5-Series (E12,E28, E34, E39, E60)Chat relating to the BMW 5-Series of all generations. Specific models include: BMW 518, BMW 520, BMW 520i, BMW 530i, BMW 528i, BMW 530i, BMW 518i, BMW 524d, BMW 525i, BMW 525e, BMW 528e, BMW 540i, BMW 535i, BMW 520d, BMW 525td, BMW 525d, BMW 530d, BMW 525i/xi, BMW 530i/xi. (BMW 5-Series Forum)
new owner of 91 535i - now it wont start in cooler weather
I recently bought a 1991 535i with 162K miles on it. It has a few issues that need to be fixed which I knew about before I bought it from a friend and also why I only paid $800. But what is happening now didn't happen to the previous owner.
When the weather is cooler (mornings or overcast cooler days - low 50's or so) the car will crank but not start. Once it warms up outside it starts right up and runs fine for the rest of the day.
When it doesn't start, I have done the following:
I have checked for spark - which there is.
I have jumpered the connections on the fuel pump relay but still would not start.
I have also banged on the gas tank near the fuel pump - but it will only start once it warms up outside.
I was suspecting the fuel pump at first but I'm leary of replacing it because it starts and runs fine in warmer weather.
Does anyone have any ideas as to what else I can check or replace to fix this problem?
Would an Intake Air Temp Sensor cause the car to not start?
I think on this car the IAT Sensor is integrated with the Volume Air Flow Sensor.
I'm not getting any check engine light.
I've seen other posts that talk about a "stomp test" - maybe I should try that to see if I get any type of code for air temp sensor.
To me, since it is only a cooler weather issue it might have something to do with a sensor that detect either air or coolant temperature. But there type of sensors usually make a car run lousy, would a bad temp sensor prevent starting at all?
Does this engine have the Thermo time switch? Also, if it has a cold start valve,it might not be working so the engine doesn't get the extra fuel for the cold start. I hope you have a Bentley or are plannig on getting one as you will need it!
Thanks for the reply jlmoreno.
It has the M30 engine so I'm not sure about the Thermo Time Switch.
A friend at work just a little while ago also mentioned the cold start valve.
He had a 1981 528i and had a problem with the cold start valve.
I'm checking Ebay for a Bentley manual - they are running $55 - $65 - but a worthy investment for sure.
After doing a bit of research - my car does not have a cold start valve.
It was a great idea - I thought we were on to something.
Marti5 - would a bad MAF only allow the car to start once the temperature warms up? In the mornings it has been anywhere from the upper 40's (Farenheit) to the very low 50's and it will crank but wont fire up. When I get home in the afternoon and the tempertature has climbed well over 70 - it starts right up and runs just fine.
I have also heard about problems with fusible links, such as hairline cracks. I'm wondering if when it is cooler the fusible link contracts making the crack larger and doesn't get power to the pump. But once it warms up it expands and the crack gets smaller therefore allowing enough current to make the pump work ???
I think I have seen info on how to test the pump wiring connector for power. I need to search for that again and test it when it doesn't start to see if I'm getting power to the pump.
I'm also going to check for moisture in the distributor cap - maybe the cooler weather is creating condensation. I live in a very dry area but it's possible. I have checked for spark when it wont start and I am getting spark to the plugs - but it is still worth checking.
You have a good point on the fusible link. Replacement is definitely a good idea. Look at the main page here of the 5 series for an online version of the maintenance manual. You can download it to your computer and read/print what you need. I think your engine has the AFM not the MAF as it is the older type wit the vane type air flow meter (AFM) instead of the Mass Air Flow (MAF). Those are known to be also problematic since they are a mechanical/sliding contact system. Go take a look at the Bentley in section 130 as it describes detailed Fuel Injection system troubleshooting component by component.
Thanks for the ideas.
I'll look for the manual too.
This morning it fired up, ran for a few seconds and died. I wasn't depressing the accelerator pedal at all. After that, it would crank but not fire up.
It might be a while for me to look into this.
My 10 year old son plays on an All Star Baseball Team and this is the 3rd weekend in a row of tournaments. The next two weekends are tournament weekends as well.
I have a little time after work on the weekdays but there's only so much I can do in a few hours.
Anyway - thanks so much for your time answering my posts and providing great suggestions. I'll post my results as I work on it.
Might have found the problem -1991 535i not starting in cooler weather
I have finally had some time to troubleshoot my car problem.
It had still been giving me problems not starting in the morning but it would start in the afternoon.
It wouldn't start for me one day and so it sat for a few days - then the batttery went dead. So I got it re-charged and it fired right up. I started searching forums and found out how to test for something that might be drawing current.
I went out and bought a new digital multi-meter (one that is fused). I set it to 200 mA, disconnected the negative battery terminal and ran the leads on the multi-meter from the negative post to the negative clamp - it blew the fuse in my multi-meter.
So I took the car down to Autozone and had them test the alternator - they said the diodes were OK but it was only putting out 30A. They tested the battery and it is fine - it is about 2 years old and is rated at 600 Cold Crank Amps but it was only at 67% charge.
So I have a new alternator on order.
The weak battery probably was why it wont start when it is cooler out.
Now with the alternator disconnected, I need to get a new fuse (or three) for my multi-meter and check to see if anything is still drawing down the battery. I'm hoping it was the alternator (even though they said the diodes are OK). If it is still drawing down, I have found instructions on how to isolate it.
Anyway - I thought I should post an update to let everyone know that helped here that I might be on to something. Once I get the new alternator in I'll see how things run for a while and then I'll post another update.
Thaks again to you and all the others that replied.
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