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Posted by: john77 Feb 26 2014, 01:24 PM

Hi

I'm the proud new owner of a 73 914/6 conversion, with a handful of minor electrical gremlins that I need to track down - so firstly, hello. And secondly, HELP!

My knowledge of car electrics is somewhere between idiot and novice, so please bear with me. The OEM fuel sender gauge has been swapped out for a 911 oil temp/pressure gauge and an aftermarket fuel sender mounted on the dash. The needle raises about 4mm when the ignition is switched on, but won't go any further no matter the level of fuel in the tank.

I removed the sender unit from the gas tank and the float isn't stuck (I have no idea how to check the sender internal circuitry). Then I checked the voltage at the positive pin of the sender and it's only reading 5.5V.

I have a Haynes manual in the mail, and am struggling to read the wiring diagrams on Pelican because, unless I'm missing something, none of them appear to have key of what each of the numbered components are. So I thought I'd seek help here because maybe the cause is something really obvious and, well, I'm impatient.

Thanks
John

Posted by: JawjaPorsche Feb 26 2014, 02:29 PM

QUOTE(john77 @ Feb 26 2014, 02:24 PM)

Hi

I'm the proud new owner of a 73 914/6 conversion, with a handful of minor electrical gremlins that I need to track down - so firstly, hello. And secondly, HELP!

My knowledge of car electrics is somewhere between idiot and novice, so please bear with me. The OEM fuel sender gauge has been swapped out for a 911 oil temp/pressure gauge and an aftermarket fuel sender mounted on the dash. The needle raises about 4mm when the ignition is switched on, but won't go any further no matter the level of fuel in the tank.

I removed the sender unit from the gas tank and the float isn't stuck (I have no idea how to check the sender internal circuitry). Then I checked the voltage at the positive pin of the sender and it's only reading 5.5V.

I have a Haynes manual in the mail, and am struggling to read the wiring diagrams on Pelican because, unless I'm missing something, none of them appear to have key of what each of the numbered components are. So I thought I'd seek help here because maybe the cause is something really obvious and, well, I'm impatient.

Thanks
John

Posted by: Cap'n Krusty Feb 26 2014, 03:10 PM

It's important that the guage be matched to the sender, and it sounds as if yours isn't. There are folks here who have incorporated the original gauge into a multi-function instrument. North Hollywood Speedometer does the same thing, but quality and knowledge carry a pretty hefty price tag.

Welcome!

The Cap'n

Posted by: john77 Feb 26 2014, 03:20 PM

Thanks Terry, I'll give that a try tonight.

I actually got the car from SC (what's with the concentration of 914 guys in the south east? ) It has a 73 2.7RS spec engine, with the rear arches 'massaged' to fit 7" fuchs.

Posted by: john77 Feb 26 2014, 03:29 PM

Thanks Cap'n

Good point, I have no idea if they are, I'll have to do some research. They're both definitely aftermarket though.

Posted by: john77 Mar 13 2014, 08:38 PM

I've confirmed the gauge and sender are compatible, so that's not the problem.

I pulled the 914 gauge cluster to check where the wires were routed and found that the live and ground wires from the aftermarket fuel gauge had been piggy backed onto the live and ground terminals of the new temp/pressure gauge.

Any idea if this could be the root of my problem?

Posted by: r_towle Mar 13 2014, 08:41 PM

I thought the fuel sender was ohms, not volts.

See if it reads zero when down and something more when up...all in ohms.

there are a few guys who remember the correct range that live here, someone will chime in .