cpt jack Posted July 30, 2007 Share Posted July 30, 2007 Ok just did the su swap on my 280z.... they ran GREAT! but now... latley they die out.... only around 4k+ they start dyin... when we put in the fuel pump the fuel hose was slightly craked but did not leakin.... but now when i do some hard driving in the higher rpms for more then a min or so they die out and the tone for the z changes as well.... so my theory is that the slight cracks are sucking air in and killin the carbs... what do u guys think? Quote Link to comment Share on other sites More sharing options...
Savage42 Posted July 30, 2007 Share Posted July 30, 2007 There's pressure in those hoses, not vacuum, so it would be leaking or spraying fuel, not sucking air. Sounds like you don't have enough volume or fuel pressure, so I'd check your filter, then look at the pump. Parts can fail, both old and new. Good luck! Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted July 30, 2007 Share Posted July 30, 2007 I'm sorry, but what the heck are you doing driving around with cracked fuel lines. Replace the fuel line and filter. Check the oil level in the carbs and top as necessary with marvel mystery oil. Quote Link to comment Share on other sites More sharing options...
ORANGEZ Posted August 28, 2007 Share Posted August 28, 2007 yeah you might wanna replace those cracked fuel lines first before driving around ... heat and open fuel dont make for a good combo you know? Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted August 29, 2007 Share Posted August 29, 2007 I'm sorry, but what the heck are you doing driving around with cracked fuel lines. Replace the fuel line and filter. Check the oil level in the carbs and top as necessary with marvel mystery oil. LOL Sometimes if you just pay attention to the little details the big problems never happen. Quote Link to comment Share on other sites More sharing options...
Tombarace14 Posted August 29, 2007 Share Posted August 29, 2007 Def. check the oil in the carbs mine used to leak alo, so I had to constantly fill them. Although I used ATF just because I used so much, and its easy to find. Quote Link to comment Share on other sites More sharing options...
bjhines Posted August 29, 2007 Share Posted August 29, 2007 I set a Zs on fire with cracked fuel hoses TWICE. The little hoses that run from the float bowl to the jet assembly are easy to miss when checking things out. The fuel feed lines are obvious. You have to remember that the carbys are right on top of the exhaust manifolds. This is a fire hazard under any circumstances. When you are driving down the road and the engine begins to missfire... then the hood paint starts to peel... you have a BIG problem before you even notice the smoke. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted August 30, 2007 Share Posted August 30, 2007 Sounds like what my 280 did when I first put the SU's on. I used the stock 280z fuel lines, and it started and ran fine. Problem was, (I think..) They were too BIG and once the fload bowls filled, there wasn't enough presure to 'pop' them open again as the fuel would just go down the line to the return. After a hard pull through 1st and second, the car would run out of fuel and start sputtering. Sounds stupid I know, but to test this theory I clamped a small set of vice grips on the return line (right after the carb) and the car drove perfect! No sputtering while runing up through the gears hard anymore! I found some stock 240z fuel lines and switched them over shortly afterwards, and havn't had a problem in 3 years. Sounds like you should be changing those fuel lines anyway! Quote Link to comment Share on other sites More sharing options...
inlawZ Posted August 31, 2007 Share Posted August 31, 2007 replace the cracked fuel lines first, check for gaps in the manifold where air can get in it. my buddy's 240 would die on him, found that the manifold wasnt air tight, now it seems fine. good luck Quote Link to comment Share on other sites More sharing options...
rejracer Posted September 7, 2007 Share Posted September 7, 2007 Make sure your choke is not on. On the bottom of the carb make sure your jets are seated fully upward. When they get worn the jets tend to stick in the downward position even when you have the choke off. To do this simply put your finger on the bottom of the jet and push up. If it moves you know you have found a problem. Quote Link to comment Share on other sites More sharing options...
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