Fuel Pump Getting Weak?

[Scoobum]

This chip is loaded with 28 lbs of fuel. Was out testing last nite at the track with the new ignition module. Let the car get well into high gear. Laid into it. Fuel pressure at 60 PSI at 20 lbs boost. Came back to the trailer and checked the PL file. 02's at 772 on default...WTF. Threw 15 percent high gear fuel at it. Went back out...let it get well into high gear...and laid into it. 02's at 823. Went out for a 3rd time. Jumped on it off the line and kept an eye on the knock gauge through the 1/8th. Checked the PL file and 02's were just a tad over 800 at the 1/8th. Ambient air temp was 85 degrees with the humidity at 45 percent. Fuel pressure is 1 for 1...but with the 02's low...this pump is weakening. 02's should have been well into the 800's on default at only 20 PSI...with 28 lbs of fuel loaded into it.

[Steve Wood]

something is changing the laws of physics.  If the fuel pressure is there, then the volume is there.  Gonna be hard to blame it on the pump

Unlesss the gauge is bad

[Scoobum]

Steve, I'm not hearing the pump come on as loud as before...you can barely hear it when you turn the key. PL file shows the 02's fall off drastically for a split second when spooling it up on that last run. 60 PSI doesn't make any sense to me either. Fuel filter is one year old. Better call my buddy at the speed shop and price a new fuel pressure gauge as well. This car is driving me nuts.

[Scoobum]

Two things that happened at the track last nite. I drove the car around the return road to bring it up to temperature. As I let my foot off the throttle to turn around...it shut off for no reason. Started back up without issue. I noticed the fuel pressure would go to zero when shutting the car down a couple of times...normal ly it stays at base pressure. Check ball fukd...or something else?

[TexasT]

The fpr might be getting flakey. Might need a new rubber in it.
I'd put a new filter on it for giggles. A year is a long time.

[Steve Wood]

yes, that sound like the check ball. 

If the fuel pressure drops any after the boost comes up, that is lack of pressure because the pump is not delivering the volume to maintain the pressure.

If your base pressure is 43, then the pressure should have gone to 63 for 20# of boost and stayed there.  If it goes to 63 and falls back to 60, that is a sign of a weak pump.

Most of these gauges are accurate to plus/minus 5% and some are 10% (or worse).  They get expensive fast as the accuracy rating goes up.

And as Rich said, sometimes the regulator is flaky as well.  It is really hard to know what is going on due to the variables.  If the voltage drops one volt, the pumps can lose 25% of their volume as well.

[Scoobum]

Thanks for the input guys. I picked up a new fuel filter today and a pump should be here Wednesday latest. An AFPR would have to come from the lower 48...so we're looking for a 2 week wait if I need one. With the car shutting off for no reason, the check ball fukd, the 02's taking a quick drop on the spoolup and lower than normal 02's at WOT on only 20 PSI with 28 lbs of fuel in the chip with a crapload of fuel tossed at it in high gear makes me think the pump is failing.

[Scoobum]

I'm gonna check for the voltage when the 02's dropped on spoolup on PL. If the volts fell off...then we have a different issue.

[nocooler]

Brad you need this pump http://www.racetronix.biz/itemdesc.asp?ic=FPS%2DG7W450EQ&eq=&Tp=

[Steve Wood]

I would think that pump would need a larger return line??

[Scoobum]

That's in American dollars...so add 30 percent. I'd need the bigger line for the return. Jack has the quick disconnect set...but we're into even more money. I'd love to have all this stuff...but the funds just aren't there. I have several people helping me behind the scenes. If it wasn't for them, I wouldn't be able to race at all. I'm not complaining... but I have to nickel and dime everything...t here's no free lunch. There's no one else racing a TR up here every weekend...for good reason. Parts are tough to come by...and add 30 percent to everything...p lus shipping.

[Scoobum]

Battery voltage is steady when the 02's dropped spooling it up and at WOT. 13.1 spooling and 15.2 at WOT with the Caspers volt booster.

[reality]

http://www.racetronix.biz/itemdesc.asp?ic=DPA-510&eq=&Tp=


http://www.racetronix.biz/itemdesc.asp?ic=RXP340M&eq=&Tp=

[earlbrown]

Do you know for sure that you have a 30R10 hose inside the tank?

If your short section isn't rated for submersion, you might have a cheap and easy fix.

[Scoobum]

Do you know for sure that you have a 30R10 hose inside the tank?

If your short section isn't rated for submersion, you might have a cheap and easy fix.

Anytime I do a fuel pump change it's always the complete kit from Jack at Racetronix.