Slightly dropping fuel pressure

I'm dropping pressure running my race tune with my 175/stocks with stock fuel system. Lowest I've seen was 38, haven't done any dead stop WOTs, the 38 was getting onto the hwy. my question is, I've wanted to do the 6.4 juggerpump mod in the future, is this a good time? Or is my stock HFCM taking a crap? Only reason I ask is cause I have been told the stock pump should be okay with 175/stocks. I really like the idea of the 6.4 pump mod and would probably add a sump also.

Add 6.4 pump? Or get a new HFCM ?

Thanks guys

If it helps at all my stock fuel holds between 50-55 at wot with 195/30s and stage 2 kc turbo. I did the blue spring and banjo bolts

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Geez really? I thought upgraded fuel is well needed by then. I do already have the blue spring. But interesting, thanks for the input

Sounds like a weak hfcm.. replace it.. fwiw- I have the 6.4 pump as a lift pump feeding a new oem hfcm. Holds 205/75's on a Race tune. That being said, I had a bone stick fuel system on 175/75's and it held fuel pressure with the blue spring. No need to upgrade your fuel system other than a fresh hfcm.

I bet the pump in the HFCM is giving out, when was the last time fuel filters were changed? I bet it would be a good time to swap in a 6.7 CM, or buy a aftermarket system.

I would change filters just to see what happens

The filters only have about 5k on them, I think I have a spare HFCM filter in my tool box so that's an option. I haven't looked too hard into the 6.7 CM but it could be an option also. I want to avoid aftermarket stuff at this point.

MNStroker316 said:

The filters only have about 5k on them, I think I have a spare HFCM filter in my tool box so that's an option. I haven't looked too hard into the 6.7 CM but it could be an option also. I want to avoid aftermarket stuff at this point.

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Swinky has a 6.7 fuel pump install writeup.

MNStroker316 said:

Geez really? I thought upgraded fuel is well needed by then. I do already have the blue spring. But interesting, thanks for the input

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You're welcome. Yeah I thought so too, but gave it a shot before I got my fass system, and regulated return. So far it's not to bad, but will be upgrading my fuel system very soon.

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I got a 6.4 pump before my stocker and my fuel pressure can't keep up at WOT, I got a 6.7 pump to go in soon.

I had a 6.4 pump feeding a stock 6.0 hfcm, both with new pumps and a regulated return and they would not keep up with my 205/100's, droped to like 20psi. Iirc they wouldn't hold with my stockers either. I now have a 6.7 pump and it doesn't skip a beat or drop any pressure. Half inch feed lines from a sump to the pump, then up to the fuel bowl with high flow fittings. And half inch return line.

BLUE SPRING WILL NOT RAISE YOUR FUEL PRESSURE AT WOT IF IT'S DROPPING!!!

If you're making 30psi wide open I don't care if you set the regulator to 150psi it's still gonna make 30psi wide open.

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Dieseljunkie said:

I had a 6.4 pump feeding a stock 6.0 hfcm, both with new pumps and a regulated return and they would not keep up with my 205/100's, droped to like 20psi. Iirc they wouldn't hold with my stockers either. I now have a 6.7 pump and it doesn't skip a beat or drop any pressure. Half inch feed lines from a sump to the pump, then up to the fuel bowl with high flow fittings. And half inch return line.

Click to expand...

Exactly what the way I am doing mine, except doing a 8an bulkhead on top of the fuel sender for a return and adding a spin on 2 micron since my bowl is gone... now just gotta find time to do it since the parts aren't doing any good still layin on my floor... lol.

The reason why u guys were not holding with the 6.4 pump is because u need to upgrade all the fuel lines... I have a 1/2" supply and 3/8 return. From sump to engine. Do that and that setup won't skip a beat- I say that, it holds 205/75's with no issues

Not sure on if mines holding pressure but egts went up when i bumped the regulator from 30psi to 55psi..... so it's at least at 40 i would say.

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