Fuel Rail pressure sensor


xtrasauce
05-13-2011, 01:57 PM
Yesterday my 2004 LS (V8) began sputtering badly while idling. Stepping on the gas caused it to die. It would start again for a few seconds with a very rough idle then die again. This happened several times until it would not start at all. After getting it towed back home it started and ran just fine. I put a code reader on it and it came up with "P0193 fuel rail pressure sensor malfunction".

So my question is this: Is this caused by a bad fuel pressure sensor or could it be something else causing the sensor to malfunction?

Also, can someone tell me where the sensor is located? There are to electrical devices attached to the passenger side fuel rail; one at the front and one at the rear of the rail. I assume that one of these is the fuel pressure sensor?

Any help would be greatly appreciated. Marc.

joegr
05-13-2011, 02:18 PM
The one at the front is the pressure sensor. The one at the back is a fuel temperature sensor.

xtrasauce
05-14-2011, 03:10 PM
Update: After some more diagnostics I believe the problem I am having is the jet pump. Here is how I came to this conclusion:

1. When I turn the key on I can here the main fuel pump run, but there is no fuel in the rail.
2. I put a gallon of gas in the car and it started right up.
3. I drove to the gas station and it only took 13 gallons

After doing some research I discovered that there is a baffle in the tank and the jet pump sends gas from the drivers side of the baffle to the passenger side where it can be picked up by the main fuel pump. I assume that the jet pump has failed, so once the gas level falls below the top of the baffle it basically runs out of gas even though there are several gallons left on the drivers side of the tank. Does this sound right?

One other thing: The fuel gauge has been acting up too. It will go down to about a quarter of a tank as fuel is used and then suddenly drop below empty as if it is not working at all. I'm not sure why this would happen or if it is related somehow to a bad jet pump. Anyone have any ideas?

joegr
05-14-2011, 03:23 PM
Yes, it could be the jet pump. There are two fuel level senders. One with the main pump, and the other with the jet pump. It's possible that both problems are related. I think it's time to pull the jet pump out and have a look. Fortunately, it is easy to do (no need to drop the tank).

xtrasauce
05-15-2011, 12:11 AM
Well, I am back to square one. I pulled the sender from the driver's side and there is no fuel pump, only a sender with a fuel pickup. the pickup line heads over to passenger side tank.

So where is the jet pump? Is it on the passenger side of a 2004 LS? I guess I will pull the passenger side next and see where the driver's side pickup line ends up. Can anyone shed some light on this for me?

joegr
05-15-2011, 10:50 AM
Well, I am back to square one. I pulled the sender from the driver's side and there is no fuel pump, only a sender with a fuel pickup. the pickup line heads over to passenger side tank.

So where is the jet pump? Is it on the passenger side of a 2004 LS? I guess I will pull the passenger side next and see where the driver's side pickup line ends up. Can anyone shed some light on this for me?

That's the jet pump. The jet pump uses the high pressure flow of fuel that comes from the primary pump to siphon fuel out of the other side of the tank. It's not an electric pump if that's what you were expecting. It's just a very simple hydraulic arrangement with no moving parts. If it gets clogged or corroded. you will have problems.

xtrasauce
05-15-2011, 11:48 AM
That's the jet pump. The jet pump uses the high pressure flow of fuel that comes from the primary pump to siphon fuel out of the other side of the tank. It's not an electric pump if that's what you were expecting. It's just a very simple hydraulic arrangement with no moving parts. If it gets clogged or corroded. you will have problems.

I see. Thank you very much! I will pull it again and have another look. I think I will wait a few days and burn off some gas this time to reduce the chance of spillage. For some reason the wife doesn't like the smell of gas in her car :)

Add your comment to this topic!