I had to replace the fuel pump in my 1990 Winnebago Warrior a few years ago. What a fiasco.
It cost me about $800 to replace it. However, afterwards the fuel gauge no longer worked. Or so I thought. I actuality, it was working backwards. I took it right back to the place that fixed it and they hemmed and hawed and were like, "Well...you can leave it and we'll take a look at it..." Of course a week later I came back and it was "Oh, well, we couldn't find anything wrong the gauge must have burned up with the pump..." This seemed plausible as when the pump burned up the emergency cut-off melted down, too.
I took it to my local repair shop when I got home, and the mechanic said the pump was manufactured wrong and he had seen it before. What he did was take the sending unit and remove it from the pump and re-attach it upside-down so that it read correctly. This worked, but the gauge is very inaccurate.
I got to researching the problem (Pump is made by Airtex) and it turns out that the pump was not made incorrectly. It's just that some pumps are wired one way and some the other. The real problem is the first repair shop installed the wrong fuel pump.
I was getting my paperwork together to sue the original repair shop in small claims court. I noticed on the Airtex web site they gave the wrong model number pump for my VIN. Originally they tried to tell me that the VIN number doesn't mean the model year of the chassis as the RV could be built later than when it was bought. But the VIN always reflects the manufacturing info for the chassis. Winnebago does not modify the fuel system of the chassis so what the VIN says should be right.
What I found out through further research is that Ford changed fuel pumps mid model year in 1990. After I pestered Airtex long enough, they finally sent me the correct fuel pump for my 1990 E350. That saved me the cost of the pump, but I am still saving my pennies to have it installed again.
The original repair shop was adamant that they "did not install the wrong pump", even though they clearly did. They installed what they thought was the correct pump but it wasn't. I told the guy that ultimately it's his responsibility to install the correct pump. But in the end I did not sue because I didn't think it was obvious that they were getting the wrong pump on a 20-year-old vehicle. Now if they had done a bit of homework after discovering that the fuel gauge worked backwards it would have been a big clue to Airtex that they had the wrong pump. And they had a week to do that and I bet they never bothered. But given the fiasco of tracking down the right pump I did not feel like it was reasonable to hold the repair shop to the error. They went to the parts store and bought the pump that the store told them was the right pump for this vehicle.
I could see where very old fuel system components might have a problem with ethanol but newer components should be engineered to handle it.
Steve