Sniper fuel issue, pump runs on key on then nothing????

64fury74charger

Well-Known Member
Local time
9:42 AM
Joined
Feb 7, 2021
Messages
553
Reaction score
734
Location
Lynnwood WA
I have updated the sd card and also made a new one, pump is new under warranty and runs fine with 12 volts direct .
1974 Charger, 400/727 and 3:55 gears.
Brand new 3.5 handheld, went through all the wiring and I have separated all the ignition, power and sensor cables. Tried power from the battery when starting just to see if it made any difference, none. There must be some error in the system and I am at a loss right now. Everything looks good and it fires for a moment on the initial squirt of fuel but the pump doesn’t kick in.
Anybody here have any ideas on how to completely purge this ecu or wipe it and start blank????? I don’t have a windows laptop so I have to go to my tower to do the sd cards. Does anyone know if you can flush the ecu with a laptop???
If so how does that work? ?? I really want to drive this car a lot more before the weather turns.
 

kiwigtx

Henchman #4
Staff member
FBBO Gold Member
Local time
6:42 AM
Joined
Jun 12, 2012
Messages
28,324
Reaction score
64,577
Location
NZ - just short of the South Pole
There has to be a breakdown in either your wiring, or the way it is wired from your car looms.

As long as everything is wired correctly, then following the sequence to program the Sniper via the handheld should be simple.
 

64fury74charger

Well-Known Member
Local time
9:42 AM
Joined
Feb 7, 2021
Messages
553
Reaction score
734
Location
Lynnwood WA
There has to be a breakdown in either your wiring, or the way it is wired from your car looms.

As long as everything is wired correctly, then following the sequence to program the Sniper via the handheld should be simple.

I have done several wiring upgrades on this car to solve other common problems and installed separate fuse panels except for the wipers and headlights. Those are on my list but not urgent. Led lights all the way around so the load is significantly reduced.

I have ground wire on just about everything and insulation or heat shrink and lots of dielectric grease. I only use fresh wire off the roll and my ohm meter is always handy. I have been fooled by a bad ground wire before and learned from that. I spent the entire day yesterday going through all the wiring and didn’t find any obvious issues. I am not saying that there isn’t anything but I have really looked carefully and it looks good. Thank you for your input and it is much appreciated.
 

Nxcoupe

FBBO Gold Member
FBBO Gold Member
Local time
12:42 PM
Joined
Jul 4, 2021
Messages
1,626
Reaction score
1,479
Location
Red Lion, OH
I have updated the sd card and also made a new one, pump is new under warranty and runs fine with 12 volts direct .
1974 Charger, 400/727 and 3:55 gears.
Brand new 3.5 handheld, went through all the wiring and I have separated all the ignition, power and sensor cables. Tried power from the battery when starting just to see if it made any difference, none. There must be some error in the system and I am at a loss right now. Everything looks good and it fires for a moment on the initial squirt of fuel but the pump doesn’t kick in.
Anybody here have any ideas on how to completely purge this ecu or wipe it and start blank????? I don’t have a windows laptop so I have to go to my tower to do the sd cards. Does anyone know if you can flush the ecu with a laptop???
If so how does that work? ?? I really want to drive this car a lot more before the weather turns.
So when you turn on the key, the pump runs, then when you crank the engine over, the fuel pump does not come on?
 

64fury74charger

Well-Known Member
Local time
9:42 AM
Joined
Feb 7, 2021
Messages
553
Reaction score
734
Location
Lynnwood WA
So when you turn on the key, the pump runs, then when you crank the engine over, the fuel pump does not come on?

Correct, it does everything fine when you turn the key on, pump fires up and runs up 60 psi, then when you start the motor the pump doesn’t turn on so the engine runs for a second or two and done. I put direct power to the pump and it hums and instantly there’s 60 psi on the inlet gauge. What’s going on with this??
 

Nxcoupe

FBBO Gold Member
FBBO Gold Member
Local time
12:42 PM
Joined
Jul 4, 2021
Messages
1,626
Reaction score
1,479
Location
Red Lion, OH
Correct, it does everything fine when you turn the key on, pump fires up and runs up 60 psi, then when you start the motor the pump doesn’t turn on so the engine runs for a second or two and done. I put direct power to the pump and it hums and instantly there’s 60 psi on the inlet gauge. What’s going on with this??
Watch your handheld while cranking, is the tach showing rpm?
 

64fury74charger

Well-Known Member
Local time
9:42 AM
Joined
Feb 7, 2021
Messages
553
Reaction score
734
Location
Lynnwood WA
The computer is not seeing an rpm signal
The monitor shows rpm’s when starting which appears normal, I am running an msd 6 al and the gray tach wire feeds the rpm signal through the white wire from the sniper. If that signal wasn’t there the motor won’t start if I understand correctly, but that’s not saying that I know anything lol…. I am so close yet so far. Thank you for your help and it’s appreciated.
 

Nxcoupe

FBBO Gold Member
FBBO Gold Member
Local time
12:42 PM
Joined
Jul 4, 2021
Messages
1,626
Reaction score
1,479
Location
Red Lion, OH
The monitor shows rpm’s when starting which appears normal, I am running an msd 6 al and the gray tach wire feeds the rpm signal through the white wire from the sniper. If that signal wasn’t there the motor won’t start if I understand correctly, but that’s not saying that I know anything lol…. I am so close yet so far. Thank you for your help and it’s appreciated.
Are you running a relay to power the fuel pump or did you run the green fuel pump trigger wire directly to the pump power wire?
 

kiwigtx

Henchman #4
Staff member
FBBO Gold Member
Local time
6:42 AM
Joined
Jun 12, 2012
Messages
28,324
Reaction score
64,577
Location
NZ - just short of the South Pole
Correct, it does everything fine when you turn the key on, pump fires up and runs up 60 psi, then when you start the motor the pump doesn’t turn on so the engine runs for a second or two and done. I put direct power to the pump and it hums and instantly there’s 60 psi on the inlet gauge. What’s going on with this??
I found that each time I made a change, I would go through every setting to make sure everything was as it should be - including RPM at idle, and engine details - size, usage etc
Use the handheld to monitor what is happening.
 

64fury74charger

Well-Known Member
Local time
9:42 AM
Joined
Feb 7, 2021
Messages
553
Reaction score
734
Location
Lynnwood WA
Are you running a relay to power the fuel pump or did you run the green fuel pump trigger wire directly to the pump power wire?

I have the relay and fuse that were on the harness with the blue wire connecting to the pump wire after the relay. The power wire to the pump is one single wire from the harness to the pump. I also tried a new relay and that made no difference. I have checked the pin connector for the white wire and it appears fully seated.
 

64fury74charger

Well-Known Member
Local time
9:42 AM
Joined
Feb 7, 2021
Messages
553
Reaction score
734
Location
Lynnwood WA
I found that each time I made a change, I would go through every setting to make sure everything was as it should be - including RPM at idle, and engine details - size, usage etc
Use the handheld to monitor what is happening.
I have rebooted the system several times and also made a new se card and checked the system and ecu and the local settings to make sure everything loaded and it looks good each time. This is making me crazy.
 

Nxcoupe

FBBO Gold Member
FBBO Gold Member
Local time
12:42 PM
Joined
Jul 4, 2021
Messages
1,626
Reaction score
1,479
Location
Red Lion, OH
I have the relay and fuse that were on the harness with the blue wire connecting to the pump wire after the relay. The power wire to the pump is one single wire from the harness to the pump. I also tried a new relay and that made no difference. I have checked the pin connector for the white wire and it appears fully seated.
Ok, I'm not following. Can you post pics of what you have? The sniper does not put positive voltage thru the fuel pump wire, it puts it to ground. Had a guy return a unit insisting the driver was bad, got the new one, which was a huge hassle for me, and it did the same thing, then they hooked it up correctly. Just trying to help you and work thru this. I'll bring up the Holley wiring diagram so I can see what you are referring to. Been a few months since I wired in a sniper unit.
Edit: After looking at wiring diagram, the blue wire is a positive output, however the sniper grounds that relay in the processor to activate it.
 
Last edited:

64fury74charger

Well-Known Member
Local time
9:42 AM
Joined
Feb 7, 2021
Messages
553
Reaction score
734
Location
Lynnwood WA
Ok, I'm not following. Can you post pics of what you have? The sniper does not put positive voltage thru the fuel pump wire, it puts it to ground. Had a guy return a unit insisting the driver was bad, got the new one, which was a huge hassle for me, and it did the same thing, then they hooked it up correctly. Just trying to help you and work thru this. I'll bring up the Holley wiring diagram so I can see what you are referring to. Been a few months since I wired in a sniper unit.
I really appreciate your help with this. The sniper efi came with the relay and fuse in the harness. Mine has blue wires running through the relay and power from the fuse. one side of the blue wire is grounded by the sniper to power the pump. I can see how people may get confused because the wire colors should have more colors but that’s probably a cost difference.
I don’t have any current pictures because I was not thinking about being here asking for help. I am going to have to go over the wiring again but I don’t know what I am looking for.
I hope this helps you draw a picture of what I am working with.
 

64fury74charger

Well-Known Member
Local time
9:42 AM
Joined
Feb 7, 2021
Messages
553
Reaction score
734
Location
Lynnwood WA
Ok, I'm not following. Can you post pics of what you have? The sniper does not put positive voltage thru the fuel pump wire, it puts it to ground. Had a guy return a unit insisting the driver was bad, got the new one, which was a huge hassle for me, and it did the same thing, then they hooked it up correctly. Just trying to help you and work thru this. I'll bring up the Holley wiring diagram so I can see what you are referring to. Been a few months since I wired in a sniper unit.
Here’s some fresh pictures from tonight. Hope these help .

C50B7237-3D9F-4D09-8444-83E09DACDBCD.jpeg


364874EC-9676-490D-AAB8-224912C8F935.jpeg


A3B78A4B-1FF0-4970-B15B-3A9ACC190465.jpeg


BE316C9C-D43C-48F0-8380-A887820A2F7F.jpeg


FBCF53A0-B805-41FA-BE95-80D12B80B494.jpeg


C872E8D7-CBE7-420E-929A-D2C89499A5C3.jpeg


DEC8DB53-4922-4577-963A-A2B6B37ADEA7.jpeg


20713B64-F3C6-4CCA-9433-892AC3E49FA4.jpeg


3B18B533-1606-417A-A179-CDD052579E58.jpeg


C73A7928-4128-4384-AA15-E9BB1889F84A.jpeg
 

Nxcoupe

FBBO Gold Member
FBBO Gold Member
Local time
12:42 PM
Joined
Jul 4, 2021
Messages
1,626
Reaction score
1,479
Location
Red Lion, OH
I'll look at a wiring diagram tomorrow and report back.
 

64fury74charger

Well-Known Member
Local time
9:42 AM
Joined
Feb 7, 2021
Messages
553
Reaction score
734
Location
Lynnwood WA
Sounds like the fuel pump is timing out.....and that coincides with the start up procedure.
That’s kind of what I am thinking but it’s showing rpm’s on the screen when trying to start, and makes me scratch my head.
 
Top