Throttle Lever on 73.5 CIS T

[ahklein]

My 73.5 CIS T has a non functioning "Throttle" lever between the seats, next to the "heat" lever. Does anyone know what this should connect to ? I often have some cold start issues and perhaps it would help if this lever worked?


Thanks

[BK911]

Some cheap plastic-ish piece that connects to the throttle linkage in the tunnel.
Some, including myself, made a new piece out of wood.

[Arne2]

Sounds like a job for a 3D printer.

[ahklein]

So as the lever is lifted up, this adds some tension to the throttle linkage and that acts to increase the throttle input?

[75 911s]

Here's the part number from pelican and a guide on replacing it.

PP # 901-424-317-00-M100

1. Remove both seats
2. Remove carpet near the parking brake, it snaps off toward the back an peels toward the front
3. Remove the parking brake boot -it will slide up over the top - no need to remove knobs.
4. Remove the 3 housing bolts (13mm) for the parking brake assembly
5. Remove the parking brake cable retaining pin clip and retaining pin so that you can move the assembly far enough off the access hole for the tunnel. The two defrost cables will still be connected. I was unable to remove the hand levers or cables for the defrost.
6. Remove the 13mm bolt, washer, two friction washers and hand throttle handle from the bolt that runs through the housing.
7. Install new valve lever, there should be a tiny washer and retaining clip that hold it on to the hand throttle.
8. Position the hand brake and housing near the e-brake cable and reinstall the pin and retaining clip for the parking brake. I used one of those long parts grabbers with the retractable claws.
9. Put a friction washer back on and loosely place the throttle arm back onto the bolt on the housing and align the valve lever on the accelerator cable barrel nut by feel. place the other friction washer, the metal stopper washer and the smaller washer and nut back on for the throttle arm.
10. Test by watching the accelerator pedal - It should depress when moving the hand throttle.
11. Reinstall housing bolts, boot, carpet. Ensure parking brake, defrost levers and hand throttle operate.

[ahklein]

Perfect!

Thank you

[javadog]

It opens the throttle somewhat to admit additional air for starting and the throttle movement activates a switch that is needed for cold starts.

JR

[javadog]

Read page 12 of this:

http://jimsbasementworkshop.com/CIS/page_images/73%20911T%20CIS%20Print.pdf

[rpc356]

Originally Posted by javadog

It opens the throttle somewhat to admit additional air for starting and the throttle movement activates a switch that is needed for cold starts.

JR

Cold start enrichment is important to avoid intake backfires (not sure that's the right term) that could damage the air box.

[ossiblue]

You have been given good direction in fixing your problem. If you are having cold start issues without the lever, you can overcome them until you repair the lever.

Pulling up the lever for cold start does two things. First, it opens the throttle plate a bit to allow for more metered air during a cold start. Second, and most important, the movement of the throttle cable trips the micro-switch on the throttle body which allows the cold start valve to operate, injecting fuel into the intake during a cold start.

You can perform the same function as the lever by depressing and holding the throttle pedal, slightly, during cold starts. Do not pump the pedal, just depress it about 2-3" and hold while the engine cranks. Once the engine starts, adjust the pedal to keep the RPMs within warm up range for a few seconds before driving.

[stevie 77 930]

One thing to remember on a 73.5 is to never depress the accelerator on a warm engine.

Because this early "cold start circuit" lacks a thermo-switch to close the cold start valve (CSV) circuit, depressing the throttle opens the micro-switch actuates the CSV even on a warm engine. As already mentioned, the CSV circuit is triggered when the micro-switch is open and you engage the starter.

As long as you have good residual pressure you should have no problems starting a warm engine.

[stevie 77 930]

duplicated response deleted

[tobluforu]

Try to do this with just one seat removed, drivers, if you can't get to it, then remove the other. I have done it twice and have done major e brake work with one seat removed (yes its tight). If you cant get retaining clip back on, no bother as the pos plastic lever is held in place by the rod/ebrake mech.

[Peter Zimmermann]

The hand throttle, once it's repaired, must be adjusted. The goal is to achieve a 7 degree opening of the butterfly in the base of the throttle body. That opening will provide the air necessary to give the correct fuel/air cold start mixture. The sliding "barrel" should be loosened, and then set in a position that will allow the WARM engine to run at about 3800 rpm when the hand throttle lever is pulled all the way up. This adjustment will allow for throttle lever bushing failures, and other minor throttle linkage complications, and must be re-set after any throttle linkage repairs are done. The adjustment should also be checked at every service interval.