TBI Fuel Pumps Specifications and Regulator Springs!

[EagleMark]

TBI Fuel Pumps Specifications and Regulator Springs!

I've been collecting some specs on fuel pumps used in TBI applications from stock to increased for higher pressure and delivery. If anyone has any other pumps or solid spec information post it up.

Information on pumps is from Delphi specifications

AC/Delco EP386, 83 kpa = 12.08 PSI. (Need LPH) This is what comes in stock TBI engines.

AC/Delco EP 377, 210 kpa = 30.45 PSI. (Need LPH) This is pump for 94-95 7.4L engines that run the small injectors rated at 30 PSI.

AC/Delco EP241, 350 kpa = 50.7 PSI. (Need LPH) This is the stock pump for 5.7L TPI engines.

AC/Delco EP381, 425 kpa = 61.6 PSI. (Need LPH) This is the 96 Vortec engine in-tank pump that looks identical to all others listed. 98 changed to the newer bucket style pump.

As I receive more information from others or come up with solid results from testing I'll update this first post for a tech link. I'm also doing some tests of springs of different strengths to go with different ratings of pumps.

There's a lot of springs for sale and some claims just don't add up from my testing depending on pump and spring combination.

Picture below:
Old spring is stock TBI. (Spring pressure specs to follow)
Gold = 16 to 26 PSI with EP377 pump (Spring pressure specs to follow)
Silver = 27 to 29.5 PSI with EP377 pump (Spring pressure specs to follow)

One combination that works well for a TBI upgrade, it's the gold colored spring used with the EP377 pump. Yields 16 to 26 PSI with a stock regulator converted to adjustable. I've tested this on my bench setup with air as pressure source and then verified in vehicle with the EP377 pump and gas.

Others have not been tested yet in vehicle with other pumps on fuel.

Links of interest:
DIY TBI Adjustable Regulator!
Stock TBI Fuel Pressure Regulator Springs Measured!
TBI Fuel Injector Size and part numbers!

[Fast355]

TBI Fuel Pumps Specifications and Regulator Springs!

I've been collecting some specs on fuel pumps used in TBI applications from stock to increased for higher pressure and delivery. If anyone has any other pumps or solid spec information post it up.

Information on pumps is from Delphi specifications

AC/Delco EP386, 83 kpa = 12.08 PSI. (Need LPH) This is what comes in stock TBI engines.

AC/Delco EP 377, 210 kpa = 30.45 PSI. (Need LPH) This is pump for 94-95 7.4L engines that run the small injectors rated at 30 PSI.

AC/Delco EP241, 350 kpa = 50.7 PSI. (Need LPH) This is the stock pump for 5.7L TPI engines.

AC/Delco EP381, 425 kpa = 61.6 PSI. (Need LPH) This is the 96 Vortec engine in-tank pump that looks identical to all others listed. 98 changed to the newer bucket style pump.

I know my 18 year old, 85K mile EP381 recently hit a horsepower wall in my Express. Ran a dyno of 375 RWHP, running lean at 13.5:1 afr. I tried a few things to make it richen up, but when the increased pulsewidth did nothing, I put a gauge on it and ran it again. When I pushed the MAF flow table higher, the fuel pressure dropped from the Marine intakes 58 PSI set point to the mid 40s at WOT.

I wish I had flow ratings at working pressure for these pumps. Would make it easy to know when you have a underperforming, weak pump or need something better.

[91dime]

How would I go about getting one of these gold springs? Iv decided id like to go with an ep 377 and the gold spring has the 20-21 psi range I need. Any help is greatly appreciated.

[udidwht]

Which spring would be for 94-95 454 TBI fuel pressure 26-32psi?

[PlayingWithTBI]

Which spring would be for 94-95 454 TBI fuel pressure 26-32psi?

Yep, a "28 PSI" spring. I have one but can't remember who I bought it from. Here's a quick search...
https://www.amazon.com/Throttle-Body.../dp/B012XLK1XE