Holley Sniper EFI and bogging down at 60mph

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pacific541
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Holley Sniper EFI and bogging down at 60mph

Post by pacific541 »

So when I am cruising down the road all fat and happy, truck is warm and radio on doing 60MPH, all of a sudden no response from fuel and it acts like I dropped a boat anchor out the back, I shift into 2nd and back into Drive and it tends to go away and recover and off down the road I go.

So history of the Wagoneer. I owned and sold it in 2014, original motor and carbed. I bought it back and now it has a jasper crate (under 1,000 miles), and now has the Holley Sniper EFI. I've looked around and didn't see anything similar to this. I don't have the sniper paperwork from the previous owner.

thoughts?
JT
1989 Grand Wagoneer
Jasper 360 Crate motor
Holley Sniper EFI-removed went back to carb...loving it!
Custom Exhaust
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Stuka
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Re: Holley Sniper EFI and bogging down at 60mph

Post by Stuka »

Plug in a computer and get the data logs.

Sounds like you are possibly having a fuel starvation issue. Maybe fuel pressure is dropping for some reason, or the computer senses something and cuts fuel itself?
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ
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pacific541
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Re: Holley Sniper EFI and bogging down at 60mph

Post by pacific541 »

Thanks Stuka! plan on getting to it this weekend, I appreciate your input!

JT
1989 Grand Wagoneer
Jasper 360 Crate motor
Holley Sniper EFI-removed went back to carb...loving it!
Custom Exhaust

will e
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Re: Holley Sniper EFI and bogging down at 60mph

Post by will e »

Do you have a fuel pressure gauge? It would be invaluable for trouble shooting issues. Put the sensor as close to the EFI body as possible.
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pacific541
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Re: Holley Sniper EFI and bogging down at 60mph

Post by pacific541 »

Will,
The PO did not install one with the system but I will try and add that.
thanks,
JT
1989 Grand Wagoneer
Jasper 360 Crate motor
Holley Sniper EFI-removed went back to carb...loving it!
Custom Exhaust

Srdayflyer
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Re: Holley Sniper EFI and bogging down at 60mph

Post by Srdayflyer »

All the sniper paperwork is download able at holley.com

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Re: Holley Sniper EFI and bogging down at 60mph

Post by Srdayflyer »

What size are the fuel lines? The feed and the return lines have to be -6 or 3/8 , holly tech told me they have to be the same size or bpotential drivability issues will arise. I have modified a stock sender with 3/8 lines as there is no aftermarket part other than changing the fuel tank ,I can send you pictures
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az chip
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Re: Holley Sniper EFI and bogging down at 60mph

Post by az chip »

If you have the Holley Sniper you should have the plug in display and controller. Put that in the cab and have a passenger watch the fuel parameter while ambling down the road at 60. Then download the file and display the fuel map. You might have to fill in some data. See if you are in closed loop or open loop mode as well. You might have a data issue with an O2 sensor causing the loop to not go closed and causing the fuel program issue. There is also help from the Holley techs and other users on the Holley Sniper forum.
'81 Cherokee Chief 81 WT Chief/MSD 6/Holley Sniper/ Rusty 4" Spring lift/ Bulltear oil adapter/K&P Engineering Oil Filter/ NP 208/ Serehill Light Harness/KC LED Headlights/ Evil Twin Fab Roof Rack and sliders/ Ross mirror mounts.
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pacific541
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Re: Holley Sniper EFI and bogging down at 60mph

Post by pacific541 »

Found some exhaust leaks and getting a custom exhaust installed now, should be back tomorrow and testing and learn will continue. Working with a really responsive tech from Holley.
1989 Grand Wagoneer
Jasper 360 Crate motor
Holley Sniper EFI-removed went back to carb...loving it!
Custom Exhaust

68J2000
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Re: Holley Sniper EFI and bogging down at 60mph

Post by 68J2000 »

Stuka wrote: Wed Sep 08, 2021 1:08 pm Plug in a computer and get the data logs.

Sounds like you are possibly having a fuel starvation issue. Maybe fuel pressure is dropping for some reason, or the computer senses something and cuts fuel itself?
I second this big time!! Getting a data log will tell you just about 99% of your problems, I think the only 2 readings the sniper won't give you is oil pressure, and fuel line pressure. It would be more ideal if possible, to have someone ride along and tune while the system is data logging. (strongly recommend having someone with tuning familiarity do that part) Tuning it would be best, but not totally necessary, the systems base map and self learning should suffice day to day type driving.

If you do change the tune it's best to save your base line tune, also remove the micro SD card from the 3.5" display or it'll end up reflashing the new tune with the old one.

All that's needed is a laptop, Holley software (free on their site), and the USB to Holley adapter (about $60)

Also sometimes the solution to a problem could be the simplest. Change the fuel filters (should be 2) and definitely put a pressure guage on the fuel supply I think it should be around 55-60psi, I have heard of the pumps crapping out too
1968 J2000 Gladiator {The Poached Rhino} : AMC 360, Holley Sniper Injection w/ Hyperspark Ign, AX15 Terminator, Dana 300, D44/D60 Truetrac 4.11 Gears, 33's (W.I.P.)

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pacific541
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Re: Holley Sniper EFI and bogging down at 60mph

Post by pacific541 »

So to close this thread out from my original post. I called Ryan and BJ's and went back to a carburetor. It starts every time and runs great!

thank you for the input,

Jeremy
1989 Grand Wagoneer
Jasper 360 Crate motor
Holley Sniper EFI-removed went back to carb...loving it!
Custom Exhaust

Old_fargoan
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Re: Holley Sniper EFI and bogging down at 60mph

Post by Old_fargoan »

I've got $2000 in Holley Sniper stuff waiting to go in. Now I'm wondering if I just need a new carb. :-)

I'll pretend I didn't see this!
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az chip
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Re: Holley Sniper EFI and bogging down at 60mph

Post by az chip »

pacific541 wrote: Fri Feb 04, 2022 2:21 pm So to close this thread out from my original post. I called Ryan and BJ's and went back to a carburetor. It starts every time and runs great!

thank you for the input,

Jeremy
That is one way to go. Thanks for the update.
'81 Cherokee Chief 81 WT Chief/MSD 6/Holley Sniper/ Rusty 4" Spring lift/ Bulltear oil adapter/K&P Engineering Oil Filter/ NP 208/ Serehill Light Harness/KC LED Headlights/ Evil Twin Fab Roof Rack and sliders/ Ross mirror mounts.
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