Fuel Pump Limits and RPM

[SixOn66]

I see flow rate charts for fuel pumps and injectors. They state GPH at a PSI. How does RPM figure in to those charts.

OK heres what I did.
I went from 868's to 55 pounders. At 5000 RPM my o2s go to nothing, nada, 0. The car noses over I lift the pedal and let it shift it picks up and o2s go back to 850 until the trap and 5000 RPM and no 02s.

On 10-5 with the 868s 5400 RPM was no problem at all.


MJH

 

[SixOn66]

Any Ideas?

 

[azgn]

rpm has very little to do with fuel pressure......your fuel pressure should increase as a function of boost...lb for lb

I ASSume you have a chip calibrated for 55's? (and the required ecm mods?)

How much Boost were you running at 5400 rpm?

 

[SixOn66]

I was using a reds 93 chip and was at 15 pounds the first run with 50psi static FP. Second run 16psi and 46 psi static. The o2s were rock steady 850s up to 5000.

MJH

 

[azgn]

at 15 lbs boost, you should be just fine with a 93 chip....more than likely you are just running out of valve spring at 5400 rpm

how old are they?

think Red wants 45 lbs pressure, line off

with a stock set up, 5,000 rpm is about the limit

 

[SixOn66]

I'm not sure about the springs, I'll have to ask Denis. With the 868 I hit 5300 and did not have a problem.

 

[azgn]

850 is waaay rich assuming you are at wot......so you could be drowning things in fuel also

chip IS for 55 lb injectors and ecm modded, right?

 

[mgmshar]

The O2's going to zero and the car nosing over could be an indication of mis-fire. If the car is mis-firing, lots of unburned air goes into the exhaust. So, the O2 sensor shows very lean (i.e. zero). Might want to look at ignition stuff (plugs, coil, module, etc.).

Are your other sensors giving normal readings when this happens? If not, you might have a loose ground, positive power cable rubbing, etc.

Just some thoughts...

 

[SixOn66]

AZGN, Yes I have a Modded ECM and chip for 55's. I know 850 is way rich. I did not want to run less FP on the first run. I wanted to start rich and work my way down.

mgmshar, all the other sensors looked good on the 1-2 later in the run the ECM did shut off and reset its self.

MJH

 

[SixOn66]

OK, I did a search again and found suggestions that the O2 might be the problem. I have a Denso 4 wire that I can swap in easily enough.

Question: would a 307 flow enough for 55's? either 50 psi static or 46 psi static running 16 psi boost.

Direct scan files below. Any help would be appreciated.

DS Run 1

DS Run 2

Thanks

MJH

 

[azgn]

you are getting close with a 307 at 50+16.....seems like the bypass kicks in at 65?

put a gauge on it and check it at wot

 

[d0n_3d]

i run 45 psi line off with 50's and about 25 lbs of boost...

so at WOT it's right around 70 psi...i have a hotwired walbro 307 pump...

 

[azgn]

50's need less volume than 55's at the same pressure

not sure on the bypass, maybe 70 psi, but it is lower than a 340

 

[87GN_70GS]

If the 307 pump is out of the car, just shim the pressure relief to make it the same as a 340.

 

[SixOn66]

I already got the 340 and put it in last night. I think I am going to put the 307 in the T though.

The pump that I bought had a white Borg Warner sock with it (kinda flat and wide). It would not fit like the 307. I had to stuff the sock between the bottom of the hanger and the pump, instead of hanging down below the hanger. I put a wire tie around the pump and the hanger to keep it from moving around. So, who is going to tell me how wrong that is and I should do it a different way.

Thanks

MJH

 

[d0n_3d]

Originally posted by azgn
50's need less volume than 55's at the same pressure

not sure on the bypass, maybe 70 psi, but it is lower than a 340

tru

 

[DCVING 6]

Originally posted by SixOn66
I already got the 340 and put it in last night. I think I am going to put the 307 in the T though.

The pump that I bought had a white Borg Warner sock with it (kinda flat and wide). It would not fit like the 307. I had to stuff the sock between the bottom of the hanger and the pump, instead of hanging down below the hanger. I put a wire tie around the pump and the hanger to keep it from moving around. So, who is going to tell me how wrong that is and I should do it a different way.

Thanks

MJH

On a side note, did you remove the pulsator on the factory hanger?

 

[SixOn66]

I think I took it off when I put the 307 on.

MJH