gauge help please!

[Sir Thomas Performance]

Customers 74 Duster came in overcharging (45 volts), fixed that issue then installed a new Painless wire harness. The fuel and temp gauges were dead so I installed new OER gauges and an IVR. Now the gauges will sweep with initial key on but slowly fall off and dont read properly. Im getting the on-off voltage cycle to the gauges and they twitch when it cycles. Im at the end of my rope need some tech help please!

 

[Murray]

The IVR "cycling" sounds weird to me. Isn't that a problem? We need more help.

 

[Sir Thomas Performance]

fuel sending unit resistamce is around 20 ohms with a full tank and temp sender is around 75 ohms cold, measured at the IP connector. IVR has constant 12v feed and cycles every 3-7 seconds or so, it varies. Intial key on cycles both gauges to where they should be, and then they slowly fall off to cold engine and empty tank when the IVR starts cycling. Too slow IVR cycle to satisfy the gauges?

 

[vames]

I had a similar problem with an IVR that I bought off Classic Industries -- needle would initially surge and then settle back down to the wrong reading.

I replaced with the solid state IVR from RT Engineering and it now reads correctly.

Thread: Fuel Guage Goes Up Then Partly Fades -- 72 Swinger

 

[Dana67Dart]

If you read the fine print on the classic gauges you gave to use their / not OEM senders / ivr?

The ive pulsing is completely normal for a mechanical ivr. It works like a blinker mechanism. It has contact, voltage flows, an element heats up, the bimetal bends, the contact breaks, the voltage stops flowing. It creates a form of square wave that has an average voltage of around 5 to 6 volts. Even the RT engineering electrical one does this.

The pegging at key on is the time it takes the element to initially heat everything up.

Watch and learn

 

[67Dart273]

I doubt you want to be using an oem style IVR. RTE or similar solid state. Check the pc board fingers where the IVR fits and solder across from the fingers to the board traces. Make CERTAIN the cluster/ pc board is grounded. VERY good idea to add a separate grounding pigtail to a common point. If you look at the traces, AKA the lighting sockets, you can trace them to a mounting screw..
Make certain the PC board pins are not loose, solder them if so.

You can use resistors or an old gas sender as a dummy sender to test gauge accuracy. There are tons of threads on this.

CAN YOU POST A LINK to any destructions for these gauges? I ain't familiar with them

 

[67Dart273]

If you read the fine print on the classic gauges you gave to use their / not OEM senders / ivr?

The ive pulsing is completely normal for a mechanical ivr. It works like a blinker mechanism. It has contact, voltage flows, an element heats up, the bimetal bends, the contact breaks, the voltage stops flowing. It creates a form of square wave that has an average voltage of around 5 to 6 volts. Even the RT engineering electrical one does this.

The pegging at key on is the time it takes the element to initially heat everything up.




Watch and learn

No the pegging and pulsing is NOT normal. None of mine ever did, and the bone stock 74 Scamp does not, either.

 

[Sir Thomas Performance]

So I connected 4 aa batts in series to power up the gauges and they work normally now. The new ivr was cycling erratic and too slow to provide any needle movevment. I appreciate all the replies and help. I learned a whole lot from reading this site..thanks

 

[AJ/FormS]

You can take the mechanical IVRs apart and clean the contacts. Putting them back together can be a challenge tho..... I agree that the solid state one I built from a magazine article is very reliable, and seems to be accurate enough.