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Runs for 15 miles then dies - Fuel Issue?

3K views 12 replies 6 participants last post by  earthworm 
#1 ·
I need help diagnosing an issue with my ’98 900ES. Current symptoms: I can drive it about 15-20 miles then it will rev up and down by itself a few times and will stop running. If I let it set for a few hours, it will run again and to drive it 15- 20 miles again. If I drive less than 10 miles or so and turn the engine off, and try to start it after a few minutes, it will be hard to start again, exhibiting the same symptoms – revving up and down and then dying. Here’s a little history…A few weeks ago it died while I was out to lunch. Prior to this, I did not have any issues with the car running correctly. I towed to the local Saab shop who diagnosed the issue as a fuel pump. They also said that I had a faulty fuel tank ( via a smoke test), an intermittent misfire due to the DI Cassette and a very small leak in the head gasket. Bottom line was a lot more to fix it than the car is worth. I removed the fuel tank and replaced the fuel pump but broke the return fitting and had to replace it. I wasn’t sure how to replace the hard plastic hose attached to the fuel pump so I used rubber gas line hose. Is it possible that too much pressure is building in this hose, causing it to leak? I still have my old hard plastic return hose that I can use instead of the rubber hose but I don’t know how these are fitted. Are they heat-shrinked? Also, when I removed the gas tank, I noticed that the vent hose was split. I think this is where the shop surmised that the gas tank had a bad weld. I fixed the split hose and bolted everything back. It runs good if it has been setting for a few hours but gets worse the more I drive it until it eventually stops. Any insights would be greatly appreciated.
 
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#4 ·
Thanks for both of those suggestions. I'll certainly try them. Is the purge valve and gas cap related? I.e. if I remove the gas cap and the car runs fine, do I have a purge valve issue?

So, it is okay that I used regular gas line hose between the fuel pump and the "out" line? I'm seriously considering dropping the tank again to make sure the rubber gas line I installed hasn't held-up...or that I haven't pinched any of the other hoses.
 
#10 ·
Sounds like crank positioning senser ,those are classic symptoms,quiting once it warms up and starting again when it cools down. GOOD LUCK DAVE S>
This is much more likely and less expensive than a fuel pump.
And there is no such thing as a "fuel tank" weld....as Saab and most all others, use a plastic tank.
Find a better repair shop, if at all possible.
 
#7 ·
Well, I didn't have time to do anything for a few weeks...I bought my wife a new (used but new to us) car and I've been driving her old one. I did have time to replace the crank sensor since it was relatively inexpensive and from other posts seemed to be the issue. It didn't do the trick. I did drive the car a few days ago as it runs fine for short distances. I made it home just fine, let it sit and tried restarting. It started but then sputtered and died just like before. I'll try the gas cap when I get home to see if it is building pressure in the tank. I've also purchased a new purge valve and vent hose (which had a split in it) and will install those this weekend when I remove the tank again and replace the hose that I spliced between the pump and the outlet valve. If that doesn't work, I don't know what else to do. Could it be the DI cassette?
 
#8 ·
Solved - Runs for 15 miles then dies - Fuel Issue?

I think the issue has been solved with my 1998 900SE Conv – 150,000 miles. I haven’t been on a long jaunt yet, but I’ve been on several short trips with no issues. Here’s the summary:
Symptom 1 – The car died one day without warning while I was out to lunch. I had the car towed to the local non-dealer Saab shop who diagnosed the issue as a fuel pump. They also identified a laundry list of other things that were $$$, like replacing the fuel tank, the DI Cassette, Crank Sensor, etc…the cost being a lot more than the car is worth. I purchased this car new and hope to keep it a few more years so I decided to tow it home and attempt the repair myself. The curious thing is the car ran after the Tow Truck dropped it off. I didn’t try to drive it so I don’t know if the symptoms I will describe later were present.
1. I replaced the fuel pump by removing the gas tank. (BTW, removing the fuel tank isn’t that bad of a task. I preferred this over cutting an access hole. During the process, I broke the return check valve and had to replace that as well. When I installed the new fuel pump, I wasn’t sure how to manage the hard black plastic fuel lines. I cut the existing one from the fuel pump and replaced it with a regular reinforced rubber fuel line.
Symptom 2 – The car ran fine and I drove it to the Airport, but it died as I was pulling into the parking lot. Luckily, I was able to coax it into an open spot after restarting it several times. On my return, I decided to try to drive the car home, with my wife following. It died again about a mile from my house. Over the past few days, I learned that I drive it about 15-20 minutes and it would die but would restart if it set for a few hours. At this point, I was not sure if my old fuel pump was really bad or if I had another issue. No codes were showing.
2. After reading some posts, I replaced the Crank sensor because the symptoms were very similar. Also, the auto shop that initially diagnosed the car mentioned this as an issue based on the codes that were present.
No change – still the same symptom as above
3. I tied unscrewing the gas cap – no effect.
4. I removed the fuel pump again and replaced the rubber gas line with a piece for hard black plastic line I cut from the old return line I had to replace. I wish someone would post how to work with these lines, because I had a very hard time fitting it to the fuel pump and T-connector. I tried heating with a torch – as expected, I could not heat it evenly and it would blister. I boiled the end in water for 10 minutes but could not get it pliable enough to go onto the fitting. Then I used a heat gun and very slowly heated it. I know when it was ready because the plastic will start getting shiny. After several attempts with the heat gun, I finally got it fitted.
5. I replaced the purge valve based on a recommendation above. This was actually real easy to do and in hindsight would have been an easy part to check – just disconnect it.
So far, I have made several back-to-back trips, albeit short distance but have gone much farther that I could go before. I still need take the car on an extended trip to thoroughly test. But, when the car was not functioning properly, I could not go on back-to-back trips. The car would not start after the first trip. So, I am left wondering…was it the $50 purge valve all along?
 
#9 ·
Glad ya got it fixed. Did you ever test the car after installing the plastic fuel line? I doubt it was the fuel line, but it'd be nice to be sure. If you tested the car between putting on the plastic line and the new purge valve we could at least confirm that all your hard work was unnecessary and future people will just use rubber fuel line. :cool:

I suspect it was your purge valve all along.
 
#13 ·
This, I'll forget not !
Several years ago a poster(unknown) bought a used tank, pump and all for $20, as I recall.
All he needed was the FP.
I'd imagine that no-one(today) sells any new fuel tanks - having one fail is rare indeed.
Burned ? out purge valves are much more common and they are not too expensive...
We do need better diagnostics - which can be "built in".
 
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