New fuel pump - loud ticking, now fuel spraying!

[anthony7777]

Re: Installed new fuel pump - constant loud ticking??

keoke, do you mean from any screw thats holding down the fuel tank sender to ground regardless of pos. or neg. ground? just to make it clear.

 

[GregW]

Re: Installed new fuel pump - constant loud ticking??

Hi Anthony,
Yes. I used one of the six screws shown below (blue arrows). I ran the wire over to the harness, then attached it to the chassis with the black wires for the brake lights. On the bumper mount.

 

[anthony7777]

Re: Installed new fuel pump - constant loud tickin

grgw, thanks i used one of the same screws but ran it directly to the rear bulk head on its own connection, i just felt as keoke that this is a very important thing to do and just wanted to clarify the arrangement for those considering doing it. /bcforum/images/%%GRAEMLIN_URL%%/savewave.gif

 

[Keoke]

Re: Installed new fuel pump - constant loud ticking??

keoke, do you mean from any screw thats holding down the fuel tank sender to ground regardless of pos. or neg. ground? just to make it clear.

Yep, and be sure and put an internal or external toothed washer under the chassis lug and under the head of it"s fixing screw.---Keoke- /bcforum/images/%%GRAEMLIN_URL%%/banana.gif- /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif

 

[Dave Richards]

Re: Installed new fuel pump - constant loud ticking??

Note: *to all who have replaced a fuel pump* It is imperitive that you add a Grounding conductor from the Fuel tank's sender housing to the cars Chassis. This applies whether you have utilised rubber hoses or just the sealing washers.--- /bcforum/images/%%GRAEMLIN_URL%%/hammer.gif--Keoke- /bcforum/images/%%GRAEMLIN_URL%%/yesnod.gif

Uuhh? What you talking about Keoke? I'm at a loss...(that's not unusual!)

 

[Keoke]

Re: Installed new fuel pump - constant loud ticking??

Note: *to all who have replaced a fuel pump* It is imperitive that you add a Grounding conductor from the Fuel tank's sender housing to the cars Chassis. This applies whether you have utilised rubber hoses or just the sealing washers.--- /bcforum/images/%%GRAEMLIN_URL%%/hammer.gif--Keoke- /bcforum/images/%%GRAEMLIN_URL%%/yesnod.gif

Uuhh? What you talking about Keoke? I'm at a loss...(that's not unusual!)

/bcforum/images/%%GRAEMLIN_URL%%/iagree.gif

That is the particular problem being addressed, it is not unusual, and the DIY people may not realize that the ground system for the fuel guage and the remaining incidental ground for the fuel tank has been compromised. Did I find you now??---Keoke- /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

 

[Ed_K]

Re: Installed new fuel pump - constant loud tickin

Hi Dave,

There is 12 volts going to the sender and the return for that circut is through the ground of the fuel tank. If a wire is added as Keoke has suggested, then there is a safe, reliable return path for the fuel gauge circut. Without the wire, you are depending on the connection to the fuel tank from the fuel line to provide the ground. That means there is a 12 volt electrical potential all the way as far as the metal fuel line goes without a break to frame ground. If there is ever a break to frame ground, then the fuel gage stops working and a spark can be created at the location of the break or end of the metal fuel line, like right before the fuel pump if you substitute a piece of rubber hose to connect to the fuel pump.
... It makes the fuel gauge operation more reliable and it prevents spark " accidents " along the metal fuel line in the future.
Ed

 

[Dave Russell]

Re: Installed new fuel pump - constant loud tickin

Hi Ed,
True, it's important to have a reliable ground on the tank unit & also a good separate ground at the dash unit. Gage calibration can be off by 1/4 tank by not having a good ground at the dash. Note the "99 ohm right" coil should be grounded. The gage mounting saddle bracket often doesn't make good contact with the back of the dash. The tank is essentially rubber mounted so originally, the metal fuel line to pump is the only ground for the tank unit. Note the separate "0-70 ohm tank" ground. Both shown as one ground in the schematic.

I don't personally think that a possible spark "accident" is an issue. The tank unit operates at around .070 amp of current. This is not enough current to create a spark at low voltages. Consider that the tank unit has a rather loosely coupled rheostat that is sealed inside the gage body, along with the fuel. This exposed rheostat could easily arc a bit & probably does. There has never been a documented case of this inside spark igniting the fuel.

See the attached schematic of the Healey fuel gage.
D

 

[John Loftus]

Re: Installed new fuel pump - constant loud tickin

The metal fuel line going the pump also gets grounded with the P clips to the sheet metal. That's all mine had since the P.O. had cut the fuel lines and used rubber fuel hoses to connect the pump. My fuel gauge worked at the highest accuracy .. swinging from 1/2 full to empty on hills .. and was good enough at scaring me near empty that I never ran out of gas. /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

Cheers,
John

 

[Ed_K]

Re: Installed new fuel pump - constant loud tickin

Dave,

Is the 99 ohm resistance from T to E a different ground than the tank ground ? If so, then there isn't anything close to 12 volts between the tank and ground if the tank ground fails. There has to be since only one wire gets connected to the sender. So I agree, there is very little chance of a spark even if the ground connection fails from the tank/sender to frame ground.

Ed

 

[Dave Russell]

Re: Installed new fuel pump - constant loud tickin

Hi Ed,
Correct. The 154 ohm, the 101 ohm, & the 99 ohm coils are all located in the dash unit & require a good ground. The 0-70 ohm tank unit requires a separate ground. It's really a "bridge" arrangement. The only benefit apparently being that the gage is not sensitive to supply voltage.

I tried creating a spark with this connection & couldn't see anything, even in the dark. There is about 8 volts present at the rear gage terminal with the wire not connected & 0 - 5 volts with the wire connected to the tank unit, depending on how full the tank is.

I used to wonder about the gage rheostat in the tank creating a spark but apparently there isnt enough current or voltage to do any harm.

BTW - many newer cars have an in-tank mounted fuel pump which even has fuel flowing through the pump internals, commutator, & brushes, for cooling. I used to wonder why they don't blow up, but I guess there is not enough oxygen in there to make an explosive mixture.
D

 

[Keoke]

Re: Installed new fuel pump - constant loud tickin

I really do not think that is the potential problem to consider. From a safety stand point you have to fill that tank with fuel. The standing electrostatic potential of isolated Items is about 10KV should the nozzel discharge to an isolated tank it can aquire the charge and arc to chassis. Further, there is an electrostatic charge mechanism called separation charging this can occur when two conducting isolated items are intermittantly in contact with one another. Consequently, If the tank is solidly grounded to the chassis no arcing will occur.---Keoke?

 

[Dave Richards]

Re: Installed new fuel pump - constant loud ticking??

Note: *to all who have replaced a fuel pump* It is imperitive that you add a Grounding conductor from the Fuel tank's sender housing to the cars Chassis. This applies whether you have utilised rubber hoses or just the sealing washers.--- /bcforum/images/%%GRAEMLIN_URL%%/hammer.gif--Keoke- /bcforum/images/%%GRAEMLIN_URL%%/yesnod.gif

Uuhh? What you talking about Keoke? I'm at a loss...(that's not unusual!)

/bcforum/images/%%GRAEMLIN_URL%%/iagree.gif

That is the particular problem being addressed, it is not unusual, and the DIY people may not realize that the ground system for the fuel guage and the remaining incidental ground for the fuel tank has been compromised. Did I find you now??---Keoke- /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

No,thanks for looking tho' Keoke. Ed K found me! I get it and I fully understand with Dave's elaboration, gotta add some wiring.

 

[Keoke]

Re: Installed new fuel pump - constant loud ticking??

I just love it DAR100 when a plan comes together.---Keoke- /bcforum/images/%%GRAEMLIN_URL%%/grin.gif