Just as the subject says. My car dynoed very lean, getting leaner the higher the RPMs over 3200, up to as high as 15.8:1. I have just borrowed a fuel pressure guage, what is the best method of checking the pressure. Key in on position/idle/WOT?

 

Ok, here are my results.
Turn key to ON position, pressure jumps to 39-40 psi. Start the car, which is already warm, drops down to 31 psi. Took the car up the street to WOT, jumps to about 34-35 til about 3000 RPM, then starts dropping til it reaches 20 psi at 5600 RPM. Not good indeed.

So my question now is: Is this absolutely my fuel pump going out due to my fuel pressure findings?

 

Since a stock pump is $220+, should I just get the Racetronix fuel pump kit from Thunder Racing? I believe I have seen this as a recommended kit on here. If so, do I just get the Assembly, in-tank wiring & installation hardware kit for $150? Is that all that is needed?

 

Changed your filter lately?

 

Filter was replaced less than a month ago at the dyno, didnt effect the AF. Actually it got a few tenths of a point leaner.

Dyno Runs
The 1st and 2nd runs are cutout closed, the 3rd with open, and the 4th with a new fuel filter. Set the smoothing bar at the top of the viewer to 0 and you can really see how choppy the runs were.

Also have a vid of the 1st and 3rd runs. Was Jan 31st, so car was covered with salt.

 

Yes, your pressure is very low. Are you getting any SES lights?

Could be injectors, fuel pressure regulator, or pump.

 

How do I check to see which it is? Is there a way to check the fuel pressure regulator, or the injectors, without removing them?

 

ttt

 

I will help you change the pump if you want.

 

Thanks for the offer Gary. I think I am going to do the access panel method for removing the pump. I'll probably be doing it at Steve's (Shiznit) garage next Friday here in Louisville, you are more than welcome to ride up and help if u want. I am going to go ahead and order the Racetronix kit so whenever I do more mods, my pump will be able to keep up.

Still no answer to the question on how do I check the fuel pressure regulator. I want to be 100% sure it is the pump before I order this thing tommorrow, I dont want to replace it and still have the fuel pressure problem.

 

I had nearly the exact symptoms you experience. It was the pump. I put in the Racetronix kit and it's been perfect.

 

I'd suggest you swap fuel regulators with a buddy or just invest in an adjustable fuel pressure regulator. It's a lot easier to replace than the fuel pump and certainly could be the cause of your low fuel pressure. I don't know of an easy test of your stock fuel pressure regulator (other than swapping it for a know good one).

 

Well I checked the vacuum line on the regulator, and it was dry inside, and fuel pressure at idle went from 31 to about 39 psi with the vacuum line removed, which is supposed to simulate WOT. However, when you actually drive the car to WOT it, pressure drops to 20 at about 5500 rpm. I went ahead and ordered a new pump this morning JIC. I have someone who will give me a stock regulator if that doesnt cure it. Hopefully its just the pump.

 

This can really effect it. I change my filter every other oil change.

But if the filter doesnt fix it I'd go the Racetronix rout, very nice peice, almost a complete drop in.

 

Well, finally got the Racetronix pump installed, also did new plugs, oil/trans fluid change, and it now is at 41 psi when turning the key to ON, and up to aout 44 psi when removing the vacuum from the fuel pressure regulator. Tommorrow I will check the psi at WOT on the road, at least if it ever stops raining. I think problem is solved, it feels MUCH smoother and a little stronger already.