Different fuel psi 350 vs. 454 tbi?

[Brett68]

I have a 93 K2500 Suburban, 454, full tank of gas with a fuel pump that just quit. I had to beat the tank with a boot while the wife cranked the motor until it started to get home.

Looking in my manual(Helms) while troubleshooting it is stated for 4.3L, 5.0L, 5.7L system pressure is controlled to about 9-13 psi.

For the 7.4L pressure is controlled to about 26-32 psi.

The parts guy was unaware of a different fuel pump for a 350 vs 454. Is there a different fuel pump?

Thanks
Brett in Boise

 

[Brett68]

I may have erred. The Helms manual I have is for the 94 model year(I do have a 94 truck). It would appear the pressure is higher for the 94-95 454 tbi.

I must purchase another set of manuals that are for 93.

 

[4X4HIGH]

There were two different fuel systems used on the 454 so it depends on which system yours uses. One of the 454 systems uses the same PSI as the 4.3, 5.0, 5.7. The 454 injectors are different between the two systems also.

 

[eagle mark]

Yup, what 4x4 said, I don't know what year they made the change but they did, early ones are same as all TBI motors and later ones were higher presuure.

 

[dave w]

This thread over at Thridgen.org has some very useful information.

http://www.thirdgen.org/techboard/tbi/559060-what-year-my-454-a.html

For me personally, I use the newer larger base 454 Throttle Body on my pickup. The newer 454 Throttle Body uses the same style TPS as my 93 350 Throttle Body did. I'm using an adapter plate designed for the newer 454 Throttle Body. I also use 350 Cop Car injectors at about 13 PSI, with the 350 injector pod / fuel pressure regulator, on my 454 Throttle Body. I'm using the 454 Throttle Body because the 670 CFM rating.

dave w

 

[Brett68]

Dave W; Would that require different fuel mapping/chip burning? Any increase/decrease to fuel economy?

Thanks
Brett in Boise

 

[dave w]

Dave W; Would that require different fuel mapping/chip burning? Any increase/decrease to fuel economy?

Thanks
Brett in Boise

Yes, different fuel mapping / chip burning. Changing the injectors for more flow needs the fuel flow changed in the chip. The VE table is also likely to change? I would always data log all changes done to an engine and correct the chip as needed. In my case, I upgraded to a roller cam, added shorty headers, and modified the factory TBI intake to accept the 2" throttle blades of the 454 Throttle Body. I noticed a huge increase in performance with my mods and "tuned chip"! As for mileage,I don't think my mileage is all that good. Legal speed limit here is 70 MPH. If I drove the speed limit, I might get run over! So I really need a performance engine! I get about 14 MPG. I can go from ZERO to 70 MPH in about 8 seconds with a 5200 lb truck.

dave w