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Join Date: Jun 2001
Location: Ellicott City, MD, USA
Posts: 99
Post Fuel Sender / Gauge on Empty?

Despite years of education and practical mechanical skills, I'm an idiot! i ran out of gas today. My problems with not starting when hot were from cranking and cranking and heating the starter selenoid. So here's the picture:

- 1974 914 2.0
- Fuel gauge parks when ingnition is off
- Fuel gauge reads and moves as fuel is added or subtracted (leadfoot?)
- I run out of gas when the fuel gauge is on the last line on the left, but not in the "zone" between parked and the first line.

So... Should I get some read in the "zone?" below the last line and the parked position.

I will take it apart, but it seems that I should have a low fuel warning or "zone."

Thanks again for your time.

Joe

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Old 10-21-2001, 09:52 AM
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Probably a sticky sender in the tank....either find a known good one and swap it, try to take that one apart or live with it....

Mine would only go to 1/2...ended up being a disconected ground wire behind the gauge,,,,
Old 10-21-2001, 10:16 AM
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Lightbulb

If you have a standard VDO combo guage on the left side of the instrument panel in your '74, you should have an illuminated colored red (faded to orange) window between what you're calling park and the first mark, which is usually "R". Check your light bulb in the guage.
If it's not the bulb, check fuses and trace the wire back to the sending unit in the gas tank.
Good luck, Wayne


Old 10-21-2001, 10:26 AM
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OK, I just had to get started on this so here's what I found:

- Removed sending unit and dismantled it
- Minor dust in lower end where the plug and nut are located
- minor dust in lower 1/3 of tube
- minor dust on gold contact disk
- Broken wire - the thicker single copper wire. I stripped some 14gauge automotive wire and used a strand with some lead-free low-temp solder to replace it.
- Ohms are reading 76 (empty) and 3.5 (full)
-Tank was clean, except for...
- Prior Owner must have replaced the sending unit seal because the old one was in the tank in pieces. Used a wire hanger cut at a sharp angle to "poke" and impale the pieces (I love fishing in gasoline).

I assume that the broken wire was preventing the fuel light from coming on.

So why the fuel shutoff?? Could be the pieces of rubber gasket that were in the tank when fuel was low. I don't think I could hear the fuel pump click on. I tested all relays and wiggled everything. Does the fuel pump go silent or shut-down without fuel in the line?

Looks like I have 3-4 gallons in the tank. Just added 3.0 gallons a couple of miles ago. Will drive and see.

I still advise all 914 owners to first buy a cell phone, then a AAA membership before registering their vehicles...

UPDATE 10/22/01:
I got out a bit toaday and had put 3.4 gallons in the tank prior to the fuel level sending tube tweaks. So I'm somewhere between 2.5 and 3 gallons. WOW the light came on! I must have drained this thing over and over thinking that the needle would go below the lowest line (it does not). So now I know that when my fuel light comes on I have @ 2+ gallons remaining.

Again thanks to all for the brief encouragement to take the pieces apart.

Joe

[This message has been edited by retro74 (edited 10-21-2001).]

[This message has been edited by retro74 (edited 10-22-2001).]
Old 10-21-2001, 01:10 PM
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The stock FI pump should run under three sets of circumstances:

1) About a 1.5 second "buzz" when the ignition goes from "off" to "on".
2) Any time the starter motor is cranking.
3) Any time the engine is turning at ~100 RPM or more.

The pump is usually audible--you can generally hear it. If not, go to Tim's 914 Fan Page http://www.914fan.net and look in the Tech Articles section for Bill Williams' "Fuel system" article. That tells all about the D-jet fuel pump control circuitry.

--DD

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Old 10-22-2001, 03:56 AM
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Followup # 2

One of the Pelican board regulars is Scott Thatcher and he is a local Baltimore electrician (he traced my melted points insulator from the relay board to the ignition to the relay board, to the distributor in under 5 minutes). He suggested that I use a small LED and hook it up to the pump to see if the electricity is cutting out.

I purchased a 12V red LED from radio shack (threaded type) for $1.99. I used @10 feet of speaker wire and soldered the two ends to the wire and covered them with shrink wrap on each connection. A larger shrink wrap covers the whole thing, including the treads on the tiny LED base (looks cool). The 10 feet of wire allows me to put this anywhere I want, including on the dash, etc. I inserted the wire carefully into the fuel pump connector and pressed it in place. Speaker wire is thin enough that it won't over-compress the stock plug and won't ruin the stock tension in the female plug side.

So it's still running (OK, I know, these cars tend to run when you put gas in them, I know, really!) and I have the little LED end fed into the cockpit. If it cuts out again, I can see if it's getting juice at the pump and work my way backwards. I can also use this setup to test 12V of any other circuit while driving and at any time. It beats using my DMM and draining the DMM batteries and it was soooo easy (under 5 minutes), I'm going to make a pair for the car toolbox.

Thanks Scott.

Joe
Old 10-22-2001, 08:21 PM
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Very cool! I may have to run over to Radio Shack soon....

--DD

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Old 10-23-2001, 07:40 AM
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