new pump

[jfirios]

Does anyone have the new in tank fuel pump and gauge that DMC has out. Supposedly it is really accurate. I am getting tired of watching my fuel gauge float almost a half tank even though it is full. I would like to get that and all new hoses. If i over fill the tank it tends to weep out and drip from under the car.

[WelmoedJ]

Does anyone have the new in tank fuel pump and gauge that DMC has out. Supposedly it is really accurate. I am getting tired of watching my fuel gauge float almost a half tank even though it is full. I would like to get that and all new hoses. If i over fill the tank it tends to weep out and drip from under the car.

Try a cheaper option first!
I changed the ground wire of the inertia switch into a thicker wire (see Bitsyncmaster's thread on this) and connected it to one of the bolts of the shifter cage.
This not only improved the accuracy of the fuel gauge.
It also stabilized the instruments lighting.

[ccurzio]

I'm pretty sure he was referring to the sender and not the gauge itself.

[Bill Robertson's Sock Puppet #1]

Fuel tank sending unit isn't grounded inside the car -- it's grounded at the radiator support bracket. Dash gauge is on the positive side of the circuit (just like the coolant temp and oil pressure gauges).

[jfirios]

Hes talking of the wires at the top of the fuel tank. right. I had the fuel sender, that little grenade pressure valve under the car which help with the hot start changed already. I know the car is plagued with bad and weak grounds. A problem I have been pulling my hair out over when installing that competition stereo system in the car. Even Stephen the owner of DMC joked with me about the ground issues with the car and how i liked dealing with it. So if you are talking about the wires coming to the fuel pump at the top of the tank, I should get a thicker ground cable and re ground the unit to a better spot on the car like I had to do with all the other grounds.
Is that right?

[Bill Robertson's Sock Puppet #1]

In theory you won't get a better ground route back to the battery than the frame itself. Of course connections at the radiator support and battery cable need to be suitably clean and tight.

Some owners have added a "ground bus" of large gauge wire from the battery through the passenger compartment and tied all original ground junctions into it. Tying in the engine and front radiator ground as well requires extending the bus out of the passenger compartment, which several owners also have done.

[Silverbullet]

To answer the question... I have the combo unit... it works GREAT. It is SOOOOOO easy to install, and worth every penny.... It is a new GM Pump that has been re-worked to fit, and I give it a 10 for the kit. fyi.

Craig

[David T]

A little "off-topic" here but as the car was built the grounding system was sufficient. Over time (30 years!) connections get dirty and corroded. If you clean things up the original system can still work without having to bypass it. If you modify the car (like adding a competition sound system) you should probably also be upgrading the grounding system for that modification.
As to the original question, there have been some posts on the Forum that after putting in the new pump set-up the owners experienced a hard hot restart problem. It has not been posted as to what was the exact cause and how it was fixed. One possibility is a problem with the check valve in the new pump set-up. Another possibility is they had the problem all along but didn't notice it till after they did the new pump. The new pump set-up makes sense if you find yourself in the position of having to replace all of the stuff in the tank and your fuel sending unit is not working. Then it makes sense. Otherwise fixing what you have and staying original by replacing a few parts is probably much cheaper. While you are in the tank you should drain it completely and wipe it out to remove all dirt and any water that may have gotten in there.
David Teitelbaum

[WelmoedJ]

I'm pretty sure he was referring to the sender and not the gauge itself.

To add to my previous reply:
I have the "model 2 DCM" fuel sender unit.
This one alike the ones before (original) or after (DMC models 2 and 3), all or most of them have the nervously acting gauge needle.
As Bitsyncmaster mentioned, the ground wire on the inertia switch is a bit tiny for the job (providing ground to the fuel pump).

I also had some instruments lighting problems, also caused by a less good working ground for the instrument lights.
Mind that the ground wire from the pump runs to the inertia switch and then to ground.
Changing the inerta switch ground wire gauge into 10 AWG and run that wire to a solid ground made both lighting and fuel gauge problems disappear.
The fuel gauge needle in my car now also is more precise, less jumpy and when the tank is full, it shows "full".

On the subject of the wiring to the fuel pump: both wires seems sufficiently capable of feeding and grounding when the connections are solid and clean.

[Bill Robertson's Sock Puppet #1]

... Changing the inerta switch ground wire gauge into 10 AWG and run that wire to a solid ground made both lighting and fuel gauge problems disappear.
The fuel gauge needle in my car now also is more precise, less jumpy and when the tank is full, it shows "full"....

As previously stated the fuel pump circuit has absolutely nothing in common with the fuel sender circuit (other than the frame to battery wire of course). They are 100% separate from each other. If you trip the inertia switch, or indeed even if you remove it altogether, the dash gauge will still work normally.