Hi guys,

I have a 01 Screw 5.4 with Vortech SC with 17k miles. I picked it up from a seller that didn't really know much about the truck. He had told me that the fuel pump had been making noise and was replaced but he didn't specify if it was a BAP or the tank unit.

Anyways my problem is when I hit WOT it sometimes is sluggish and barely moves up the rpms. I have a boost and fuel pressure guage and noticed when I'm hauling butt the fuel pressure gets over 60psi but when it's sucking big ones the pressure is about 45psi. Because of this result I'm geared to say it's one of these items.

I've been searching this forum and others stating BAPs and FMUs aren't great to use. Is there a way to test them?

I'm trying to troubleshoot which is the problem or if it's something else.

I already changed the fuel filter , sparkplugs and COPs. Each replacement made the truck run much better. Tranny fluid is still good color with no smells.

UPDATE

I spent 4 hours swapping the Lightning fuel pump out. It was a PITA. The fuel pressure at idle jumped from about 37 to 45!

When I romp on the gas it's definitely an improvement but it still lags at times. My next step is to remove the FMU. I bought some 42# injectors and have a Lightning maf coming in Monday from Ebay. I already bought my other parts to build an intake.

 

If you're seeing 60 psi and 45 psi at the same boost level and rpm, something's not right and if you're seeing 45 psi when it should be 60, you're probably dangerously lean. You really should ditch the FMU, get the appropriate size injectors and a MAF that's large enough to handle air flow and have someone tune around them instead of the FMU. All an FMU does is dump more fuel by overdriving an injector that was designed to use 39 psi of fuel pressure.

 

so it sounds like you think the FMU is the culprit.

yea i was thinking to get 42# injectors. Do you think a Lightning maf would be the best combo?

 

It could be the pumps, but would be hard to narrow down unless you know one or the other was at fault. I just think any application should resort to appropriate injectors and MAF to make the correct fuel metering calculations. Unless you're running some obscene amount of boost, the Lightning MAF should be more than adequate. Ford Racing offers a Lightning replacement. You'll need a tuner to program the proper injector slopes and offsets and modify the transfer function for the MAF into the PCM.

 

Cant you drop in a lightning twin fuel pump setup in? JDM is selling a complete factory setup for under $200 I beleive..

 

many people go this route...

and it's the best way

 

Do you guys think it could be anything else than those 2 parts?

I don't mind upgrading the pump.

 

here are the plugs i had pulled out. the gap on the passenger side were all .030 but the other side had two at .032 and two others at .035

 

Don’t worry about the gaps being different. The plugs gap will always open up due to the heat in the chamber. No biggy there. I personally wouldn’t use platinum plugs on any kind of blown application unless the boost was real low like 6psi max imho

Fmu are total junk. I threw my powerdyne fmu in the trash and gave away my vortech fmu!!!
1 IT range colder for the plugs
42lbs FI
90mm L maf
Single or duel 255lph FP
Custom tuning
and then you’re good to go!

 

yea i'll go with custom tuning.

i was told to run 4 inch piping from the maf all the way to the blower.

anybody know where to buy or put together an intake?

oh and are Bosch injectors fine or should I go with Ford Racing only?

thanks all

 

any of 'em are fine, I have run both and I know I like the solid Ev1 to Ev6 adapters VS the wire ones

 

and as far as teh 4 inch piping, just have a muffler shop do it up for you and grab a couple sililcone adapters and some hose clamps

 

Better description of the same problem I'm having. Great info, I'm like a sponge over here!

 

http://www.lightningrodder.com/forum...ght=fuel+pumps

i'm sure you can find a setup used also if you are on a tight budget...

 

where do the fittings for the intake go for the hoses? I'm thinking either drilling some into the piping or get an elbow and cut into that.