THUNDERZ Posted April 14, 2004 Share Posted April 14, 2004 I have been having this problem over the last couple of years. Sometimes the fuel pump shuts off. I have replaced fuel pumps and am running a holley blue. My car is a 260z with an L28 triple dellorto set up. Should I just wire to 12v and put a switch in? This is really getting annoying so any help would be great. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted April 14, 2004 Share Posted April 14, 2004 How big are the main power feed wires going to the relay/then to the pump? The relay 'switch' wires can be tiny, but the power feed wires should be nice and big..... Tim Quote Link to comment Share on other sites More sharing options...
THUNDERZ Posted April 14, 2004 Author Share Posted April 14, 2004 the wires are stock size maybe 16AWG Quote Link to comment Share on other sites More sharing options...
Drax240z Posted April 14, 2004 Share Posted April 14, 2004 Replace the posative wire with a 10AWG, use a 10AWG ground as well and make sure it is a really GOOD, clean ground. That should solve your problems. A relay is a must. Quote Link to comment Share on other sites More sharing options...
THUNDERZ Posted April 14, 2004 Author Share Posted April 14, 2004 Replace the posative wire with a 10AWG, use a 10AWG ground as well and make sure it is a really GOOD, clean ground. That should solve your problems. A relay is a must. So you are saying I should replace the wiring from the relay back? 10AWG is huge! Have you had this same problem? The pump is only supposed to draw 3amps! : I also am not clear on why a relay is a must. It could be switched...It doesnt hurt to run the pump for a few seconds before and after running on a return set up does it? Quote Link to comment Share on other sites More sharing options...
THUNDERZ Posted April 14, 2004 Author Share Posted April 14, 2004 I ran a bigger gauge wire right from accesory power tothe pump and grounded it with heavy gauge also.I taped my pressure gauge to the hood and drove a couple minutes fine and then saw it drop to zero, it stayed there until I got home. Right when I pulled in I looked at the glass fuel filter in the engine bay and it was gurgling a few drops of fuel. I ran to the back of the car and heard the pump running and saw fuel in the rear inlet filter but it had air in it too. I dont know what this means. I had drained gas out of the tank a few days ago to test a pump on the bench and it poured right out. It is a mystery to me. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted April 14, 2004 Share Posted April 14, 2004 Well my first suggestion is to be a bit more descriptive when you ask a question. I assumed a few things like we were talking high pressure here. First if your pump only draws 3A max, you are right 10AWG is big. (I personally use 10AWG with my Walbro high pressure pump though) 14AWG should be fine for your application. Still, be sure you are getting a good clean ground. Also I would still recommend using a relay if there allready isn't one installed. (I can't remember on the 74 if there is one or not) It won't hurt to let the pump run for a few seconds while the car isn't running. Quote Link to comment Share on other sites More sharing options...
THUNDERZ Posted April 14, 2004 Author Share Posted April 14, 2004 I have been having this problem over the last couple of years. Sometimes the fuel pump shuts off. I have replaced fuel pumps and am running a holley blue. [My car is a 260z with an L28 triple dellorto set up. [/color']Should I just wire to 12v and put a switch in? This is really getting annoying so any help would be great. Drax240z wrote: Well my first suggestion is to be a bit more descriptive when you ask a question. I assumed a few things like we were talking high pressure here. I thought this was descriptive enough to say low pressure or that it was a holley blue pump....anyway... the wires arent hot any more but problem is not solved.(see last post) Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted April 15, 2004 Share Posted April 15, 2004 What kind of condition is the pick-up in? Gosh, It sounds like you are sucking air into the fuel system. Also, how close is the pick-up and return lines? I've heard of the return line causing airiation(sp?)yes, I have been drinking) problems when they are too close to the pick-up. Quote Link to comment Share on other sites More sharing options...
THUNDERZ Posted April 15, 2004 Author Share Posted April 15, 2004 I dropped the tank today to see if there was sediment build up blocking pick up but it looks new inside of tank. I figure I needed to replace those 30yr old hoses under there anyway. I blew out all connections to tank with air and rinsed out with water. I am running the fuel to carbs and then back through return line. Should I just dead head it? Wont that damage the fuel pump? AAARRRGGGHHH!!! Quote Link to comment Share on other sites More sharing options...
pparaska Posted April 16, 2004 Share Posted April 16, 2004 Thunder, my Z had a fuel problem like that, and it was a clogged fuel sock on the inlet pipe of the tank. I fixed that by adding another pickup tube with a new fuel sock (homemade). No more fuel starvation, except when the fuel level is low and I'm standing on the go-pedal. But I'm running EFI without a surge tank or EFI-baffled gas tank, so that's to be expected. I plan to fix that soon as well. Quote Link to comment Share on other sites More sharing options...
THUNDERZ Posted April 16, 2004 Author Share Posted April 16, 2004 Thunder, my Z had a fuel problem like that, and it was a clogged fuel sock on the inlet pipe of the tank. I fixed that by adding another pickup tube with a new fuel sock (homemade). No more fuel starvation, except when the fuel level is low and I'm standing on the go-pedal. But I'm running EFI without a surge tank or EFI-baffled gas tank, so that's to be expected. I plan to fix that soon as well. How did you know the sock was clogged? Did you have sediment in the tank? Quote Link to comment Share on other sites More sharing options...
pparaska Posted April 19, 2004 Share Posted April 19, 2004 Well, I check EVERYTHING else. And I found that the Eastwood tank sealer had started to flake off and intemittently clog the sock. I found that out when I relocated the fuel supply hose to a fitting I installed in the drain plug hole. After the car stalled many more times on a few short trips, and then started to leak a bit (thanks dcarrow for pointing that out at Mikelly's shindig!), I pulled the fitting from the drain hole and found it jammed with the sealer. After pulling the tank, I found large pieces loose on the bottom of the tank. Quote Link to comment Share on other sites More sharing options...
THUNDERZ Posted April 21, 2004 Author Share Posted April 21, 2004 Well this has turned into a saga now. I made an attachment to run fuel from drain plug hole and am still having the same problem. Fuel pressure drops off in a couple of minutes driving. If I close the restricter valve a little I can get it back up, but it ventually goes back down to 0. There is a little sediment in the new clear filter element before the pump, but it hardly looks like enough to plug it. This is driving me Fing crazy! Again my set up is... gas tank-filter-holly blue fuel pump-filter-triple carbs-gate valve(for back pressure)-return to tank. I must be doing something stupid...This is so simple yet It isnt working. HELP! Quote Link to comment Share on other sites More sharing options...
clint78z Posted April 22, 2004 Share Posted April 22, 2004 When it comes to wiring, heated wires comes one thing poor connection. If we go back to the basics of electricity. You 3A pump should have the correctly sized wire, you can calculate what size you need for the length. Now what if you only have one strand connecting the pump. That's right the wire heats up. Redo the power and ground terminals, get rid of corrosion. Check your relay too. Quote Link to comment Share on other sites More sharing options...
THUNDERZ Posted April 22, 2004 Author Share Posted April 22, 2004 ok I am going to start a new post since this one has changed direction from electrical to plumbing I think. Wires are not hot anymore. Quote Link to comment Share on other sites More sharing options...
Buzz Posted June 10, 2004 Share Posted June 10, 2004 HI: I'm having a similar problem with holly pumps,loss of pressure,and now the pump just stops.It over heats and shuts down on over tempature.same thing from fuel tank,to filter,to fuel pump,to fuel block,to triple webers.I've replaced the pump,lines,filter,put in heaver wires#12 way big enough!I removed the tank,boiled it acid washed it,resealed it!I did find loss of pressure on gauge may be dude to heat under hood.I installed a liquid filled gauge and it seems once it heats up it shows a loss in pressure even't though there isn't one.so I installed a non liquid filled gauge and it stayed constant.HUMMM! the pump seems to slow down after it warms up causing loss of pressure,and now just stops on over temp after about 4 miles.WTF!I emailed Holly's tec's But no responce.I may have to change the position of the pump to verticial.You shouldn't need a return line with low press.I tried that too.I just ordered a new WALBRO pump from JC whitney $50. turns on and off when float in carbs opens, It must have built in switch.I'm giving up on HOLLY CRAP!!!! Quote Link to comment Share on other sites More sharing options...
THUNDERZ Posted June 11, 2004 Author Share Posted June 11, 2004 I am pretty sure I found out what was happeneing in my situation. The gauge was not reading right. In reality I was pumping like 15 psi when it sad 5 and blowing open the needles in the carbs. There goes the pressure. I am not positive yet though. Quote Link to comment Share on other sites More sharing options...
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