EvilC Posted January 2, 2009 Share Posted January 2, 2009 Well after driving my Z for year and half (7500 miles)......I am swapping the drivetrain and all to another, cleaner Z. My first Z has been a great learning experience and I am glad many of you talked me out of it when I had it up for sale back then. Also of course 1 tuff z (David) helped me out big time while I built the car at his house and Vihn did the wiring for me when I got back to NYC. Here is a pic of the original EVIL Z and a glance of the "new" EVIL Z. EVIL Z: "new" Z: While doing this exchange I plan to buy new GM motor mounts, do the UD pulley, FAST 90/90 intake and TB, recoat the LS1 headers, clean and paint suspension parts and get everything working....like HEAT! =) My biggest concern/question right now is in regards to the fuel system. I know lots of us drives our cars hard and I need some input about low fuel/fuel starvation. I know if let the Z tank get below quarter tank, I get fuel starvation under hard braking and cornering. As some of you know, sometimes it may cause the car to die right where it is. My concern and question is.....could this be because I am using the fuel rail as a dead end vs using the pressure regulator as a dead end. Also do aftermarket fuel rails help in anyway of helping with "flow" of the fuel. I am thinking I am getting air into the system and by doing that it gets trapped in the rail. My set up right now is.....sumped/baffled 240 tank, right to a filter then a walbro pump......then to the FPR in the engine bay and then to the rail. Worse case is I just do the ATL drop in fuel cell in the tank and call it a day. Just would like to input first because I know Rags (Joe) bought Dales 280 LS1 car and it does not have the same problem I do...no matter how low you run it on fuel. Major difference in the fuel systems are, aftermarket rail and FPR after the rail. Anyway, thanks in advance and reading through my long post.... =) Any other suggestions anyone can think of let me know, any while you are at it things. This would be my first time pulling the motor back out after getting it in. Quote Link to comment Share on other sites More sharing options...
janaka Posted January 2, 2009 Share Posted January 2, 2009 Personally I don't think an aftermarket fuel rail is 'needed' for these motors untill you are pushing LOTS of power. I was looking at the upgrade just recently and on ls1tech.com a sponsor says that the stock rails will support upwards of 1000hp with some modification. I don't think we are there just yet As for the your setup it seems good. I'm personally running a stock 280z tank with welded -AN fittings for my supply/return. My system is plumbed like this Tank -> A1000 Pump -> filter -> FPR -> rail and my return is off the FPR back to the tank. Are you running the stock fuel lines? That may be another thing to consider upgrading. I'm running braided lines -10AN from tank to pump, -8 from pump to filter to regulator to rail -6 return from regulator to tank. I've never had any kind of fueling issues. Quote Link to comment Share on other sites More sharing options...
rags Posted January 2, 2009 Share Posted January 2, 2009 Hijacking here a little Clive, to ask a different way. Besides the low fuel / fuel starvation issue, what would cause an extremely hard to start condition when the car is run dry? With Clive's car that has the deadended fuel rail, this is a real problem where as on my cars, (pump -> fuel rail -> fpr -> return to tank) I can run dry and start the car right up after just priming with the key. The way the fpr is plumbed seems to be the only difference. Brrrrrr.........looks cold in that garage! Joe Quote Link to comment Share on other sites More sharing options...
EvilC Posted January 2, 2009 Author Share Posted January 2, 2009 Joe, The way you asked was clearer than how I said it...I was type/ranting lol and yes it does get cold in there with no heat and having to door open so the gas fumes doesn't get into my parents room! =) Janaka, I am running braided lines feed and return, forgot what size though. Maybe that is something else I can look at where in Joe's case....he is using a line slightly larger than stock. I remember on Vihn's friend Cobra LS1 Z, I believe he used the stock lines until he got to the engine bay. So that leaves us two issues: Fuel line size a factor? FPR....before vs after fuel rail? Quote Link to comment Share on other sites More sharing options...
mark Posted January 2, 2009 Share Posted January 2, 2009 Clive, When you run the new lines, use the teflon braided line. My lt-1 car always leaves gas fumes in the garage and the ls-1 car does not. The ls-1 car has the teflon line. Both fuel systems are very similar. I used -6 line on both cars for the feed and return line. The ls-1 car is uses a fuel safe cell with an internal pump to aftermarket rails (I liked the look) to regulator to return line. When the engine coughs, the tanks is near empty. I bet a return line would cure the hard start issue. Possibly air in the lines when the fuel runs low and has no where to go with out a return line. (italics not intended) Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 2, 2009 Share Posted January 2, 2009 If air in the rail is the problem, then it seems to me a simple surge tank is the easiest fix, and would probably end up 1/10th the cost of the ATL solution. Quote Link to comment Share on other sites More sharing options...
EvilC Posted January 2, 2009 Author Share Posted January 2, 2009 If air in the rail is the problem, then it seems to me a simple surge tank is the easiest fix, and would probably end up 1/10th the cost of the ATL solution. Jon tell me about it. I am going to research this one pretty hard before I cough up the $700 or so to do the tank mod. I am waiting to see if more LSX guys can post their fuel system setup so I can pick through them all and try and figure out why David and I had the same porblem....same setup. While others will almost the same setup does not have that problem. Also another thought of mine is, where do most of you guys have your walbro pump mounted? I am wondering if distance and height from the feed can cause and issue. Also should the filter be before or after the pump, I don't think it should matter. You would want the filter before the pump so the pump doesn't go bad. Also the walbro pumps are pushers and not pullers of fuel correct? Just throwing some more ideas out there. Quote Link to comment Share on other sites More sharing options...
rags Posted January 2, 2009 Share Posted January 2, 2009 Clive, We could very easily move your Walbro down to where mine is mounted to see if that has any effect. Won't cost anything and we should see results quite quickly. Joe Quote Link to comment Share on other sites More sharing options...
janaka Posted January 2, 2009 Share Posted January 2, 2009 here's my pump regulator setup and my pump location if it helps at all Quote Link to comment Share on other sites More sharing options...
bucket240z Posted January 2, 2009 Share Posted January 2, 2009 Is your fuel pump mounted higher or lower than your gas tank? Quote Link to comment Share on other sites More sharing options...
EvilC Posted January 2, 2009 Author Share Posted January 2, 2009 Is your fuel pump mounted higher or lower than your gas tank? Higher =( This is one of my concerns. I should move it lower and see if that helps. Quote Link to comment Share on other sites More sharing options...
bucket240z Posted January 2, 2009 Share Posted January 2, 2009 When i was doing mine i asked my uncle(mechanic) where to put it he said lower. Try that and it might solve your problem :]. Quote Link to comment Share on other sites More sharing options...
ColtGT4g63 Posted January 2, 2009 Share Posted January 2, 2009 For my fuel system, I was running an inline walbro 255, with the stock C5 regulator / filter. I was feeding the rail with the stock 240Z fuel line even. Car dyno'd 411hp like this. Car started hot / cold every time, anytime. Quote Link to comment Share on other sites More sharing options...
rags Posted January 2, 2009 Share Posted January 2, 2009 Here is what I think is happening. If you look at Janaka's picture of his FPR, I'm assuming you have a feed from the tank coming in on the left, the return on the bottom, and the right port going to the dead ended fuel rail. If this is the case as it is with Clive's, if the pump were to pull any amount of air, if the bubble were to get past the FPR, the only place it would b dispersed would be through the injectors causing a major stumble. Does that statement make sense? Joe Quote Link to comment Share on other sites More sharing options...
m1noel Posted January 2, 2009 Share Posted January 2, 2009 Clive, For what it's worth, I'm running my pump in the stock location for a 280, stock lines to the engine bay, then AN lines to regulator, to the rail, and out of the FPR to the stock return line. Filter before pump. I've only run a couple of auto X's and 4 runs at the drag strip with probably 1/8th to a quarter tank, but no stumbles at all. Mike Quote Link to comment Share on other sites More sharing options...
janaka Posted January 3, 2009 Share Posted January 3, 2009 Here is what I think is happening. If you look at Janaka's picture of his FPR, I'm assuming you have a feed from the tank coming in on the left, the return on the bottom, and the right port going to the dead ended fuel rail. If this is the case as it is with Clive's, if the pump were to pull any amount of air, if the bubble were to get past the FPR, the only place it would b dispersed would be through the injectors causing a major stumble. Does that statement make sense? Joe FPR - Right fitting comes from tank, return on the bottom and the left is feed to the stock rail Quote Link to comment Share on other sites More sharing options...
Guest NESS89 Posted January 3, 2009 Share Posted January 3, 2009 hey you guys that are using the 240z fuel tanks, did you guys have to modify it for the ls1? or will the stock tank work fine? Quote Link to comment Share on other sites More sharing options...
heavy85 Posted January 4, 2009 Share Posted January 4, 2009 So what are you trying to fix exactly? Seems you have two issues. First is starvation then if it does starve it's hard to start. First is a function of where the pick-up is located and lack of baffling allowing the pump to suck air. Carbs with floats can handle this but fuel injection there is no accumulator to store some fuel until it sucks fuel again (except old VW's did have a fuel accumulator but...). All the lines changes in the world are not going to help this. Second is most likely a routing issue. Fix the first and you dont have to worry about the second. I'm running a stock '02 Camaro tank with the in-tank pump and regulator. It's probably the cheapest way out and I've not had problems in autox, drag, track days. Cameron Quote Link to comment Share on other sites More sharing options...
S30TRBO Posted January 4, 2009 Share Posted January 4, 2009 Jon tell me about it. I am going to research this one pretty hard before I cough up the $700 or so to do the tank mod. Clive, I would go the route I did from the get go. If you don't already have a 240Z stock tank I have one for cheap in great shape. Take a look at my thread then you decide. http://forums.hybridz.org/showthread.php?t=130970 Quote Link to comment Share on other sites More sharing options...
EvilC Posted January 5, 2009 Author Share Posted January 5, 2009 Joe, I did get the tank done at the same place! =) Joe was over today and heard first hand the car stumble on low gas. First line of busn is to move the pump lower, this will have to wait a few weeks..I got two Z cars to work on before it! I know I know...I am a Z addict now. Quote Link to comment Share on other sites More sharing options...
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