1969-1984 [Subscribe to Daily Digest] |
Swede, sounds like vapor lock in the fuel lines, rest pressure is going away.
Rest pressure is held to near 20-30 lbs by capturing the run pressure when the engine is shut off. To do this, at one end is the check valve in the top of the pump, and the other end is #1 the warmup regulator and #2 the line pressure regulators. (77 and later with Lambdia have the frequency valva as a third return possibility). In-between the fuel accumulator with a diaphram and big spring, act as a "pressure resevoir". When you stop for 1-3 hours, your pressure dissapates within 5-15 minutes, and the fuel in the lines to the injectors boils and becomes air. CIS injectors do not pass air well. Take a good engine and quickly put on just one new fuel line and restart the eng. It will only hiton three and take a full minute to purge the air and get 4 cyl's smooth. This is with the sensor plate lifted by idle RPM too.
The pumps check valve is the first culprit, and the valve can be replaced individually. Very early valves were hand threaded below a cross hair inside the pump nch, later ones are plastic assemblied threaded in and out bu tweesers or small snap ring pliers. Later the check valve became external and brass and was mounted on top of the pump. Up front the line pressuer regulator is on the fuel distributor and unscrews, have an assistant briefly jump the pump to flush out the inner piston which is where the o-ring that seals the front fuel return system is. When you do this have a clean cloth to catch these parts in as they WILL COME SHOOTING OUT. The pressure accumulator is also suspect to haveng its spring break after many years and
they do no always leak externally. You can softly put a bent piece ofwire up the vent hose and contact the back side of the diaphram. Charge the pump briefly and lay under the car and "follow the movement of the diaphram with the wire. This is a kinetic pressure loss test that will #1 reveal a broken spring, or#2 a big pressure losss in the system. On shut off the diaphram moves .75 inch then stabilizes and will stay there if system holds pressure, if broken spring there is no movement and if a valid pressure drop it will retrn in 1 inch more in 15 -30 minutes.If pressure loss fix is unobtaineable, then a hot start pulse kit is availiable to pulse the 5th inject to fire the motor with your foot into it to get enough air thru the sensor plate to readily purge the fuel lines of air faster, Good luck, Don
posted by 152.163.25...
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
