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Discussion Starter · #1 ·
Okay, so for what it's worth I am posting an experience I recently had.

Car was sluggish and died going up a hill, low gas level. After that it would crank but would not start.

Didn't pull DIC to check for spark but was close to doing that. Fearing ruining the DIC kept that from happening right away.

Was told that if the tachometer doesn't jump when cranking without starting then its the crankshaft position sensor (CPS). Common problem. But being an expensive part and a PITA to change, didn't jump right at it.

Decided to check fuel pressure on the rail and only got a dribble when pressing the Shrader valve in with a screwdriver, not a burst like expected for 40 PSI of fuel pressure. Hooked up a rental fuel pressure gauge and didn't get a reading. Not having done that test before and using a rental gauge I wasn't confident it was being done right.

So after re-confirming that the tachometer should be moving a little bit when cranking and not starting it was decided the CPS was bad. Changed it out with a brand new one and 1-2 hours of cursing and tried starting the car. Still nothing, just cranking and no starting. The tachometer was still as still could be, no movement at all from the tachometer.

So it has been my experience that checking the tachometer for no movement is NOT a dead giveaway that the CPS is bad. This is just my experience but it would be interesting for someone with a good running car to pull their fuel pump fuse and try starting the car and check if the tachometer jumps a little or not. I suspect not. It makes sense on paper that the CPS feeds the tachometer with signal and that is why I believed it, but in reality is not how the system worked on this car.

So changed out the fuel filter in front of the rear passenger tire thinking the filter was clogged from running the tank so low. Still nothing, just cranking.

Long story short(er) the car had a problem with the fuel pump....PITA fuel pump assembly removal later. Apparently the fuel pump core replacements out there are for changing just the fuel pump and not all the extraneous stuff fitted to the actual fuel pump assembly in the tank. Saves money not changing out all the other parts. Part of changing just the fuel pump requires a shrink vinyl gas line to be cut off from a small black plastic tee fitting. The kits come with a new pig tail of rubber gas line and two screw clamps to reconnect everything. Seems fine right?

Well the last time this fuel pump was replaced the person just cut the line from the end of the tee fitting and left the vinyl tubing in place on the end of the tee fitting covering the ribs on the tee fitting. Then the rubber gas line was placed over the smooth vinyl bumps and clamped. Not sure how long it lasted but the rubber fuel line eventually pushed off the smooth vinyl tubing bumps on the tee fitting. Makes perfect sense and confirms our fuel rail test and pressure gauge test.

So we spent 30 second with a utility knife to cut off the last little bit of vinyl tubing to get down to the rigid ribbed tee fitting surface. Placed the new rubber fuel line on and clamped. Got the fuel pump assembly back in the car (another PITA) and after 20 seconds of cranking it started right up.

So it's worth a peek into the fuel tank to check the hoses on the fuel pump are all connected if you are hearing the whir from the pump but not getting any fuel pressure at the rail. It wasn't hard to pull the fuel pump assembly up 2-3 inches from the mounting surface in order to peek inside and see what was happening. It was immediately apparent that the line being loose wasn't right. Most of the time spent was actually removing and replacing the assembly from the tank, the fix took 5 minutes and a few bucks in parts from the local Saab shop. Fuel pressure was checked and registered using the rental gauges and a big burst of fuel from the Shrader valve when disconnecting gauges.

If you are changing a fuel pump in the future, do yourself a favor and spend the extra few seconds to cut all the vinyl tubing off the tee fitting in order to get back to the rigid ribs on the tee fitting surface so that the new fuel line actually grips when clamped.

Interesting side note is that the Saab shop we went to got the core kits also and stored the rubber fuel line pig tails and clamps. They didn't use them. They actually replaced the vinyl fuel line and shrank it back down onto the cleaned tee fitting. It looked like factory after they were done. But they did hold onto the rubber fuel line pig tails and clamps and sold them to us for cheap.

Just an FYI...use it for what its worth.
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