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

[Chipstien]

Well... . there went #2. If it wasn't for the fact that I have Ultra-lite's for my other guages I would drop kick this Fuel pressure guage to Guam. Why can't A-M build a sending unit that stays working? Looks like I need to call A-M tomorrow and have them send me out a new one. At least their good about warrantying their products and ship it right away too.

 

[Sregorb]

Welcome to the club, we'll hand out buttons next time..... Seems I've lost the EGT probe from my Autometer Ultra-lite series also. It's good that they're standup warranty people. I'm awaiting replacement... .....

Out of curiosity, I'm looking to put in a FP also and wondered about your setup. What should I go with/stay away from?



Brian

 

[TradedV-10foraCummins]

I just recently lost my 4361 fuel pressure gauge too. I wasn't sure exactly what went bad, so I sent the whole thing back to AM. I just received a new one. They didn't fix the old one, but sent me a whole new set. Interestingly, the new gauge (08-02 manufacture date) no longer has the black box that goes between the gauge and the sending unit. On this one the wires go straight from the sender to the gauge. Also, the sender looks different (smaller and all metal) and hopefully is more durable. I just haven't had a chance to get it back in yet to see how it works.

 

[dresslered]

I've had great success with autometer. Just out of curiousity, where are you mounting the sender? Is it properly snubbed and located off of the engine? Most senders will fail immediately if mounted directly on the injection pump test port and even when located on the engine.

 

[ToolManTimTaylor]

Ditto... thats why I mounted mine up at the cowl area with a 24" pice of 5/8 braided ss inbetween the vp`44 and the sending unit itself

 

[Chipstien]

Yep, I used the rubber hose when mounting the sender. Called AM today and it looks like the 4361 is not suited for diesel. So I might not be able to get a new sending unit, I will know tomorrow. If I'm stuck with a $200 guage that I can't use I will be pi$$ed off. Needless to say I won't spend my own money on a sending unit that is only going to last 3 months. Apparently the isolater on the mechanical fuel guage is also not rated for diesel but it seems to be holding up for some members here on TDR. Looks like I will be trying the mechanical guage here soon. I'm beginning to wish I might have gone with another brand.

 

[EMDDIESEL]

You dont need an isolator for a mechanical fuel pressure gauge in a DIESEL application. The pressure is low and the fuel is not an explosion hazard. Autometer cant tell you that for insurance reasons. I have mine run with braided stainless line, there is no chance of catastrophic gauge failure with 15PSI of diesel i assure you. I used to run a mecahincal oil pressure gaige from Autometer in my TransAm and say over 90PSI of oil pressure on a regular basis, no problem, no isolator.

 

[dresslered]

The 4361 works just fine with a diesel application unless they have changed the sending unit that goes along with it. I have had zero problems in 1-1/2 years with mine.



Here's more reading:

https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=5895&highlight=diesel+and+4361

 

[Ramafid]

My Autometer mechanical fuel pressure went south about a month ago. Don't know if the isolater is at fault or the guage. I've had them too long for the warranty so I guess its out of pocket for me. The warranty is only 1 year right?

 

[Big P]

Chipstien, what was your gauge doing that you knew it was bad. I have the same guage and I'm having problems too. Pressure reading flutuate from pegged, to the needle going crazy bouncing from 9-12psi, then down to 0psi. Basically it's a mess. With the same sender on the truck, I get air into the braided line to the sender(sender is on the fire wall with a -4an line to the injection pump) and it works as smooth as the boost and egt gauge until the air gets pushed out. I just got a fuel pressure resticter from AM. I'll probably install it tomorrow and I'll post again.

 

[ToolManTimTaylor]

Originally posted by EMDDIESEL

You dont need an isolator for a mechanical fuel pressure gauge in a DIESEL application.

Well will The raeson for failure is in a sense just like "Water hammer" ... ... you know that wicked vibration when you turn off the hot or cold water pipes in your home raelly fast and the pipes bang ... ..... do that 1650 times a seccond at 1500 rpms and that is what kills the sending units (ELECTRICAL) mainly. The mechanical units transmit that vibe to the guage in many cases making one heck of a racket.

 

[dresslered]

I get air into the braided line to the sender(sender is on the fire wall with a -4an line to the injection pump) and it works as smooth as the boost and egt gauge until the air gets pushed out.

The ToolMan has it right. The stainless steel lines look great, but you need a snubber or the "water hammer effect" is going to beat the little transducer to death. Rubber tubing (i. e. grease hose) doesn't look as purty, but it will absorb the pulsations from the injection pump. Either get the mechanical snubber or swap your steel with rubber.

 

[Scot]

What about some sort of spring loaded accumulator?

 

[Chipstien]

Originally posted by MPagnucco

Chipstien, what was your gauge doing that you knew it was bad. I have the same guage and I'm having problems too. Pressure reading flutuate from pegged, to the needle going crazy bouncing from 9-12psi, then down to 0psi. Basically it's a mess. With the same sender on the truck, I get air into the braided line to the sender(sender is on the fire wall with a -4an line to the injection pump) and it works as smooth as the boost and egt gauge until the air gets pushed out. I just got a fuel pressure resticter from AM. I'll probably install it tomorrow and I'll post again.

I honestly think that too high of pressure might be the culprit. Since I have moved the stock lift pump back to the tank I have been pretty steady at 15 to 16 psi. I not sure if the 16 psi is hurting it... I think that the fuel system is spiking when on it hard and then cut the throttle. I think because of my high pressures I will need to go mechanical. (The Ultra-lite 15 psi mechanical guage is only 37 bucks at Summit) I did get AM to send me a new sending unit but why put it on and blow it too.

As far as the symptoms, this one was pretty mild. It worked when I started it and the all of a sudden it was stuck permanently on 16. (Yes I no there is no 16... you get my picture ) MPagnucco, my first sending unit was exactly as you subscribed. WORD OF CAUTION... ... ... . IT ENDED UP BEING THE DEAD LIFT PUMP THAT TOOK OUT THE SENDER. I would suggest buying a setup like Briar's guage and test it just for peace of mind.

 

[illflem]

Originally posted by Scot

What about some sort of spring loaded accumulator?

It would be an overkill when a needle valve or snubber will do the job for less than $5. My unsnubed mechanical gauge pulsed so bad it shook the dash, gauge bounced between 0 and 40. Only ran it 30 seconds before a snubber went in.



Mechanical FP gauge is the only way to go, senders don't seem to last. Many times when they fail the only way to really know is by comparing the reading with a mechanical gauge. They seem to like reading the pressure they see most often with no in-betweens even if it's incorrect.

 

[Chipstien]

Illflem... . aren't you running the isolater on your mechanical guage or is it straight to the guage. I have been curious as to how those isolaters are holding up.

 

[illflem]

No isolator. I have faith in my plumbing skills plus the pressure is low. In fact I just use plastic boost tubing inside a protective sheath of 1/4" hose to the gauge. No Teflon tape! The whole key is the snubber, all it is is very tiny hole or sintered material the fuel must pass though. With a needle valve you run it almost shut. The snubber should be the first thing in line from your pressure source. With a snubber if you ever have a leak I doubt if it would even amount to a quarter cup per hour of non-flammable diesel.

 

[Chipstien]

I am having problems trying to picture this snubber. I have a piece of rubber hose running to the sender... is that what your referring to? I will be ordering a mechanical guage soon and want to make sure I plumb it right. Detail, details. Thanks illflem.

 

[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.

 

[Sky]

Originally posted by MPagnucco

Chipstien, what was your gauge doing that you knew it was bad. I have the same guage and I'm having problems too. Pressure reading flutuate from pegged, to the needle going crazy bouncing from 9-12psi, then down to 0psi. Basically it's a mess. With the same sender on the truck, I get air into the braided line to the sender(sender is on the fire wall with a -4an line to the injection pump) and it works as smooth as the boost and egt gauge until the air gets pushed out. I just got a fuel pressure resticter from AM. I'll probably install it tomorrow and I'll post again.

This is happening to me too. I am pegged at 15+ at idol or light throttle. Then when I stomp on it, the neddle goes to 0 and moves so fast it bounces all over the place. So when I go up a grade it just sits at 0 and I dont know if its just my guage thats a POS or if my lift pump is bad.