1993 k2500 suburban 7.4l power loss
 

I am not new to troubleshooting, but am having a hard time finding a spec for the fuel VOLUME output.It really feels like a fuel starvation problem. It used to show up more when towing a 10k# trailer, but now it shows up under hard acceleration. The usual tune-up done like plugs etc. I bought an inline fuel pressure adapter which takes the place of the fuel filter. I haven't installed it yet. From what I have read, 12psi seems to be the norm for that year. Just thought I would have the facts before changing the pump out. FWIW, that pump has been in there for ~10 years. Ideas, head beatings etc wanted :-) Thanks!

Re: 1993 k2500 suburban 7.4l power loss
 

Connect fuel pressure gauge, route it inside the truck. Find a safe place, stab the throttle--heavy load, high RPM, maximum fuel demand. If the pump can maintain pressure at max load, it's probably fine.

Alternatively, you could watch the short- and long-term fuel trim numbers on a scan tool, again heavy-foot driving to increase fuel demand. While the scan tool is connected, you could look for any other anomolies such as EGR operation, TPS or MAP problems, etc.

Fuel pressure spec is likely to be 9--13 psi, towards the top end is probably preferred. Some 454s had higher pressure, but I think they were later model years.

DON'T replace the fuel pump unless you've verified that it's getting proper voltage. You must test voltage as near the pump as you can get. The farther away from the pump, the less accurate the voltage measurement will be.

Re: 1993 k2500 suburban 7.4l power loss
 

The test of the fuel pressure showed a rock solid 10psi. Doesn't really move under high load. I guess it is time to look elsewhere. I have also considered checking the exhaust back pressure. I have only seen that caused twice in my career, but not being that familiar to american cars, it could be a possibility since it has tons of power in the lower range. Illl try a vacuum gauge first and see if that gives a clue.