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Fuel gauge reading

limeyboy

Member
Midlife,
I've just read an old post of yours explaining that to get the fuel gauge to read correctly you need to "alter" the CVR.
I've just fitted an electrical oil pressure gauge ( taken from a Tee piece back of the block) and a water temp one ( sender fitted into the water pump 351 Cleveland).
The readings seem good 77 / 80c and 5 bar cold fast tickover to 1.2 bar 600rpm hot tickover and 5.4 bar cold 3,500 and 4.4 bar hot 3,500 with 2.4 bar 1,000 rpm hot.
The original oil pressure gauge has always read flat out only dropping to halfway at lowest when hot ( 600 rpm) going back to High when reved up much and the temp gauge has never moved very far from Cold.
Now my fuel tank ( California tank so 16.5 UK gallons ) goes a long long way passed Full when filled and I think it has about 4 or more UK gallons left in it at Empty so if I should alter the voltage regulator would that -
1- drop the Fuel tank reading
2- drop the oil pressure reading
3 - RAISE the temp gauge reading ( as I believe it reads low)
A lot of explaining for a simple question so thanks for reading it and replying hopefully.

Jeff
PS would a transistorised CVR cure this?IMG_20220118_101316.jpgIMG_20220118_101341.jpg
 

Mach1 Driver

Well-Known Member
If you change the voltage it will affect all the instruments. The 69 and 70 use the same flex circuit, so I suggest you follow this link. It will tell you how to fix anything on the dash. The meters are adjustable, but even though the IVR (instrument voltage regulator) is adjustable, I wouldn't adjust it:
 

Midlife

Well-Known Member
Staff member
Moderator
Your oil and water temperature readings are from those gauges between the seats? If so, they are not factory and typically those aftermarket gauges need to be matched to aftermarket sending units. They typically do not use the IVR to control their readings.

You can adjust the IVR to have the fuel read correctly (I typically set it so that a quarter tank of gas (based on mileage) reads 1/4 on the gauge. I forget which way to turn the trim-pot on the IVR, so you'll have to experiment a bit.
 

limeyboy

Member
The new gauges have their own matched senders ( I left both the original senders connected ) I was wondering if altering the dash voltage would "drop" the oil reading and "raise" the Temp one.
I've had the dash completely out before to change all the bulbs to LED's but want to be sure it will be worth it to take it out again.
 

limeyboy

Member
Mach 1, I followed the link but it wouldn't let me open the document probably because I'm in the UK :-(
 

Mach1 Driver

Well-Known Member
Mach 1, I followed the link but it wouldn't let me open the document probably because I'm in the UK :-(
Become a member of 69Stang and sign-on. It doesn't care if you're from across the pond. Its free and the site is for your specific car as 69s and 70s are very similar. .

If you change the voltage of the IVR it will affect all the instruments- oil, water, and fuel. They will all go up or down with the voltage. That's why I don't recommend doing that, but adjusting the gauges if needed. Its a PITA, but doable. Chances are you will just have to sort out problems with the sender(s) and not adjust the gauges.

1642764654784.png
 
Last edited:

B67FSTB

The NorCal dude from Belgium
Or you drive to Belgium and get some help with this.

Verstuurd vanaf mijn SM-A605FN met Tapatalk
 

limeyboy

Member
Harsh words Midlife :oops: we are so "woke" here now we have to wear sackcloth and ashes to atone for all of our previous sins as a country ( of which there are many apparently)
 
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