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

[Doorkicker]

I have a similar setup and was faced with an oddity, which may or may not apply, but worth sharing for giggles. In short, the return fuel line created back pressure in the tank after prime, which would cause the pump to shutoff. I had this weird issue and once I relieved the gas tank pressure (i.e., opened the fuel cap), everything went good. I've since solved the back pressure issue.

What would be really helpful is if you would share your GCF file and, if possible, send over the datalog file... the DLZ for the last time you tried. It'll be small, but may show something. Just turn on datalogging by RMP and set to 0... if you haven't already. That way we can see cranking data too.

I may have missed it, but what fuel pump are you running?

I'm assuming you've confirmed pwr and ground at the pump and the Sniper is connected directly to the batt.

OK... one more, just our of curiosity, are you showing less than 11volts during cranking or after the initial start?

 

[69ChargerR/TSE]

Call tech support and have them help with diagnostics. It kinda sounds like your TPS.

 

[Nxcoupe]

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.

Do you have the yellow wire connected to the negative side of the coil? It comes out of the 7 pin connector

 

[Nxcoupe]

And as mentioned above, watch the voltage on your screen as you are cranking.
Next question, does your screen stay on while you are cranking?

 

[Nxcoupe]

I think these two pages may have your answer. You are not supposed to use the white or yellow wires with CD(MSD) ignition, you are supposed to use the purple and green twisted pair connected as the second pic shows.

 

[69ChargerR/TSE]

I have a 550-872, and hopefully this is the same.
Not sure the model you have.

BASIC WIRING INSTALLATION
The Sniper EFI throttle body has the following connectors and connections. Wires are labeled as well for identification. Not all of these wires will always be used. The following is a main overview, with more detailed installation information following.
7 Pin Connector – Main Sniper Wiring Harness: Mating Harness PN 558-490
Pin Color Labeled Name Function
E Red Battery Positive (+) Connects directly to battery positive terminal
G Black Battery Negative (-) Connects directly to battery negative terminal
C Blue Fuel Pump Output (+) +12v Fuel Pump Supply from Relay
A Violet Crank Signal Positive (+) Engine Speed Signal Input (see Ignition Wring Section)
B Dark Green Crank Signal Negative (-) Engine Speed Signal Ground (see Ignition Wiring section)
D Yellow Coil (-) Input Engine Speed Input (see Ignition Wiring section)
F Pink Switched Ignition (+12v) NOTE: must remain powered during cranking

10 Pin Connector – Mating Harness PN 558-491, 8 wires are populated. This connector contains:
Pin Color Labeled Name Function
A Orange Input #1 (-) Optional - Connect to a ground triggered A/C relay
B Yellow Input #2 (-) Optional - Connect to a programmable ground input
C Light Blue Output #1 (-) Optional – Connect to Fan #1 relay ground trigger
D Light Green Output #2 (-) Optional – Connect to Fan #2 relay ground trigger
E Grey Output #6 (-) Optional – Connect to ground side trigger of A/C shutdown relay
F White Points Output Used to trigger a CD ignition box or the included Coil Driver Module
G Dark Brown Tach Output Used to drive an aftermarket tachometer
H Tan Digital Gauge Output Used to drive Holley EFI analog gauges via 554-130 Gauge Module

 

[kiwigtx]

Also make sure you have a full return pipe to the tank for the fuel.

You cannot 'dead-head' the fuel supply with the Holley Bypass regulator like one diagram in the Sniper manual suggests. Full flow & return also helps to keep the fuel cooler as it continually cycles through the system.

I know that doesn't relate to the issue of the fuel pump cutting out after start-up - but it is worth noting for anyone in future reading this.


Also **** Holley fuel pump model #HLY-12-890 is junk. I had two of them fail almost immediately after first use. I now run a Bosch pump.

Here's the proof on video....they both had the same issue - loose fitting plastic parts...

 

[69ChargerR/TSE]

I like the Holley 12-319 Holley OEM Style EFI Fuel Tank Modules | Summit Racing

 

[64fury74charger]

I think these two pages may have your answer. You are nit supposed to use the white or yellow wires with CD(MSD) ignition, you are supposed to use the purple and green twisted pair connected as the second pic shows. View attachment 1352064View attachment 1352065

I will change the wire over later this week when I get some time. My brain totally lost this step because I was looking at that page the other day and when I wired it up I used the white wire. I have the single lead wire that came with the kit. Hopefully everything will work properly and everyone can have a good laugh

 

[Nxcoupe]

I have a 550-872, and hopefully this is the same.
Not sure the model you have.

BASIC WIRING INSTALLATION
The Sniper EFI throttle body has the following connectors and connections. Wires are labeled as well for identification. Not all of these wires will always be used. The following is a main overview, with more detailed installation information following.
7 Pin Connector – Main Sniper Wiring Harness: Mating Harness PN 558-490
Pin Color Labeled Name Function
E Red Battery Positive (+) Connects directly to battery positive terminal
G Black Battery Negative (-) Connects directly to battery negative terminal
C Blue Fuel Pump Output (+) +12v Fuel Pump Supply from Relay
A Violet Crank Signal Positive (+) Engine Speed Signal Input (see Ignition Wring Section)
B Dark Green Crank Signal Negative (-) Engine Speed Signal Ground (see Ignition Wiring section)
D Yellow Coil (-) Input Engine Speed Input (see Ignition Wiring section)
F Pink Switched Ignition (+12v) NOTE: must remain powered during cranking

10 Pin Connector – Mating Harness PN 558-491, 8 wires are populated. This connector contains:
Pin Color Labeled Name Function
A Orange Input #1 (-) Optional - Connect to a ground triggered A/C relay
B Yellow Input #2 (-) Optional - Connect to a programmable ground input
C Light Blue Output #1 (-) Optional – Connect to Fan #1 relay ground trigger
D Light Green Output #2 (-) Optional – Connect to Fan #2 relay ground trigger
E Grey Output #6 (-) Optional – Connect to ground side trigger of A/C shutdown relay
F White Points Output Used to trigger a CD ignition box or the included Coil Driver Module
G Dark Brown Tach Output Used to drive an aftermarket tachometer
H Tan Digital Gauge Output Used to drive Holley EFI analog gauges via 554-130 Gauge Module

I'm a Holley EFI dealer, that is just the wiring diagram off their site.

 

[69ChargerR/TSE]

I'm a Holley EFI dealer, that is just the wiring diagram off their site.

I was wanting to copy and paste the diagram as well. I am glad you did screen shots.

 

[Wietse]

When i prepped for EFI, i bought a separate in-tank fuel pump i had pre-wired already when i received the Holley Sniper kit.
Then i realized they have the relay and fuse in their harness for the fuel pump but i removed this.
I ran a 12V (fused) direct from battery through a relay that gets energized by a switched 12V source of the key.
This causes the pump to always run and has no interference from the Sniper ecu, which will switch it off after some time.
(I even added a on-off switch on the 12V source for the relay so i can leave the pump off if i need to power up but not starting, and i a hidden place it works well as anti-theft also)
Not sure about that as i do not use it as it was intended, perhaps you can try and re-wire your pump as well to have direct power without any connection to the EFI, if that pump stays running constant you could solve the issue.

 

[69ChargerR/TSE]

I would wire it as per Holley's instructions, I did without issue. I did add a switch in the pink wire, so I would have a master kill switch, if I needed to crank the engine over and not have the EFI system come on. It also acts as anti theft.

 

[Nxcoupe]

When i prepped for EFI, i bought a separate in-tank fuel pump i had pre-wired already when i received the Holley Sniper kit.
Then i realized they have the relay and fuse in their harness for the fuel pump but i removed this.
I ran a 12V (fused) direct from battery through a relay that gets energized by a switched 12V source of the key.
This causes the pump to always run and has no interference from the Sniper ecu, which will switch it off after some time.
(I even added a on-off switch on the 12V source for the relay so i can leave the pump off if i need to power up but not starting, and i a hidden place it works well as anti-theft also)
Not sure about that as i do not use it as it was intended, perhaps you can try and re-wire your pump as well to have direct power without any connection to the EFI, if that pump stays running constant you could solve the issue.

This works, of course, but the whole point of the computer controlling it is in the event of an accident and the engine stalls, the fuel pump shuts off so you don't have to scramble to turn it off. I even have my race car set up this way. My fuel pump doesn't come on until it sees a certain rpm cranking. This allows the engine to get oil pressure before it fires. Lots of stuff the Holley can do besides inject fuel. It uses Boolean logic for the IO operations.

 

[Wietse]

This works, of course, but the whole point of the computer controlling it is in the event of an accident and the engine stalls, the fuel pump shuts off so you don't have to scramble to turn it off.

You are right, it's a safety thing really.
I had in mind before to purchase one of those g-shock devices that you install on the pump power supply that will cut off the power in case of a hard impact.
Mine needs 2 "pump shots" the ecu initially gives to get started easiest (cold) most of the time so i need to cycle the ignition twice and have the fuel pump going or it won't start.

 

[64fury74charger]

Great news. Changed over to the single purple that connects one side of the distributor signal and fired right up. I really had a brain fart on this one. Thanks again to everyone for your help.

 

[kiwigtx]

There has to be a breakdown in either your wiring, or the way it is wired from your car looms.

Post #2 for the win.

Very pleased that you have found the problem.

 

[Nxcoupe]

Great news. Changed over to the single purple that connects one side of the distributor signal and fired right up. I really had a brain fart on this one. Thanks again to everyone for your help.

Great news. Glad I could help. If you need any tuning help, I can try to help you along.

 

[Archie Duiker]

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??

Mopars have two 12 volt wires from the ignition switch. One supplies voltage when the key is in the crank position, and one when the key is in the run position. You need to connect both together (and bypass the ballast resistor) on the sniper system. That way the fuel pump will run as long as the key is on.

 

[64fury74charger]

Mopars have two 12 volt wires from the ignition switch. One supplies voltage when the key is in the crank position, and one when the key is in the run position. You need to connect both together (and bypass the ballast resistor) on the sniper system. That way the fuel pump will run as long as the key is on.

I tossed the ballast resistor years ago when I first put msd on this car with the previous motor. Since it’s a 74 the firewall “emergency “ push button set up was deleted as well.
This Charger has been a fantastic learning tool. I have the hyper spark distributor and black box ready to go but I want to run it without spark control for a while before installing that system.