saab 900 classic will not start with a warm or hot engine

bertieirl

hi i have a little problem with my 900 turbo from 86 flat nose. recently i found out that the car will start no problem even on cold morning . but after driving for a few minutes or a good while if i stop the engine it will not start ( sound like if it is flooded) but if i leave the car to cool down five minutes it start straight away. any suggestions? thanks a lot

PaulK_CCI

bertieirl wrote: »

hi i have a little problem with my 900 turbo from 86 flat nose. recently i found out that the car will start no problem even on cold morning . but after driving for a few minutes or a good while if i stop the engine it will not start ( sound like if it is flooded) but if i leave the car to cool down five minutes it start straight away. any suggestions? thanks a lot

Because I have a few classic Saabs myself, I am a member of the Saab Forum in Holland, where this problem has been discussed a few times since it seems to be a problem that pops up once in a while with the Fuel injected 2.0litre 8V's/16v's.

From some of the suggestions made, three stood out for you to check:

1/ The cold starting is regulated by a number of sensors dotted around the engine. One of these sensors can be faulty, causing the engine management system to think the car is still cold instead of hot when you turn the key, and provides a (way too rich!) mixture, activate the 5th injector, and the car will not start... Check out your Thermo Time Switch and Warm up regulator, these are the most likely culprits.
2/ Fuel pump could be faulty. When warm, it might not provide enough pressure
3/ Starter motor. I know this sounds weird, but this turned out to be the problem in two cases.

In any case, not an easy problem to diagnose precisely, so good luck

bertieirl

:rolleyes:thank s a lot paulk

mike65

Dont roll your eyes at the man!

Bosch K-series fuel injection systems most likely weak point is a dead water temp sender.

Mike

PaulK_CCI

mike65 wrote: »

Dont roll your eyes at the man!

Bosch K-series fuel injection systems most likely weak point is a dead water temp sender.

Mike

but would that not give you a very clear signal by a false reading on the temp gauge on the dash?

galwaytt

not sure about the Saab, but there are two temp sensors on my MX-5, one for the gauge, one for the FI - if it's the FI one, you'd never know......just get fuelling issues........maybe the Saab is similar ?

mustang68

PaulK_CCI wrote: »

3/ Starter motor. I know this sounds weird, but this turned out to be the problem in two cases.

Starter motor not working when hot isn't that weird, it happens on US cars a bit, lots of heat and the starter won't turn, or not turn at a good enough speed. They even sell blankets for them to keep them cool

MercMad

mike65 wrote: »

Dont roll your eyes at the man!

Bosch K-series fuel injection systems most likely weak point is a dead water temp sender.

Mike

.............its as you say Mike. The Bosch K uses seperate sensors, a Temperature Sender for the dash gauge and a Coolant Temperature Sensor for the ECU to know the temperature of the engine.

I am not familiar with Saabs but on other cars with this system you can disconnect the cold start injector to see what way the car behaves. Disconnecting the Collant Temp Sensor will not improve things.

PaulK_CCI

MercMad wrote: »

.............its as you say Mike. The Bosch K uses seperate sensors, a Temperature Sender for the dash gauge and a Coolant Temperature Sensor for the ECU to know the temperature of the engine.

I am not familiar with Saabs but on other cars with this system you can disconnect the cold start injector to see what way the car behaves. Disconnecting the Collant Temp Sensor will not improve things.

That sounds like you're contradicting yourself here Ben but maybe I am just picking it up incorrectly. 1st you say the Coolant Temperature Sensor is for letting the ECU know what temp the engine is, and therefore vital for giving the various sensors the correct information, and then you say that disconnecting the Coolant Temp Sensor would not improve things ....

As I mentioned in my original post (and please note I am by no means an expert on the finer mechanics of FI engines, but it's just that I passed onthe info I found on the Dutch Saab forum) there are several sensors dotted around the FI system. One of these might be faulty.
The system is slightly different for 8V and 16V engines, and there are some small changes through the years as to where the sensors are placed, so it's important to find out which car you have

Have a look and read at this pdf linkie that I have borrowed from someone kind enough to put up the relevant Haynes pages on the FI system, very helpfull indeed!

http://www.velde.co.uk/saab/haynes-saab-thermotime2.pdf

MercMad

PaulK_CCI wrote: »

That sounds like you're contradicting yourself here Ben but maybe I am just picking it up incorrectly. 1st you say the Coolant Temperature Sensor is for letting the ECU know what temp the engine is, and therefore vital for giving the various sensors the correct information, and then you say that disconnecting the Coolant Temp Sensor would not improve things ....

As I mentioned in my original post (and please note I am by no means an expert on the finer mechanics of FI engines, but it's just that I passed onthe info I found on the Dutch Saab forum) there are several sensors dotted around the FI system. One of these might be faulty.
The system is slightly different for 8V and 16V engines, and there are some small changes through the years as to where the sensors are placed, so it's important to find out which car you have

Have a look and read at this pdf linkie that I have borrowed from someone kind enough to put up the relevant Haynes pages on the FI system, very helpfull indeed!

http://www.velde.co.uk/saab/haynes-saab-thermotime2.pdf

.............I never contradict myself.......................I just make mistakes regularly !

No.....what happens is that if the sensor goes faulty, it will always inform the ECU that the car is cold, therefore inject more fuel. If you disconnect the injector you CANT get more fuel, so the car should behave itself when warm starting. However if you simply disconnect the temperature sensor again the ECU will think the engine is cold !

Are we ..........................CLEAR ??

Can you HANDLE the truth ??

PaulK_CCI

MercMad wrote: »

.............I never contradict myself.......................I just make mistakes regularly !

Are we ..........................CLEAR ??

Can you HANDLE the truth ??

The 'truth' and Saabs.... do we really want to go there ...

only messing, but yes, it;s clear.

I got confused because you were looking at it from a 'troubleshooting' angle (disconnect the 5th injector=reaction, disconnect sensor=no difference)
whereas I looked at it from a 'replacing' angle
(swap 5th injector=no difference, swap temp sensor and if it was faulty=reaction!!)

bertieirl

thanks a lot guys but i absolutly know nothing in terms of mechanic, do you a saab specialist in the kildare area .i m near naas. i heard about ben curran in newcastle but it seem impossible to contact and i contact saab center in kildare town but i don t think they are interested to look at a classic of that age. thanks

Gerry

Hi Bertie, I remember your car seemed to be a bit reluctant to start when hot at the terenure show. Unfortunately most of the advice on this thread doesn't directly apply - your car is an early T16, with bosch LH 2.2 electronic fuel injection. It might still be on the right track though, its possible that your coolant temperature sensor is not working properly. Its worth taking the electrical connector off and cleaning up the contacts a bit for a start. Replacement isn't difficult or expensive either if it comes to that.

mike65

Hmmm I wonder if this got sorted - last year...