52 PSI fuel pressure in 1998 4.3 too low?
 

52 PSI fuel pressure in 1998 4.3 too low?

(4 door, 4 wheel drive) (I am first owner of the truck so know full maintenance history)

I read online I need 60 - 62 or so.

Starts / runs OK but is low on power while towing or not towing.

I am also seeing a little bit of overheating - maybe I am running lean and that is causing the higher temp?


Brian

Fuel pressure and leakdown must be checked with the engine off. On 1998 and newer, in the underhood fuse panel there is a vacant terminal next to the fuel pump relay. This is the "fuel pump prime terminal" and it goes directly to the fuel pump. Connect a jumper wire from battery positive to the terminal. After the fuel pressure stabilizes, it must be 60psi to 66psi. Then remove the jumper wire and the fuel pressure must remain above 55psi for at least 10 minutes. If it fails either or both parts of the test, there is a problem with fuel delivery and further testing is required to pinpoint the problem. Post your results.
Attachment 31677

Ok will try it and report back. Orig. fuel pump last 125K. Have had 3 new ones since that orig. one. I have very good hearing and can hear the pump produce an additional noise when on accelerator and not when off. I am assuming no noise is preferred but no one can hear it but me. I was going to run a microphone to it while driving but this fuel pressure testing is prob more telling.

The pump can make a different sound when under a load, and also if the fuel filter is restricted. Gotta be careful with fuel pumps on these vehicles. A/C Delco or Delphi should be used whenever possible, avoid the aftermarket stuff, they don't last ;)

Replaced fuel filter the other day prior to all this. With jumped on it went right to 62 then with it off quickly dropped to 54 then down to 51 after 10 min.

I wanna bet its a aftermarket pump?