Car stalls while driving, EFI fuse melted but not blown?

WIEBKE.BE

MEMBER
2001 TOYOTA LAND CRUISER PRADO
3.4L
6 CYL
4WD
AUTOMATIC
231,000 MILES

When driving the car very infrequently stalls. The more often this happens, the more the EFI 15 Amp fuse melts, but doesn’t blow.

We have monitored when the stalling happens, and it seems to be not/less related to heat (happens in 35 but also 20-degree weather). We noticed that it once happened often on a gravel road, the next day not at all, the next day it happened while driving over a bumper after the car had literally been started 2 minutes ago. Therefore, we believe it might be related to movement rather than temperature.

After stalling, it can sometimes start right away, other times it’s required to try multiple times to get it started again.

It also seems like after replacing the melted fuse, the problem will not occur for a longer time.

Our assumption is therefore a circuit short but we do not know where is it coming from. Any ideas? Mechanics have so far not been very helpful.

5 Replies

JACOBANDNICKOLAS

MECHANIC
108,336 POSTS

Hi,

In most cases when a circuit fails, the fuse will blow. Since that isn't happening, I have a feeling that there is a connection issue.

When there is a poor electrical connection and arcing can occur, it creates heat that can melt down the fuse. If you remove the fuse, are the connections it plugs into in good condition? Check to see if there is any corrosion or if one of the connectors is pushed into the box.

Next, please understand this model isn't offered in the US, so I don't have schematics to reference the circuit. I am basing my suggestions based on past experience. Check things such as connectors on the fuel injectors and anything the fuse powers.

Let me know what you find or if you have questions. Also, here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

Take care,

Joe

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Monday, January 9th, 2023 AT 6:52 PM

WIEBKE.BE

MEMBER
3 POSTS

Dear Joe,

Many thanks for taking the time and your advice, highly appreciated. We bought this car a few weeks ago and noticed a week after that the previous owner had a wire replace the EFI fuse. Then we replaced the wire with the fuse and a few weeks later our car has multiple stalls daily, almost every day.

After reading a lot on the internet, I think you are right and there is an electrical connection issue (loose?) in the EFI circuit, or a connected component is drawing too much power (?). The fuel pumps aren’t the issue as it happens on both tanks which have separate pumps. The fuse box and all the obvious connectors we can see under the bonnet look fine.

Thank you also for the link. The problem is that the wiring can’t really be checked because there is nothing to be found unless it’s the second the stalling happens or am I wrong? That’s also the reason why auto electricians can’t or won’t really help us and they just say we shall continue to drive. Problem is we’re driving through Australia and still have around 10k km (lots of it very remote) on our schedule before selling the car and leaving the country. So, we are in a pretty bad situation right now and I appreciate really any help I can get! We are quite handy ourselves and could try a few things, but I am not sure where to start.

Found the circuit diagrams online.
(http://htftp.offroadsz.com/marinhaker/programi/VSI4KO%20ZA%20TOYO/Land_Cruiser_1996_Electrical_Wiring_Diagram1.pdf - model 5VZ-FE)

But kind of tough to follow for a non-pro. Any ideas what we could do to help ourselves? Do you understand which components are part of the circuit? Those would be easier to find for us than understanding the wiring diagram. :)

Thank you!
Wiebke

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Wednesday, January 11th, 2023 AT 5:03 PM

JACOBANDNICKOLAS

MECHANIC
108,336 POSTS

Hi,

We need to get this fixed for you. I looked at the wiring schematic you sent. Unfortunately, I can't read the writing. It is too blurry.

Can you take a pic of the wire that was replaced? Also, check where the new wire is connected to make sure there is a good connection and that the wire it connects to appears to be of the same gauge.

Also, check the connectors at the fuel injectors. Make sure they are tight as well. If I had to guess, and keep in mind, this is a theory, I suspect the power supply to the injectors is spliced at one point. That is normally what I see. You have one wire from the fuse, and it splices into several wires for each injector. I have a feeling that it wasn't repaired correctly.

If possible, take a few pics of what you are dealing with. Hopefully, it will help me.

Take care and stay safe.

Joe

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Thursday, January 12th, 2023 AT 6:44 PM

WIEBKE.BE

MEMBER
3 POSTS

Hi Joe,

Thank you so much for trying to help, highly appreciated!

Maybe there was a misunderstanding, just to clarify: there was a wire in the fuse box instead of a fuse, put by the previous owner, probably to bypass the car stalling as it will take more heat (?). I have attached a picture of the wire. So, there wasn’t, to my knowledge and what I can see, any bad repair that could cause the trouble.

A mechanic will replace the fuse holder today, maybe that helps. If not, we will try to check the connectors going to the injectors. Unfortunately, the fuel pumps are in the tanks so that’s not that easy. Any other connections to components that you suspect?

I have also attached the circuit in better quality hopefully.

Thanks again!
Wiebke

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Thursday, January 12th, 2023 AT 7:19 PM

JACOBANDNICKOLAS

MECHANIC
108,336 POSTS

Hi,

Wow! You are lucky it didn't catch fire. A fuse is designed to fail when a certain amount of voltage/amperage is exceeded. It does that to prevent wiring from melting down due to excessive power draw.

Placing a wire in there jumped the fuse and took away all protection. Remove that wire. That is why the box melted. Excessive voltage draw.

Replacing the box will help. Tell him to replace the wire with the proper fuse. Hopefully, it won't fail. If it does, then we have a short and it needs attention. Don't put another wire in place of the fuse. That is a disaster waiting to happen.

Let me know.

Joe