Engine/Transmission (1994 - 1998) Fuel shutoff solenoid longevity...

[DPinkston]

... with key on engine off. How long? I heard they can be burnt up pretty quickly. Is there electricity going to the fuel shutoff solenoid from the ignition-on circuit while you have a wait-to-start light? I was wondering if the computer overrode the circuit to prevent prolonged warmup waits from damaging the solenoid. It doesn't look like it does in the wiring schematic, but then I am no electrician.

Danny

 

[Joe G.]

The pull up circuit (high amps) is on ONLY when the key in is the start position. The hold circuit is on when the key is in either the run or start position. The wait-to-start light has nothing to do with the fuel shutoff solenoid.

 

[DPinkston]

I understand about the 2 separate circuits. Will it damage the shut off solenoid if the key is left in the run position for an extended period of time if the pull up circuit was never energized?

Danny

 

[Howard Durand]

As near as I can tell by the wiring diagrams, the hold in coil is energized as soon as the ignition key is turned on and remains so until the key is turned off whether or not the starter has been engaged.

The coil is designed for continuous service so I can see no reason why it would be damaged.

 

[Joe G.]

Howard,



You are pretty good at this electronic stuff. I've been thinking that some sort of one shot device in the fuel shut down circuit would be a good idea. Set up so that the solenoid pulls up and then disconnects the pull on coil so that the hold coil would hold it up for the rest of the start. That would prevent things like stuck starter contacts from burning up the solenoid. What do you think?

 

[CarlJensen]

If you put in an anti theft circuit switch on the solenoid you could cut it off any time you want to.

 

[Joe G.]

I have that. What I'm thinking about is a modification that causes the pull on circuit to only stay on until the solenoid is pulled up. Then automatically disconnect. That's what I mean as a one shot circuit. The hold circuit is on as long as the key is in the run or start position so it will hold it up as soon as it pulls up. The pull on circuit is not required after that.

 

[Howard Durand]

Joe,



There are probably a couple of different ways this could be done. It looks easy but I want to think about if for a while.

I'll draw out a diagram of the circuit and see what it looks like.

Jumping from one page to another in the manual is confusiing.

I think a time delay relay would probably work. They can be made to close on engergization then open after a set time or do just the opposite.

 

[Joe G.]

Howard,



I wonder if just using a one second time delay relay in place of the fuel solenoid relay would do the job? One second is plenty of time to pull up the solenoid.

 

[Howard Durand]

Joe,



I would use a timer circuit to operate the fuel solenoid relay because it is rated for the current that the pull up coil draws.

If your manual is the same as mine, on sheet 47 of the wiring diagrams it shows the fuel shut down relay.

Cut the wire on the hot side of the operating coil for that relay and feed it from a switched source through the timer relay.

When the ignition switch is turned on the timer relay would be energized. It would, in turn, energize the fuel shut down relay and then drop it out after the set time with the holding coil keeping the solenoid picked up. The timer circuit would reset when the switch is turned off.

The timer circuit and it's relay could be placed in a small black box and mounted anywhere.

I can't think of any reason why this wouldn't work. It would completely remove the solenoid from any association with the starter so it couldn't be damaged in case of starter failure.

 

[Joe G.]

Thanks Howard,



I think I will do that. I already have a relay in the high current circuit as a theft delay device. I'm going to rebuild my relay box before too long anyway. It's getting out of hand.