Need advice on diagnosis

So I have a Nissan Altima 2005 2.5L automatic that lost power, while driving the gas pedal didn’t send gas to the car eventually stopped and turned off. It would not start. I got it towed to my house took a look at the cabin filter and engine filter and it was disgusting changed it and the car powered on. I decided to do other maintenance on it. I changed the ignition coils along with spark plugs and fuel pump. After everything was installed, the car wouldn’t start. Check battery checked alternator checked fuses checked the pump. Also checked the spark plugs for spark and they work well. The car wants to start dash is on but once I try to start it. It sounds like it wants to start then just fails and buzzes. It turned on at one point but shut off almost immediately. I feel like it’s something simple that I can’t figure out. I was hoping maybe a different insight or just someone who went through it or a similar situation can help. Car worked fine before changes

The more changes you introduce, the more complicated it becomes.
Get it running first, then start checking out the items which are overdue for the maintenance.
You do not know if you introduce additional problems as you blindly throw parts on the problem.
By now, you know you have spark.
Do you have fuel?
The fact you replaced the fuel pump does not necessarily answers “yes”, as you might have clogged filter or injectors dirty or not firing or your pump might be not receiving the electricity from ECU.

I would suggest testing:

  • is pump getting power? is it buzzing for few seconds upon ignition turned on (but do not crank the engine yet)?
  • can you measure the fuel pressure pump provides to the injector rail?
  • do you have any in-line fuel filter? replaced this on recommended interval if yes?

So the fuel pump is showing the amount of fuel in the tank. When the car is on accessory 2 it’s makes a noise as it’s pumping the fuel for about two seconds. I don’t believe it has a in-line fuel filter. It’s a whole assembly that’s underneath the rear seats. The car has no codes. Took it for a look at a mechanic and he gave up after 3 days. Said might be the computer and sent me to Nissan. I’ve read it’s an estimated cost over 1,000 if needs replacement. The car started right before the changes so I feel like it’s something that could’ve been installed wrong but I retraced my work and everything is installed properly

Why? That has nothing to do with your issue.

So you threw a bunch money at parts you guessed might need changing and that didn’t solve the problem? A very expensive way not to fix your car.

Remove the air filter and squirt a little starting fluid into the intake. Try and start it. If it runs for just a moment, it is a fuel issue. Was the check engine light ever on? Did you retrieve the error codes? No codes, no fuel, and I’d suggest the crankshaft position sensor just failed.

You may have done every replacement correctly BUT you did not find the problem, so you did not fix the problem.


You neglected maintenance for so long that air would not flow through your fuel filter. And then when you got the car running you changed things willy nilly, including things that are not maintenance items like the fuel pump and coils.

You have introduced so many variables that the car now has to be diagnosed from scratch.

If you were capable of this diagnosis you would not have replaced the pump and coils. Get a professional diagnosis.


I tried the starting fluid it gave it a little extra kick but not enough to start it. No codes no lights.

I did and he spent three days and couldn’t figure it out and have towed the car back and forth.

I’d check for spark again. If you aren’t getting fuel OR spark, the computer is a possibility. I’d find a better mechanic that the one that tried and failed for 3 days. That one isn’t very good!


Yea I was thinking that but the fact I have to keep paying for tows is an issue. I’ve heard you can get a used computer and just install it, but some people say it still needs to get done by nissan. Some say( YouTube channels and other online blogs) it’s as easy as just putting it in. I wouldn’t want to spend over 1,000 just to do it through the dealer

I wouldn’t want you to spend $1000 if you hadn’t exhausted ALL the other possibilities and narrowed it down to the computer. If the tech powered up the car and could communicate with the computer, it is probably OK. If he can’t communicate, that is a red-flag. You are trying to repair something by parts swapping in the dark. A good mechanic has the tools to address this and can make informed decisions. A $100 tow is better than tossing a $1000 computer at the car with no good result.

I see that RockAuto sells remanufactured ECU’s but is out of stock on all of them. That is a hint that it is a parts swap and very likely does not require a marriage or re-flash from Nissan. A junkyard swap may work. I would not risk much money on it as you can’t usually return ECU’s for a refund.


Thank you so much

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If you replaced the fuel pump you may need to have it run an extended period of time before it fully pressurizes the fuel rail… Problem is when you turn the key to on… or get ready to push the start button… Your fuel pump will have only run a 2 second prime. The pump wont run constant till you get a tach signal.

I would pull the fuel pump relay and bridge the two terminals that send power to the pump to run it constant …while also paying attention to the schrader valve on the fuel rail to see or verify pressure in the rail.

Until you do something like this…it may take a whole bunch of starting attempts to accomplish the same.

If you have an ignition key in this vehicle… You could try “cycling the key” a bunch of times in order to string together those 2 second pump primers you get when key goes to run position…

Just my thoughts… Then again… you did introduce many unknowns here.


Repair/exchange is a way to go for Nissan.
Their ECU is married to the transponder in the car key.
Look on ebay for “ECU repair”.

My guess is the new fuel pump isn’t working correctly. Unless you installed a Nissan OEM fuel pump, faulty pump should definitely be suspected. A faulty fuel pump can be easily verified by a shop, requires some fuel pressure testing is all.

A 2 1/2 second blast of starting fluid should start up ant engine if it is a fuel problem.

I would have thought you you would get a malfunction code. Are you sure you ran out of gas, or the fuel pump failed, rather than your engine shut down? Crankshaft sensor issues are fairly common on Nissan’s of that age and with that engine. Do a bit of research on the issues it causes. Cutting out, refusing to start while the engine is warm, and then being able to start anew sometimes an hour or so later, is what happens. Good luck figuring it out.

Easily half of the failed crankshaft position sensors I’ve replaced have never generated any kind of fault code or even illuminated the check engine light at any time


No codes mechanic said he couldn’t connect to computer. So I think it might be a computer issue

Would that cause it to lose power while driving ? Cause that will be a cheap fix. Im currently looking into a used ecm alot which say it has to be flashed. I have no idea where would I get that done since the car won’t turn on

I would not suspect the ECM right off the bat like this. In my humble experience in things Automotive which exceeds 30yrs of hands on “training” in the prestigious School of Hard Knocks. ECM’s rarely fail…its possible of course, just not very common is all.

Did you pull your fuel pump relay yet? Check the fuel rail pressure…even if it was only by opening the schrader valve on the rail ? (sometimes not available however). Your FPR should be located in a small black box near your windshield washer filler neck opening.

Fuel pump relays used are just simple devices…and if you look on the side of said relay…it shows you a map of its contacts usually. From this you can ascertain which terminals on the fuse box you will need to jump with a piece of wire to supply the pump with power to run…this is what that relay does using commands from the ECU essentially. Doing this diag trick lets you quickly rule out quite a lot in one shot. Most common terminals to jumper are relay terminals 30 and 87.

I wouldn’t do anything till that was completed honestly. Its pretty important. There are other ways to accomplish the same thing really, but this method is tried and true and quick.