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Fuel System testing Posted by Gary Stottler [Email]  (#1463) [Profile/Gallery]
(more from Gary Stottler) on Mon, 29 Apr 2013 09:33:00
In Reply to: Re: that sensor is not used --, Richard Buckthorpe-Cooper, Mon, 29 Apr 2013 00:43:21 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I believe that the sensor was used early on but proved so problematic that it was disabled as a service fix. If there are no wires going to it you probably don't need to worry about it. Here are some steps you can try to verify fuel system function.
1) Go on eBay and see if you can find a real Saab Service Manual (red cover). The Haynes one is pretty awful.
2) Make sure the car has fresh gas in it. It's easy to drain a 99 - why struggle with issues caused by old fuel, water, etc. Consider putting in a dose of Techron with your fresh fuel.
3) To jumper the fuel pump relay, pull the fuel pump relay out of the relay panel (should be marked which one it is - panel is on top of right wheelhouse). Use a jumper wire to connect the top (horizontal) and bottom (vertical) terminals in the panel. I don't have a manual handy right now - maybe someone can verify which terminals for you. You do not need to turn the key on, you should clearly hear the pump running and fuel "whooshing" through the system as it flows up to the distributer and is recirculated back to the tank.
4) If you can't get the pump to run, you'll have to get into standard electrical troubleshooting, but it does not sound like you have that problem.
5) WARNING!!! Do these next steps only with the car OUTDOORS and with an assistant holding a fire extinquisher! Wear safety glasses.
6)Remove the 4 injectors from the manifold by removing the two screws that hold in the two retaining plates. Leave the injectors attached to the lines. Lift the injectors into a container - I usually use a drain pan.
7) Now remove the black rubber bellows covering the airflow sensor (comes off with two screw clamps and some twisting).
8) You should be able to grip the head of the bolt holding the round airflow plate to the arm and lift the plate up. It should offer little resistance (when the pump is off) and should rise and fall easily and smoothly. If it does not, then the plunger in the fuel distributor is probably stuck, see more on that below.
9) Now jumper the fuel pump relay. With the pump running (Don't forget - this is where you need the fire extinguisher handy - you are about to spray finely atomized fuel all over the place!), slowly pull up the airflow plate with the pliers. You should get a uniform spray from each of the 4 injectors that increases as you increase the height of the plate(but only when you pull up the plate - if any of the injectors spray when the plate is all the way down then you have a fuel distributor internal failure or the plunger is stuck).
10) If the spray varies smoothly from off to lots as you lift the plate from it's rest position, you should be all set (I'm assuming you've verified engine compression, camshaft timing and spark advance).
It may be (hopefully) that all you need to do is lift the plate once to break free a minor case of stickiness. If that does not do it, then you will need to remove the fuel distributor and tap it on a block of hardwood to gently remove the plunger and get it cleaned up. The surface finish on the plunger is incredibly fine and extremely important (it seals high pressure fuel with no gasket or seal). So don't try to pull on it with a tool and be sure not to drop it - any damage to the surface finish of the plunger will ruin it and you'll need a new fuel distributor. Use a towel to catch it and to handle it. Once it's out you can clean it with carb cleaner and scotchbrite. Keep cleaning until it slides smoothly in and out of it's bore. Don't forget, it will fall out if you turn the fuel distributor right side up, so don't drop it when putting the distributor back in the car!
Once you have fuel flow in relation to moving the airflow plate, you should be able to put everything back together and get the engine started. If it is delivering fuel to the cylinders but still runs poorly (given compression, timing, and spark) then you may need the pressure gauges to look at line pressure, control pressure, and leakdown. Don't try to set the mixture or idle speed until you know you've got the proper control pressure. I always set spark advance first, then adjust the mixture for smooth idle at about 800-1000 rpm, and then finally set the idle speed (using the 10mm bolt - don't mess with the screw that adusts throttle plate angle!).
Sorry for the long-winded response, hope it helps!
Good luck,
Gary
posted by 198.208.15...
_______________________________________ Gary Stottler
, Tue, 30 Apr 2013 04:38:04, Thu, 2 May 2013 07:29:35, Mon, 29 Apr 2013 09:33:00 <-- Viewing This Message
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