Author Topic: 1967 convenience low fuel light remains on  (Read 5665 times)

Offline jwc66k

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Re: 1967 convenience low fuel light remains on
« Reply #45 on: February 21, 2018, 12:11:51 AM »
The one from WCCC was backordered, so I'll look around at other options, then test and report back.
I got a thermistor from NPD, installed it on a 67 Fastback and it worked fine. That was about 12 years ago so I can't say what the quality of the current offering is.
Anyone care to double check my calcs?
Sober?
Jim
I promise to be politically correct in all my posts to keep the BBBB from vociferating.

Offline 67gta289

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Re: 1967 convenience low fuel light remains on
« Reply #46 on: February 25, 2018, 10:16:26 AM »
I ended up doing the same, buying one from NPD.  I measured the resistance, or should say attempted to, while on the bench.  In one direction I saw 1 kohm, and in the other it was open.  The thermistor is not a simple resistor, so that should not be shocking.  Sorry for the electrical pun, I couldn't resist.

Then I installed it in the trunk.  I had the thermistor loose, not attached to the sending unit, so I used two jumper wires to complete the circuit.

At 13.2V (Ign), with the thermistor in the air (shop temp ~70F) it took just under 3 minutes for the thermistor to heat up enough to turn the low fuel light on.   

When I submerged the thermistor in a small cup of water, the light went out almost immediately.  After extracting the thermistor, it took another 3 minutes or so for the light to come on.

I'm including this information so that (1) if you don't measure resistance on your thermistor, you don't necessarily have one that is broken, and (2) you know the timing involved so that if you do your own test, you don't give up too soon and start spending more money!

John
John
67 289 GTA Dec 20 1966 San Jose
7R02C156xxx
MCA 74660

Offline 67gta289

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Re: 1967 convenience low fuel light remains on
« Reply #47 on: April 01, 2018, 12:02:45 PM »
Here is a document that I put together to help understand how the system works, which should help in troubleshooting as well.
John
67 289 GTA Dec 20 1966 San Jose
7R02C156xxx
MCA 74660

Offline ruppstang

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Re: 1967 convenience low fuel light remains on
« Reply #48 on: April 01, 2018, 12:12:14 PM »
Nice work John!
Jeff I think this should go in the library.

Offline 67gtasanjose

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Re: 1967 convenience low fuel light remains on
« Reply #49 on: April 01, 2018, 02:01:55 PM »
Nice work John!
Jeff I think this should go in the library.

+1 on both counts. I know it was suggested a few years ago to put together an article on the whole system. (This was by Jeff within the other lengthy thread on the whole system). Certainly, this Low Fuel circuit is crutial to the content needed for an article, this circuit being the most difficult to understand of the 4-lamp warning system.

Thank you for a beautiful job on this John.
« Last Edit: April 01, 2018, 02:11:04 PM by 67gtasanjose »
Richard Urch

1967 (11/2/66, S.J.) GTA Luxury Coupe, 289-4V w/Thermactor Emissions, C-4, Int./Ext. Decor +many options

2005 (04/05) GT Premium Convertible, Windveil Blue, Parchment Top w/Med. Parchment interior,  Roush Body Appointments

Offline jwc66k

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Re: 1967 convenience low fuel light remains on
« Reply #50 on: April 01, 2018, 02:02:16 PM »
Well done.
Nice work John!
Jeff I think this should go in the library.
Agree.
Jim
I promise to be politically correct in all my posts to keep the BBBB from vociferating.