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Fuel pressure dropping during acceleration

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dynoman said:
You tested the regulator and it works , but is the regulator seeing the boost pressure ? Are any lines pinched restricting fuel flow ? Check the relay in the hotwire circuit ( burned contacts inside ) . ALL electrical connections front to rear .
I use this intake pressure tester for finding vacuum / boost leaks .
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The regulator is definitely seeing good vacuum, so reason to believe that line has an issue, I’ve inspected it, looks fine. As far fuel lines, that’s next on the list. I will look into that tester just because that’s great to have on hand. But I do not think vacuum leaks is the issue at this point.
UPDATE…in the driveway sitting still, FP still drops, so I’ve eliminated actual acceleration as the issue. Took the fuel cap off and did the test again, FP rose with boost! Thought I was good to go, modified the fuel cap to flow air better, no joy, driving with no fuel cap, no joy. Tank is full at this point so I don’t know if acceleration is still a factor if the fuel is filling the neck and not allowing air in? At this point I am probably going to need a new tank, or at least a new hanger with the correct fuel vent set up.
 
New UPDATE:
went to drain some fuel from the tank to eliminate the possible fuel in the neck issue, when I put power to the pump it barely was making a sound, and I noticed the volume was way low, it took like 20 min to drain 4 gallons….that isn’t right. It’s so weird that it can build 40+ psi pre start, maintain 38 psi at idle (vac on). Drives normally even on that little of volume, I’m baffled. So next up like mentioned before, wires and fuel lines will be inspected.
 
I'm not familiar with the Aeromotive tank/pump setups but I had a similar issue on my big block Chevelle with I converted to a Holley Stealth Terminator EFI setup. I purchased everything from Holley, EFI system, tank, pump assembly, ect so there was no finger pointing when I had problems. The install went well and the car drove great the first few weeks and then I started to develop a fuel delivery problem. It turned out the pick up sock on the fuel pump assembly was only about 1/16" off the bottom of the tank. This starved the pump of fuel and it kept up initially but overworked the pump and ended it's life quickly. This was my fault for not actually checking these dimensions but was told this was a "plug and play ready to go" tank and pump assembly right from Holley so I didn't bother to take it apart and check anything. Lesson learned for sure.

If your in the tank might be worth looking to make sure nothing is hindering fuel to the pump.
 
TylerDurden said:
Chuck,
I don’t know the PN, and I would agree it’s not the correct version, it was recommended to me by a long time reputable Buick shop. I won’t name drop that just yet as I have to get them on the phone to discuss this issue. I am still working replacing all cracked vacuum lines, but I’m leaning toward thinking it’s a pickup issue, easy enough to test by adding another 5 gallons and testing acceleration. Doing that tomorrow and will post results.
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If that's Don Cruze call him and get the right parts.
 
Chuck Leeper said:
Next up get the right damned parts!
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Lol Chuck, no we have never discussed this before, I got aeromotive on the phone and determined this is a gen II Buick GN setup, and if you look on their website, sure enough it’s ventless when you zoom in (no clue why anyone thought ventless was a good idea). PN 18449. Tank is down and troubleshooting pump right now. I don’t think it’s a venting issue anymore, with the cap off the car and emptying the tank via Hotwire, flow seems awfully low. Good ground, and 12+ volts coming from the harness. Pump coming out soon for inspection.
 
UPDATE: all pump wiring checks out, filter taken off and it seems good as well, easy to blow thru. Put a hose on the line pre filter and ran the pump, again low volume IMO, same as the fuel rail amount of volume coming out before. The line from pump to filter appears good so it’s looking more and more like a pump issue, or in tank line issue.
 
FWIW when I was installing my fuel pump setup I was getting low flow from a pair of DW300 pumps; I had less than 5 gal in the tank and it took 6-7 min to empty out most of it and it wasn't a constant stream almost like it was cavitating but it was submerged in fuel. One DW300 (340lph) should be closer to 1.5gal/min.

I ended up sending the whole assembly back to DW to check to make sure I assembled it right (DW X2 Fuel Pump Module in a custom Ricks Tank). They said the it was assembled correctly and they were a bit low on flow and replaced both pumps. The replacement pumps flow like they should.
 
@TylerDurden See posts #3 and #4. Your symptoms sound very similar to mine when I had a vent line issue. I tried a "vented" gas cap but it wasn't keeping up with the displaced fuel from the tank. I fixed my vent line issue & replaced my pump, all was well.

I'd verify your vented gas cap is able to vent when you're pumping a lot of fuel. Replace the tank assembly with the one Chuck mentioned (w/ vent line) and see if that helps too.
 
I apologize Chuck, I misinterpreted your question about talking about this before, is there any chance you could msg me directly?
 
TylerDurden said:
I apologize Chuck, I misinterpreted your question about talking about this before, is there any chance you could msg me directly?
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No need for that.
It's very obvious someone sold you the wrong combo.
Hope you get it made right! ;)
 
The tank and pump are correct to a Buick, the “hat” is an old style and would agree, incorrect. On the aeromotive website the monte/Malibu hat is correct. However after taking the pump out, the spongey foam crap they use surrounding the pump is already deteriorating, another wtf aspect of these tanks. For the price this thing cost, it’s a hard to pill to swallow after 4 years and only 10 hours of use, this whole setup is junk. Been in touch with Don, future plans are being discussed.
 
TylerDurden said:
after 4 years and only 10 hours of use
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You've found the cause. The shitty gas we get is a major factor in the foam degrading to mush.
Many small engine mfgrs say 30 days and the gas is fast failing. Some won't even consider warranty.
If you want, send me your injs and I'll see what they have in them.
 
Chuck Leeper said:
You've found the cause. The shitty gas we get is a major factor in the foam degrading to mush.
Many small engine mfgrs say 30 days and the gas is fast failing. Some won't even consider warranty.
If you want, send me your injs and I'll see what they have in them.
Click to expand...
I will take you up on that offer, I may be driving down to Covington on Saturday, I can drop them off if you like?
 
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