obzidian

Ok, very simple.

My buddy has a 2001 c5 with a maggie.

The car is dropping fuel pressure at WOT. (stock pump + BAP) It's rock steady around 56psi (should be 58psi) but drops 52psi wot.

Anyways, we checked the BAP and voltage does increase with boost to 17v's.

So the next step is to see if the fuel filter, fuel pump and regulator is working properly.

My questions are about the fuel filters and regulators/dampners associated with the c5's. My understanding, the 97-98's have a regular fuel filter with a regulator on the rail. Is that correct?

Now the 1999-2004's have a fuel filter with a built-in regulator and a fuel dampner on the rail. Is THAT correct?

So, if I wanted to check the regulator and filter it would be the same unit on my buddies 2001 and there is no need to worry about the dampner on the rail?

The dampner, on the maggie kits, are taken off the stock rails and installed into a housing right after the fuel line hook up on the stock magnacharger fuel rails.

With that, what is the role if the dampner and does it also regulate fuel pressure? Would a failing dampner cause a drop in fuel pressure?

Thanks guys.

obzidian

Anyone?

mobius

I believe you are correct about the filters. 97-98 no regulator and the 99-04 due have it so replace the filter if he has a 01. It may not be a bad idea to also put a bigger pump in if he is close to the limit of the stock pump.

lingenfelter200

It is better to replace your stock fuel pump to another one. Why don't you go for Walbro 400LPH can hold around 700 rwhp.

obzidian

Right.... and thanks guys.

The idea was to go step by step and find the problem without throwing parts at it. I do agree that perhaps a new pump (high volume) would be a good idea given that eventually we'll be adding water/meth.

I've been looking at the racetronix kit with the GRJ420 pump. Comes with the harness and PnP for the bap.

Anything else out there that is comparable for the price? $277.00 for the pump and wiring doesn't sound to bad considering with the bap she'll hold close to 700rwhp.

FixedRoof

Change the fuel filter first regardless. Change it if you feel you are having any fuel issues. My buddy had one on his 01 C5 that was semi-clogged. Gained a couple psi of pressure at WOT by replacing it.

Couple years ago I had a 1 year old filter on my truck that was plugged up causing fuel pressure to dive down to 20 when you gave it gas. It ran horrible. Couldn't even blow through it when I took it off.

Replace it with a quality filter like an AC Delco or a WIX. Not some cheapo autozone or advance filers, have read of issues with cheap filters. The C5 style filters with the built in regulator are very common with LS1 swap cars.

You may see a slight drop in pressure regardless with the rear mounted regulator. That's why the high HP guys run the 97-98 style setup with the regulator up front.

Make sure the car isn't running lean....

obzidian

Update:

Replaced the filter/regulator. No change.

Went ahead and had the injectors cleaned: No change.

So at this point we're thinking its the pump. However, how much of a problem would the stock return less fuel system is and is it contributing to this issue?

I wonder if we just swap the stock filter with a none regulated filter and add a regulator by the rails if that might stabilize the fuel pressure.

With that, what would be the recommended for this app? Reliability is crucial. I'm looking for a pump that installs with headaches either!

Racetronix

Read our technical note here:
http://www.racetronix.biz/itemdesc.asp?ic=FPWH-007&Tp=

Smoove

Testing fuel pressure...@ idle but not at throttle input,..if you have no restriction from debree/filter/whatever....your pump has a supply issue. Put a gauge on the car,...if its cool at idle,..but not under load,...pump is the issue.