Cranking But Not Starting Issue

I have a 2011 Toyota 4Runner SR5. When COVID started, it sat in the garage for almost 2 months and when we went to start it, the battery was completely dead. We replaced the battery. A few months later, the engine would crank, but it wouldn't start. It would eventually start, but it could take up to 5m and multiple attempts. A few months later, the battery was dead again--and so we replaced it (AutoZone basically traded us outright for it). This combination of events has taken place for the past 2 years. Our local Toyota was unable to duplicate the problem each time we took it to them to look at, and because the batteries kept having to get replaced, they were unable to locate any "error codes", so we had to wait this out. The cranking but not starting problem isn't something that we can re-create; it might happen once every 3 months, or once every 3 days, or even once every 3 hours. It varies--no consistency to it. We were advised to take a video when it happens, which we did (we have several videos) and showed it to our local Toyota. The cranking and not starting problem has been occurring more frequently, and fortunately the battery is still working so the error codes could be read by Toyota. They used a "flow chart" to troubleshoot and said the issue is either a faulty ECU that controls the fuel pump or a faulty fuel pump based upon the error codes. On 10/13/2022, they replaced the ECU, but within a few days, the problem happened again, so they said we need to replace the fuel pump, which was done on 10/26/2022. Two nights ago, the problem happened yet again. Now, we have paid over $2,000 for an ECU and fuel pump and we still have the problem!! I called Toyota yesterday and told them that it is happening again, and they asked where we get our gas because if we don't get it from Shell, that might be the problem. We do get it from Shell, but not all the time, but I seriously don't think that has anything to do with this issue. They told me that when it happens again, to try turning the key to accessory mode for 10s then try to start it. I wanted to share my situation with the hopes that someone out there who might read it can offer me some advice. Our local Toyota doesn't think there is a correlation between our batteries dying and this cranking and not starting issue, but we do. We are not mechanics, but there has to be a connection because have had to replace 3 batteries in a 2 year period. Many thanks for your assistance.

 

I am not a mechanic by any means, but I do understand fuels since I work in that industry. I don't think the fuel type or brand is the issue here. These are made the same and qualified in a similar manner. The battery thing is obviously the common denominator here and I believe you might have some galvanic corrosion going from the battery terminals thru the cables throughout the system. This is hard to spot without removing them or replacing them. You mentioned the 4R sat for a while...and I wonder if during that time of inactivity the corrosion just grew over time and damaged some of these components. Sounds like the fuel system has been replaced..so no need to mess with that. Spark plugs? And cables around that area? Look for things that could be chewed or cracked.
Good luck.

 

FWIW - when I let my 4Runner sit for only a couple weeks, I found mice nesting in the engine bay and chewed up some wires. Maybe look around for chewed wires...just a thought...

 

From your description I would think that something drains your battery, maybe some faulty connection or some old mod your forgot about, like led bulbs for example, or you have something plugged in. Also I always thought that average car battery fully discharges in about 2-3 months is not dicsonnected.

 

Sounds like you have a parasitic draw. If you have a multimeter you can check for one pretty easily. Here’s a decent video below on how to do the initial check and track down the circuit that is a causing it.

The other potential issue could be high resistance in your positive battery cable that is not allowing enough current flow from the alternator to keep the battery charged and conversely from battery to starter which could explain why it’s so random. Note that on most modern vehicles the alternator connects through the starter to the battery. This is a bit harder to test for since you need to be able to connect your multimeter to both ends of the cable (at starter and at battery). I actually had this happen on one of my cars due to too much flex / vibration at the battery terminal connection that allowed the individual strands of wires to separate and increase resistance.

The reason your battery keeps dying is due to the cells becoming sulfated due to its state of charge dropping and varying too much / too often. Either one of these issues will cause it. Both issues could also cause the intermittent no start due to insufficient charge of battery to both crank the engine over AND trigger the ignition system. Good luck.

https://youtu.be/KF1gijj03_0

 

Man, this sounds like a tricky one I think just about any tech is going to pull out their hair on this! Intermittent no start like this with a known good battery and fuel system, and known issue of dead batteries would make me think open/ short circuit from damaged wiring. Find a reputable shop that's not a dealer and explain the problem. Tell them how many batteries you've gone through, about the new ecu, new fuel pump. It's going to be hard to track down though since it's intermittent, maybe a thorough physical inspection finds a damaged harness?

 

you did the battery charger for 3-4weeks .. the 4runner is the PCM and the battery is using the break down discharge , the electric components ..
so you did the engine running to charge the battery well the battery is and the engine has a lot of issues in the garage...
also use the gasoline additive ,,, alcohol is a old gas and the fuel is a corrosion/dirty ..

 

have you performed parasitic draw test on your truck?
use an amp meter with logging function to capture current values for 24 hours to locate intermittent parasitic draw instead of static one
guess some wire short may cause ECU/BCU can't fall sleep randomly
It's very hard to trace down all possible sensors