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Hi everyone!

My car : SAAB 1996 convertible SE turbo 2 litres (173 000 km) manuel transmission

My symptoms :

Car cranks and cranks but won’t start from the past few weeks now.

Last year, it was starting normally but then it began to crank a little more and more and more till it just wouldn’t start at all (it still was easy to start it when engin was hot then). I first changed the fuel filter. And it went back to normal for a couple of months. And then the none starting issue when back… I decided then to change the fuel pump as it was a bit noisy. But no luck.

Then I looked for malfunctioning crack position sensor or fuel pressure regulator but trying to check that on I noticed (for the first time) that some of the indicators (Check Engine and Oil level indicator) in the instruments cluster were not showing up when I was placing the key on the « on » position of the ignition switch before I start to crank the engine. Airbags/battery/antilocks and other are brighting up but not those two importants signals….

It’s like if the ECU box is not doing its job of checking everything out and letting the voltage go to injectors/ignition system to make the car runs…?? Still I can hear the (new) fuel pump working all that time on « on » position waiting for me to crank…. I’ve interchange some of the relay (fuel pump/injectors/starting) in the beige box on left next to the pedals but no luck. I simply got no voltage on these fuses when I check with my multimeter instrument….

I’ve checked the wires that reaches the ECU box and I do have some female points which have 12 volts voltage on at that time. But it like if the ECU box doesn’t give signals back to cluster to clear check engine and let energy flows to other components then….

Now, here’s the thing. I don’t thing the ECU box is dead because when I open the throttle body and put 1/8 cup of fuel and crank, then it starts right up. And I went for a long one hour ride a couple of evening ago and the car when running like a charm, with no hesitations, no rpm bouncings, non high fuel consumption, no chenck engine lights on, no nothing…

And yes there is fuel going throught the injectors path and fuel regulator seams find with out leaks. And the two check valves at the fuel pump are fine. (there is fuel in the lines). Crank position sensor is also ok to me if 1) I can end start the car with fuel and 2) I don’t get rough idle/hesitations at all while driving.

My problem happens before that, as I just don’t have any visible (Check Engine/Oil level) signs that ECU box is doing its job…. I’ve looked under the driver seat to inspect the immobilizer box. It seems fine with no rust/water around. Would it block the ECU signal? And the car starts easily with in TB anyway.. I also checked for faulty grounds. Maybe I have missed one somewhere..?

Any ideas everyone?

Tonight, I plan to start the car with my "TB-1/8-cap-of-fuel" technic and check for voltage in ECU box wires. I also will plug my OBD II to search for any codes… what else?

JM
 

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Happens sometimes. Bad connection from ECU to fuel pump relay. Add a manual fuel pump relay feed from the ignition switched supply and it will probably be fine
 

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The warning lights in the dash are all independent - the oil pressure switch is a physical device on the engine, the check engine light is a trigger from the ECM. If those lights are not coming on, or not going off, then something external is amiss. Possibly the ignition switch. You need to be methodical about troubleshooting - when the problem presents itself, determine what's working and what's not working. That will help paint a picture of the issue. If putting fuel in the intake manifold gets it to start, you need to determine why fuel isn't getting there by itself - check the injectors for proper pulsing, check the fuel pump to be sure it's running, and check for correct pressure at the rail.
 

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Discussion Starter #4
Thanks guys for your inputs!


I double checked my relay last morning and heard some sort of pinchy sound coming from there. I interchanged the "Motor Starter Relay" with the "High Beam" one, which I definitely knew it was working well and, miracle (!), it worked!!


Now. I still don't have "Check Engine" light on "on" position before I start (or even when it is running) but the car works very fine.


So I'll keep searching for new clues on that and tell you the rest of this story in a few days :)
 

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Could just be a burned out bulb... I would be sure of that state - you don't want to be driving around with a flashing check engine light that you cannot see.
 
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