I have a 2005 MDX Touring that barely gets used. Noticed that the battery was always dead so I tested and found that there was a draw on the FI-Back-up fuse. So when I parked I pulled the fuse and would reinstall the fuse when I was going to drive it. No problems, battery was never dead and it always started. Well then it started getting cold and I knew I wasn't going to be driving it over the winter months so I pulled the battery. Now it is summer and I put the battery back in and reinstalled the fuse and it will not start. I can tell it is not getting any fuel to the engine, there is no check engine light on but I decided to plug in my scanner to see if I could learn anything. I have used the scanner with the MDX many times to diagnose issues over the years but this time the scanner would not detect the MDX. I tried the scanner on a different vehicle and it works fine. So i'm not sure where to start with the MDX. Others have suggested the relay or fuel pump which I have not replaced yet. I thought maybe some other electrical issue or computer perhaps? I do not hear the fuel pump turn on with the key and the motor will crank all day long without firing. I did check to make sure I am getting spark and I am. What should I check next?
Doescher
Couple things you could try. Both are based on suspecting the fuel pump is not getting power.
One is the pgm-FI relay. Under the dash, passenger side of the steering column. Kind of a pain to get to but you could swap that out. Search YouTube for how-to.
Other one is trying to get power directly to the fuel pump. The connector is under the second row seats, drivers side. You have to remove the seat. There’s a precut section of the carpet that you’ll have to finish cutting. The hatch to the fuel pump is under the flap. Connector is there so you can disconnect and check for voltage at the connector. If there is none, it’s prob the relay. If there is power, it’s prop the pump. You could try wiring direct to the connector with wires from a battery.
One is the pgm-FI relay. Under the dash, passenger side of the steering column. Kind of a pain to get to but you could swap that out. Search YouTube for how-to.
Other one is trying to get power directly to the fuel pump. The connector is under the second row seats, drivers side. You have to remove the seat. There’s a precut section of the carpet that you’ll have to finish cutting. The hatch to the fuel pump is under the flap. Connector is there so you can disconnect and check for voltage at the connector. If there is none, it’s prob the relay. If there is power, it’s prop the pump. You could try wiring direct to the connector with wires from a battery.
A quick way to confirm a no fuel situation is to spray about a 1 second shot of starting fluid into the intake tube at the air filter housing. The engine may not fully start, but if it at least barks with the fluid, and not without the the fluid, it's 99% confirmation of a no fuel condition.
The relay and fuel pump were my first guess, haven’t tested yet though, I will do that next. The reason I haven’t done it yet was because after my scanner wouldn’t connect to the vehicle I stated questioning the main computer. I did spray starting fluid and it does fire the starting fluid.
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