What must I log to tell if fuel pump is maxed?

[Plimmer]

Need help figuring out if my fuel pump is maxed out. I have a twin turbo 2015 coyote Mustang at 10psi of boost. The stock fuel pump has a VMP boost a pump fitted. What PID should I log in the scanner to tell if my fuel pump has reached the max it can deliver?

Reason I ask is when I increase boost a few psi the fuel trims go really high and lambda leans out as the fueling tries to keep up. My MAF might be off, but the load being reported for this amount of boost seems really high. At 10psi I'm getting loads over 2.1, which makes me think that as I've increased the MAF flow for that period point, I might actually be compensating for poor fuel flow.

[06300CSRT8]

That is actually exactly how you can know. You can log the fuel pump duty cycle but in most cases you will either see 49% or 99%, which it will show everytime you go full throttle.

The only way to know if you are out of fuel pump is to see fuel pressure drop in the rails (needs a mechanical gauge) or as you have seen, no response to airfuel ratio per the wide bands even when you ask for more fuel. This assumes you have a large enough injector as well, since that will have the identical "no response" to additional fuel if you are out of injector as well.

What size turbos?

[15PSI]

You need to use a mechanical fuel pressure gauge. The fuel PID will not provide any evidence with the stock returnless system.

[tbrtuning]

What is it these pumps and a voltage booster are considered good to? Something like 700 whp I believe. 10 psi with two decent size turbos and much timing at all with put an 11:1 Coyote right up there. Depending on injector you'll see it run out of fuel sooner because some can max out and deal with the dropping rail pressure for longer.

[06300CSRT8]

Very in depth testing by Whipple and others show a completely unmolested factory pump with no booster is good to about 650whp

Add a voltage booster and usually SAFE to roughly 750-775whp or so, but that's really pushing it, we see most guys make the switch (on 93 octane) to a dual pump type setup at around that 730-750whp mark.

[Bob_Kurgan]

our 2017 Mustang GT has id1300s and a BAP and has made 897rwhp through an auto on e85... it has also trapped 150mph in the 1/4 ..

[Plimmer]

OK, thanks, these comments are all helpful. I don't think my fuel pump is going to get me to 897rwhp. Car is using twin comp 6262 turbo's and ID1050x injectors, and as an example on Sunday I tried a 14.5psi test hit (I've got 10psi working OK) with the following from my scanner:

Lambda 0.96 and dropping to 1.00 as rpm climbs, when I'm asking for 0.82
Fuel pump duty cycle is 49%
Injector pulse width is 21.3 ms at 6,000 rpm
Absolute load is 287%, but does not make sense for this boost
Total Fuel Trims are 7% and climbing as they seem to be trying to keep up

Never been on the dyno, but its looking like the fuel pump can't deliver more with these injectors