7.4L Vortec Fuel Pressure Regulator

[Tom P]

So I replaced the FPR in my truck a few months ago. It solved a lot of issues I had with the truck when I bought it. Since then, the recently replaced fuel pump died as well. I never had good fuel pressure with the pump that was installed in the truck before I got it. Once I was finally able to condemn the pump, we replaced it, added the new wiring harness, fixed the ground and called it a day. It immediately put out the 56psi required, but now the FPR makes an awful sound that can be heard inside the cab. I guess its relatively common, as these regulators are also used in some of the LS series engines which seems to be where most of the issues stem from but it is happening in the 7.4's too.

I originally purchased and installed the Delphi FP10021 which is spec'd by Rock Auto, Amazon, and various other websites as being the correct regulator for the 7.4's. Since the Delco OEM and Delphi units look to be Identical, I decided to save a couple bucks and buy the Delphi unit because they probably make it for Delco anyway. Now that the truck has sufficient fuel pressure, the FPR is buzzing. According to reviews on multiple websites (rock auto doesn't do individual product reviews which is a downer) the buzzing is common on the Delphi, Delco OEM, and Delco Professional versions as well.

I would like to get the issue fixed. I know a lot of guys have replaced these FPR's and I'd like some input on whats worked and what hasn't. My plan is to buy the Delco OEM and just pay the full money for it but since it's considered one of the worst offenders, I'll get a few opinions before moving along.

 

[Tom P]

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[shamrock246]

The one on my Delphi spider will make the same noise when i run the pump with out the engine running not sure it's hurting anything.I haven't tried a Delco one yet.

 

[Tom P]

The one on my Delphi spider will make the same noise when i run the pump with out the engine running not sure it's hurting anything.I haven't tried a Delco one yet.

Unfortunately the fuel injection systems for the small blocks are vastly different to the system on the 7.4L but thanks for your input.

 

[BowtieBrody]

I can't say I've had any issues, nor have I experienced any buzzing with my Delphi FPR; and I've got close to 10K miles on that and new injectors, maybe try another Delphi unit to see if it's just the one currently in your truck?

 

[Tom P]

That’s the plan for now I think. Need to get one coming because I plan to swap it out this weekend.

 

[Tom P]

Replaced it with another Delphi unit. When I pulled it apart, the small oring was missing and there was fuel in the vacuum line. Still makes the annoying noise, but I'm not going to tear into it again. Turn the music up louder I guess.

 

[BowtieBrody]

Hmm. I wonder if my truck isn't pushing enough fuel pressure? It runs fine, but my FPR doesn't make a sound...

 

[Tom P]

Hmm. I wonder if my truck isn't pushing enough fuel pressure? It runs fine, but my FPR doesn't make a sound...

Possibly. I had the fuel pressure up to 42 psi (with the old, bad pump) and it wouldn't make any noise, mostly because the regulator wasn't opening and fuel wasn't passing through it. As soon as I got the new pump installed it sounds like a garden faucet now. Almost as if there's some turbulence in the line. One of the easiest ways to check if you have low fuel pressure, if you don't have a gauge, is to hook up an OBDII scanner with live data and check your long term fuel trims. If they are in the +10% or higher range, then you probably have low pressure. Right at the end of life for my pump I saw +26% fuel trims. Now I'm consistently seeing them in the 0% to -8% range. Or just rent a pressure gauge from schmucks.

 

[BowtieBrody]

Possibly. I had the fuel pressure up to 42 psi (with the old, bad pump) and it wouldn't make any noise, mostly because the regulator wasn't opening and fuel wasn't passing through it. As soon as I got the new pump installed it sounds like a garden faucet now. Almost as if there's some turbulence in the line. One of the easiest ways to check if you have low fuel pressure, if you don't have a gauge, is to hook up an OBDII scanner with live data and check your long term fuel trims. If they are in the +10% or higher range, then you probably have low pressure. Right at the end of life for my pump I saw +26% fuel trims. Now I'm consistently seeing them in the 0% to -8% range. Or just rent a pressure gauge from schmucks.

I may just buy a cheap gauge from Napa in that case then, I've got a cheapy little Harbor Freight Scanner but I don't know if it can read and show live data; I'll have to dick around with it when it's warm out I guess.