Looking for some advice. I have a 2004.5 Volvo S40 i 2.4L. Last week, the car would not start, and I was getting a P0091 code. The car would turn over and start briefly but would immediately sputter out. I replaced the Fuel Pressure Sensor, and the car started right up and I drove it about 30 mins away. After 2-3 hours, when I tried to restart it would start briefly, drive for a few hundred feet, and sputter out. By keeping RPMs high, I eventually got it to run steady, and drove it back home 30 mins. The car would not start the next day. I checked the codes and there were no active codes, the P0091 was showing in freeze frame. I cleared the codes completely

The car now starts and seems to run fine. However, 2 things that I have noticed when trying to debug.

1) When I turn the key on, but don't start the engine... there is a clear whining that sounds like it is coming from under the back/middle of the engine. It sounds to me like an electrical pump. It is constant when the key is on. it does not stop after an initial period.

2) The fuel pump has a low, guttural sound periodically. It overall seems to be louder than previously , but this may just be because I am paying more attention.


Should I be worried about my fuel pump going bad? Is there anything else I should be checking? Or should I just drive it and see what happens?

Thanks,
Lee

 

my first guess as to the noise by the back of the engine is the vacuum assist pump. Its job is to help build vacuum in the brake booster when the car first starts up (otherwise you'd have a hard brake pedal for about the first 100 feet of driving...).

For the fuel pump, yes you should have it tested out along with the relay. As to the sound of the fuel pump - do you smelll any odors suggesting the mount is loose? As a test of the pump, you should be able to measure current draw. Worn pumps tend to draw too much current which may burn out the relay. The extra current can pit the contact points in the relay which can make it overheat and open circuit until it cools. As a quick test, you can measure the fuel pressure at the rail prior to a cold start then see how it builds as the engine cranks and starts up. If the engine doesn't start, you can jumper the relay (google/YouTube for directions but if I recall the two small spades are the signal to control the relay and the two large spades are the power circuit. Once you jumper the pump will run regardless of whether the engine is on or off so you should try starting immediately and once running you can measure the pressure. Don't leave the jumper in other than testing as the relay is a safety device.

 

@mt6127 Thanks for the ideas. I will plan to check the fuel pressure at the rail tonight. As far as the relay goes, I have not been able to determine where the relay for the fuel pump is actually located. I have googled and looked on Volvo parts websites to determine the location. Diagrams I found online and the fuse box diagram shows a "Fuel Pump Relay" in slot 74, but that is just a 15A fuse. Do you happen to know where the relay is physically located for my specific model? I have the 2004.5 S40i. It is a 2004 model, but has the new 2005 body for the S40.

Thanks,
Lee

 

I haven't had a lot of time to debug this over the last few weeks, and I haven't driven the car much during this time. However, I have confirmed the relay is fine and pressure at the rail. Car seems to run fine when I drive it, but the P0091 code remains. Any ideas on what to check next?

Thanks!

 

@mt6127

I measured the voltage and current draw at the Fuel Pump relay. I am seeing 11.5V and about 4 Amps. Are these in the correct range? Does this help narrow down where issue might be?

Thanks,
Lee

 

my first guess as to the noise by the back of the engine is the vacuum assist pump. Its job is to help build vacuum in the brake booster when the car first starts up (otherwise you'd have a hard brake pedal for about the first 100 feet of driving...).