sparkycon

Car starts and idles fine. I replaced the fuel pump about a year and 1/2 ago. The pump started getting louder and louder but worked fine. Today I was driving at it started bogging down and backfiring. When I came to a stop, of course, it idled almost perfectly. But any push on the pedal immediately bogs it down. The buzzing noise of the fuel pump also disappears when I press on the pedal. One other thing, I just started it up and drove it around the block after it sat for a couple of hours and it ran much better. Any help woul be greatly appreciated.

pnoyslimm

sounds like you have an o2 sensor going bad. or your air filter is dirty and needing to be replaced. but im betting its your o2 sensor. im new to the 280's so i dont know if it would throw a code for it. but from experience ive had some cars throw a code and some wont. imo, replace o2 sensor if it hasnt been done yet already. go NGK or DENSO brand. try to stay away from BOSCH.

WildmaN

All I can say is, check all your connectors, and make sure they are clean. You can use WD-40 and a toothbrush. Then let them air dry, and see how that goes. Dirty connectors can cause all kinds of havoc. Good luck.

sparkycon

I've read in other threads with similar problems that cleaning the AFM helps including the connectors, is it worth the effort?

NismoPick

This.

It's worth it if it's the problem. We have a how-to in the Gen Tech Area.

Also check the ignitor... common cause of "warm shut down".

sparkycon

Ok, sorry for being such a dope, but I could not find ignitor anywhere in the Rock Auto parts list. Is that the same as the ignition control module? I'm sorry, I'm car challenged. Electronics? Those I know.

NismoPick

Yes.

https://www.zdriver.com/forums/280zx...m-36014/page2/

sparkycon

I cleaned the AFM and it did not help. I guess I will look at the 02 sensor and the igniter next. I replaced the plugs, but have not had the timing set or the parts in the distributer replaced since I have had the vehicle. That probably has something to do with it too...

zedsdeadbaby

A fuel pump that suddenly starts making noise, you don't look at your AFM.

Likely your fuel pump is overheating. Time for a new one. An in-line pressure gauge to verify fuel pressure when the bogging occurs would put the nail in the coffin.

Check your tank for crap while you're in there.

sparkycon

The fuel pump is relatively new (maybe a year and 1/2), and it's been louder than normal for about a year. Maybe it's defective. Thanks I'll look into that...