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Mercury Montego Fuel Pump and gauge problems

11K views 7 replies 4 participants last post by  Trevin 
#1 ·
I am new to this forum and have a couple of questions I hope someone can help me with.

I will begin with a long story with some info then have a couple of questions.

I have a 2005 Mercury Montego Premier with approx 130K miles on and have had it for about 5 years. A couple of years ago the CEL went on the day after I filled it and the gas gauge went to 1/2 full. Checking the codes it indicated a fuel gauge error so I ran it a bit and changed to a higher grade of fuel. Things went well for about 15K miles then when my son was getting ready to take it to college he ran it through a car wash after filling it up and forgot to put the gas cap back on. After a stop or two he said the gauge went to 1/2 again and the CEL was back on. I put some dry gas in it, again went to a higher grade of gas and things seemed ok for the last 3 months. Now as I was taking him back to college from the weekend the light came back on with code PO193. It came on as I was running with a large pack of cars on the interstate about 70MPH (which is the limit where we were) and going up a long grade. The car seemed to run ok but since I had the scanner handy I went ahead and cleared the codes as we were running to see if it was a hard code. I ended up driving it another 130 miles or so mostly on the highway but did have about 5-7 miles in town. The light did not come back on but now I am concerned about what is the best course of action.

At this point I am thinking the problem is in the fuel gauge/ pump. I guess that is my first question. Digging in online at first I thought the gauge was in the tank under the drivers side back seat and the pump was on the passenger side back seat. Now as I look online for the parts it appears both are part of the pump assembly under the passenger side. Is that correct and if so is there anything under the drivers side?

My next question is which is the best brand or place to get one at?
I usually get the OEM but I am sure the price will kill me and the Bosh ones sound just fine. Does anyone have any experience with them?

Again I am thinking this is a pump/sending unit problem since I have had know issues with fuel in the past and think it may have contributed to the problem.

Thanks so much for any help and opinions.

Steve
 
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#2 ·
Well I have never put a fuel pump in a 500/freestyle platform. As for the p0193. It is full rail pressure sensor circuit related. There is a fuel rail pressure sensor in the fuel rail near the upper intake. If your scanner shows freeze frame data I would recommend looking what fuel pressure was at the time the code was set. Have seen many fuel rail pressure sensors fail over the years. I would try and test it first. But with the fault being intermittent could be difficult.
 
#3 ·
Thanks R-Clar for the response.
I hate to say it but I probably cleared the freeze frame data when I reset the light. I was too worried about it being a problem right away and forgot about the freeze frame data. I also figured it was the fuel gauge again and did not realize it was a different code until my son looked it up right after clearing it.

I had thought about the fuel rail pressure sensor but with the issues I have already had with the fuel gauge in the past was thinking it may have to do with whatever crap I got in the tank awhile back. The light also came on while climbing a long grade at speed and figured that would be the time the pump or pickup would be working the hardest.

After thinking about it overnight I remembered wiring on both sides of the tank and was thinking one was the sending unit and the other the pump. I just took the back seat out and on the driver’s side there is a two wire connector and no hoses and the passenger side has two hose connections and a 4 wire connector. So if the pump and sending unit are all in one what is two wires for on the driver’s side?


Thanks again for the input,

Steve
 
#5 ·
I wondered that but I only see two wires and thought most had three. I also do not see one offered for sale online for that side unless I am missing it.

That would make sense though since a while back when the CEL light went on and the fuel gauge dropped to half it may have seen the imbalance and set the light and code.
 
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