fuel pressure on a stock 420a

[xsboost]

I did a search but couldn't find any thing specific for a 420a n/t. I've always had 4g63 eclipses and talons so I know little to nothing about the 420a. A friend of mine recently bought a 95 RS completely stock except an aftermarket intake pipe. His car started idling extremely rough and it drives like it's horribly misfiring. He replaced the plugs and wires with no result. I asked him if he's throwing a CEL he said no but I found out his light doesn't work (he's supposed to be getting it checked out today to see if he has a CEL on). He took the car to his cousin's shop and checked the fuel pressure a day or so ago. At idle he's getting 28psi and at 4000 rpm he's getting a max of 32psi. Since I don't know anything about the 420a I have no Idea what the fuel pressure is supposed to be. Can anyone tell me? Also, can low fuel pressure make it run like this or could misfiring adversly effect the fuel pressure?

 

[silvreclips]

That fuel pressure is to low. I believe it should be around 45psi. maybe a little less at idle. That would cause the car to run lean so yes that is probably the problem with his car.

 

[xsboost]

Thanks

 

[Locke]

No less than 45. Ideally, close to 50psi, regardless of vacuum. 2gnt's do not use 1:1 FPR's like the 4g63.

 

[xsboost]

Okay. We're going to change out the fuel pump and filter tomorrow (or I guess technically later today) and see if it helps. Also, he found out today it's throwing a code for an O2 sensor, he didn't specify which one. We'll get it figured out. Thanks for the help.

 

[OneSlowL36]

Sorry if this is a little late but should the fuel pressure vary between key on engine off and key on engine on?

 

[VelocitàPaola]

Sorry if this is a little late but should the fuel pressure vary between key on engine off and key on engine on?

Yes.

With the key in the "on" position but the engine off, the fuel pump is only pulsed for a brief moment. The fuel pressure should be relatively high, but perhaps not as high as 45-50psi. Also, since the fuel pump isn't on consistently, the pressure will slowly be released.

With the engine on, obviously the fuel pump will be on, and the fuel pressure should be at its normal operating level.

 

[OneSlowL36]

I was reading about it and AllData said about 58 (I think)with the key on initially and its supposed to drop into the 40s when you start it. I did a fuel pressure test and I had full pressure key on and it didn't go down when I started it. Fuel pressure regulator gone bad?