bad fuel pump??

[bmxr152]

Alright so my ex started running like crap a few days ago, It runs at an idle almost if it has a cam or something. really rough no matter cold or hot, and rough at throttle until at WOT around 3800 it clears up and runs perfect then when i let off and press the gas again it runs like crap, till i repeat the wot pull. i scanned it and got code 42r with indicates system is lean. So i changed the o2 sensor, cleaned the maf, IAC. Also the coil, plugs, wires only have 4k miles on them. Anything else i should look at or check? vacuum leak maybie or fuel pressure related? I just dont know why i would get full power and smooth running at around 4k rpm and it be rough and slow like a miss under that rpm? Please help
here is what i got from the fuel pressure test
26 psi key on engine off
33 psi engine on
40 psi vacuum line off engine on (no gas in vacuum line)

 

[Tbars4]

...This may be of some help for testing..
http://www.explorerforum.com/forums/showthread.php?t=221335

 

[bmxr152]

...This may be of some help for testing..
http://www.explorerforum.com/forums/showthread.php?t=221335

Yeah, kinda helps. I tried replacing my fpr with another spare one and it still runs like crap. You think only having only 33 psi while the engine is running can cause it to run bad and idle rough until about 3800rpm and then clear up. Also it took a while for the fuel pressure to come up when the key was turned. about 2 seconds to get to 28 psi. The pump kinda whines and makes some other weird noise but i dont know if that is normal or not?

 

[Tbars4]

...Your description sounds exactly like what Dannyboy's problem was when he started that thread...

..Your fuel pump should Whir up for about 3 seconds and not make any other noises..

..That thread has all the info you need to test but if you have already replaced yur fuel filter and the pump is making some noise while taking a while to prime up, I would guess it's your fuel pump...Doing those test would give you an better answer...:biggthump

 

[bmxr152]

Well i dont have leaky lines, or leaky FPR, and pretty sure injectors are not leaking because im getting a lean code on the scanner. i guess its either the pump check valve or fuel pump. Ok where is the check valve? could it be a fuel pump relay. Dannyboy never said what he did to fix his problem.

 

[Anime]

It the fuel pump sounds funny, or makes anything other than the usual whirr when priming, I'd agree with a replacement.

Usually it's worth it to replace the fuel pump anyway, especially if it's the original and has high mileage. You can get the whole pump assembly for ~$100, which is only slightly more than just replacing the pump itself, and completely worth it if the old assembly is all rusty and nasty, which it usually is. You'll need a lock ring too, since you'll probably destroy the old one getting the pump off the tank. Good time to replace the fuel filter, too. Just wait 'til the tank is low before dropping it, if the bolts aren't stuck too bad and you have all the parts, it takes just a few hours max to drop the skidplate, tank, replace the pump, and put it all together again.

Replacing the pump solved a LOT of running issues I thought were other things.

 

[Blacksheep Josh]

Just wait 'til the tank is low before dropping it, if the bolts aren't stuck too bad and you have all the parts, it takes just a few hours max to drop the skidplate, tank, replace the pump, and put it all together again.

Replacing the pump solved a LOT of running issues I thought were other things.

Who said anything about dropping the tank?!?!

http://www.explorerforum.com/forums/showthread.php?t=182160

I'm not sure if I'm going to drop or cut... I'm thinking about doing a disc brake rear axle conversion and new fuel pump all at once while I'm "down there"

 

[bmxr152]

yeah, i ordered a new pump so it should be here by friday. i pulled the new plugs out and found this interesting..
first pic is 123 cyls, second is 456 facing the block.

So is cylinder 5 running rich? bad injector maybie?

 

[WickedWindsor]

When you're idling, do you smell gas and see black smoke?
It could be running rich. A couple years ago, my main harness ground wire corroded which left the injectors running constantly leaving bad idle until higher rpm. New ground wire fixed it.
Just a thought outside the box!

 

[bmxr152]

yeah i do smell gas at idle. where are the grounds located? but would that cause just one injector to dump fuel?

 

[WickedWindsor]

It happened to me on the way to work one day and I didn't have time to fix it myself so I had to take it to the Dealer at the time.
For me, it was the big negative ground cable they replaced which comes attached with other ground cables on it from the dealer. One of the connections is for the injector harness. I guess once they became ungrounded, the injectors stopped pulsing and stayed on.