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Old 07-01-2020, 04:29 PM
Jonsie Jonsie is offline
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Default '66 GTO fuel sending unit

Hey fellas...........Correct sending unit ohms for a '66......30 or 90 ohms (or other)?
Also, did AC cars have a return line to the tank?

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Old 07-01-2020, 05:44 PM
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Peter Serio Peter Serio is offline
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Zero or 1 Ohm = E
44 or 45 ohms = 1/2 scale.
88, 89, 90 or 91 ohms = Full.

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Old 07-01-2020, 06:17 PM
Jonsie Jonsie is offline
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Thanks, Peter, for your reply. I think I went about explaining my 'problem' the wrong way. "Problem": '66 GTO is difficult to start after shutting down while hot. Cranks slowly (new battery). Heavy fuel odor. Thinking vapor lock. Needs 1/2 hour or so cool-off period to finally fire-up. Question: will a sending unit with a return line help me out? My '65 Cat w/AC has the return line, never a hot start problem. I have an extra sending unit w/return line, stamped 90 OHMS on the small housing. Would this be correct for the Goat, or the Cat? Or both? No other part #'s visible. If this unit would be correct for the GTO I'd drop the tank and swap them out, and run a return line from the fuel filter up front. Hate to drop the tank and find out it won't work.

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Old 07-01-2020, 06:43 PM
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I had real bad vapor lock on a car I had a while ago. I was driving back from Norwalk on a 90+ degree August day.

It was an old 63 Lemans with a V8 engine. That car did not have A/C but it also did not have a vapor return line. I solved the problem by insulating the fuel line from underneath the firewall up to the fuel pump also from the pump to the carb (just in case). I used Part # 14005 Thermo sleeve. It's made by a company called Thermo-Tec.

I ended up needing 2 packages to do the whole job. www.thermotec.com As I recall I ordered it on-line from it from Jegs.

I do not think that a sender from a full size Pontiac will interchange into an A body gas tank. And vise versa. But please check with others to be sure.

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Old 07-02-2020, 05:37 PM
Jonsie Jonsie is offline
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Peter- I think what I will do is order a new sending unit, 1/4" return line, and correct filter. I am quite sure this will end the hot-start vapor lock problem. Do you know if the new unit should be 90 Ohms? Thanks!

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Old 07-02-2020, 05:49 PM
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Peter Serio Peter Serio is offline
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Yes, for a 1966 GTO the fuel tank sender would be zero to 90 ohms range span.

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Old 07-02-2020, 07:38 PM
Jonsie Jonsie is offline
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Thank You, Peter, for your help. Hope that you and yours have a Happy 4th !

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