Put on a new filter today and there seems to be a noticeable difference in FP.

I could not find enough road to push it to redline, but it is acting much better. There was even a noticeable difference in sound after I put in the new filter. I'm definitely not convinced it is fixed, but the FP is tracking with boost now.

I'm going to try to put it on the dyno this week and see what is up.

I was looking things over and could not help but notice the 90* turn on the connector where the stock plastic line goes into the fuel filter. It seems like using a straight line at that point would help flow quite a bit.

Does anyone make adapters for those quick connect fittings? A better flowing aftermarket filter would also probably help.

 

But .. but.. i thought you could only make 500 rwhp on the stock bottom end...

 

Thanks for that info. Was it the stock filter that you replaced, the one outside the tank?

 

Wish that was the case for me. I replaced the filter on my '99 (with integrated regulator) and it didn't make any difference in fuel pressure. I had ~88k on it too.

 

Yea, been there and done that before also. Just to give you guys some quick background.

I put the blower on my car back in '02, before there were many FI c5s on the road. I started with the standard '02 fuel system (that quickly showed a pressure drop). So I added a racetronix pump + KB bap. This helped quite a bit, but I kept getting some pressure drop. So I swapped over to a 97 rail, return, filter, and boost referenced it. This solved my fuel pressure issues for a few years.

A few months back I was at the track and suddenly started loosing FP. The pump also started making a really strange sound, so I concluded that it was going bad.
Things started working normally again the next day after the pump had cooled, but I figured the pump was showing its age and it was probably best to replace it. I put in a brand new racetronix unit (same as the lpe pump). Things seemed better until I took it to the track last week where the FP dropped to about 30psi. This time the pump still sounded normal, and I had just put in a fresh tank of cool gas.

So, I started testing every aspect of the system. Regulator, BAP voltage, pressure switch... Everything checked out. I ran logs and found that the pump was not even keeping the pressure where it should at low boost. My last thing to try was a new fuel filter.

Sure enough, after putting it on there was a noticeable difference. It is now keeping up at low boost with cool fuel. Other tests are pending.

Like I said in the original post, I'm not convinced it is fixed. I just know it helped quite a bit.

I thought about actually bypassing the filter altogether, but that would probably be stupid considering how dirty they can get.

Why can’t the stupid gas stations filter the fuel for us

You are going to see some pressure drop until you regulate at the rail. That is just a fact of the remote regulation design. A small pressure drop that stops is no big deal, but if it keeps tracking down you have a flow issue.

 

How many hours of driving would you say you had on the new pump before going to the track and seeing the pressure drop?

 

Total: about 20-30hrs (I have been daily driving it lately since one of our cars is in the shop for body repair).

That day:2hrs

 

I asked because it seems a number of people have been having trouble with new Racetronix pumps maintaining pressure and flow when hot.
My first one worked fine until it got warm (not very warm, temp was freezing outside)
Second one, same thing. Continued to drive while waiting for the third, and after about 15 hours, it seemed to get much better. Might say it fixed itself.
Got a third one anyway.
I asked Racetronix to comment on this problem.
Didn't feel like that helped too much, but they might be saying that they've seen a problem as well ("Again this problem does crop up from time to time in cars which use fuel modules. It is not specific to Racetronix pumps as we have been using the GRJ420 (LPE) version in the C5 since March 2005 and we have still seen it happen from time to time.")
Which may mean that you keep putting in Walbro-based pumps till you get a good one.

I was wondering if yours (like mine) might get better with time, but you have quite a bit of time on it already.

 

yes that would be my call

 

If you are talking about an AN adapter to attach to the hard line from the fuel sender - they do make them. I bought mine from thunder racing. I don't see it on there site right now. I think speed inc carries them too.

 

I would like to replace as much of the line as possible with AN braided hose.

 

You mean you guys don't hang on every single word I type on this forum! I posted the solution to this in my other thread! Hehe, just kidding (on the first part).

See my fuel system thread here:
http://forums.corvetteforum.com/show....php?t=1409242

Follow the two braided lines coming out from the firewall. If you look closely you can see that part of one of the braided lines is actually the factory line. It hooks into a GM Quick Connect to AN -10 adapter made by Aeromotive. It's kind of dumb because the adapter is unnecessarily large, but it doesn't stick out too much. The GM line has the ID of a -6 line but I think Aeromotive up-converted it to -10 for LT1 Corvettes to have plug and play compatibility with some of their -10 fuel filter and fuel pumps. They also rip you off hardcore in the price, it was something like $40 but whatever, it works and didn't require me to modify any of my lines to add on my ECS fuel kit.

You could pretty easily use that adapter and mount your filter at the front -- would be easier to clean and service that way too. There are plenty of relatively small -6 and -8 fuel filters that would fit up there, especially if you added aftermarket rails and fed fuel in the front.

Hope this helps.

 

Good fix above. I think OEM line ID is way to small IMO.

When I was running my intake 255, I must have replaced the stock filter four times. Makes a big difference. Also puts a lot less wear on the pump.

I am now running two Barry Grant filters on seperate lines with duel external Bosch 420l's. Point is, a good flowing filter makes a huge difference.

 

Don't be so eager to get into braided stainless... if I had a way to make my whole fuel system hard lines, I would. The only real reason to go to braided stainless (IMHO) is to plumb into aftermarket components or to plumb where the factory fuel system just can't go (or isn't already). Also you want braided stainless in areas where flexibility is required (like for the connection between the rails and the factory feed line.. the vibration/movement of the motor would put stress on a hard line that would likely wear quickly).

As an example, I have a feed and return line for my secondary pump in my driver side rocker panel... but I retained my factory feed line for the primary pump. I could have easily plumbed extra braided for the factory feed, but:
* it would be extra cash, about $6 per foot of hose and $10-$20 per hose end, depending on the angle required for the hose end
* if you don't match the hose to the hose end properly and install the hose end properly you'll end up with either a big leak, or one you'll just smell and regret the rest of your life
* braided must be properly clamped/secured or it will end up wearing everything it touches... I've seen braided rub noticable chunks of those aluminum tunnel plates


Again, just IMHO, hard lines are just as good if not better and I would do everything I could to retain the factory hard lines I already have.

 

If you lean out your tune to about 12.5:1 and then richen it back to 11:1 or thereabouts with Meth, the demand on your pump will decrease and pressure drops will decrease.

 

Hard lines are good but trying to bend them like factory without a lift - very difficult. I gave up and went to braided stainless. I may replace it down the road.

 

Fair point, and one that I missed... braided is much easier to do than hard lines, even with a lift. Braided can be done with a die grinder/cut off wheel but hard lines require special tools, especially if you use steel hard lines. I'm not a fan of aluminum, it just seems too flimsy.