Fuel Pressure Gauge???

[swampinboy]

Fairly new to this stuff still, bear with me, here goes-

I am looking at gauges, FP, TRANSTEMP, BOOST, AND PYRO. I have been looking at autometer ultra lites but the dilema on the FP gauge has me wondering why an oil pressure gauge wont work (elect. ) other than saying "OIL"? Maybe I am missing something here but doesnt the sending unit read pressure off from an electic current generated from the pressure on the line, in other words the gauge doesnt know whats putting pressure on the sending unit right? This way I wouldnt have fuel in cab or be messing with an isolator not rated for diesel fuel. Again maybe I am missing something obvious here.

 

[illflem]

I've done it but the senders don't last long.

Then again senders for a 'real' FP gauge have never lasted long for me either.

Few hundred dollars later finally gave up and went with a mechanical gauge, fuel in the cab.

Six years later still working perfect.

Another problem is most oil pressure gauges are 80+ psi, too high for a FP gauge.

 

[Deezul1]

I have been using a oil pressure gauge for 2 years and the sender finally gave up but a new one is $25. 00 so no big deal. Dont like the thought of fuel in the cab though there are some mechanical gauges set up so that wont happen and one of them is here http://www.piersdiesel.com/Gauges.htm



browse the site till you find it

 

[swampinboy]

Thanks for the quick turn around guys, when you say the sending units gave out, you mean they broke from vibration or they just quit sending? If they broke, couldnt we use a short piece of braided line like areoquip or earls as a vibration dampner? I dont really know just ideas popping into the cranium cavity. thanks.

 

[Deezul1]

mine leaked and it was on the end of 18" of rubber hose

 

[WadePatton]

I bought a used Westach electric gauge and sender. It's still working fine 40k later.

 

[illflem]

When mine failed one leaked the other four started only reading zero and the pressure the sender saw most often leading to a false sense that the gauge was still reading correctly. There were no in-between readings. All of mine that failed except the one that leaked were isolated from the engine with hose and had needle valves for snubbers.

Using a needle valve shut almost all the way down at the head of a mechanical gauge line results in just a slow drip even with the line completely open. You can also shut it all the way down if does leak. I can live with this much fuel in my cab. Isolators tend to fail and are expendsive to boot.

One member here reported his electrical gauge leaking fuel into the cab. The fuel traveled from the leaking sender into the cab though the wire insulation.

 

[swampinboy]

Looking like I should just get a mech FP gauge and go in cab with the go juice (no big deal). Illflem, you said a needle valve, I like this idea, where did you tap for pressure and where did you put the valve? If the valve mounts at tap then flex mech line to gauge I wouldnt need anything for vibration, right?



Any pics from members on gauge tricks and taps would be cool to see. I am thinking about removing the drivers visor and putting a custom mounting box there with 4 gauges.



thanks to all.

 

[Jerky]

Illflem - What brand of mechanical fuel gauge do you use? Thanks

 

[illflem]

From Grainger I use a

5HK51 30lb gauge for 24 valves and a 5HK52 60lb gauge for 12 valves. Use this for a needle valve

These gauges don't have lighting and you will have to figure out how to mount them yourself, L bent piece of sheet metal with a hole in it works for me. I mount these on the dash low right in front of the 4wd shifter. Location and lighting really isn't important, it's not a gauge you need to look at often nor read the numbers, needle location is good enough once you learn how the scale runs. If you want to mount the gauge in an A pillar or dash pod or want lighting a 30 psi boost gauge for 24s or a 40 psi for 12s works great. They are available from most any source if you want it to match your other gauges. It will say boost on it though.



The needle valve is attached directly to an injection pump inlet banjo bolt that has been tapped to 1/8'' NPT. You can tap it yourself or buy one from Genos. Between the gauge and needle valve I use 1/8'' nylon boost tubing that is pushed though 1/4'' tubing to form a protective sheath. This protects against kinking and cuts plus makes the tubing much easier to work with. You can buy the tubing and the compression fittings needed for each end from any auto parts store seperately or as a kit made for mechanical oil pressure gauges. Doing it this way you will have a reliable FP gauge set up for under $25. I have been recommending this set up for several years here, many people are using it with excellent results.



Notes: don't use Teflon tape, Permatex #2 or anti-seize are better for a thread sealer.

Never tighten compression fittings more than hand tight plus one half turn with a wrench, they will leak. If you ever need to take things apart use a new ferrule in the compression fitting.

Don't worry about bleeding air from the tubing, it makes little difference.

Have someone watch the gauge as you open the needle valve, engine running, stop when the gauge just starts to read.

 

[Heavy Metal]

My FP guage is an Isspro EV mechnical set up with a needle valve just as illflem describes. Works great. Only difference is that I made my own braided lines when I relocated my lift pump and did away with the banjos which allowed me to use a 1/8" guage adapter between the lift pump and injector pump. Just curious, why not Teflon? That's what I used where the needle valve is threaded into the adapter.

 

[illflem]

Teflon and diesel don't get along, it will eventually leak.

What's even worse is if you ever have to take things apart the only way to remove potentially pump/ injector damaging tape debris is with a wire brush and compressed air. This can lead to having to remove everything from the engine to clean it rather than just one joint.

 

[Heavy Metal]

So what you're saying is that I should get rid of the Teflon ASAP. I guess the safest route would be to put in a new adapter for $8. 50 and it's only two compression fittings to loosen.

 

[Shovelhead]

I use this stuff.

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It's normaly called pipe dope at your local Home Depot.

It's a teflon paste.

 

[illflem]

Originally posted by Heavy Metal

So what you're saying is that I should get rid of the Teflon ASAP. I guess the safest route would be to put in a new adapter for $8. 50 and it's only two compression fittings to loosen.

Or you could wait for it to start leaking before you change it. Only problem is one of your taped joints is in the cab...



I fought leaks (more like seeps) on my 1000 farm tank for around five years before a guy who runs a bulk fuel plant told me to use Permatex #2. I tried everything, Teflon and non-Teflon pipe dope, silicone and even new fittings. Some would work longer than others but eventually started seeping again. The Permatex fixed it right up, no seeps for at least the last ten years.

 

[Heavy Metal]

The only place I used Teflon was on the male end of the 90 that threads into the Aeroquip adapter. I put nothing on the back of the guage. No leaks yet, but Permatex will go on next. Easy enough. As for the adapter, I loosened the compression fitting from the hose to the needle valve, loosened the two compression fittings at each end of the adapter then removed the adapter needle valve and all. I did't touch the Teflon infected fitting until the adapter was out of the truck. Then I completely cleaned and blew out each. Did this yesterday. Couldn't quit thinking (worrying) about it. Anyway thanks for pointing this out illflem. You have saved me from my own ignorance.



Bryan



BTW I didn't notice until now that I said it was between the lift pump and injector pump. I meant to say between the injector pump and fuel filter.

 

[Briar Hopper]

Originally posted by illflem



One member here reported his electrical gauge leaking fuel into the cab. The fuel traveled from the leaking sender into the cab though the wire insulation.

I think maybe Bill is talking about me? True. That happened to me. However, my last (3rd) sending unit(AutoMeter) has lasted for over a year, and 50,000 miles, and still reads accurately.

The ONLY drawback is it's 0-15 psi range, if you're running a FASS system, or a pusher pump.

The handheld test gauges I developed and built (thousands sold worldwide) are still a great alternative to a full-time in-cab FP gauge.

I do wish AutoMeter would build us two unique gauges: a 0-30 psi FP gauge, mech. or elect. , and an 0-100 boost gauge.

Come on AutoMeter, we need you.

 

[DToy]

I've been through 2 Autometer electric fuel pressure gauges in the last 3 months. Neither one has ever read accurately, first one read 18-20 psi @ idle, until the gauge completely died, second one reads 10 psi @ idle and has developed a crack in the gauge face. Dealer and local diesel shop tested pressure at 15 psi @ idle, so I'm scrapping the Autometer altogether and going with something else... just not sure what yet.

 

[dieselshu]

FO pressure gauge

Hey all, I installed a Dakota digital with a VDO electric sender, I bought the special banjo and threaded into the vp44 fuel inlet and came off it with a aeroquip S/S 90, from there I went with about 2 ft of 2556-4 aeroquip hose and S/S straight female fittings on each end, from there I installed a double FNPT needle valve, one one end was a -4 straight aeroquip s/s fitting at the other end the pressure sensor. All thread fittings were sealed with Aviation permatex #2. The sensor was wrapped with a strip of 1/8" thick rubber and then some black foam rubber and used a wireband(wiretie) with eyelet and mounted the sensor to the dipstick tube bracket using S/S hardware. I have been running this set up for a year and half with zero problems.

If its one thing I have learned from being a machinery tech and working on Motor lifeboats with 6v53's and 6v92's that are designed to rollover and reright is never ever use teflon tape or teflon base products in fuel systems. The distillates in diesel and gas will breakdown the teflon and cause it to clog filters and worse injector tips. Teflon is best for water systems. Now the key to electric sensors lasting is minimizing or eliminating the pulses and vibrations, the needle valve will eliminate the pulses and the rubber hose helps the vibration, the other is mounting it on the engine not the firewall. Hope this answers some questions.



Dave

 

[KLockliear]

Mechanical is the only way to go for FP. Gotta isolate it, then the only question is black or white.



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