1JZ supra wont start in the morning when below 40 degrees

[viperkillertt]

Hey everyone,
OMG! I have had the worst winter with my supra. In November the supra wouldn't start on random mornings. I thought that i had let the fuel tank get too low and so it got a little condensation. So to fix it, i just started keeping my fuel tank above 1/2 mark all the time. Well, that worked for like a week. Then i filled the tank fully and the next morning it took 15 minutes of chugging to get her to start. This was the very end of November.

So i went out and bought myself a few bottles of the Heet fuel antifreeze. Wa la! It worked. If i poured 1 full bottle, the car would start very quickly. But at 2 bucks a bottle, this was going to become very expensive. It also didn't work flawlessly. Sometimes it wouldn't work at all. It would take upto 10 minutes of chugging to get her to start when i would put a 1/2 bottle of heat in the car. I was thinking because the car was 1/2 down, that she wouldn't need a whole bottle.
I had no way to drain 14 gallons of fuel so i thought i needed to just get the tank pretty low and then i could drain it.
Well, that took over a month and a half to get it that low. Yesterday i drained the whole tank and then i put 9 gallons of premium in the tank.

I also want to add that once i get the car to run, it runs all day. As long as i start her again within about 4-6 hours i have no problems with getting her started again. It seems only to be problem when she hasn't been run for more then 8 hours.

This brings us to today. No start. After all that, no start. She just chuggs and chuggs. I have to try about 30-40 x to get her to actually start.

It really felt like this was a water in fuel line issue. Now i have absolutely no clue what is going on. This is my 3rd winter with this 1JZ supra. I didn't have any issues with starting until last October. I don't remember anything changing since then. The engine is relatively stock. Stock twins and 380cc injectors. About 2 months before this issue, i was having a very strange idle issue that fixed itself after about 2 weeks. She just wouldn't idle and it sounded like she was running on 5 or 4 cylinders, but magically it stopped after about 4 drives in the car. Any advice would be greatly appreciated. Thanks for reading.

 

[supraman7mgte]

I'll tell ya why it won't start.
It's too friggin' cold!
How about a block heater?

 

[viperkillertt]

haha, umm, well i have been driving MKIII supras for the last 10 years and i have never had this issue. Is it really that simple?

 

[Victor Charlie]

It could be the fuel pump. It often will function with more than half a tank, i think because it can prime itself better. Often it will keep running once started, even when fuel level drops to 1/4. Eventually it will probably fail completely, which may be the case with your car. Or the EFI maybe confused by the failing pump. you could try pulling the EFI fuse for 30 seconds, but definitely try starting it with a full tank. Custom electronics, especially replacement ECU's, are much less sophisticated at adjusting to all possible driving conditions, temp and altitude, and can fail to start at conditions other than what existed during the original tune. Otherwise there is the manual which has the protocal for troubleshooting failure to start:

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=12

 

[viperkillertt]

It could be the fuel pump. It often will function with more than half a tank, i think because it can prime itself better. Often it will keep running once started, even when fuel level drops to 1/4. Eventually it will probably fail completely, which may be the case with your car. Or the EFI maybe confused by the failing pump. you could try pulling the EFI fuse for 30 seconds, but definitely try starting it with a full tank. Custom electronics, especially replacement ECU's, are much less sophisticated at adjusting to all possible driving conditions, temp and altitude, and can fail to start at conditions other than what existed during the original tune. Otherwise there is the manual which has the protocal for troubleshooting failure to start:

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=12

The pump does work fine any time the temp is over 40 degrees. It is only when it is colder then 34 that i run into issues. Would that sync with a bad fuel pump. If it is a bad pump, i am going to be so mad i just drained and refilled my tank I have 9 gallons to use up now.

 

[steveo]

I go with a block heater... I have one on my Supra... Works AMAZING. lol -30 Celsius as long as it is plugged in it will start. I love it.

 

[Victor Charlie]

The pump does work fine any time the temp is over 40 degrees. It is only when it is colder then 34 that i run into issues. Would that sync with a bad fuel pump. If it is a bad pump, i am going to be so mad i just drained and refilled my tank I have 9 gallons to use up now.

I don't know the answer to that. I think it is possible. All you have to do is check fuel pressure when it isn't starting. You should be able to pinch the return line and feel if there is return flow if it is totally not priming. When my pump started failing there was some flow, but barely any and you could pinch the line all the way shut easily. It sounded like it was pumping air bubbles with the fuel.

 

[kwnate]

no way you'd need a block heater in Washington.

 

[viperkillertt]

no way you'd need a block heater in Washington.

That is what i was thinking. We rarly dip down to the teens. This winter we have had a low of maybe 18. It has been really warm. Something else very strange is going on. A block heater might be a band aid, but it isnt going to fix the problem.

 

[viperkillertt]

I don't know the answer to that. I think it is possible. All you have to do is check fuel pressure when it isn't starting. You should be able to pinch the return line and feel if there is return flow if it is totally not priming. When my pump started failing there was some flow, but barely any and you could pinch the line all the way shut easily. It sounded like it was pumping air bubbles with the fuel.

But wouldn't you have other issues if the fuel pump was dying? My car runs perfect all day long every day except for the first start in a cold morning. It was in the 40s for 2 weeks, the last 2 weeks and i drove every day without any problems. We just got cold again and she stopped starting.

 

[IJ.]

It could be the fuel pump. It often will function with more than half a tank, i think because it can prime itself better. Often it will keep running once started, even when fuel level drops to 1/4. Eventually it will probably fail completely, which may be the case with your car. Or the EFI maybe confused by the failing pump. you could try pulling the EFI fuse for 30 seconds, but definitely try starting it with a full tank. Custom electronics, especially replacement ECU's, are much less sophisticated at adjusting to all possible driving conditions, temp and altitude, and can fail to start at conditions other than what existed during the original tune. Otherwise there is the manual which has the protocal for troubleshooting failure to start:

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=12

Where is the pickup on fuel pumps?
(hint it's at the bottom submerged in fuel)

 

[Victor Charlie]

Where is the pickup on fuel pumps?
(hint it's at the bottom submerged in fuel)

Yes, I know, but I've had two vehicles that had the same symptoms as the fuel pump fails. The mechanic I use when it's too cruddy out to work myself says he has seen many vehicles with this symptom as the pump fails. I recognize and greatly respect your expertise, but this is how I am thinking. Please correct my if my assumptions are wrong:

I believe it is a wet pump, so the internals are immersed in fuel, Right? There must be a low pressure side that sucks in the fuel with a failing seal higher up in the interior of the pump you could get the symptoms he is describing, even though the inlet is in the bottom. Does this make sense?

 

[IJ.]

Only time I could see level making a difference is when it's very low and the pump starts to overheat, not really an issu with a stock Denso pump though it's more an aftermarket hi press/volume pump thing.

If a pump can't lift 2" head of fuel there's something seriously wrong with it and I doubt the car would run ever.

 

[supra90turbo]

Whoever thinks 40*f is too cold is ignorant. I just fired my Supra up tonight and it's 8*f out here. 3 cranks and it caught, and that is sans-CSI.

You've got something else going on there. When was the last time you changed your plugs? Fuel Filter?

 

[viperkillertt]

Whoever thinks 40*f is too cold is ignorant. I just fired my Supra up tonight and it's 8*f out here. 3 cranks and it caught, and that is sans-CSI.

You've got something else going on there. When was the last time you changed your plugs? Fuel Filter?

Plugs are about a year old. Fuel filter has not been changed because it is in tank. I know having issues at 40 degrees is very silly and strange. That is why i am here asking questions.

 

[suprastanger507mgte]

How old is your battery? Recently it dipped here in California around 32 or so and I could not get any of my cars to start in the morning. They all went weak since it was so cold. Once I came home during warmer temperature in the day and was able to start the cars without any problems. If you haven't already, I'd suggest to at least check the status of your battrey under cold conditions. I was told by the dealer that there are batteries for colder climates and warmer climates...and I've researched that as well.

 

[viperkillertt]

How old is your battery? Recently it dipped here in California around 32 or so and I could not get any of my cars to start in the morning. They all went weak since it was so cold. Once I came home during warmer temperature in the day and was able to start the cars without any problems. If you haven't already, I'd suggest to at least check the status of your battrey under cold conditions. I was told by the dealer that there are batteries for colder climates and warmer climates...and I've researched that as well.

My battery is fine except for the fact that i cant get my car to start. that causes me to kill it a few times a week. It will chug and chug for about 15 minutes in the cold, so the battery is definitely ok

 

[IJ.]

Next time it won't start try for a few minutes then pull a plug and report back what you find.

 

[viperkillertt]

Next time it won't start try for a few minutes then pull a plug and report back what you find.

Ok,
I will try it tomorrow and let you know if it is dry or wet.
Thanks!

 

[viperkillertt]

After 2 months i am still having the same problem. It is not fuel related at all. I removed all the fuel and refueled. I am wondering if anyone has had an issue with the ECU being too cold. I know it sounds strange, but i am running out of ideas. I replaced all of my spark plugs about 3 weeks ago, it didn't change anything. I also changed the oil and cleaned the K&N. I have never had a starting problem like this on a fuel injected car.
Other issues: The ECU relay seems to not turn off after the car turns off. I don't know if this is related at all. This causes the car to use a little extra power while turned off and has killed my battery very often. My boost controller and tach adapter stay on all night. I disconnected my boost controller in November because it didn't turn off.

The plugs smelled like fuel when i changed them. They were pretty black.

Has anyone had a similar problem with the supra? Is there a cold start injector that might get clogged? My friend mike mentioned a cold start injector. I don't remember seeing one on our cars.