Back in April, I asked about a sputter that our motorhome had one the way home from Ohio. After the advice of those on here and talking with the Workhorse service department, I determined that it was a plug wire issue, since this chassis is known for being hard on plug wires. I replaced the plugs, wires, and fuel filter and for about 200 miles everything seemed fine. Last Thursday, the motorhome started sputtering again when it would get close to 3000rpms (never stalled this time).

I called the workhorse service department again and they said I should check the fuel psi and it should be between 55-62psi at idle and then go up when giving it throttle. When I checked it the psi was at 48psi and would go down when hitting the throttle. I ordered a new Delphi fuel pump and installed that on Saturday. With the tank still out of the motorhome, I hooked up my pressure gauge again and the pressure was reading 49-50psi at idle and would jump up to 60psi when hitting the throttle then fall back to 49-50psi. After shutting the motorhome off, I left the gauge hooked up and the static pressure went up to 55psi after sitting for a few minutes.

I tried doing a little research and noticed a few people on RV message boards mention the fuel pressure regulator. Could a faulty regulator be the reason behind the low fuel pressure? If not, is there something else I should look for that would be causing the fuel pressure to be a little low?

Thank you for any suggestions or advice!

I just read from a GM tech answer page that the 8.1L fuel pressure should be between 55-62 with the key on but engine off. Mine was around 58psi. They said it would be 5-7psi lower with the engine running and then jump when quickly hitting the throttle.

Does this make sense? If it does, is it safe to believe that my issue may actually be fixed without replacing the regulator.

Thanks again!

After doing some more research, I have found more GM pages that say the fuel pressure with key on/engine off should be 55-62psi and running according to the GM Master Spec sheet it should be 44-48 psi. If that's the guess I would say mine is fixed. Sorry for all the questions and replies to my own post lol. Helps me think out the issue (if there is an issue) sometimes.

Let us know how it goes.