5point1

I have a turbo charged Mach 1, built motor with return style fuel system.

Magnafuel 750 pump. 1300 cc Injectors. -8 feed -6 return. 18psi. Glenn's sleeper tank (sump in the front, hidden).

For some reason my car keeps going lean around the 3.5k rpm mark, which at that point, it's only making 200ish rwhp and pretty much no boost, since the precision 7675 takes a bit to spool.

When we command more fuel, through the tune, nothing changes. Still the same lean AFR.

Fuel pressure is normal the whole run, going from 42 to 44ish psi, from start to 3.5k rpms.

We thought the injectors might be clogged. Pulled them and flow tested them... They are perfect.

I don't know why its not putting in more fuel. The regulator is connected after the rails, right before the return line. Any help or ideas would be very appreciated.
Wisdom is simply the awareness of your own ignorance...
HAVOC
3.4L Whipple

Derf00

An in-line pump? Where is it installed? It's possible to have the pressure correct but the flow be insufficient so you'd starve the engine at higher RPM. Im curious why you went with an in-line pump vs an intank upgrade?

5point1

It's a magnafuel 750 external. It's an a return style fuel system utilizing a glenn's sleeper tank, with front sump. It's not an uncommon set up. I shouldn't be having issues at 200hp.

Here is what the graph looks like currently.,

Derf00

yep, way out of my wheelhouse for experience/knowledge but I'm still going back to a feed issue.

Here's an older thread from a different forum discussing their setups with Glenn's sleeper tank. I noticed they make mention of fuel starvation as well as having multiple in-line fuel pumps to keep the flow up.

http://forums.corral.net/forums/turb...wer-700-a.html

Also, what size MAF are you running? You could be outflowing it's capabilities so the PCM cuts the fuel.

5point1

I am running an SCT BA 5000 stot style MAF with a JMS MAF Extender. But I'm not even in boost at that RPM. Even a stock MAF wouldn't be pegging at that rpm.

Derf00

Agreed, that leaves fuel delivery or something that would affect fuel delivery.

From what I've gleaned 8 feed/6 return is more than sufficient in size to handle the volume needed for high HP applications up to the limit of the pump, let alone before you get into boost.

I'm tapped on potential causes or sources of the fuel cutting out or the power dropping out like that at 3500 RPM.

Have to see if any of FI gurus comment.

5point1

Posting this as an update/fix:

A tuner I was talking to on Facebook told me this:

"Aircharge Anticipation logic. Turn it off Or get your load with failed MAF table correctly reading the load the engine is reading. I've had this happen and three different builds. 03 Mach. 03 Mach. And 02 GT. Every time adjusting the LWFM table correctly to represent what the engine is actually seeing for load has fixed it For starters just to see if that is the problem, take your LWFM table everything above 1 load change to 1.9"

After giving that info to my tuner, this is what he replied:

"I have good news! Your guy was correct. It was flipping over to the failed MAF table. I still do not know how that is possible unless the MAF adaptation switch isn't actually connected to anything. I don't have time to finish the tune today I will say that it is running very strongly."

PROBLEM FIXED!!

Derf00

Nice,

let us know what numbers it puts down once it's like it should!

5point1

Sigh... my McLeod RST started slipping before the tune could be finished. But at least we figured out the fuel issue...