Another Auto-Meter fuel pressure sending unit bites the dust.

[Chipstien]

Originally posted by illflem

Chip, the hose isn't a snubber. I can't link directly to the pictures so go to www.grainger.com and do a Grainger item# search for 5WL13 and 6MN31 . The first number is a snubber, unfortunately it is 1/4". The second number is what I've been using, an 1/8" needle valve. Both pictures are much larger than actual size. I like using the valve better because if you ever run into a leak you can just shut it down. What you do is after installation have someone watch the gauge, start the engine with the valve closed then slowly open it till the gauge just begins to register. The packing nut under the valve handle can be tightened to prevent vibration from changing your setting.



Grainger only sells to companies, if you don't have one they also have middlemen. My local Ace hardware can order Grainger parts for anyone, maybe they all can.

So when the valve is just barely open is it responsive to sudden canges in pressure or is it slow to change? Boeing employees can buy inexpensive parts, (not heat pumps or compressors, etc), from Grainger. Thanks again for the info Illflem.

 

[Chipstien]

Sky, try calling AM and tell them adamently that your sender is bad. They will send you a new one most likely. The guage itself rarely will have a problem. BTW, the AM fuel pressure guage is extremely sensitive to a less than perfect ground. Try checking and tightening the ground.

 

[illflem]

Chip, your gauge will respond plenty fast, just not 1650 times per second. Not sure where Toolman came up with that number.

 

[Big P]

Sky, my needle is pegged because I have a pusher pump set-up, and I had the lift pump on the engine changed at the same time the pusher pump was installed about a month ago. So, I don't believe the pressure fluctuations are due to a bad lift pump. Also I don't think a bad ground or a bad sender is causing the bounce because when air is in the line all is well. I did install AM's fuel restrictor this morning and so far so good, but it's too early to tell if the problem is solved yet.

 

[Chipstien]

Cool

Thanks Illflem. Oo.

 

[Sky]

Originally posted by MPagnucco

Sky, my needle is pegged because I have a pusher pump set-up, and I had the lift pump on the engine changed at the same time the pusher pump was installed about a month ago. So, I don't believe the pressure fluctuations are due to a bad lift pump. Also I don't think a bad ground or a bad sender is causing the bounce because when air is in the line all is well. I did install AM's fuel restrictor this morning and so far so good, but it's too early to tell if the problem is solved yet.

Keep us updated. As far as I am concerned this thing is useless right now, other than it looks good.

 

[BFC]

FWIW,

you can use an Autometer 0-35 boost gauge for a mechanical fuel pressure gauge(if you don't mind the gauge saying boost). Even pusher pumps won't peg that!



Mine I just run a -4 SS line from the test port on the fuel filter to the gauge, I have a 98 so it's works well. No vibrations, no snubber, valves or leaks. I used Aeroquip fittings and adapters.



Glenn

 

[98rammer]

i have the ultra-lites too (no fp though). the first package didn't even come with the thermocouple so i had to send the whole kit back to DIS (<-- good people there). the boost guage was on backorder for a while too. but they do have a great warranty as people have stated.

 

[Vaughn MacKenzie]

I've run my mechanical AutoMeter gauge for 20K+ with no problems. Like Illflem I use the small plastic tubing used for oil & boost gauges piped to my gauge (retreaded back of gauge to accept 1/8" NPT) and I haven't used a snubber. I read pressure off the bottom of the filter canister and have a rubber hose to the injection pump which probably quells most of the hydraulic pulsations.



$35 investment and working great so far.



Vaughn

 

[illflem]

Seems like most 24 valves can get away without a snubber while some can't. Could be a symptom from a failing lift pump or just the location of the pressure tap that causes them to pulsate. On a 12 valve there's no way to get by without a snubber. For $5 it's pretty cheap insurance that the gauge works right the first time.

 

[Bigsaint]

No doubt, cheap insurance with a snubber. I never bothered to snub the sender to my SPA gauge, which is located at the outlet of the fuel filter, not the inlet of the injection pump. So far, so good. It's been there for over 1 year now. I do have a mechanical gauge ( now using the Ultralite vac/boost gauge, 0-20) for pre-filter numbers as a back up to immediately remove doubt from a faulty sender.



I agree with illflem, if I were to do it again, the mechanical gauge is more than enough for me. If you have just one FP gauge, and it's electric, erratic psi's cause you to troubleshoot the sender and the lift pump. Erratic psi's with the mechanical gauge equal lift pump. Just my $0. 02.



Scott W.

 

[Chipstien]

Update............

Well that's it. Got the new sending unit in and put it on. Everythings great... ... ... ... ... for about a week. Sender died two days ago. Thats 3 sending units in 4. 5 months. Needless to say this guage is going back. Called Summit and they said "no problem, just send it back and we will refund your money. " Ordered the 4311 (mechanical guage) and figured I will use the $200 smacks that I get back on the Skyjacker springs for the front. I guess it just wasn't ment to be. #@$%!

 

[Chipstien]

Update #2.............

Got the Mechanical fuel guage installed and is working excellent. Used braided stainless line and a small brass needle valve. Thanks illflem and other for the enlightenment and advice. FYI... ... . Had the guage hooked straight to the injector pump with no snubber of sorts and experienced NO noise and vibrations/pulsations at the guage. But as illflem said, if by some slight chance you have a problem you can turn off the fuel supply at the needle valve and still drive till you get it fixed. So I installed the needle valve anyway.

 

[GOTSOOT]

Fuel pressure gauge

If you guys are having trouble with F/p ga. `s you might try a Hewitt brand , which uses a spring loaded iaolator filled with anti -freeze in the line to the ga. works like a champ! Rod @ wildcat has these