Accessory AND 'start' power source with Painless harness

Chamba

Active member
City
Vero Beach
State
FL
#1
Hello Scrambler brains trust,

Quick question for the gurus out there: what source of power are others using to supply their efi's fuel pump power with during accessory/run AND cranking power?

I've got a painless harness and previously i was using the coil power but I'd like to find its own dedicated source. The wire which painless suggests (called 'fuel pump', funnily enough) is only powered in accessory position but -oddly- looses power during crank. This would work with a carb electric pump obviously as the float has enough fuel to power through the crank but it is a problem with the efi where a constant flow of fuel is required.

I thank you all in anticipation of your time.
 
Last edited:

Randyzzz

Blown Budget
LIFETIME
CJ-8.com Member
SOA Member
City
Redmond
State
OR
#2
I think the coil wire is your best source. You can always us the coil wire to activate a relay that powers up a dedicated fuse block if needed.
 

Chamba

Active member
City
Vero Beach
State
FL
#3
That's how I've got it set up now. I was hoping I could avoid that little Rube Goldberg setup now that I'm going from an FiTech to the Holley Sniper. Thanks Randy.
 

ag4ever

Average Nut
LIFETIME
CJ-8.com Member
City
Richmond
State
TX
#4
The sniper instructions say to not use the coil as the key on source.

Not sure how that can be done since it is connected to the only ignition source that is hot while in run and crank. I plan to use the choke power since it give more wire between the coil connection and the ignition/efi connections. I spent a fair bit of time tracing wires (and cleaning them) looking for a nice power source, and that was the best I could come up with. But then again, that is the o wire harness.
 

Chamba

Active member
City
Vero Beach
State
FL
#5
I used that choke wire with my old harness and it worked, but the choke wire on my painless losses power during crank, which seems really odd.

That warning in the Sniper installation manual caused me concern as well. I had the relay setup for my FiTech and it worked fine. Now I'm trying to figure out a work around for the Sniper. Really, a relay should provide the required clean power but I really wanted to clean up the fender well area a bit where all my relays are.
 

ag4ever

Average Nut
LIFETIME
CJ-8.com Member
City
Richmond
State
TX
#6
I’ll need to check the choke feed, but I am fairly sure it had power in both positions. Wired that the painless harness would be different.
 

FLCJ8

Legacy Registered User
City
Palm Bay
State
FL
#8
Hello Scrambler brains trust,

Quick question for the gurus out there: what source of power are others using to supply their efi's fuel pump power with during accessory/run AND cranking power?

I've got a painless harness and previously i was using the coil power but I'd like to find its own dedicated source. The wire which painless suggests (called 'fuel pump', funnily enough) is only powered in accessory position but -oddly- looses power during crank. This would work with a carb electric pump obviously as the float has enough fuel to power through the crank but it is a problem with the efi where a constant flow of fuel is required.

I thank you all in anticipation of your time.
I posted this on your other post as well...
maybe it will help.

InkedSniper_LI.jpg
 

jpnmaine

Member
CJ-8.com Member
City
East Wilton
State
ME
#9
Chamba. In my FSM there is a 15A fuse block labeled IGN LPS 15A. It is hot in start and on. Wiring is for up shift switch/dash indicator, and goes to the EEC coord not sure if the rig is using any of this original stuff. If you are not going to wire in directly from the ignition switch sources this might be a legit source of power. Just quickly looked and do not profess to be an expert.
 

Chamba

Active member
City
Vero Beach
State
FL
#10
Chamba. In my FSM there is a 15A fuse block labeled IGN LPS 15A. It is hot in start and on. Wiring is for up shift switch/dash indicator, and goes to the EEC coord not sure if the rig is using any of this original stuff. If you are not going to wire in directly from the ignition switch sources this might be a legit source of power. Just quickly looked and do not profess to be an expert.
Thank you. I'll check that out. Thanks all for the help.

I think we'd best let this thread die off now.
 

Jeeperdd

CJ-8 Member
CJ-8.com Member
SOA Member
City
Gordonsville
State
VA
#12
I used the coil wire to power the sniper more than once and have not had an issue. But I did not use that same wire for the ignition system. I upgraded the ignition to hei and used the 10 gauge wire that powered the ignition box on the driver fender to run the distributor.
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
SOA Member
City
Biloxi
State
MS
#13
They might be telling you not to use the coil wire because some vehicles have a ballast resistor on this wire/circuit. So, you would get 12 volts at start but it would drop to like 8 or 9 volts on run.

I have always checked/verified on my Scramblers and CJ7's, but pretty sure the coil wire on all of mine have always had 12 volts start and run. Some of the repair books/wire diagrams will show a ballast resistor, but I think that is more common on the earlier ignition systems.

If I were you, check and verify your coil wire. It will probably be what you need. Or, use the wire JeeperDD is talking about that goes to the ICM. IIRC that big red wire also branches down to the coil. Could be wrong there, but I know the ICM gets 12 volts start and run.
 

ag4ever

Average Nut
LIFETIME
CJ-8.com Member
City
Richmond
State
TX
#14
I believe some use a resistor wire in lieu of the resistor ballast. My ‘84 has about 4‘ of wire snaked back and forth in the harness to the coil. It could be that long to add resistance and drop the voltage some to the coil. :shrug::shrug:
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
SOA Member
City
Biloxi
State
MS
#15
I believe some use a resistor wire in lieu of the resistor ballast. My ‘84 has about 4‘ of wire snaked back and forth in the harness to the coil. It could be that long to add resistance and drop the voltage some to the coil. :shrug::shrug:
Yes, the resistor wire. Easy enough to check voltage at coil with engine running to see if it has the resistor. If it does, tap into this wire upstream of the resistor, should be 12 volts start/run.
 

FLCJ8

Legacy Registered User
City
Palm Bay
State
FL
#16
Thank you. I'll check that out. Thanks all for the help.

I think we'd best let this thread die off now.
The image I attached here and on the other thread clearly shows the factory wiring that has crank and run power available.
Does the Painless system have these also?
(I would think it should :shrug:)
 
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