Hi,
My grandparents had a 1989 LTD Crown Victoria with the 5.0L fuel-injected engine. It wasn't running, and after a little troubleshooting, I found that the fuel pump was frozen. I removed the fuel tank and the pump and -- after seeing a fair amount of rust present -- wasn't surprised that the pump had died (how much rust is there supposed to be in a gas tank?). I bought a new pump and was initially surprised to see that it was noticeably smaller than the original, but the guy at the store assured me it was the correct model and just that pumps have become more efficient over the years, hence the reduction in size. (The pump came with a new rubber noise damper so that the new pump would fit the original bracket.)
Anyway, I installed the pump, cranked the engine and -- hooray! -- it turned over and started. We took it around town for a couple of days (probably about 4-5 starts), and it was fine -- although it did seem to require excessive cranking to start. Additionally, the new fuel pump would sometimes make a loud, high pitched whine after running for awhile (15 minutes?) -- noticeably louder than the last fuel pump ever did (when it worked). Finally, we were leaving a store and _no_ amount of cranking would start the engine. It doesn't even try -- you can hear one singular "pop" indicating that the engine is getting a little fuel, but after that it seems as if there's almost no fuel being delivered to the injectors.
I didn't have a fuel pressure gauge with me, but I verified that -- while the fuel pump is running -- fuel does come out of the Schrader valve where you're supposed to connect your gauge. However, as soon as the fuel pump stops, there doesn't appear to be any fuel pressure whatsoever. My understanding (from the Hayne's manual) is that this is wrong -- the fuel system is supposed to hold pressure. On the other hand, the fuel return line going into the gas tank just has a small rubber ending on it with a 'slit' opening so... what is supposed to ensure the fuel system returns pressurized? Is there a check valve somewhere?
My working theory is that the fuel pressure is simply too low to be making it into the injectors with enough volume to run the engine. That would explain why the car took excessive cranking to start, although not why it was working fine for awhile and then suddenly stopped... I would think that perhaps the fuel pump 'partially' died, becoming weak, but I have a hard time believing a new pump would do such a thing... but then again, it did make those loud high-pitched whining noises, so who knows?
Any ideas? The Haynes manual says that if the fuel pressure is low and there aren't any leaks (there aren't!), you should replace the fuel pump... but it seems to me the lack of holding pressure might indicate some other problem? Or should I just replace the fuel pump (again!) and see what happens? (The fuel pump has a lifetime warranty.) Also: The fuel filter has ~30k miles on it and -- although you can't see into it -- I could blow through it, so I wouldn't think it was clogged. (Plus I can't imagine the fuel filter just suddenly clogging like that.)
Thanks,
---Joel Kolstad