately measuring the airflow and controlling it.

 

[zdatjeep]

By "didn't respond so well"; what do you mean?

By did not respond so well is that this motor likes to run a lot of fuel, if trying to lean out it starts to buck, it likes it rich, I had to target a 12.5 afr at cruise so its a flat afr range, typically one might get 13.5-14.5 at cruise for efficiency, . At WOT I have not yet experimented to see what develops the most power, it is not like the old iron head is a power horse so I am basically going to look for efficiency. The EFI has no problem developing power, I can get it to run much better than a carb and it actually use more fuel than a carb. So far my challenge is finding the best lean range the motor can tolerate.

This is a very generic table:



I tried something like this below and the Jeep did not like the low AFRs at less than 60% fuel load.
What I have circled are what the motor most often uses.
The idle zone on the Jeep motor is basically the 6 lower left boxes and then the rest of the table is utilize as one accelerates through the RPM and load ranges.
I am now running a flat table with 12.5 across the board except at idle I am about 13.0.
I have since narrowed my table down to 4000 RPM to gain some resolution, I plan on starting with my 12.5 afr based tune and making small adjustments to gain best lean cruise, then experimenting with the WOT.

I am basically looking to see if someone with a known good running system knows what their AFRs look like on a similar set up, same cylinder head/ manifold etc.
Cruising at 1500-2000 RPM WOT from 3-4000 is what I am looking for to get an idea of what has worked best for others.

 

[zdatjeep]

The sniper does allow you to go into the tables and make modifications. It also “self” tunes based on target AFR.

I have not had a chance to drive it around due to my ignition issues. The replacement plugs are still not working.

I also have been having a very lean AFR at idle, I think I have a vacuum leak that needs to be fixed preventing the throttle body from accurately measuring the airflow and controlling it.

Yeah you definitely need to fix any vacuum leaks. I run a MAP based system and that was one of my hiccups as I found the PCV system was not tightened down and it was no fun as the leak got bigger and bigger eventually the system could not compensate but initially it did provide more fuel so overall it was amazing that it was able to run with what ended up being a giant leak.
I do wonder how generic your Holley AFR table will be, if its not dialed in for your motor you will have to make the adjustments and learn what works best.

 

[zdatjeep]

Yeah you definitely need to fix any vacuum leaks. I run a MAP based system and that was one of my hiccups as I found the PCV system was not tightened down and it was no fun as the leak got bigger and bigger eventually the system could not compensate but initially it did provide more fuel so overall it was amazing that it was able to run with what ended up being a giant leak.
I do wonder how generic your Holley AFR table will be, if its not dialed in for your motor you will have to make the adjustments and learn what works best.

And also by letting the system self tune it is basically trying to ahieve the AFR you have set by altering another set of tables that meter the fuel at any given point. If you let your system learn while you have a leak you will have to start all over when you fix your leak. Ask me how I know!