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 Steady cruise AFR problem and pressure at WOT 
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Joined: Sat Jun 01, 2013 8:02 pm
Posts: 356
That's what I did, used a bulkhead and a piece of pipe to keep about 2" off floor of cell in the corner away from the sump pick up area also..

74 Firebird 3620 lbs
10.02@131.96 1.377 60 ft

Fri May 26, 2017 6:52 pm

Joined: Mon Nov 30, 2015 3:55 pm
Posts: 47
Location: Jupiter, FL
All hooked up and plumbed. For the time being, I'm using the AN fitting welded to the top of the cell. I'll consider the tube once I work these things out. It's 92 degrees here and feels every bit of it. I haven't driven the car yet; it's just way too hot.

Observations thus far - first, the idle is's leaner and doesn't smell the same. That strong smell of gas is gone. Secondly, the pump is a lot quieter. I'll get the are out Monday or Tuesday and report back. Thanks a lot, once again. Have a happy and safe holiday.

Sat May 27, 2017 3:47 pm

Joined: Mon Nov 30, 2015 3:55 pm
Posts: 47
Location: Jupiter, FL
Drove it last night. Seemed to be ok but wasn't a long drive. At first, the carb flooded over. I pulled the N&S and cleared out a piece of trash from the fuel lines that apparently didn't get blown out. I'm going to give the carb one more one point at idle when coming to a stop, the AFR went very lean, up to 17, but it was an anomaly. I cleared it out with a hard hit on the pedal and it didn't do it again. Might be more gunk in the lines that I didn't get out. All the lines are new from cell to reg and back. Only thing I find strange is pressure still fluctuates just a bit (.5 lb) at idle, and drops nearly one pound on moderate to heavy acceleration.
Pump is new. Regulator is new. Lines are new. Filters are clean.

Mon May 29, 2017 12:54 pm
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Joined: Fri Feb 08, 2013 2:37 pm
Posts: 1701
Dropping a little pressure at WOT is normal unless the regulator is manifold pressure (vacuum) referenced.

Years ago a pal bought a fuel cell, electric pump, regulator, lines, fittings, etc, from a mail-order joint and installed it all in his hot rod. All was good but soon the pressure started acting up, there one minute, gone the next. The culprit found inside the pump was a plastic protective film off a chrome mounting ring for a shifter boot, the 6' square, 1/2" wide chrome plate the screws go through when you install the boot. It looked like a big flatworm. It must have been in the fuel cell before it was shipped and worked its way into the pump (Holley Blue), because no such shifter boot or ring was anywhere near his car.

Mon May 29, 2017 4:01 pm

Joined: Mon Nov 30, 2015 3:55 pm
Posts: 47
Location: Jupiter, FL
Good to know. It's so freaking hot here in South Florida that driving it just isn't comfortable. I'll get it out tomorrow night for a long drive and report back on the AFR at cruise, etc.

Mon May 29, 2017 8:17 pm

Joined: Mon Nov 30, 2015 3:55 pm
Posts: 47
Location: Jupiter, FL
:thumbl: So here is the latest and, once again, thank you for all of your input.

Right now, it's 93 degrees with the heat index and 60% humidity.

Pressure is set at just below 7 psi (this was set at idle speed for the time being). It fluctuates at idle but stays within the 6psi range.

Started up just fine with one good shot of the pedal and idled without any throttle input after about 20-30 seconds or so.

Idle was about 900, which is ok, but could be a hair higher. RPM drop into gear was very minimal.

AFR at idle was in the 14s with the temp still at or below 120. After a few minutes, temperature began to rise over 130 degrees and the AFR settled in the high 13s, low 14s. It felt happy.

Once warm, idle in gear had an AFR of 13.8, give or take.

Cruising, the results were as follows, RPM followed by AFR:
2100, high 14s
2300, mid 14s
2400, mid 14s
2500, in the 15s
3100, low-mid 15s.

Throttle response is strong, heavy acceleration from a slow roll felt excellent. Looks like the AFR at WOT is in the 12s, but today wasn't the day, nor was I in a good place, to give it a good go.

I drove about 4-5 miles to the parts store and let the car sit for about ten minutes. Once it started, I drove right home, but it was noticeably hotter outside. When I got home, pressure seemed to be a bit bouncier than earlier, but again, it didn't dip below 6psi. AFR was much richer at idle (in the high 12s, low 13s) and my idle speed was up a few hundred rpms (to 1200 or so). I'm attributing this to heat.

I'm going to insulate the feed lines best I can. The fuel lines are wrapped nearest the mufflers already. I had the feed lines wrapped, but for the sake of a fair comparison to the previous regulator system, I took the wraps off.

Tue May 30, 2017 11:18 am
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