Do you always need a diagnostic exam


Okay, I am the worried parient. My daughter called stating that her 2001 nissan sentra totally stopped while driving in town. Her friend’s husband has offered to fix the car saying it is the fuel pump. ( he works out of his home) No diagnostic was done. All fuses were checked. I am 12 hours away. Is this a good thing?


If the fuel pump is the problem it’s a good thing. How did this fellow come to his conclusion? He did a diagnosis or sorts, but you and your daughter are gambling that he is correct. Does he work as a mechanic out of his home, or does he just work out of his home. There’s a difference.

There is an inertia switch that shuts off the fuel pump in case of a crash. If this switch has tripped, or is faulty, it will keep the pump from working even though the fuses, wiring, etc., are intact.

I wonder if he checked that?


NO, it is not a good thing. Diagnostics need to be done to determine what caused the car to quit. Without diagnostics he will be installing parts with the hope that it fixes the problem.

Ask him this question… if the part he installs doesn’t fix the problem is he going to charge her for the work he performed?

Basic diagnostics need to be done first in a case like this. The first step is to see if there is spark and fuel. Ask him if he at least checked for spark and fuel. If he has not then I would get the car towed out of there and find a shop that will do some basic diagnostics.


Changing a fuel pump is a tough job. The gas tank must be drained and then dropped unless there is access via a port in the bottom of the trunk. If he is wrong, he will have worked hard for nothing except experience. If he can do it; why not let him fly?


Let him have a go at it. It is not so hard to determine that a fuel pump is not working. If this guy knows what he is doing he has made the right call and he will save your daughter a bundle. If he is wrong he will have done no harm.


Thanks for the ideas. I don’t have the mechanical background at all. I will take note and send off the suggestions. Thanks!


It depends on how he arrived at the conclusion the fuel pump is bad. It’s a simple matter to determine if there is no fuel pressure without resorting to diagnostics.
Determining if the pump itself is bad is a bit trickier but not difficult to do.
If the vehicle has well in excess of 100k miles (fuel filter ever been changed or examined?) then it’s quite possible the pump could be bad.


Checking fuel pressure is so simple, even a caveman could do it! Or, at least an half-pass mechanic could! Fuel pressure gage kit: $42 at Sears. Peace of mind … priceless. ---- My motto: go for the cheap parts first–like, fuel filter, fuel pump relay. Then, do some troubleshooting!


Well, the other part of this is ACCURATE diagnostics. If the fuel pressure is low or zero, it is not necessarily the pump. It could be a fuse, relay, wiring, security system override etc etc etc. The harder the job and the more expensive the parts, the more worth there is in proper diagnosis before changing anything.