2300 Sniper Fuel Hammer

[MPH]

Hi all. I'm running a Sniper 2300 on a late '60s GMH 6 cylinder 161ci with a returnless 340 LPH Sniper retro fit pump setup. The fuel tank has been sealed and cleaned spotless before use.
While I've only driven it a couple of times so far, at idle and when slowing for stop signs I can really hear the fuel hammer. I have a Earl's fuel pressure gauge at the Sniper and the needle fluctuates rapidly across the 60 psi mark. Normal driving steady take off and cruising is great, but if I give it a flat to the floor full throttle from traffic lights it has a big flat spot until I back off and feather through it then back to normal cruising (maybe another issue?). Holley said when I inquired, it would work fine with the 2300 and returnless. While I'm not certain if it effects the driveability of the vehicle, it doesn't sound right and I don't want to damage parts whether it's over a short or long period. The first start with the Sniper and idle for a few minutes didn't have the issue, maybe it was still just priming and pressuring the system, or the Sniper in tank pressure regulator can't keep up with the fuel flow the 340 LPH pump and is to much for the 2300s needs.
I feel there is a few options from my research just looking for peoples experiences or ideas for the most correct way to fix the issue the first time round.
1. Try a fuel dampener in the line?
2. Install a smaller pump maybe 240 LPH pump on my return less retrofit?
3. Run a return line and convert either the retro fit pump drill and tap it to take a return line or use the OEM supply line at the tank as a return point but this is 5/16" size. Thank you.

[a b c]

Do #1 on your list first. Get a good quality damper. Your bog issue is most likely related to your tune. Follow Danny's links/instructions to upload the GCF downloaded from the ECU along with a datalog of the issue and we'll take a look.

[Danny Cabral]

Originally Posted by Danny Cabral For further assistance, post your Config File and a short datalog of this occurrence for us to analyze. Also, review the datalog and inform us of exactly where in the datalog (time/seconds) the problem occurs. Datalog & Global Files can be linked to a document hosting website. I use Dropbox.com. Files can also be "zipped" (compressed zipped folder) & attached directly to a forum post ("Upload Attachments"). Your Config File is in the "Documents", "Holley" folder, "Sniper" folder, "Config Files" folder (.hefi file). Your Datalogs are in the "Documents", "Holley" folder, "Sniper" folder, "Data Logs" folder (.dl file). Someone will analyze/troubleshoot the problem & offer advice. https://www.youtube.com/watch?v=iqHOtDNiTNA (How To Record & Email A Datalog)

Overlay the datalog onto your Config File, and pay special attention to the center paragraph in blue print:

Originally Posted by Danny Cabral Quick Datalogger Information: Always provide data, not just symptoms. Is the AFR & ignition timing optimized? Overlay the datalog onto your Config File. Ensure the Target A/F Ratio table is properly programmed for your engine. Ensure the ECU is "Learning" (Learn Table LINK). Scroll through the datalog to the problem area. Then look exactly where this happens on the Base Fuel & Timing Tables. Scrutinize: RPM, MAP, MAT, TPS, CTS, IAC, Target AFR, AFR Left, CL Comp, Ignition Timing, Duty Cycle, Fuel Flow, Fuel Pressure & Battery. When the engine is tuned & running well, you should decrease the Closed Loop & Learned Compensation Limits % to lock in a good tune. Using the Holley Sniper EFI software (LINK), look at where the live cursor moves to during this occurrence, and manually tune that area of the Base Fuel Table (enrich or lean) & Base Timing Table (optimize ignition timing). I find the most helpful datalog function, is overlaying the datalog on your Config File. I'm in the habit of using the datalog Overlay feature every time I review a datalog. Click on "Datalog" (on the top Toolbar), "Activate Overlay", then "Open Data Log". You can literally "playback" a recorded event, and watch it as it happened on any screen. Minimize (shrink) the datalog window, and move it to the bottom of any Config File screen. Then click & scroll anywhere on the datalog, and watch it playback on your Config File (EFI software). http://documents.holley.com/techlibr...9r10543rev.pdf (Holley EFI Datalogger Instructions) https://forums.holley.com/showthread...s-amp-Datalogs (Datalog Information - Read "NOTES") https://www.youtube.com/watch?v=iqHOtDNiTNA&index=25&list=PL24C6FEA0BB99AF 17 (How To Record & Email A Datalog) https://forums.holley.com/showthread...7531#post77531 (Closed Loop Datalog Tuning - Posts # 2, # 4 & # 6) https://www.youtube.com/watch?v=rHjLwJQ45Kw (Holley Sniper EFI Datalogging Tech Video)

[63 bomb ohc]

I can't speak for your specific scenario, but I had good success with the fuel damper:
https://forums.holley.com/showthread...ght=returnless

[MPH]

Thank you for the feedback and links. I've been through the links and the rabbit holes of links and other posts to follow and found a great deal of more information i also had questions for.
I'm waiting on my laptop cable to arrive before I can do the datalogs.
I'm going to order one of those fuel dampeners like 63 bomb, not sure if to get the 40-70 psi or 40-100 psi? I've read a few success stories with them.
I also was going over my setup again and realized my -6 inline filter located under the car after the Sniper in-tank fuel pump is actually for a carburetor, not sure if this is the whole issue or just adding to the problem. It's hard to get a definitive answer on what inline filter to use just before the Sniper and what micron rating using standard 95 octane petrol.

[Danny Cabral]

This is just a copy & paste of one of my other posts:

Originally Posted by Danny Cabral A loud fuel pump is usually an indication of fuel pump cavitation or maybe a clogged filter(s). Inspect/troubleshoot/service the fuel system (fuel pump, cavitation, plumbing, voltage, filters, pickup tube, tank venting, etc.). A datalog will just verify a problem with the fuel pressure, injector duty cycle, pulse width, etc. An EFI fuel system needs two filters: Before fuel pump - 100 micron pre-filter. (Or the OEM in-tank sock filter.) After fuel pump - 10 micron post-filter. (40 micron is for carburetion.) The 40 micron (carburetor) fuel filter has no place on an EFI fuel system. (I know you're not using it.) It's too "fine" of a filter to be used before the pump, causing fuel pump cavitation. FYI: The sock filter (HydraMat or OEM) of an in-tank fuel pump, is the pre-filter. Don't add another one. http://documents.holley.com/holleyfu...ems_chart1.pdf (Fuel System Selection Chart) http://documents.holley.com/flyer_ho...el_systems.pdf (Holley Fuel Systems Brochure) https://forums.holley.com/showthread...395#post223395 (Related Forum Thread - NAPA 20 Micron Pre-Filter) Contact Chris Myer at EFISystemPro.com. He's a Holley EFI parts professional, Holley EFI Dealer & fuel pump/fuel system specialist.

[MPH]

A small but unsuccessful update on the fuel pressure. The Radium fuel pulse dampener showed up. So I installed it about 6" from the Sniper on a temporary bracket to see if it works or not. The first startup it sat quite steady although it was high. A 66 psi maybe fluctuating between 62 psi and 68 psi, but I had a fuel leak so shut it off. Fixed the leak and started up the vehicle and it's back to large fluctuations on the fuel pressure gauge which is at the Sniper. I also opted for the more expensive and larger range radium pressure dampener. Would anyone have suggestions going forward? Plus I’ll try and get a datalog. (It seems when it had the fuel leak it held steadier almost like a bleed off or return line might work).

[a b c]

I'd try moving the damper closer to the pump. If that doesn't do it, I'd put an external bypass regulator on a return line back to the tank. Then do a little research on what to do with the in-tank regulator.