[mynegus8u]

CAR: 1984 4 door SAAB 900 FI


hi all, i am new to the community here i have done some searching multiuple time without reallly finding anything that i could use towards my issue, just some that may be falling under the umbrella or what ifs.

to start i dont really know a whole to lot about the saab motors themselves. i was a mechanic for two years and decided to go somewhere else at the time, i dont mind doing the work and know atleast what im looking at and can do..

the 1984 saab 900 i picked up about a month ago and when i bought it, it did have a idle issue but thought we had gotten it sorted out with the set screw behind the carb. i got it to where the vehicle would start by its self it was always intermittently starting with the key. sometime i would push the pedal to the floor to disengage the fuel injector and it would start..

about a week ago i went to start the vehicle. it cranked a few times, tried to start, and it backfired through the carb.. up until this point the vehicle was able to start on its own ( without starting fluid) when it backfired i put everything back together, the tubing had just came apart from my throttle body to carb. so i put it back and tried to get it started.. it wouldnt start so i rolled it down the hill and dropped the clutch and got it going, the vehicle ran very rough, when i would give it gas, it would die down a bit. ( kinda like it was flooding) then it would go away after i ran it about 3k rpm for a minute..

the only way i can get the vehicle started now is with starter fluid, i have about a half a tank of gas, once its started, i cant let it drop under about 1500 RPM otherwise it dies. once it dies, starting fluid is needed again. even though once started will stay started untill it drops to about 1500rpm it starts running rough shakes then will die if i let it.. being as this is a issue its driveable i had to drive about 10 minutes from my house to get internet from my parents, so as you could imagine a lot of heel toe was used to not the let vehicle die while comming up to stop lights and intersections..

my first though would be my gas tank/fuel filter?? maybe i have rust in my tank, or the filter is dirty. im not 100% though.. it would be greatly appreciated if anyone could help me out, any pointers or anything.

Thanks in advance

 

[Jim Mesthene]

It has no carb, moving the accelerator when it's not running does nothing, the idle is not adjusted with that screw. It's not a problem with fuel or filter.
You probably need to find a large vacuum leak (check the oil cap). Make sure you have the right plugs.

 

[mynegus8u]

oil cap is loose but hasent gotten any water or condensation in the motor.
plugs are good and correct. they are new(er).

how would it not be a fuel pump issue? i dont hear it turning on when i turn the ignition on, but when i use the starting fluid the car will stay running till i let it drop under about 1500.. and i dont adjust the accelerator while its not running, that screw is so touchy and will kill the car when depressed while running.. i was told that the (accelerator ) that your talking about was the amount of gas it was intaking..

 

[Jim Mesthene]

oil cap is loose...

That's a large vacuum leak.

how would it not be a fuel pump issue?

It takes something like 57 psi to open an injector (they're not electronic). If it runs at all on it's own, the fuel pump is strong.
You can't do too much harm with the Throttle Stop Screw, but other adjustments can cause running troubles if they've been fiddled with by someone unfamiliar with the K-Jetronic (Continuous Injection) fuel system.
K-Jet is quite durable and trouble-free, but is very different from most modern cars.

 

[mynegus8u]

okay thanks sir for your advice, now question i dont and wont be able to get access to a cap for a couple days here as im located in a very small town in iowa right now.. would i be able to take my oil cap off since it is looose and cover the neck with tape or something tto test that? or what would you recommend..


i know i have had loose and/or no existant oil caps before with other vehicles but would this be that different to where it wouldnt start like so..

 

[Jim Mesthene]

Seal it with anything that stops air. Duct tape won't stick, but saran wrap or the like, with rubber band might.... Squirt carb cleaner (not starting fluid!) at suspect areas to find other possible vacuum leaks; idle will increase when you squirt a leak.
Some PCV systems use a negative pressure crankcase, most don't.