jhennessey69 Posted July 5, 2015 Share Posted July 5, 2015 Hey, I have a '78 280z, with a fresh l28et and ms3. I recently got it running and decided to put a walbro fuel pump, aeromotive afpr and aftermarket rail on it. I got the car driving around with a decent air to fuel ratio. It will hold a solid 40psi for a while driving it and all of the sudden it drops as I get into boost. I'll be driving the car and all of the sudden it leans right out as I put the pedal down. Even just revving it in my driveway it drops off from 40 to 0 in about 2 seconds. The pump seems to be fine but does start to whine a tad more as this happens. I have it wired to the stock setup. I have also bypassed the whatever valve is beside the stock pump. It seems happens intermittently and I don't know why. Any help would be much appreciated! Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted July 5, 2015 Share Posted July 5, 2015 Had similar situation in the past, and it was a dirty fuel tank...crud would get picked up into the pump and clog the fuel filter...I acted intermittent as well. regards, Mike Quote Link to comment Share on other sites More sharing options...
rags Posted July 5, 2015 Share Posted July 5, 2015 I went crazy troubleshooting a situation just like this and it turned out to be the stock wiring to the pump. Seems it would heat up enough when the pump was running to increase the resistance in the wire effectively shutting down the pump and reducing fuel pressure. A temp wire to the pump and letting it run in the driveway while monitoring fp will tell you if your wiring is ok or not. Joe Quote Link to comment Share on other sites More sharing options...
TimZ Posted July 5, 2015 Share Posted July 5, 2015 Could also be plugged tank vent - does the problem go away if you loosen the gas filler cap? Quote Link to comment Share on other sites More sharing options...
jhennessey69 Posted July 5, 2015 Author Share Posted July 5, 2015 Had similar situation in the past, and it was a dirty fuel tank...crud would get picked up into the pump and clog the fuel filter...I acted intermittent as well. regards, Mike I actually just filled and drained the tank with some fresh fuel a couple times to get out the little bit of crud that was in it. I did it before I put the new pump and fpr in but neglected to put a new filter in... I suppose that's where I'll start. Thanks Mike I went crazy troubleshooting a situation just like this and it turned out to be the stock wiring to the pump. Seems it would heat up enough when the pump was running to increase the resistance in the wire effectively shutting down the pump and reducing fuel pressure. A temp wire to the pump and letting it run in the driveway while monitoring fp will tell you if your wiring is ok or not. Joe I was wondering about this, I did a long search trying to figure out if I should rewire it or not and most of the answers I found led me to believe the stock wiring would work fine. I'm definitely going to give this a go though! Thanks Joe Could also be plugged tank vent - does the problem go away if you loosen the gas filler cap? I actually tried that last night, the first time I popped the cap it immediately stopped. I gave it another go after letting the car sit a while and then running it again and it made no difference. Thanks Tim I really appreciate the replies Quote Link to comment Share on other sites More sharing options...
jhennessey69 Posted January 29, 2016 Author Share Posted January 29, 2016 It turned out to be the fuel pump... switched it out for a Bosch 044. Solved the problem Quote Link to comment Share on other sites More sharing options...
240zdan Posted January 29, 2016 Share Posted January 29, 2016 (edited) Experiencing a similar issue when i Run below 1/4 tank on hot days. Also running a walbro 255. I am going to try a Holley Billet EFI pump next. Alot of people have reported issues with the walbro 255 not coping with heat well. Thing gets noisey as hell when it happens too. I laugh when people say its normal Walbro whine when it happens. Not when your afrs lean out 1 full point, your fuel psi drops 15 psi, and you knock like mad.... Edited January 29, 2016 by 240zdan Quote Link to comment Share on other sites More sharing options...
Chickenman Posted February 6, 2016 Share Posted February 6, 2016 (edited) Note: One important thing regarding new fuel pumps. The original Nissan pump was a roller vane style. Those can pass a surprising amount of dirt and crud with minimal damage. However, most aftermarket pumps are now high efficiency Ceramic Turbine pumps. Thye can build more pressure and volume than a Roller Vane pump and are quieter. However, these Turbine style pumps ( Walpro, Bosch 040/044, Aeromotive, Airetx etc) have extremely close tolerances inside and will not tolerate ANY dirt. You absolutely must install a Fram G3 filter between the fuel tank and pump before running the pump. Failure to do so will result in scoring of the Turbine impeller and loss of pressure in very short order. Airtex has various technical articles on the different types of pumps, and why clean fuel is so important with the new style pumps. Edited February 6, 2016 by Chickenman Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 6, 2016 Share Posted February 6, 2016 I took one of the newer style pumps apart and it was the roller vane type, not :"turbine". Same form as the typical Bosch or Airtex pump. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.