Modifying the DMCH Reproduction Fuel Sender

[Chris 16409]

I have been running the reproduction fuel sender for over a year now, and have been unsatisfied by the way the fuel needle moves down under acceleration. When I would come to a stop, the needle would shoot up and then eventually settle in the correct position. My needle would move down as much as a quarter of a tank when I'd be taking off from a standstill. The thing I hatted the most was when I had a quarter tank and the fuel light would come on and off all the time.

The other day I decided to try an experiment, and I removed the sender from the fuel tank. Back when I put it in, I noticed there were two holes in the bottom of the sender which are supposed to let fuel into the sender. One of the holes had been plugged by a screw. The other was open, and I believe the hole is too big because it allows the fuel to exit the sender too quickly causing the needle to move under acceleration. I decided to put a screw in the second hole and see what would happen. I didn't want to seal the sender off completely as to not let fuel into it. So, I didn't put the screw in fully, which I believe leaves enough of a gap to allow the fuel to come in but not come out under acceleration.

I've been running my modification for about a month now, and I am very pleased. The needle doesn't move under acceleration any more. I actually don't notice it moving at all really. Once I've been driving for a day or so, I will noticed the needle had moved, so it seems to behave as you would expect. When I put gas in the car, it does take longer for the needle to report the change, but I'd rather have that then a constantly moving needle. Additionally, I don't think it is good to have the fuel gage constantly moving. Who knows, it could wear out faster. If this bugs you like it's been bugging me, I'd try this mod out and let me know what you think. Maybe you have already done this.

[jbreeden]

That sounds like an interesting idea. I've been bugged by the same thing, but I was wondering how difficult an electronic solution would be, that would average out the signal over time or something.

Another thing I think would be cool is to set it up so, like modern cars, once the low-fuel indicator comes on, it stays on until the car is shut off. This, of course, would only be useful if it were a little more accurate about when it's empty.

[r00b]

The light coming on and going out tells me how low my fuel level actually is. By the light I know if I have 50+ miles or if I must stop at the next gas station.

[jbreeden]

You don't REALLY need to stop for gas till the car starts bucking ;)

[DCUK Martin]

You can create a simple latch using a relay on the fuel light wire. Having a very small inlet to the unit is the best way by far to "average" the signal.

Personally I'm not sure why owners get so fussed about the absolute accuracy of their gauges - if it tells you when you need to fill up, and once you know how it behaves, you know how far you can go on what's left...

I guess it's testimony to the reliability of the rest of the car that we can afford to get bothered by the behaviour of the fuel gauge! If it weren't for DMC we'd still be in the same boat of a lot of other marques, struggling with gauges that won't work at all! 8)

[DeloreanJoshQ]

Any way to correct the sender so it reads full after filling up instead of 3/4? I have only noticed this issue vs. needle moving up and down while driving....

[DCUK Martin]

If when you take it out (letting it drain) you turn it upside down and it still doesn't read full AND when you unplug it the needle points to 12 o'clock, I'd suggest the sender is at fault.

[The Aviator]

If when you take it out (letting it drain) you turn it upside down and it still doesn't read full AND when you unplug it the needle points to 12 o'clock, I'd suggest the sender is at fault.

good to see your back as well martin! im so gassed the site is up and running!! :aniclap:

[DavidProehl]

Any way to correct the sender so it reads full after filling up instead of 3/4? I have only noticed this issue vs. needle moving up and down while driving....

Josh - I'm having the same problem. When I take the fuel sender out and flip it over it will read full, but it never reads better than 3/4 on a full tank. Did you ever figure this out?

[DeloreanJoshQ]

Josh - I'm having the same problem. When I take the fuel sender out and flip it over it will read full, but it never reads better than 3/4 on a full tank. Did you ever figure this out?

nope....still searching for a solution...

[Chris 16409]

I think this problem is what you would call "normal behavior" for these units. Mine never stays on the 4/4 mark for very long. I think some are worse than others. I think my friend Ruben was telling me his never really goes to 4/4 either. I would try the mod I suggest, it will keep the fuel from escaping the sender as easily, and may allow the needle to display 4/4. It's worth a shot.