[19914x2]

For about a month my 1991 Nissan(auto , 4x2) would sometimes have a rough idle and sometimes stall as it slowed to a stop. Two days ago it refused to start after a 50 mile trip in which it ran fine. Engine turns over and I have confirmed the plugs are getting a spark. Have new air and fuel filters and checked for leaking vacuum lines. I checked stored trouble codes and got 55 which is normal operation. I have noticed one odd thing however, when I pull the fuse for the fuel pump to take pressure off the lines to change the filter, the engine will start and run until it uses up the gas left in the lines and rail. If I restore power to the pump it wont start. I would very much appreciate any ideas or help!

 

[zanegrey]

check relay on inside passenger fender fuse box..

 

[19914x2]

I checked the relay according to the diagram printed on the top cover. Applied 12 volts to 2 pins and after hearing the contacts click I read 12 volts accross the other two pins. Also I can hear the pump running when the ignition is on. Is there anything in the fuel line that could restrict flow when the system is pressurized but allow flow after the pressure is released? Thanks!

 

[4X4D21]

when you tried starting it did you pump the gas pedal to get the gas back through the lines?

 

[zanegrey]

crap in the tank..

the crap ( for lack of a better word) gets pick up as the pump is turned on,
the sock filter gets saturated and the clogs op.

when you let off the pump it releases al the crap and falls back to the bottom..

 

[19914x2]

Man I really hate to drop the tank to clean it out, but I dont know anything else to try. Thanks guys!

 

[zanegrey]

it is not really that difficult..

syphon most of the gas out first ..so it is lighter.

remove the rubber fill hose and vent tube from the filler spout by the tire.

becareful not to tear or break the smaller vent tube and filter and becarefule not to

damage fuel lines when dropping tank..

remove all bolts except one in the middle of the back side of the tank.. just loosen it..

jack the truck up about a foot..

with the tank mostly empty it will be an easy drop with just your hands..

good luck ..


remember it is gas so no sparks source ...

 

[19914x2]

Thanks for the advice on dropping the tank, will do it this weekend.

 

[CMax03]

when you tried starting it did you pump the gas pedal to get the gas back through the lines?

Pump the gas? This is fuel injection man.....I think it's a bad(intermittent) pump!

 

[19914x2]

Update on fuel delivery problem. Tank was pretty clean. Still no start after reinstall. I next installed a fuel pressure gage between the filter and the engine. To my surprise engine started and ran! Gage showed around 40 psi. I changed out fuel filter again on the chance that something may have lodged in the filter body and was sometimes blocking flow. Truck started and ran after removal of pressure gage and installation of new filter. Will see how it goes this week. Not sure if original problem with idle is solved yet or not. Thanks very much for the help guys! If problem returns , I will repost.