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Good Afternoon, first time post. First off, thanks for all the help and information you guys (especially Eric) give. Please keep up the good work.
Now, onto my dilemma… I have a 2001 Nissan Maxima with 190,000 miles. About 1 year ago, I had the fuel pump replaced and since then, the fuel gauge has acted rather strange. I will do my best to explain… If I fill up, the gauge reads full (every time). When I begin driving, the level drops as it should (as it always has) UNTIL it reaches just above 3/4 of a tank, then it stops. 95% of the time, the gauge will become “unstuck” at roughly 1/2 a tank, but occasionally, the gauge will not come “unstuck.” As a result, I have to track mileage on my trip meter so I don’t accidentally run out. Fortunately, I know my car well enough that I know about when it’s time to fill up again and I’ve never run out of gas.
Through reading the service manual, I know access to the fuel pump is gained under the rear seat. Also, the sending unit must come out to access the pump inside the tank (it sits on top of the tank and the fuel lines and electrical connections run through the cover of the sending unit down to the pump).
My question is this… Before I spend $130 for an OEM sending unit or go through the trouble of pulling all these components out, is it possible the unit is simply “sticking?” Unfortunately, I don’t have a voltmeter, but plan to get one. Is there any insight that can be offered as to the direction I should take on diagnosing this issue?
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You are on the right track… Pull the fuel pump assembly and check the float to see if it is sticking or binding…
Karl
Did you watch the fuel sender gauge episode?
Sounds like you have a “dead zone” which yes, could be verified with a voltmeter.
I have a similar problem, but have not dropped the fuel tank yet.
I have not seen it, but thanks for showing that.
Wouldn’t a dead spot cause the gauge to basically stay in one place as opposed to behaving more like the float is binding on something? I’m just curious because judging by the video and what I’ve read (very little…), it seems a dead spot would cause the gauge to not move at all as opposed to mostly behaving normally except in one spot where it sometimes works fine and sometimes doesn’t. Please correct me if I’m wrong, though… I have no real experience to back up my assumptions.
Sometime this week, I’ll try to get into the tank and pull it out, though. The only way I’ll ever be able to find out seems to be pulling it out of the tank and doing some basic testing on it.
Thanks for the help.
It is true to test it directly you’ll need to remove it from the tank. You might also consider unplugging the sending unit and turning on the key to see how the gauge reacts. If it goes full or empty then it’s likely an issue with the sending unit. If you don’t notice a change then it might be an issue with the gauge. Good luck and keep us posted.
I realized after pulling the back seat out and unplugging the connections that the gauge sweeps every time I turn the key to start the vehicle. You live and learn!
The gauge sweeps normal without binding. I wasn’t able to go further due to other things going on but I plan on pulling the sending unit tomorrow and checking the float.
Well here’s the scoop. I had a really hard time with this. I had no issues getting to the unit, but was simply unable to pull it out of the tank. I was able to move the arm to see positive results on the gauge. This is when it got tricky… Somewhere in the past, the wrong sized o-ring was put in the seal between the tank and the sending unit and no auto parts stores carried it. Because of that, I was simply unable to get al the small screws in. I was able to put 4 of 6 in… To make matters worse, the gauge is now completely unresponsive and only reads empty (with the low fuel light on). I guess I’ll be investing in a new sending unit now. Needless to say, this test was deceptively tough and frustrating.
Well, I took a stab at round 2 of fighting with getting the sending unit today and successfully removed the unit from the tank. I discovered a wire that was no longer connected to the side of the float (where the signal is sent from the side of the float). I also was able to come across a voltmeter and the unit is, indeed, toast. There was nothing on the side of the assembly, nothing in the tank, or no resistance in the arm’s freedom of movement, so the verdict is a “dead spot (as asetoftools said).” I was able to talk to a local Nissan dealer today to discover sending units are a common problem in these model cars and came across a new OEM unit and seals for around $100.
The sending unit comes out of the tank as an assembly on top of the fuel filter and pump, and is attached to eachother via an electrical connection and 2 hoses (one pressurized hose, and I’m assuming a return hose). I was able to undo the electrical connection to the fuel pump, but decided not to fight further because I was unable to undo the hose connections on the underside of the sending unit (the hoses are held on by “internal” clips… you squeeze two tabs and supposedly pull the hoses off). I plan on taking the assembly to the dealer tomorrow and hopefully get a little help in swapping these parts over without tearing anything up, since I have no experience in dealing with these components.
Thank you guys very much for your insight and help.
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