Fuel Door Solenoid

Scorpio / Scorpio Cosworth Discussions - Questions, problem resolution, general talk, technical tips and modifications.
Post Reply
Merkur Club web site
john keefe
Level 7
Level 7
Posts: 1069
Joined: Sat Sep 02, 2006 1:13 pm
Location: Campbell, CA

Fuel Door Solenoid

Post by john keefe »

Good info under search. I took one apart (relatively easy to do), found the thermal fuse (141C), tested the windings, which have continuity and works fine when by-passing the fuse. Tested the fuse for resistance... its shot.

So, Radio Shack is out of business around here, and techies @ Fry's looked at me like I was from another planet when I asked about "thermal fuses." Rather than ordering on-line (I don't need one for $12.99, and I don't need a pack of 5 which I'll never use) I thought I'd get this working a different way.

I was considering a mini-type fuse in place of the thermal. Fusible link is out of the question. I'd add extra wiring to the fuse socket so I could relocate it away from the solenoid for easy access to check or replace as needed.

Testing the soleniod @ night was pretty cool. Definitely a sizeable spark, combined with the pop of the solenoid... didn't expect that. :D But, considering the energy, and the specification for a thermal fuse, and that these obviously fry, I'm wondering if a 30A fuse to match the circuit is too much. Should it be a 20A? Better to blow an underated fuse than fry the solenoid and get worse consequences.

Opinions?
Ed Lijewski
Level 8
Posts: 8412
Joined: Thu Sep 04, 2003 5:53 pm
Location: The Belly of The Beast

Re: Fuel Door Solenoid

Post by Ed Lijewski »

Good used fuel door solenoid w/linkage: $45 shipped.

YMMV ;)
Descartes: "Cogito Ergo Sum"
Lijewski: "Sum Ergo Drive-O. Mucho!
john keefe
Level 7
Level 7
Posts: 1069
Joined: Sat Sep 02, 2006 1:13 pm
Location: Campbell, CA

Re: Fuel Door Solenoid

Post by john keefe »

Ha! Ed... if I had two nickels to rub together, and/or weren't so cheap, I wouldn't be a "create your own mechanical/electrical solution" Merkur owner. :D Just to hedge my bet, if this don't work I'll probably be asking if you've still got one.
User avatar
milehighXR
Level 7
Level 7
Posts: 2317
Joined: Tue Mar 23, 2004 8:17 pm
Location: Longmont, Co

Re: Fuel Door Solenoid

Post by milehighXR »

Find an independent "radio shack" for lack of better term. I have one in Boulder that I go to for that kind of stuff. They had all the parts I needed to upgrade my post war Lionel ZW transformer so it would work the whistles on the modern locos, and so it would fry the electronics in them. There should be at least one independent electronics stores in any town of sufficient size with a university. I found my local independent electronics store years ago, because our radio shacks turned to pooh a long time ago...

Digikey may be a source, but I reckon you've probably ruled them out for cost, or quantity reasons.
Johnny


1 86 XR aka Naomi- my first love, now daily driven project

DCLXVI
john keefe
Level 7
Level 7
Posts: 1069
Joined: Sat Sep 02, 2006 1:13 pm
Location: Campbell, CA

Re: Fuel Door Solenoid

Post by john keefe »

milehighXR wrote:Find an independent "radio shack" for lack of better term. I have one in Boulder that I go to for that kind of stuff. They had all the parts I needed to upgrade my post war Lionel ZW transformer so it would work the whistles on the modern locos, and so it would fry the electronics in them. There should be at least one independent electronics stores in any town of sufficient size with a university. I found my local independent electronics store years ago, because our radio shacks turned to pooh a long time ago...

Digikey may be a source, but I reckon you've probably ruled them out for cost, or quantity reasons.
Hadn't ruled them out... hadn't even heard of them. :D I'm getting stubborn in my old age, and will try to test a series of mini-fuses tonight to see it that works. Hey, I can see the convenience of having an exposed fuse to replace. One less arm movement and wrenching. :D
User avatar
brokencase
Level 7
Level 7
Posts: 1596
Joined: Sun Dec 06, 2015 12:18 pm
Location: PA

Re: Fuel Door Solenoid

Post by brokencase »

Google "thermal fuse 141C". Plenty of options.

I doubt Radio Shack would have had anything like that anyway.
Specialization is for Insects
Ed Lijewski
Level 8
Posts: 8412
Joined: Thu Sep 04, 2003 5:53 pm
Location: The Belly of The Beast

Re: Fuel Door Solenoid

Post by Ed Lijewski »

Logic 1.01 (2017 version):

Thermal fuse in solenoid power circuit fails.

Thermal fuses are designed to fail if powered device draws too much current.

Ergo Installing new thermal fuse will renew circuit and solenoid trouble free functions.

YMMV
Descartes: "Cogito Ergo Sum"
Lijewski: "Sum Ergo Drive-O. Mucho!
john keefe
Level 7
Level 7
Posts: 1069
Joined: Sat Sep 02, 2006 1:13 pm
Location: Campbell, CA

Re: Fuel Door Solenoid

Post by john keefe »

Ed Lijewski wrote:Logic 1.01 (2017 version):

Thermal fuse in solenoid power circuit fails.

Thermal fuses are designed to fail if powered device draws too much current.

Ergo Installing new thermal fuse will renew circuit and solenoid trouble free functions.

YMMV
I appreciate the practical thinking... was just curious on how this solenoid works, so it was worth the fun to take it apart. The iron bucket and the plunger's piston are pretty neat little designs to ensure the air gap closes when the coil is energized. And, it works, albeit not without the working TF.

The problem source, as I see it, is the solenoid's input & ground wiring is like 18ga. Ford might have used a thermal fuse because of the small gauge, as I doubt there's a practical 24ga. fusible link out there (I wouldn't want it anyway), and you wouldn't want to wrap a FL up in the solenoid foil... Or because a TF was more cost-effective than a mini-fuse.

Given the small gauge of the voltage/ground wiring, then a simple mini-fuse with the same wiring gauge should work. Just a question of testing to the 30A load of the circuit, and then sizing the fuse down until it blows out repeatedly in each test, then go back up the next fuse size. Or, I could pull out all the EE books until I remembered enough to calculate what's needed, but that's no fun. Sparks is better. What d'ya think?
Post Reply