: Erratic fuel level gauge & a few other ???

11-18-03, 07:47 PM
Hey guys, great site! I had a question regarding my '97 STS. My wife came to pick me up today after lazik surgury and we pull out onto the street only to have it die, wouldn't restart and I pushed it off the side of the road. We had it towed, thinking it was a bad fuel pump (No pressure) and it turns out that it was out of gas, but gauge showed 1/2 tank. Gauge has been acting strange all week, empty to full to empty to 1/2 and back to empty and then full again :bonkers: . Of course, everytime it gets to showing empty the low fuel level warning comes on and is quite irritating. What could I do to fix this? My friend at the auto shop where it was towed said that the baffles in the tank have come loose, but a call to the Caddy dealership says that he's never seen bad baffles in anything newer than a '94. ???????

Another thing is that this STS is very hard to start. Our first one had 80k miles but it got totalled after a few months, this one has 110k miles. I haven't checked fuel pressure when starting and I was thinking that the fuel filter and plugs would need to be replaced, any other suggestions??


11-18-03, 08:33 PM
PUMP IS BAD!!! The fuel guage sending unit is on the pump assy, so the guage will get better once thats replaced...... The filter also must be replaced!!!

Has the filter ever been replaced.... Even if it was replaced 1 time, its probably killed the pump!!!

11-18-03, 09:40 PM
the pump is bad?

Because the fuel guage is erratic? ALrighty then

Did u pull the codes from the DTC? Mine says fuel sensor open /shorted to ground "B0533" everytime the gauge goes crazy, also 97 STS

11-18-03, 09:48 PM
The reason I think the pump is bad is from the hard starts, but it could be a filter also.... Replace that DEFINITELY before you replace the pump!! Always fix the cheap stuff before you do the expensive stuff..... However, a pressure test will reveal if the pump is bad!!

And I could be wrong on the guage.... Whenever you get electrical things like that its always a good idea to do a visual inspection of electrical connections and things of that sort!!!

I also forgot to mention that the plugs are a good idea to do, but probably arent the reason for your hard starting..... if a plug was bad, you'd have a misfiring cylinder!!!

11-18-03, 10:56 PM
I would check the fuel pressure regulator before replacing the fuel pump. The FPR can cause hard starts - there should be plenty of info on this in the forums. It fixed my hard starts. I also have an erratic gauge, it goes to half at when there is about 1/4 tank left. I just use the trip meter and usage monitor to gauge how much is left and I dont let it get below 1/4.

Of course I have heard that you can burn a pump out if you let it run dry.

11-19-03, 04:56 PM
You can greatly increase pump life by filling up before its absolutely necessary, IE at 1/4 tank.....

11-19-03, 05:26 PM
Yes,Fuel pressure regulator fixed my hard start problem and poor gas milege.According to someone in this forum the FPR fails,causing fuel to go to the vacuum line resulting to rich fuel.To check turn on the fuel pump disconnect the vac.line, if fuel is coming out of the vac.line nipple, you have a bad FPR its about $140.00.The FPR is a small cannister like part thats attached to the fuel rail line.

04-10-04, 09:56 PM
Hey guys,
figured I'd come back (Email never notified me that I had responses!) I really appreciate the suggestions. I ended up buying the entire tank out of our wrecked STS (if you might need parts for a '97 STS call five j's in albuquerque!). That fixed the fuel level gauge problem, but after 6 months it's still hard to start. I replaced the filter (it was stock!), replaced the plugs (also stock!), still hard to start and sometimes backfires through the intake. I'm going to check on the FPR right now. Thanks again!

04-10-04, 10:08 PM
It's a bad FPR!!! I can't express my gratitude for the replies! I never would have thought it to be a FPR!