Fuel Pressure Gauge Recommendations

[CADDY97STS]

My 97 STS starts hard in the morning. I changed the FPR but the problem remains. I guess I must now test the fuel pressure to see if maybe the fuel pump is going bad.

Can someone suggest what fuel pressure gauge I should buy?

And maybe comment on hwy it cranks sooooo long in the morning before it coughs and finally starts

Thanks in advance

Jeff

[derone]

I think you're in the right ballpark with the fuel delivery. Either low fuel pressure, dirty injectors, or worse case a ah leaking headgasket that leaks coolant in a cylinder when cold. The fuel rail pressure check fitting is the same as old R-12 A/C charge fitting... or Summit sells the complete guage and hose combo too to check the rail pressure.

[Ranger]

Have someone turn the key on (do not crank) while you put an ear to the open fuel filler pipe. Do you hear the pump run for 2-3 seconds? If not, check the fuel pump relay. If it is bad, the pump will not run until you build son oil pressure by cranking. If you do hear the pump run, then the relay is OK. Then check the pressure.

[NHRATA01]

Have an autometer electric in my other car with a remote sender, but they run about 250, so they're not cheap. But I imagine you could rig up a mechanical off the fuel rail for pretty cheap.

An alternate thought, it's possible the check valve in the pump is no good, and the line is draining back into the tank when the car sits, causing hard starts.

[CADDY97STS]

I finally had the fuel pump swapped out and it fixed the hard starting problem. But now my fuel gauge is off by about 1/8 of a tank. A week after I had the new pump installed, I ran out of gas when the gauge said I had about 1/8 tank and the digital information center said I had 84 miles to go. How do you calibrate the new pump to the car??

Thanks in advance

[cctgene]

Just a thought - I doubt that a new fuel pump itself would have anything to do with your gas gauge being off. More likely your fuel sender assembly got banged up or the wire float arm got bent in removing or installing the pump.

[CADDY97STS]

Actually the fuel pump, fuel sender and check valve are all in the same unit.

Thanks

[Ranger]

Are you sure? Admittedly, it has been many years since I've done one on a GM car, but can't imagine that they have changed much. That one was two separate units that plugged together.

[N*Caddy]

Originally Posted by CADDY97STS

I finally had the fuel pump swapped out and it fixed the hard starting problem. But now my fuel gauge is off by about 1/8 of a tank. A week after I had the new pump installed, I ran out of gas when the gauge said I had about 1/8 tank and the digital information center said I had 84 miles to go. How do you calibrate the new pump to the car??

Thanks in advance

I just changed the fuel pump in a Grand Prix today, the sender unit is attached to the pump (not part of the pump), I am sure Cadillac is the same. As for the off gauge thing probably your floater arm is bent. Either way if you ran out of gas it means you run the car with low fuel level, that’s a NONO! It will cost you another fuel pump, the gas in the tank act as a coolant for the pump. I always fill up when I am half tank, but maybe I am too much, but try not to run the car with less than 1/3 of a tank of fuel. Is not like you save any money, in the end you pump the same amount of gas.

[cctgene]

Originally Posted by CADDY97STS

Actually the fuel pump, fuel sender and check valve are all in the same unit.

Thanks

I checked several online auto stores, NAPA, Autozone etc., and it appears that you are right. Starting with the 96 model year, for his car, nobody carries the fuel pump itself as a separate item. The only thing listed is a complete assembly which includes the pump and sending unit together.

Learn something new every day!