Knock Retard top of 2nd, fuel pressure dropping off

[monteperformanc]

Last time I was at the track I was getting a few degrees of KR. So I installed a Powerlogger to see what was going on. I made a quick test hit and I see fuel pressure dropping off towards the top of 2nd gear. It goes from around 70 to low 60's. This is obviously causing a lean condition but what could cause this to happen?

The map sensor is saying 30 psi but the mechanical gauge is saying about 26 psi. Fuel pressure is 40 at idle, 46 with vac line off and plugged.

Car is basically stock with Walbro 255 lph, hotwire, 60# injectors, E85. I have an Accufab regulator and I have heard they can be problematic, but not sure if that would cause the pressure to drop off.

Any help would be appreciated as I don't have any experience with tuning. PL file attached. I see things going south at around frame 661.

 

[TexasT]

Fuel filter new?
Injectors fresh?
Something wrong if the pressure is dropping off. Need to tend to that.
Pump might not be up to the task? Have you measured the voltage at the back of the car?

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[monteperformanc]

Fuel filter is about one year old, less than 1000 miles. Injectors are 3 years old. Pump is 4 years old.

 

[TexasT]

What about tank fuel level? Is it below 1/2 tank? Do you have a stock tank with the baffle?

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[monteperformanc]

I had just filled the tank. And yes it is a stock tank. I'm thinking that either the voltage at the pump is low or maybe the strainer on the pump is clogged/dirty? Or is this pump just out of steam? I thought it would be enough to max out 60# injectors but maybe not.

 

[RmvBfrFlght]

Your out of pump. The injectors flow more then a single 255 lph Walbro at 76 psi (base + boost) can provide. Note that you are also out of injector with the DC% over 100.

RemoveBeforeFlight

 

[monteperformanc]

Your out of pump. The injectors flow more then a single 255 lph Walbro at 76 psi (base + boost) can provide. Note that you are also out of injector with the DC% over 100.

RemoveBeforeFlight

I think you are right. I guess I just wasn't expecting to run out of pump already as I am only in the mid 12's.

I am looking into the DW 300 pump and 80# injectors.

 

[Mr.Spool]

I guess I just wasn't expecting to run out of pump already as I am only in the mid 12's.

e85 requires a lot more fuel than gas,the 60lb injectors can go a lot more but your out of pump or pump isn't flowing what it could due to age or fuel or lack or volts.

 

[Mr.Spool]

Any help would be appreciated as I don't have any experience with tuning.

don't run or beat on the car till the fueling is right.

 

[Eric Stage I]

You don't have the greatest voltage, so the pump output will be a little less. If you want to push the pump a little further, you could use a volt booster.

Your wideband reading doesn't look right, and may be reading leaner than it really is. What kind is it? Notice at idle, your stock O2 shows 800's, but the wideband shows 19:1.

 

[monteperformanc]

I thought the afr looked too lean even before the pump pressure started dropping. It's an innovate LC-2 and its in the test pipe a few inches behind the down pipe.

I have a volt booster that I haven't installed yet but I will give that a try.