Should the fuel pumps run all the time...

[ertech]

Hi guys
Trying to troubleshoot the yellow relay.
With key on engine off should the fuel pumps run indefinitely ?
89 turbo
Thanks

[fredmeister]

No they should shut off as soon as the engine stops. The CDI box will run for about 10 more seconds to burn off residual fuel. There is a cutoff switch in the fuel head that is supposed to stop the fuel pumps from seeing any electrical power when the engine is off and the CIS metering plate is on its stop.

I editted this post to say CDI not CIS box.....

Also thanks everyone else for expounding on my explanation.....the wiring diagram should explain it really well.....a picture worth a thousand words.

Fred

[ertech]

How about if the key is in #2 position ( key on engine off )?
Thanks

[cole930]

The pumps should only run when the engine is running. And as
Fred said the engine will run on for a few seconds when shutting
off the engine but the fuel pumps will be off. If you turn the key on
and pull the green connector off at the metering plate housing the
pumps will run when the metering plate is depressed.

This might help you chase down your issue !!!!!







Cole

[mark houghton]

Originally Posted by cole930

The pumps should only run when the engine is running and as
Fred said for a few seconds when shutting off the engine. If you
turn the key on and pull the green connector off at the metering
plate housing the pumps will run continusly. Cole

Just a smidgen of clarification: The pumps should shut off instantly when shutting down a running engine (a safety feature to keep your car from becoming a pile of molten goo in the event of an accident, keeping the pumps from spewing liquid fire when the engine is dead). It's the CDI electronics (i.e., spark) that will continue for a few seconds in order to burn off residual fuel in the lines. I always have to think twice about this every time the topic comes up....

[cole930]

Thanks Mark !!!!!

Cole

[Benny771]

Hay Cole:
When you figure out whats going on let me know. My pumps run when the engine is off as well. I think something on the car has been bypassed. Mine is a 89 as well.

[cole930]

Guys:

I'm going to be s o l on the later models with the infamous Yellow Relay.
Mark may have some ideas there as his car is a later model and he has
experience with Yellow Relay woes. The only thing I can offer is pull the
Yellow Relay, clean the pins and socket, then spread the pins slightly and
try it. There are a ton of posts on here referencing it, just do a search on
yellow relay.

Cole

[RarlyL8]

In order for the pumps to run when the engine is off and the key in the first detente the connector at the air meter assembly must be unplugged or the fuel pump relay jumped. The fuel system may also be wired directly to the battery via the aux switch.

[mark houghton]

You guys have covered it. All I can offer is a nice little picture that will show you how to bypass your yellow relay in the event it fails and your pumps won't run as a result.