98 frontier HELP

[Nickd447]

I have a 98 frontier. I bought it a few weeks ago and in would run perfectly until it warmed up then it would run ROUGH and stall out. It threw a code for a cyl 4 misfire and that it was running lean. Since then I changed the front o2 sensor, maf, fuel pump, and fuel level sending unit. Now my fuel pump won't activate at all (which was why I bought the sending unit) and I'm getting aggravated with this truck, I looked for the fuel pump relay which I couldn't find, checked the fuel pump fuse and its good, I plugged both the old and new fuel pumps in and neither are activating. What could the issue be?

[Desert Rat]

Fuel pump itself may have died. Not unheard of in a 16 year old vehicle. Since you were in there replacing the sending unit anyways, did you inadvertently disconnect something else? Is the gauge at least working?

As for the original symptoms, those could stem from something so simple as an EGR clogged up with carbon. Remove the EGR and inspect it to see. The carbon can build up in these things restricting or cutting off flow, and she'll stall on you. Did you get the truck running long enough before the fuel delivery issue to know if you cleared up that Cylinder 4 misfire?

These KA motors are pretty simple and usually dead reliable. Just gotta find the gremlin.

[Nickd447]

I put a brand new fuel pump in it before I did the sending unit, as for the wires none of them are unplugged, but I haven't had it running well yet. I put the new o2 sensor on it and cleaned the old maf and it ran great for maybe half an hour. I drove it around then it started acting up again and quit on me. Also my gas gauge didn't work before I replaced the sending unit but it does work now. I'm just more worried about getting the fuel pump to activate, I know it isn't bad because its brand new

[Desert Rat]

Get a multimeter and test the power leads to the pump to see if you have juice going to it. A bad part new in the box isn't unheard of. Is it an aftermarket or OEM part?

You can check the EGR as I'd suggested for free.

[Nickd447]

Thanks for the help, I figured out the problem yesterday. The maf did fix the rough running but my issue was that my power wire broke right behind the plug underneath the cab. I just spliced the two wires together and taped it up and now it starts runs and rides perfectly.

[Desert Rat]

nice.
always the simple stuff.