Fuel Filter Gauges - Necessary or Not?

[Wotname]

First a short background.

I have never had a gauge on my fuel filter and never felt the need for one.
I note that many on CF do have them and some sing praises to these gauges.
I get that on big engines (say > 60 or 80 hp), they could be quite useful.

But what is everyone's take on such gauges on small engines (say < 40 hp)?

Do they really foreshadow looming filter problems or just tell you that right now, the filter is clogged - you know, just after the engine is coughing or has died from file starvation!

And if they are so good, what is better. A differential gauge across the filter or an absolute gauge on the output side of the filter? I can see theoretical reasons for both methods but I have no experience with such matters.

The poll is multiple answer so feel free to tick as many as you feel best describes your viewpoint.

[DeepFrz]

I definitely am an advocate of a gauge on the output of the filter. IMO the gauge should have a "Tell Tale" so you can see what the highest reading was even after the engine has been shut down. Whether it tells you if the filter is getting plugged up or gives you a reading after the engine dies on you depends on what sort of blockage/contamination you have. The fuel problem that I had was a sudden blockage of the fuel line at a 90 deg. elbow and resulted in engine failure. The gauge still would have indicated that the problem was upstream of the gauge and therefore eliminated the pump and fuel line downstream of the gauge. Just my opinion.

[chouliha]

I am one of those who has been using a vacuum gauge for 30+ years and sing there praises. It will immediately tell you the state of your fuel filter. We use to replace the filter when we saw crud in the bowl but once installing the filter we have found we get MUCH more mileage out of the fuel filter. When the vacuum starts to increase we know that sometime in the near future we need to change the filter.

I love the idea of the gauge showing you the highest vacuum when you shut down the motor. That way you can inspect the gauge without having to run the engine when you are in the engine room.

BTW we are running a 40 hp Yanmar.

Chuck



www.jacarandajourney.com

[Wotname]

Originally Posted by chouliha

I am one of those who has been using a vacuum gauge for 30+ years and sing there praises. It will immediately tell you the state of your fuel filter. We use to replace the filter when we saw crud in the bowl but once installing the filter we have found we get MUCH more mileage out of the fuel filter. When the vacuum starts to increase we know that sometime in the near future we need to change the filter.

I love the idea of the gauge showing you the highest vacuum when you shut down the motor. That way you can inspect the gauge without having to run the engine when you are in the engine room.

BTW we are running a 40 hp Yanmar.

Chuck



jacaranda-journey

Are you using a differential gauge across the filter or an absolute gauge on the output of the filter?

I guess the "mental difficulty" for me is that I have never seen crud in the filter and just replace the filter every year or so because it seems like the right thing to do. I am fairly fastidious when it comes to fuel quality and tanks and so on even though I have purchased fuel in some parts that clearly isn't the best in purity. Although that has been decades back and everyone says fuel doesn't keep as well as it used too.

[chouliha]

I have the vacuum gauge installed on the engine side of the Racor 500. It is between the Racor and the engine filter. So it is measuring vacuum between the Racor and the tank. The gauge is attached to the Racor with a T fitting. Racor - T fitting - Vacuum gauge. The fuel hose to the engine filter comes off the 3rd part of the T.

I also am a fanatic about clean fuel and we pre filter every drop before it goes into the tank. In 17 years of international cruising many of those in Central & South America and the South Pacific the worst fuel was from Pearson fuel dock in San Diego... haha what a surprise that was!

We are currently on almost 3 years with this one Racor filter and it's just starting to show a tiny amount of vacuum. I know some folks will beat me up about not changing it every year but we are along way from West Marine and there is no need to change it out for the sake of maintenance.

Chuck








www.jacarandajourney.com

[Roy M]

I have had the delightful experience of having the engine RPM's suddenly rise and collapse, indicating a fouled fuel filter. I've had it too many times, generally at a most inconvenient moment, for example, entering a narrow channel in foul weather with following seas. On my own boat I have a vacuum gauge installed in the cockpit, alongside all the other important gauges. I even have a Racor vacuum switch installed in the line, with a piezoelectric buzzer and a red LED above the vacuum switch, just in case I'm totally out of it (or asleep with a novice crew at the helm). The vacuum switch and gauge indicate when things are clean and happy, when things might be getting "iffy" and when things are about to go terribly badly. I hate surprises with the fuel, especially when making a final approach in less than ideal conditions. P.S., the amber LED above the vacuum gauge is for the Racor water sensor, just in case the filter has failed to remove all of the possible water in the fuel. I also have a parallel fuel filter so, if the buzzer and light(s) go on, I can instantly switch to a clean fuel filter and take care of the problem later. Oh, and by the way, some of those incidents with fouled fuel filters looked like liquid mud when the filter was extracted. It's a real eye-opener (or mud in your eye).

[S/V Alchemy]

Originally Posted by Wotname

First a short background.

I have never had a gauge on my fuel filter and never felt the need for one.
I note that many on CF do have them and some sing praises to these gauges.
I get that on big engines (say > 60 or 80 hp), they could be quite useful.

But what is everyone's take on such gauges on small engines (say < 40 hp)?

Do they really foreshadow looming filter problems or just tell you that right now, the filter is clogged - you know, just after the engine is coughing or has died from file starvation!

And if they are so good, what is better. A differential gauge across the filter or an absolute gauge on the output side of the filter? I can see theoretical reasons for both methods but I have no experience with such matters.

The poll is multiple answer so feel free to tick as many as you feel best describes your viewpoint.

I have a Filter Boss of the old type, because there was a sale at the boat show, the Canadian dollar was above $1 and at the time, I did not have the confidence to do the clean pipe bending and flare fitting needed to make a nice one. I installed it this summer, and perhaps you will enjoy reading how the gauge pointed me to problems and also indicated when said problems were remedied. Now, this is a dual, switchable underway fuel filter setup. A single filter might just be a complication, but clearly I thought that with two tanks (three with a post-filter day tank that will be "known clean") and a bunch of labelled valves, I am going for the belt and suspenders approach. Hope this helps. By the way, I have several flawless hours on the engine now, so I think all is well.

The world encompassed: These fuelish things, revisited

[S/V Alchemy]

By the way, all these comments are excellent and "real world"!

[jhulmer]

I had a 2GM20 on a Hunter with a Racor filter. I changed the filter in a routine maintenance and didn't notice that I had grabbed a 2 micron filter from our spares. We always used 10 micron filters but the filter came with the 2 micron, so I saved it for "just in case".

We live in Mississippi and a run up the river to escape Hurricanes is routine. On one particular run the route to the back bay was rough and I assume the fuel tank had enough particles in it to clog the 2 micron filter, which it did, and we couldn't get full power. we managed with what we had under the circumstances. Unfortunately, we damaged the injector pump in the process. Cost us about $800.00 to have it repaired.

I researched the possible solutions and realized that a $65 gauge would have help prevent this problem. So I have been a huge fan of the gauges ever since. It's a great piece of mind to glance at the gauge during engine checks and know that want happen again.

[Roy M]

jhulmer just reminded me that I didn't include my full description to my filter bank. My engine (Yanmar 3GM30F) has a 2 micron filter located adjacent to the high pressure pump. Unfortunately, it is located in a spot that is almost impossible for me to get to for servicing (to avoid the issue that happened to him). So, downstream from the parallel 30 micron filters, I installed another Racor with a larger 2 micron filter. Now I am protected completely. The vacuum gauge and switch measure the total system prior to entry into the fuel pump. The parallel 30 micron filters both have the water separator alarms wired into their clear yellow bases, which allows me to visually inspect the status of possible water in the operational filter, and to drain it if necessary.

[mikequig]

I installed a vacuum gauge downstream of a Racor 500 which feeds my Yanmar 3YM30. Honestly, I can hardly tell any difference on the gauge readings because the vacuum is usually so low (3-5psi). If I restrict the line however, I can see a noticeable spike in the gauge reading, so I guess the guage might be useful at some point should the filter suck in some crud.

[boeing1]

agree, filter gauge good indication on filter/fuel condition

[alctel]

So thinking of doing this
Fuel Filter Gauge | Cruising World

Where would I stick it? In between the engine and racar filter?

[Cheechako]

I think it depends. I have had them and not had them. Frankly I never looked at it. It depends on how well you know your whole fuel system. If you have a clean tank, know how it is all constructed, clean fuel and maintain the system, you don't need one. If yo have an old boat, old tank, messy fuel etc, you can have one and it will help tell you why your engine wont run... but it wont make your engine run!

[ontherocks83]

If nothing else it is a great diag tool especially if it has a tell tale or shadow needle, what ever you want to call it. If your engine dies, then looking at the gauge will tell you instantly if it is a problem in between the tank and the gauge or not.

I'd rather know I have or don't have a fuel restriction problem with one glance then have to diagnose it. If the gauge reads perfect then you know to look else where and not waste your time.