frustrating problem

[jfirios]

I just got the car back from the shop after doing almost everything to the engine and all, short of the stage 2 upgrade, but one of the problems that I am having and had before going for all the upgrades is that the fuel gauge isnt reading right, and it floats at least a quarter tank up and down as I accelerate or take turns. I thought it might be the fuel sender so I did the fuel system upgrade minus the tank. It is still doing it. I filled the tank to where it actually overflowed at the station. So I know I am full. When I started the car it barely went over 3/4 tank full then slowly went to almost 4/4 full. Then I drove it 15 miles and I am almost down to half a tank, with it floating all over from half to full. What can i do to get stabalized or is this one of the things with a delorean?

[WelmoedJ]

The type of float we have in the D is very sensitive to level fluctuations.
Since the fuel can move freely through the tank, each accelaration or decelleration will cause the fuel to slosh forward and backward.

The original fuel senders seem to be more accurate and less prone to these effects.
The second and third generations from DMC show less accuracy.

The best get-arround is using your trip counter (set to zero when full) and note the miles you can drive before the engine starves from lack of fuel (take a can with fuel with you for that moment).
Now you know haw many miles you can go before a refill is imminent.

My fuel sender also drops to 3/4 shortly after leaving the filling station.
It hits empty without the light being always on and I still can go for some 50 miles.
A fuel sender with a float on an arm like many cars have not only is more accurately but also shows full and empty more correctly than the one we inherited with the car.

[jfirios]

yeah that sucks. It is frustrating, is there a way to put a new style float in our tanks. Or do the new tanks from DMC have the newer float system in it?

[WelmoedJ]

I had an idea of putting in a combined fuel pump/level senser of a GM Trans Sport, but that needs a lot of modification (different way of mounting: flat tank top and find a way to seal the old sensor mounting hole, re-arranging fuel lines).

Besides that I have only recently found the measurements for that unit.
If you're interested I can dig up the info and tell you if it can be done.

[LEVY]

.

There was a thread on the old forum where people found a acceptable solution by covering a hole on the fuel sending unit and make it smaller, some one might have pics and maybe wanted to share.

[Jonathan]

My fuel sender also drops to 3/4 shortly after leaving the filling station.

I see this in my car too. I fill it up until the pump clicks off automatically and I don't top it off. When I start the car back up it seems to be about 7/8 and then a few miles later it goes to 4/4. What's the science behind this phenomena? I've got a replacement sender in and I know what they look like inside but don't know why there is this delay at full.

I keep track what % full I am when I fill up and compare to how much goes in and I feel like there is only about 40 litres of useable volume (compared to the manual saying 51 I think it is). I fill til it clicks off and no more as I don't need any spills up the neck so this might the missing capacity.

[Jacko]

An accurate, reliable gas gauge shouldn't be too much to ask for. But apparently in a Delorean it is. To my knowledge no one has found a solution. So, as mentioned above we have to use our own set of ground rules. Reset the trip meter at fill up and learn how far your car will go until the next fillup.
One thing about a Delorean is the low fuel light is deadly accurate. When it comes on you have approx. 50 miles left until she starts sucking air. Dave S. at DMCMW explained that the sender in the tank has two circuits with the one for the low fuel light operating on a different principle than the sliding one for the gauge. Simply put, if there is gas in the tank the float will float; when not , it won't.:smile:

[TTait]

Sealing the top of the tank isn't that tough. Get two pieces of steel, cut them into circles just a bit larger than the opening at the top of the tank and cut a notch in one of them (a-la pacman), so it can be rotated through the top opening in the tank. Drill a hole in the center of both, and then coat them with gas tank sealant.

Then take your lower boot and use a band saw to cut off the inner section so you just have a gasket that goes over the lip of the tank. Get a stainless steel nut and bolt, and a copper sealing washer for the top.

Put the new lip seal in place.

Put the head of the bolt into the lower plate and lower it into the tank, put the bolt through the hole in the top plate, put the copper washer in place, and tighten the nut until the top plate is tight on the lip seal. Should hold up nicely even in a rollover... But don't test that...

[Chris 16409]

Take a look at this post I made a while back. It details how I modified my sender so it doesn't move the needle under acceleration.

http://dmctalk.org/showthread.php?81-Modifying-the-DMCH-Reproduction-Fuel-Sender

I've had no issues since I've done it. It literally takes lees than 30 minutes.

[jfirios]

after doing that mod to your sender, you no longer have that worrysom quarter tank float problem

[Chris 16409]

after doing that mod to your sender, you no longer have that worrysom quarter tank float problem?

I don't have any problems with it. The needle will not move down under acceleration, and it doesn't rise really high when braking. I never see the needle move anymore. I especially like this mod because it stops the gas light from going on and off when you have just a quarter tank.

[Sidaries]

An accurate, reliable gas gauge shouldn't be too much to ask for. But apparently in a Delorean it is. To my knowledge no one has found a solution. So, as mentioned above we have to use our own set of ground rules. Reset the trip meter at fill up and learn how far your car will go until the next fillup.
One thing about a Delorean is the low fuel light is deadly accurate. When it comes on you have approx. 50 miles left until she starts sucking air. Dave S. at DMCMW explained that the sender in the tank has two circuits with the one for the low fuel light operating on a different principle than the sliding one for the gauge. Simply put, if there is gas in the tank the float will float; when not , it won't.:smile:

My car is a bit different. When I fill up, it slowly goes a bit over 4/4 and then is goes down as it should, when I use the car. When I reach 1/4 the gauge goes crazy and make these symptoms when braking or accelerating. The low fuel level light seldom works, but mostly not. When it does it usually flashing. When this light should work?

[jfirios]

I will have to try that mod. On a different note, though, what kind of MPG are you getting. I am still running with all the new stuff put on the engine and kicking all the old deposits out of the engine. I think i am getting about 12-15 MPG. Which is terrible. especially in a 12 gallon tank. Just wondering what everyone else is getting.

[Jonathan]

I get about 9.6 litres per 100 km, which is about 25 MPG. I have an automatic with mostly stock everything. I just put the cold air intake mod in so that might slightly change things. I have the upgraded digital shift computer governor and that made a huge difference a couple seasons ago.

[jfirios]

yeah i would be happy with about 20MPG for the 5 speed. But right now needing to adjust everything i am getting about 12-15

[Chris 16409]

On a different note, though, what kind of MPG are you getting.

I'm getting things in order to do a tune up and I'm getting about 23 MPG. I suspect after that, it should get better. I also realized my tires were way under inflated. I'm kicking my self for not catching that, so that should be affecting my milage.

[robvanderveer]

My car is a bit different. When I fill up, it slowly goes a bit over 4/4 and then is goes down as it should, when I use the car. When I reach 1/4 the gauge goes crazy and make these symptoms when braking or accelerating. The low fuel level light seldom works, but mostly not. When it does it usually flashing. When this light should work?

I have *exactly* the same problem, without it ever reaching under 1/4 (because it is empty by then and I don't want to risk my fuel pump). It just seems it is a quarter too high. If you ever find a solution for the over-4/4 phenomenon, please let me know.

[WelmoedJ]

The original fuel senders seem to deteriorate internally and than the float can't get as low as is necessary to reach bottom level (no gas in tank).

The newer generations by DMCH can reach bottom, but have other issues.

You can check if you have an original (three soldered wires to the top of the sender) or a later DMCH model. The wires are covered by black plastic and on top if it the website URL is printed (this was the first series, not sure if the second series also have that marking).

You won't destroy the pump if you only one time try to empty the tank while driving. I've done it several times with both this car and my daily driver without destroying the pump (daily driver now has over 150k miles on it).
While trying it is wise to have a spare can of fuel with you ;)

Just fill the tank until it shuts off filling, reset the trip counter and drive away.
Once empty (or at least until the engine cuts) you observe the trip counter and you will know the average distance you can travel until empty.
The low fuel warning starts flashing (activated by the sloshing fuel) usually around 1/4 of the gauge's scale. Once it's on all the time, there's some 50 miles left to go.

On some car's the warning light stays on after reaching zero sign, other cars at 1/4 so you have to find out for yourself which is true for your car.

[jfirios]

a friend was telling me there is an Iphone app that calculates MPG and distance, instead of using your trip meeter. The phone uses the gallons entered and then uses the GPS for distance traveled.
Might be a cool thing to check out.
I hope i can get my mpg up in the 20s again, i dont know why it is so low. Maybe I need a new lambada or something since everything else is changed in the car.

[Bitsyncmaster]

a friend was telling me there is an Iphone app that calculates MPG and distance, instead of using your trip meeter. The phone uses the gallons entered and then uses the GPS for distance traveled.
Might be a cool thing to check out.
I hope i can get my mpg up in the 20s again, i dont know why it is so low. Maybe I need a new lambada or something since everything else is changed in the car.

If you drive like a bat out of hell you will never get 20s in city driving. I only check my MPG on trips even though I drive to save gas in town. The best I have recorded is almost 30 MPG.

[WelmoedJ]

Such an app gives only averages.
It's nice to know how far your "reach" is, but you still need to watch either the ODOmeter or the trip counter to get an idea of the remaining part of your range.

If you feel your car uses too much gas, there are a few things you can check:
- are you running rich?
- do you have vacuum leaks?
- is the ignition distributor's advance okay?
- are your injectors' spray patterns okay?
- is there enough "juice" in the spark plug wire to make optimal combustion?
- are your spark plug gaps correct?

What also influences the consumption somewhat:
- if you still have the heat riser, then: is the valve inside opening fully after warmup?
- tire pressure (too low pressure is waering out your tires, but also contributes to more fuel consumption)
- air temperature
- weight of your foot

My average MpG is somewhere in between 25 ~ 31 depending on the distance and speed and in a way the time of year.

Good luck in finding a solution to your gluttonously car.

[jfirios]

well i just replaced all the injectors, and replaced all the spark plugs, wires and coil. I have the stage 1 exhaust installed too so no hot air intake anymore, and i have a very heavy foot. ;)
I will wait and see how things pan out after my next tune up on monday when everything gets adjusted a little more, after burning out all the carbon and crap deposits that were in the engine before all the work was done on it.

[Chris 16409]

I have attached a picture of a suitable screw that you can use to semi plug up the second hole on the bottom of the sender.