Finally Found Problem Need your help

[Mustang64p]

1985 720 4x4 4wd 5spd.

Ok guys I figured out whats wrong with my truck but need your help to learn what to do to fix it. I posted earlier about my engine dying randomly and everyone said they would start with the fuel pump, well that is sorta the problem. Also the truck while running intermitently prior will no longer crank. Heres what I did.

1) Pulled fuel line off of carb cranked. no gas to carb. 2) pulled fuel line off of fuel pump cranked no gas. 3) hooked up fuel pump directly to battery worked like a champ. 4) hooked line back up ran off of battery fuel out at the carb like a champ

Now basically the parts work but my fuel pump will not run when i start it with a key. Now a couple times i turned the key up untill u crank and barely turned it past so that the engine didn't turn over but i did here the pump fire up for a few seconds tried to start nothing and couldn't really get it to do it again. Any thoughts? I checked wiring from pump all the way untill it goes into the passenger floorboard checked good, i also of course checked the fuse. nothing. Is there some mystery component that controls fuel pump at start up? all ideas welcomed and appreciated. Thanks in advance

Heres a link to previous post:

zerothread/428239

[seang]

Could it be a fuel pump relay?

[2kredz3]

I bypassed that whole s***ty system just a few months ago. (the PO had also done it but not to the extent that i did)

you can t tap off the radio (yellow wire i think) which ever wire gives switched 12v to turn on the radio. from there install a 30a relay and fuse block so when you turn on the ignition switch it kicks the relay on and turns the fuse block on. run a wire from the fuse block to the pump and then make sure the ground for the pump has a good chassis ground.

I dont know if i will have time to make a diagram of it for you, but i have a pic from when i first started building it (orginally for the electric fans)

[Mustang64p]

Thanks for the input. It turns out that it was the fuel pump relay. I popped a new one in and it runs like a champ. So much frustration for such a little part, but thats how it goes right?

Second Q anyone know where I can find a fuel filter that goes inside the fuel pump? Nissan doesnt make them anymore. Thanks for all your help and suggestions ODPL puts another Datsun back on the road THx!

[2kredz3]

Thanks for the input. It turns out that it was the fuel pump relay. I popped a new one in and it runs like a champ. So much frustration for such a little part, but thats how it goes right?

Second Q anyone know where I can find a fuel filter that goes inside the fuel pump? Nissan doesnt make them anymore. Thanks for all your help and suggestions ODPL puts another Datsun back on the road THx!

kwel, i have a universal fuel pump from autozone which doesnt have an internal filter. . .so it has a filter pre-pump. the fuel pump was 40 bux so if your looking to spend more then 50 on the internal filter i say swap the pump

[breadbox]

second that.