I have started a business called TheAmazingFunBus which is a 30’ RV filled with video, arcade games, karaoke and have been to over 200 birthday parties and events. The newer FunBus is '95 Airstream on a Chevrolet 458 chassis with only 60K miles.
It started to run rough in December so had a completed tune-up. It then got worse and broke down, diagnosis was bad feul pump, sensor and then a bad sender from the tank, ALL replaced twice. It has been towed back three times $$$$$$$$. It now drives for 10 minutes and basicaly will stop and crawl along at 8 mph and not go up an incline.
This may kill our business have no idea how much longer we can survive and suggestions on what this could be???
Has a lack of fuel pressure actually been verified with a fuel pressure gauge? Presumably the fuel filter itself has been replaced in the midst of all of this? Has all of the wiring for the fuel pump been thoroughly checked?
First things first - get a fuel pressure reading and find out if fuel is actually the problem.
Cigroller is correct. Some “mechanics” will change fuel pumps and never change the fuel filter, or check the fuel pressure; or, not check it correctly, eg. at idle, AND with the engine under load (in Drive, 2000 rpm).
IF the fuel pressure is low (with clean fuel filter), it could because of a partial blockage in the fuel lines, etc. An able mechanic can figure it out.
IF the fuel system checks OK, INCLUDING the wiring circuits, and computer controls, inputs, outputs, the ignition system (spark) needs a good checkout. The sensors need to be checked, also. For example, a defective MAF (Mass Air Flow) sensor can lead the engine computer to command fuel flow (fuel injector control) which is too low (or, high).
Many, many thanks for this I will take it to the mechanic tomorrow. I spoke with him today and he is not sure if it is the fuel and is thinking electrics now. It makes sense to me for it to be fuel pressure but they have checked this time and again but I am not sure if they have used a feul pressure gauge.