Engine/Transmission (1998.5 - 2002) Auto Meter FP Guage Observation

[Big P]

I've got a question for you guys with Auto Meter FP guages. When I first got mine installed (had the plastic sending unit) it worked great for the first 30min-30miles, the needle was ROCK steady then it developed a slight bounce in the needle. I drove it like this for about two weeks until the sender went bad, it was leaking. So, I got it replaced with the new metal one, no leaks since. When the metal one was installed, same thing, the needle was ROCK steady for the first 30min-30miles. After that the bounce was back. So the other day after I changed my fuel filter I again experienced the same thing. My guess is that after the fuel system is drained and re-primed air is getting in there somehow.

The sending unit is mounted on the firewall horizontally. I have tried to bleed it while the motor is running by cracking the line open at the sending unit but the bounce is still there. I'm thinking of putting the sender in a vertical position so that it might bleed more efficiently. Does it sound like I'm on the right track?

 

[illflem]

The pulses are due to back pressure from your VP. I've noticed senders to be more steady when they aren't bled, but they bleed themselves pretty fast. The air acts as a cushion. That's probably what you're seeing. Sorry but my experience with electric FP senders is they don't last, pulsation kills them. I went though three senders in just over a year before giving in to a mechanical one, it's been great, leakless for five years now. Most all of the folks here have had their electrical FP gauges in for less than a year, my feeling is that's why you see reports about them working fine. Give them more time. A gauge snubber or needle valve will help with longevity but I still feel the senders still won't hold up. Been there done that.

 

[BK]

I just installed a Westech FP sender and gauge... . after not hearing my LP anymore. . ya it was 2-3psi@WOT. 8psi@idle.

Anyway. . a few things I noticed on installs from reading the posts here...

1) it seems some are reporting success with rubber grease gun style hoses. Not so good with SS braided hoses.



2) I see a lot of install posts say they are using teflon tape, the last I thought diesel ate teflon tape for lunch.



I used a diesel/heating oil proof pipe thread sealer and a 24" grease gun hose. I did not bleed my hose out, but made sure all connections were sealed with the blue junk for heating oil pipe threads. My install is going on 5 days now and about 200 miles... no leaks and no bounce.

My sender is loosely mounted on top of the fuse box, horizontally.

I used the 45deg fitting Geno's sends with the Westech kit, that's mounted on the fuel filter housing, then the 24" hose gently curves past the master brake cylinder over to the sender. I used some plastic wire looming to cover the hose.



Could it be an Autometer thing?



illflem, what senders have you eaten up?

how were they installed?





B0b

 

[illflem]

They were all Stewart-Warner. Last two were installed with grease gun hose and the last one with a needle valve used for a snubber. When they fail it can be tricky even noticing it, my last two read only zero and 22psi (12 valve). When the senders failed they seemed to only like reading the pressures they saw most often. Can lead you to a false sense of security.



Teflon tape does not work with diesel it will eventually leak.

 

[Bigsaint]

If you are using the inlet of the VP44 as a source, try moving it to the outlet ( bottom) of the fuel filter. I've had my electric sender for my SPA gauge there ( un snubbed) for over one year with no problems.



Scott W.

 

[dresslered]

My Autometer Ultra Light Fuel Pressure guage has been working flawlessly for over a year (in fact, its already caught a failing lift pump). I used the grease gun hose mounted to a tapped banjo bolt on the bottom of the fuel filter. The sender is mounted on a custom bracket mounted to one of the brake master cylinder studs. As illflem suggested, I also trap air in my line for extra dampening. I use Permatex thread sealer on all the fittings.

 

[Big P]

Thanks for the suggestions. I think I'm going to try to mount the sender so that the hose will be going straight up when it goes into the sender. Hopfully this will make it harder for the air to bleed itself.

 

[illflem]

Try to keep the air cushion if it isn't too much hassle. One of my early experiments to keep the gauge steady (long before TDR) was a clear inline fuel filter in the grease gun hose for an air trap. It worked great for a week then slowly filled with fuel till the pulsing started again.

 

[Big P]

Well I moved the sender and so far so good. When I took off the hose (4an stainless) I let some fuel come out and I shook out the sender to get the fuel out of there too. So now with the hose pointing straight to the sky I hope the air cushion gets trapped in there for good.

 

[Gary - K7GLD]

I keep seeing references to the use of "grease gun hose" in these installations, but it seems that hose's main advantage is the amount of pressure it will accept? But, with a max of somewhere around 20 lbs in the LP line/ what's the NEED for that heavy a hose?



Why wouldn't ordinary diesel-compatible fuel hose work satisfactorily?

 

[illflem]

Gary, the main reason is that you can't buy diesel rated hose and two fittings for the price you can a gg hose, I've seen them for $2. Another plus is that the ends are crimped on nicely and the extra pressure rating/thickness makes them highly resistant to abrasion.

 

[BK]

Originally posted by Gary - KJ6Q

I keep seeing references to the use of "grease gun hose" in these installations, but it seems that hose's main advantage is the amount of pressure it will accept? But, with a max of somewhere around 20 lbs in the LP line/ what's the NEED for that heavy a hose?



Why wouldn't ordinary diesel-compatible fuel hose work satisfactorily?

Gary,

Your right, I asked myself the same question... but came up with the follow-



I don't know what the original thoughts were. But I thought it was a great idea cause:

-the crimps are a lot more secure than the barbs and hose clamps. (made to handle the pressures, which is a lot more than our pressure in this applications as you point out. also should handle the vibration better)

-cheap - got the fittings and 24" hose for 8 bucks.

-It's made to flex for it's original application... which good for our application.



Other than that... . your right and my own view points to the positive points of the grease hose maynot mean a thing to others or to you. . but it seemed good to me.

 

[WAYNE]

I've had the autometer eletric fuel pressure gauge with the eletric sender mounted on the fuel filter housing almost two years with no problems at all.

 

[dresslered]

MPagnucco-

I think that I see your problem. I didn't realize that you were using stainless steel lines. These are very rigid and don't offer any "snubbing". The advantage of the rubber grease hose (although not as cool looking) is that it flexes and offers snubbing on its own. I would suggest that you add a mechanical snubber in line with your stainless line just in case you loose the air.