Hi, in my intro post I stated that we are having fuel problems with the Dads 90 mustang. We do not want to drop $1600 on the Vortech fuel system up grade and were hoping maybe there was a better solution.

When she was put on the Dyno, the tuning shop stopped the pull at about 4k rpm due to the lack of fuel and lean conditions on a FI motor. At 4k rpm we saw 400 rwhp on a built AOD trans.

Here are the specs, maybe somebody can see what we are missing.

GT40 upper/lower intake
Crowler E40270 cam I/E 293 w/ 533 lift
Rocker Arm ratio 1.6
World Snr heads
4340 H beam rods
8.5 to 1 JE pistons
30thou overbore
Block and heads have been o-ringed
Crank- 28 ounce balance
331 stroker
42lb injectors
Ford 255 LPH in tank fuel pump
Vortech 255 LPH in line fuel pump
Vortech S-trim charger at 10 psi
MAC longtube headers, H-pipe, and 3 chamber Flow master mufflers

fuel lines and fuel rails are stock.<next on the to do list>
has Vortechs self adjusting FP regulators

runs out of fuel on the 1/4 but still turns 11.33 at 127mph. This should be a 10 second car easy.

Dads Car in Action---IGNORE TOW PACKAGE-----

thanks for any input you guys provide

 

I was going to ask but saw it in the video....the first thing you need to do is ditch that FMU! You don't need it and that could/likely is your problem.

My own '88 LX had an S trim and GT40 intake just like that one with 36 lb/hr injectors through an Art Carr AOD and it made 413 HP/ 497 TQ at the wheels at 10 lbs of boost out of a non stroked 302 with a perfect A/F ratio....and stock fuel lines, stock fuel rails and a 255LPH intank pump with a Vortech T Rex external.

Also one I built for a customer was a 331 with seriously ported Dart Sr. heads, Anderson B cam, GT40 intake, Vortech S trim....stock fuel lines, 42lb/hr injectors aftermarket fuel rails, 255LPH in tank pump with Vortech T Rex external and it made 507 HP/498 TQ at the wheels through a 5 speed with a perfect A/F ratio

Both these cars had NO FMU.....

Just trying to save you some money.....

I've built a lot of other cars with aftermarket lines and rails but these were 2 good examples similar to your setup .

 

So the stock fuel rails and lines should be good?

Excuse my lack of knowledge here but what does the acronym FMU stand for?

FMU: Fuel management unit?

 

The stock fuel lines/rails are not causing your limited HP number....your combination is capable of far more and you will likely need to upgrade if you plan to make much more than 500....but you also run into other issues there like making the block live shortly past that HP level....tuning is key but the stock blocks have a history of cracking around 550HP.

Keep in mind with fuel lines/rails that you can only flow as much fuel as your smallest diameter...so installing aftermarket rails will gain you nothing if you are still running stock fuel lines.

As far as FMU it means Fuel Management Unit and it is the round unit you have located on the passenger side inner fender. It looks like this.... But may be a different color...yours appears black in the video.

 

Also you didn't mention it but you DO have an adjustable fuel pressure regulator on there don't you?....and a gauge so that you know what your Fuel pressure is?

 

Yes we have the same FMU but its black and is set for 42lbs injectors. And yes there is an adjustable fuel pressure regulator on the fuel rail, and a gauge

idle is at 36lbs goes to 42lbs for a couple of seconds and then drops to 30 before he gets out of the throttle.
This is with slicks on, on street tires, the problem is not that bad because the street tires are unable to put a load on the motor like a set of slicks or dyno will.

 

I know you can bypass the FMU with a single hose, but would it be recommended to do? if so, how would you recommend bypassing the FMU?

 

Remove the FMU completely! You do not need it. In the past I have always had tuning problems when an FMU was installed and since then we never install them anymore....I actually have a half dozen here in the shop that are essentially useless. From a Fox Mustang to '97 Cobra....we have never installed the FMU's and as a result have not had the tuning problems that we used to have in the past.

I gave you the 2 examples because they were close to your setup....with the '88 LX I had being VERY close to yours....no FMU on either.

 

kewl, thanks!!! you have been very helpful. I will have him bypass it this weekend, if it is the solution we are looking for then out it comes!!

Thanks again