datASSun Posted September 29, 2014 Share Posted September 29, 2014 (edited) Hey guys, Another day another dollar another hour another datsun problem So when I stomp on the gas my car revs for a split second and then the whole car jumps as if it's hitting a rev limited .. Just like those supra's making 10000000000hp with stock fuel pumps just hitting fuel cut left and right. I'm using the stock 280z fuel pump and I understand that may sound crazy. I figured that the 280z was fuel injected so it might just work.... I'll be damned the thing worked great for 2 months hahahhaa SOOOOO What Fuel Pump do I buy now ? Keep in mind this must be a inline fuel pump as I still have the stock 280z tank. Edited September 29, 2014 by datASSun Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 29, 2014 Share Posted September 29, 2014 You could do some math - http://www.fuel-pumps.net/fuelpumpsfaq41.html - then check specs. Of course, it doesn't look like you've confirmed that you need a new fuel pump. But you'll find out after you replace it. The pump doesn't know how much horsepower you're making, it just sits and spins, so no reason for it to wear out any faster with 10,000 HP than 10. If it worked for two months, it was sufficient. Quote Link to comment Share on other sites More sharing options...
ktm Posted September 30, 2014 Share Posted September 30, 2014 Not enough information to help. Have you checked for any codes? I am assuming you are using the stock PCM. \What is your fuel pressure set at? For an LS1 you should be at 58 psi. You may have worn out the pump since the LS1 fuel pressure is quite a bit higher than the stock 280z fuel pressure. Hell, many modern fuel pumps are not rated to 58 psi. Quote Link to comment Share on other sites More sharing options...
mattd428 Posted September 30, 2014 Share Posted September 30, 2014 If it was starving for fuel it would most likely die at wot and no fuel. Domz is using a stock 280z pump with no issues so far. Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 30, 2014 Share Posted September 30, 2014 It's just math. Here's some Google - http://www.onallcylinders.com/2013/05/16/what-size-fuel-pump-do-i-need-your-top-tech-questions-answered/ The typical auto store replacement pumps, like the Airtex E8312, are rated to 75-90 psi, 30 gph. He might have one on his car already. Crazy. Quote Link to comment Share on other sites More sharing options...
datASSun Posted September 30, 2014 Author Share Posted September 30, 2014 If it was starving for fuel it would most likely die at wot and no fuel. Domz is using a stock 280z pump with no issues so far. I spoke to Dom yesterday via txt and he said the same thing. I've now started to suspect my o2 sensors are bad because the car is running SOOOO FAT. My tune was just a "get it to the shop" tune which I've just been "getting it everywhere" with so I know it was set up to be on the rich side just for safety purposes. I suspect that the additional fuel made it foul the o2 sensors which is just making it run even more rich.. so when I floor it the car either surges with power or jumps (the jumping is what I mistook for fuel cut) Quote Link to comment Share on other sites More sharing options...
mistafosta Posted October 3, 2014 Share Posted October 3, 2014 02 sensors do NOT make the car do anything in a WOT condition. It doesn't really reference them at all, so they would not be your problem. Maybe get the tune fixed first, then start looking at issues.. You might have fouled the plugs (Which is pretty tough to do on an ls) or the tune is just way way off. (Which is easy to do with an ls) Quote Link to comment Share on other sites More sharing options...
Domzs Posted October 3, 2014 Share Posted October 3, 2014 He didn't mention that he has a stock 5.3 with mild cam and running a base tune. Quote Link to comment Share on other sites More sharing options...
mistafosta Posted October 3, 2014 Share Posted October 3, 2014 Do you have a fuel pressure gauge? If its fuel, the pressure will significantly drop as well. You said it was working fine, then did this? Or has the 5.3 always done this? There are a few tables in the stock ECU that can cause a low RPM rev limit like that. Quote Link to comment Share on other sites More sharing options...
datASSun Posted October 6, 2014 Author Share Posted October 6, 2014 Thanks Boys. Got it figured out this weekend. No more jumping car! However, anytime you fix something without knowing how you fixed is isn't really success.. Anyhow , looks like my stock datsun fuel pump is enough for the occasional romp around town or normal daily driving but when the hammer is down it just doesn't keep up... I did manage to drive the car 250+ miles from Austin to DFW then drive around all weekend with buddies and the gf before going to the drag strip last night running a pathetic 8.9 at 80mph.. and driving it another 250+ Miles back home ohh and then to the office today. Thanks guys I appreciate all ya'lls help. Hybridz is unlike a majority of forums in the sense that everyone is passionate about these types of cars and there's minimal keyboard kings. Much appreciated ! Quote Link to comment Share on other sites More sharing options...
socorob Posted October 6, 2014 Share Posted October 6, 2014 Someone said earlier the airtex only flows 30gph. I think the wahlbros flow around 55. Even though pressure is the same, volume isn't. Quote Link to comment Share on other sites More sharing options...
datASSun Posted October 6, 2014 Author Share Posted October 6, 2014 Someone said earlier the airtex only flows 30gph. I think the wahlbros flow around 55. Even though pressure is the same, volume isn't. This sounds about right. My car has lots of low end and decent mid range power but falls on it's face on the big end .. The bigger issue I have when I think about it is that my cam is suppose to make big power from the mid range on up. My guess just like everyone elses now is the fuel pump not being able to keep up. At the same time Domz uses a stock 280z fuel pump and has no issues however, it's his weekend toy and isn't used daily nor does it have a cam in it.. So I think that's why his results are so much better than mine. Quote Link to comment Share on other sites More sharing options...
NewZed Posted October 6, 2014 Share Posted October 6, 2014 (edited) I'll be damned the thing worked great for 2 months This statement is the main problem with your logic. You didn't "stomp the gas" for the first 2 months? Edited October 6, 2014 by NewZed Quote Link to comment Share on other sites More sharing options...
datASSun Posted October 6, 2014 Author Share Posted October 6, 2014 This statement is the main problem with your logic. You didn't "stomp the gas" for the first 2 months? It held fine for 2 months and no I didn't stomp on it all the way through the gears for 2 months. Maybe once or twice a little 2 gear romp but no 4 gear test passes. Not because I was worried about the car but it's hands down by a very long margin the fastest thing I've ever owned or driven. Not to say I haven't been stupid fast in a lot of cars but it's in how the power comes on that I wasn't ready for... just keep in mind 195/60/15 sumitomo tires 5.3 big cam and T56 ... Most of the v8 Z car guys on this website have much beefier tires .. if not flares. Quote Link to comment Share on other sites More sharing options...
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