NewZed Posted October 21, 2010 Share Posted October 21, 2010 I have an essentially bone stock 1976 280Z but hope that someone with track experience may have experienced this and have some knowledge and advice. After using about 13 gallons of fuel (based on several fillups), with the gas gauge getting close to E, apparently the pickup tube in the tank is getting uncovered on wide left turns, if I am accelerating. The engine loses all power, acceleration stops, usually I'm heading straight about then, and the engine regains power. It only happens close to E. This is all just normal road driving. Is this common or do I have a bent or holed pickup tube? I'd like to get closer to using the 17 1/8 gallon capacity of the tank, but don't know if this a left hand turn issue only or if there's an abnormal problem. Full disclosure - I have a small dent in the tank right next to the differential housing where the car slipped off a floor jack. Is the pickup tube in that location and maybe I bent it up? Any ideas appreciated. Thanks. Quote Link to comment Share on other sites More sharing options...
z2go Posted October 21, 2010 Share Posted October 21, 2010 I doubt that you bent the pickup tube, usually it is located close to the drain plug, where the lowest point of the tank is (but not touching the lowest point). It seems to me that you might have a hole in the pickup somewhere. If the tube were bent though, I would imagine it would bend at the solder at the top, and you would have a lot bigger problem than that. Have you ever had the tank dropped to inspect it? You might pull it down and maybe take the fuel level sender unit out to try to take a peek at the tube, and the general condition of the inside of the tank. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 21, 2010 Share Posted October 21, 2010 Sounds normal to me. I have seen 240's start cutting out on lefthanders with 1/4 tank. We rarely used more than 11 gallons from the tank while running LeMons before getting feed issues, and we KNOW we had a good tank (NOS Sticker was still on the tank, and internal inspection confirmed the 'new' condition! They just don't handle well when the fuel is below 1/4 tank when you put any kind of serious G Force to it. Quote Link to comment Share on other sites More sharing options...
NewZed Posted October 21, 2010 Author Share Posted October 21, 2010 I've never dropped the tank. Overall, the fuel supply system hasn't shown any signs of problems, besides this low fuel level cornering issue. I thought of a few new search terms, "surge tank" and "sump" and looked around using those. I get the impression that, as Tony D suggests, the issue is not that abnormal, based on all of the racers modifying their tanks, and various reports of fuel starvation, usually on modified cars though. I have an aftermarket Airtex 8312 fuel pump and an Aeromotive regulator (not for performance, the old ones just wore out) that might flow more fuel (from inlet to return line) than the stock setup (I'm guessing). I wonder if this isn't emptying the fuel line system more rapidly than the tank baffles were designed for, so instead of an sir bubble I get empty lines. The Airtex is reported at 30 gph, but I don't know what the stock pump flows. Thanks for the ideas. I guess I'll just fill up sooner, or drive slower, or start modifying. Quote Link to comment Share on other sites More sharing options...
rossman Posted October 21, 2010 Share Posted October 21, 2010 (edited) I agree with Tony...sounds normal. I had a '76 that did exactly the same thing as you describe. My gauge was brokend and that little hesitation on left hand turns was a cue to stop at the next gas station and fill up . Edited October 21, 2010 by rossman Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 22, 2010 Share Posted October 22, 2010 If it's near "E" you will have problems. If you put in a lift pump and about a 2L surge tank with the return line flowing to it, you can extend your tank pickup right to the bottom and suck down to nothing in the tank and never miss a beat. Just make sure the tank is TALLER than it is around. Kind of tough to do in the space at the back of the Z. The #75 Cunningham Racing Z32 had TWO surge tanks, almost 48" tall! They were fed by two pumps apiece, and then the main pumps went forward each fueling one set of injectors. The tanks were about 3" in diameter, and went from the top of the skid plate under the car to literally touching the roof skin! They did NOT want to suck an air bubble into the main fuel pumps under boost. That engine was capable of making 1100HP, and in most races was restricted through two 26mm intake orifices on the turbos to only 760HP... The key to not sucking air is not allowing the fuel to slosh away from the pickup, a Tennis Ball Can would be almost the perfect size for a stock car, some 3" aluminum tubing with a conical bottom (slosh baffles at the top of the cone), with the fuel picking up out of the bottom of the cone, and fuel feeding in tangentially midway up the tank with fuel return off the top...piece of cake. Now make it fit back there with two pumps and an R200... Quote Link to comment Share on other sites More sharing options...
NewZed Posted October 23, 2010 Author Share Posted October 23, 2010 Thanks rossman for a real-world example. It's good to know that my pickup tube is probably not about to fall off or disintegrate. Tony D, thanks for the detailed advice on a surge tank. The Tennis Ball Can tank description gives a good visual. With some math, I should be able to figure out how long the turn can be before I run out of fuel. Maybe I'll design it for the 217 N to 26 W merge ramp... Quote Link to comment Share on other sites More sharing options...
emoximuu Posted October 23, 2010 Share Posted October 23, 2010 (edited) I've been looking into a surge tank myself for future plans. http://www.ratdat.com/?p=168 has a good description and how to for making your own. My plans are to use a N2 tank used for paintball. Should get a little over a liter with a 62 cu. inches tank, you could always go bigger/smaller. You can always get them really cheap on Craigslist. Edited October 23, 2010 by emoximuu Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted October 23, 2010 Share Posted October 23, 2010 Mine did, and still does. Â The Z's can out perform their fuel tank. Quote Link to comment Share on other sites More sharing options...
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