Fuel Sender and Hydraulic Lifters oh my

[Thumperbird]

Hey all,

Has anyone found a fuel senser that does not drift as it warms up?
I've tried 2 now, autometer and an Amazon special, both drift from 6psi cold to around 4.5 psi warm.
I'm quite certain the pressure is not changing as the analog gauge installed on the rail is fairly steady although it too drifts a little bit.  I can stomp on it and it is rock solid where ever it is at so fairly sure a temp. thing.
0 to 10psi.

Also, fun side note, I preloaded my Morel lifters from ~3/4 turn to ~1-1 1/8 turns on a 7/16-20 adjuster, had some noise in one that bugged me, noise is reduced and picked up around 1 inch of vacuum at idle.  Not loving Morels in general.  Snow and cold now but wondering if I will notice any behavior difference on the road next spring. 

Thanks.

[BattlestarGalactic]

Liquid filled gauge?? That's the problem, trust me.
I ran a liquid fuel gauge for years and wondered why pressure changed all day.  Emptied the fluid and now rock stable.

[Thumperbird]

Yes, the one under the hood is liquid filled Holley needle gauge, it drifts some and of course the needle bounces around some.  Will try and drain or get a non liquid filed.
The sender for the Autometer servo gauge inside the car is the one that is most annoying due to thermal drift. 
It's not like it's connected to the block either, hanging in air on the fuel rail about 6 inches above the manifold so gets warm to the touch but that's about it.

[Falcon67]

Throw it away - liquid filled not recommended

[My427stang]

As far as the lifters, I go deeper on Morels.  Usually shooting for .060 preload, I have been using Brent's non-adjustables, so I use custom pushrods, but with yours it'd likely be 1 1/4 turns at a 20 threads per inch pitch.  I have run as little as .046 and as much as .070 though with success

You are in the ball park, and could even go a smidge more.  Modern lifters like the Morels control oil pretty well.  No need to keep them at the top of the lifter bore like the old pump ups.

[My427stang]

Yes, the one under the hood is liquid filled Holley needle gauge, it drifts some and of course the needle bounces around some.  Will try and drain or get a non liquid filed.
The sender for the Autometer servo gauge inside the car is the one that is most annoying due to thermal drift. 
It's not like it's connected to the block either, hanging in air on the fuel rail about 6 inches above the manifold so gets warm to the touch but that's about it.

I have never used a sender for a fuel gauge, but liquid filled gauges usually go to zero with heat because they functionally compare the liquid pressure to the fuel pressure and it expands as it gets hotter.  If the sender is similar, it won't need much heat to act goofy, I would ask Autometer. 

[BattlestarGalactic]

So the Autometer is electrical with a sending unit on the rail?

Like this:


I've only seen issues with my antique VDO gauges with slight fluctuations on battery(alt) power.  Turn on the headlights and the gauge would change slightly.

[Thumperbird]

Yes, electrical and similar shape to your image.
Both brands of sensor slowly decrease in value as engine heat soaks in everywhere (maybe).
Fairly sure 12V system is solid but yes good point I should check the 5V supply the meter puts out to excite the sensor, could be the gauge input itself is drifting as well.

[BattlestarGalactic]

Is the pump dropping in pressure due to heat/expansion and it's not actually the gauge??

[cammerfe]

For what it's worth, I believe the only gauges that should be electric are the ones that are reading volts, etc. Pressure gauges should be reading directly (through isolators). Both my gasoline and methanol pressure gauges are set up that way. I even have a cable driven tach.

KS

[RustyCrankshaft]

I'm guessing it's a 2 wire thermister type sensor? If so, figure out what range it operates in and buy a higher end sensor in the same range. Brand doesn't matter as long as the resistance curve is the same. You may have to change connector types depending on what new sensor you go with.

A lot of the automotive aftermarket gauge sensors are pretty poor quality, I frequently try and buy a good gauge and then source my own sensor when possible.

Also, some liquid filled gauges are not temp. compensated and their displayed value will drift in a somewhat linear nature with the heat. You can buy a better quality liquid filled gauge that will read consistently over a wider heat range.