Pre-pump fuel filter options
Thread Starter
Staging Lane
Joined: Aug 2016
Posts: 92
Likes: 1
From: Florida
Pre-pump fuel filter options I've been battling lean fueling under boost since the car has been running. I've addressed the issues by adding an AEM 380 pump, Holley rails and a boost reference FPR. At the track on Sunday I made my first pass and made the VE corrections to adjust the AFR. Next pass, the AFR was still too lean. I should have thought about it earlier, but I'm starting to believe that my pre pump filter might not be capable of flowing the fuel required when under boost. It's the same fuel filter that's been on the car for a while - looks like this guy http://www.autozone.com/filters-and-...ter/527730_0_0
I'm running my stock G body fuel tank with 3/8 lines from the tank all the way to the rails. My solution is a 3 stage solution, starting with the easiest and cheapest.
Stage 1) I'm going to bypass my filter to see if it's the culprit.
Stage 2) I know that my tank and 3/8 lines pre pump aren't ideal, and a sump with -8 or -10 lines feeding the pump will come if the filter isn't the only problem. In fact, the sump will happen sooner or later regardless.
Stage 3) The only other thing that could possibly be holding fueling back is the -6 fuel lines, even though I've seen people getting away with 700-750 wheel on them. If stage 1 and 2 don't fix the problem, I'll bump up to -8 an feed and -6 return.
I'd like a filter that can grow with the system when the sump and -10 lines are put in, so something like an Aeromotive 12304 or a Summit SUM-230117-B looks good to me. I'm also looking at a RobbMC 1025. Any other options out there? Not a huge fan of the price tag on the Aeromotive unit.
I'm running my stock G body fuel tank with 3/8 lines from the tank all the way to the rails. My solution is a 3 stage solution, starting with the easiest and cheapest.
Stage 1) I'm going to bypass my filter to see if it's the culprit.
Stage 2) I know that my tank and 3/8 lines pre pump aren't ideal, and a sump with -8 or -10 lines feeding the pump will come if the filter isn't the only problem. In fact, the sump will happen sooner or later regardless.
Stage 3) The only other thing that could possibly be holding fueling back is the -6 fuel lines, even though I've seen people getting away with 700-750 wheel on them. If stage 1 and 2 don't fix the problem, I'll bump up to -8 an feed and -6 return.
I'd like a filter that can grow with the system when the sump and -10 lines are put in, so something like an Aeromotive 12304 or a Summit SUM-230117-B looks good to me. I'm also looking at a RobbMC 1025. Any other options out there? Not a huge fan of the price tag on the Aeromotive unit.
Last edited by rworcester; Apr 11, 2017 at 03:21 PM.
Staging Lane
Joined: Dec 2015
Posts: 66
Likes: 1
From: Mpls,MN
I am using a jegs 555-150006 as a pre-filter to a 4303.. -10an stainless steal element. Can handle all gas and reasonable priced. I don't think jegs is a sponsor here so I won't add a link but you can copy and paste.
Thread Starter
Staging Lane
Joined: Aug 2016
Posts: 92
Likes: 1
From: Florida
Not yet. I would make a pass, then make adjustments in the VE table and run again. The logs showed similar AFRs no matter what I changed, so I'm confident that it's a fuel starvation problem. Only reasons for that would be old filter or too small of a feed line to the pump. Both are getting addressed.
Well the danger here is you are assuming that fuel pressure is dropping without actually knowing. While you may be accurate in the assumption, there are other possible causes as well. such as a poor performing pump, or that changes in the ECU are not reflecting injector duty, for example.
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Thread Starter
Staging Lane
Joined: Aug 2016
Posts: 92
Likes: 1
From: Florida
Gen IV 6.0, LJMS ST 2, S475, 80#s, TH350, AEM 380 on 93 pump gas. -6 feed and return w/ boost reference FPR. This Summit filter is -10 in and out with 100 micron filter. Since the pump has less than 4 hours of run time on it, I'm making an educated guess that there is a restriction between the tank and the pump. Working on converting the system over to a -10 feed from tank to pump and sumping the tank. First step is this new filter/fittings/hose. I should be able to tell fairly quickly with a pull whether or not it fixed the problem.
Restricted User
Joined: Mar 2014
Posts: 7,192
Likes: 109
From: Ohio
Using a small pre-pump line with an external pump isn't a good idea.
You can make a lot of power on -6 AN line because of fuel pressure. Pre-pump, flow is greatly reduced for a given line size. A -6 AN line will never flow as much pre-pump as it will post-pump.
You can make a lot of power on -6 AN line because of fuel pressure. Pre-pump, flow is greatly reduced for a given line size. A -6 AN line will never flow as much pre-pump as it will post-pump.