Converting to MSD atomic EFI

[HawK5]

Hey Guys,
A little background for context before I get into my plans: I just completed a 3 day long off road excursion in Washington, whenever the truck was at 45° angle or more, the carb would starve and the engine would not stay running without gas pedal. If it died I lost PS and PB which made for some hairy backward descents down long technical hill climbs, being a manual made it more tricky, lots of 3 pedals with 2 feet stuff.. Have the Holley Truck Avenger 650 on a Jegs 300hp 350, sm465. The carb probably needs a rebuild and tune, but for the cost of that, to still have starvation issues, I figured I’d consider going to Fuel Injection..
I just bought a barely used MSD atomic EFI, has the TBI, Computer and controller, but I am missing the wide band O2 sensor and fuel pump. The O2 sensor is only $150ish, NBD, however I was shocked to see the fuel pump, filter, line and clamp are $700?!?! And that’s for a return less system, even more for return style.. Now everything I’ve read here and across the web says to run a return style with pump in the tank, so I’m wondering if there’s a lower cost alternative fuel pump option. I see there are EFI conversation tanks with everything you need for $600, but still thinking maybe there’s a cheaper alternative. Is there a different brand fuel pump I can put in my stock 1980 tank? How would I wire that up? I’m trying to balance being a cheap ass with reliability. This is a low priority, so if it’s best to save my lunch money and wait to get the right parts I’m open to that..
TIA!

 

[Bent77]

First off, don’t bother if you’re not going to do a return

Second, an ep381 pump in a stock tank and sender should feed that fine

 

[HawK5]

First off, don’t bother if you’re not going to do a return

Second, an ep381 pump in a stock tank and sender should feed that fine

To run The ep381 just cut the stock pickup tube, attach the pump, and clamp it on to something?
Is there a way to run wires to it in the tank? For wiring it, just find an open fuse block that gets key on power? What size fuse would one need? Will I need a regulator?With this configuration can I run my stock steel line as the feeder and then is the return line just an FI rated rubber hose from the TBI back to the tank? Is there an open/available port to dump it back in?
Sorry I have so many questions, this is my first attempt at an EFI conversion

 

[Bent77]

To use an ep381, you want a Tbi era tank and sender. Return and wires are attached, and they can be adjusted to bolt in. The benefit is replacement parts can be had almost anywhere

To run The ep381 just cut the stock pickup tube, attach the pump, and clamp it on to something?
Is there a way to run wires to it in the tank? For wiring it, just find an open fuse block that gets key on power?

You can use a wire off the existing wiring to trigger a relay and run extra power off the battery to a terminal


What size fuse would one need?
Depends on what all you have wired in. I think I have mine at 10A


Will I need a regulator?

Yes, and it will need to be set according to the requirements of the manufacturer. Usually 43 or 58 psi


With this configuration can I run my stock steel line as the feeder and then is the return line just an FI rated rubber hose from the TBI back to the tank?

You can, but don’t be a tightwad about “rubber hose”
There is Efi rated hose, and it is definitely not cheap. Typically they use some type of aftermarket fitting, as a 5/16” hose clamp won’t cut it

Is there an open/available port to dump it back in?


No

Sorry I have so many questions, this is my first attempt at an EFI conversion

That’s ok. Start by finding or downloading the instructions for that system, then print out a wiring diagram for your truck

 

[Wes Harden]

Amazon.com

Amazon.com

install pump of choice

 

[Bent77]

Amazon.com

Amazon.com

install pump of choice

Is that tank baffled?

 

[Wes Harden]

yes is direct replacement for a 1990 and spectra no less

 

[Blue85]

Holley Truck Avenger

This is the reason for stalling at angles. If all you want to do is make it run on hills, you could just swap a Quadrajet in. I understand there are a few mods that can be done to the Holley to make it better off angle, but the Q-Jet design is just inherently better at this.

Is that tank baffled?

It's not baffled in the normal sense of the word or like the factory TBI tanks were. It has this metal tray that the pump sits in with small drainback holes to hold fuel a little better than an open tank. I can tell you from experience that when you're down to the last 2-3 gallons acceleration or hard cornerning can starve the engine. I just keep a little more fuel in it for wheeling and don't have any problems. That being said, I don't know that we have anything better in the stock-replacement type. The OEM plastic baffle tanks held the fuel better, but they broke off after enough years and they are long out of production. Picture lifted from eslewhere:

 

[blackhemirt]

Just my opinion but the MSD atomic is a POS.

 

[Blue85]

With this configuration can I run my stock steel line as the feeder and then is the return line just an FI rated rubber hose from the TBI back to the tank? Is there an open/available port to dump it back in?

When I did this, I found a set of factory fuel lines from a TBI truck. It's generally not recommended for the whole run to be rubber hose, especially the feed line. There are many options out there, especially when you start looking at speed shop and -AN type parts, but factory O-ring types work well. In general you want solid line along the frame, with flexible hose at both ends. You go flex (rubber, PTFE, etc.) from the sending unit to isolate the noise and allow disconnecting. You go flex from the frame to the engine to allow for flex in the motor mounts.

The factory sending unit has an outlet from the pump, the return fitting and a port to connect for EVAP (charcoal canister).

 

[HawK5]

Just my opinion but the MSD atomic is a POS.

What gives you this opinion? From what I was reading, most people who have had problems with this system were running return less systems with pump mounted externally, once they switched to a return style and put the pump in tank their problems were resolved. It also sounds like ensuring no exhaust leaks before the O2 sensor is critical.. but if you have different experiences I’m all ears, I got no problem reselling this unit

 

[Bent77]

Yes please share experiences of what you have learned on this system

 

[HawK5]

Thanks for all of the replies!
Regarding the carb, the truck will see 70+ degree momentarily during steep climbs while going over an obstacle. It is common to get stuck here and this I think any carb will struggle. Switching to a different carb doesn’t seem like the answer I’m looking especially if it needs tuning..
So I’m gonna run the truck avenger until I swap to efi..
For EFI here is what I would need:
1. TBI Tank
2. TBI pickup/sender- Anyone know if the fuel level sending unit is the appropriate ohms or whatever to match the gauge?
3. TBI Factory hard lines or FI rated rubber, I read about corvette style filter/regulator, then the return line would be a lot shorter and I wouldn’t need to find all of the fuel lines, or get a regulator.
As for a regulator, manual says ~45 psi for less than 600hp.. I’m seeing the corvette style are preset and non adjustable for 58psi, I assume it won’t hurt anything to run 58psi when the manual says about 45psi for less than 600hp?

 

[Blue85]

Your gauge should be set up for 0-90 Ohm and if you get a TBI sending unit, it will be too.

If the ECU thinks you're at 3bar, but your regulator is 4bar you'll have to re-scale the flow rating of the injectors. Most injectors are fine with 4-bar, but you should check on the ones you have.

 

[blackhemirt]

Ok, maby POS was a little strong. But my experience with the atomic and the sniper was not good, Just expensive. Both seemed to have the same f"""n problem with working great one day, then the next day it would run like shit. The car is a 1969 mustang coup, fresh professionally built 302 mild roller cam, brodix heads. Fmx automatic The atomic ran good at first but after a few weeks it became inconsistent, meaning it would suddenly start running rich and dump fuel. I believe the electronics in these are not reliable. I went through all the tech support crap for weeks,and reset after reset, firmware updates bla bla bla.
Same shit ran ok for a few drives then would start to run rich and the O2 would show dead lean. Gave up on the atomic after a few months of double checking wiring, replacing O2 sensor and troubleshot the whole checklist with Msd/holley tech support and all good,home run wiring, intank pump with return no issues there so they offered me the sniper at a discount i foolishly agreed and bought a sniper... the first one they sent was faulty out of the box.dead! holley sent another one that worked,for a while. After but about a month it started doing the same dam thing the atomic would do, O2 would stop working and it would dump fuel bad enough to make the oil smell like gas.
My blood pressure is going up now just thinking about it.
I Got rid of all of it and bought my square. Much happier now lol

 

[Blue85]

OEM is forced to spend millions on validation testing and revisions to achieve reliability under all operating conditions. Aftermarket is forced to spend $0 on validation and may go to market on 1 or 2 total test vehicles. But Aftermarket does look shiny.

 

[Bent77]

Ok, maby POS was a little strong. But my experience with the atomic and the sniper was not good, Just expensive. Both seemed to have the same f"""n problem with working great one day, then the next day it would run like shit. The car is a 1969 mustang coup, fresh professionally built 302 mild roller cam, brodix heads. Fmx automatic The atomic ran good at first but after a few weeks it became inconsistent, meaning it would suddenly start running rich and dump fuel. I believe the electronics in these are not reliable. I went through all the tech support crap for weeks,and reset after reset, firmware updates bla bla bla.
Same shit ran ok for a few drives then would start to run rich and the O2 would show dead lean. Gave up on the atomic after a few months of double checking wiring, replacing O2 sensor and troubleshot the whole checklist with Msd/holley tech support and all good,home run wiring, intank pump with return no issues there so they offered me the sniper at a discount i foolishly agreed and bought a sniper... the first one they sent was faulty out of the box.dead! holley sent another one that worked,for a while. After but about a month it started doing the same dam thing the atomic would do, O2 would stop working and it would dump fuel bad enough to make the oil smell like gas.
My blood pressure is going up now just thinking about it.
I Got rid of all of it and bought my square. Much happier now lol

No offense, but two different systems doing the same thing at the O2 sensor leads me to suspect an exhaust leak close to the O2 sensor

That said, not all of these systems are great, but not all of them suck either

 

[blackhemirt]

No offense, but two different systems doing the same thing at the O2 sensor leads me to suspect an exhaust leak close to the O2 sensor

That said, not all of these systems are great, but not all of them suck either

None taken,your suspicion makes logical sense,but was not the case here. Brand new fully welded exhaust with no leaks. Besides my problem wasn't a skewed reading from the O2, the display would show essentially no fuel at all like 30/1 ratio. Unit would compensate by adding alot of fuel. I believe my symptoms were a result of an internal fault, and it carries over to the sniper as well with essentially the same ecm. This is a known issue at this point, spent hours taking to holley tech and they have admitted to being aware of this problem. I shouldn't condem them all, but I do.

 

[HawK5]

Well thank you for sharing your experience. Everything makes sense, I’ll make sure to hold on to my Holley for a while just to be sure I’m in the clear of any gremlins.

 

[sweetk30]

i went down the rabbit hole with the sniper 1st round . worst 3 months and 500 miles of hell .

2nd round is much better with edelbrock pro flo 4 and still working great .

hind sight 20/20 ................... should of just LS swapped or even factory L31 vortec swapped my truck and kept it all oem and way better in the end .