Where to start?

[baby6]

OK, so I cannot figure this out myself so i need everybodies expertise. I have an 86 gn with slight mods, and i have been having an intermittent fuel fluxuation issue/ o2s leaning out at WOT in 3rd gear (from high 700s to low 700s in third). I dont know if these are related to each other or not but i dont like it. I changed out the pump and tank and the fuel pressure was solid, then i was adjusting my pressure and it started bouncing again. replaced a ground in the rear and it doesnt do it as much.....
i ran power straight to the pump and pressure was rock solid, no fluxuation. Are there any grounds that are correlated to the pump on the motor? I also bypassed the hotwire kit and still same issue so its not the hotwire...please help!

 

[SHADOWII]

Is your alternater output fluctuating? Are you able to moniter the voltage, by p/l or voltmeter,etc.? Are you using a volt-booster? What's the condition of the fuel pump relay, sometimes the coil gets weak or low voltage can cause an issue.
Any codes?

 

[Reggie West]

The Hotwire kit relies on the factory grounds to supply proper grounds to the pump. They have been found to be marginal at best.

I would suggest running a ground wire just as thick as the Hotwire in the kit ( don't know the size sorry ) from the battery right to the ground wire to the pump on top of the tank. Solder it in.

It's getting to the point with these cars that any mods made have to be ground to the battery. The age of the cars and so called repairs or mods done to the cars are hard to figure out sometimes.

Shadow is right I would check voltage under rpm at the alternator too but wiring is a pain when it's not right.

 

[baby6]

I just put an alternator in a few days ago, and its very possible that this one is bad as well, at wot it gives off a burning smell, I checked voltage at the battery while on though and it travels anywhere from 13.4 to 13.8.
I believe its a ground so I will run a ground from battery to pump, and I will check the condition of the relay. Any other suggestions?

 

[Reggie West]

You need some way to check the alternator under load. A parts store might be able to help. At the very least you can use a voltmeter. Dtstt the car and turn on the AC. Rev and hold at 2000 rpms. Check voltage at the battery and check at the back of the alternator. See if you have a drop in voltage. You can also check the pump in back for voltage. Be very careful doing all of this. Keep fingers and toes intact.