Vacuum Gauge

[Doug]

Beginning of winter here in the Pacific NorthWest, Canadian version. We winter our boat in Squamish at the head of Howe Sound, so last weekend I left Pender Harbour saturday morning and motored into a light southeaster down the coast to Gibsons. About halfway there the engine started to lose revs, only 50 - 100RPM, but enough to be heard and worried about. The revs would go back up and the engine would run fine for another ten minutes or so, then the same ominous drop in revs, sometimes as much as 4 or 5 hundred RPM. I suspected the primary filter and went below to find the spare, but of course the spare was what I had used last time and I'd forgotten to replace it. I called my wife, who managed to buy a couple of filters and drove down to Gibsons to meet me. I fueled up and replaced the filter but didn't want to leave for Squamish at the hour of 5:30 PM in case the problem hadn't been the filter after all, and I got stuck somewhere up Howe Sound in the night with no engine, no wind, and no moon. So we spent the night in Gibsons marina and I left the next morning. It must have been the filter, since the engine ran perfectly for the next 5 hours. I've decided I would like a vacuum gauge to indicate when the filter needs to be replaced, and here's my question to everyone: since my model of Racor doesn't have a spot to install a gauge, can I simply cut the fuel line between the Racor and the engine, install a tee, and put a vacuum gauge on the tee? I don't see why not, but could use some reassurance before actually doing it.

[Randy]

Yes you can do that. I added one a few years back on our boat to monitor the filters. Just make sure it is on the outlet side of the filter and in the line. Here is also a good link that I have had in my book marks, I hope it helps you.
Randy

http://www.maesco.com/products/racor/r_access_fit/r_vac_gauge/r_vac...

[Doug]

Thanks for the info. As soon as I get home from sunny florida I'll put one in. Hope that won't be too soon though :)

[keylimejay]

I think removing the fiiting that the hose to the engine attaches to and put a brass tee there, attaching the vac gauge directly onto the Tee and the outlet fitting to the other port. A word of caution. Years ago I encountered a similair problem before I also installed guages. A mechanic told we that the fuel is the sole source of lubrication the injector pump receives. Don't starve it or it will get very expensive!

[h]

Doug,

If you post it in Zen and the art of sailboat maintenance group, the information can be used as a reference for others in the future. It will not be lost in the many topics in the Forum.

h

[Lou illiano]

I think you mean a fuel pressure guage. Vacuum guages are usually used to measure intake manifold pressure, positive or negative. I will give a VERY qualified yes to the possibility of installing a Fuel Pressure Guage after the filter, not knowing the type of engine, fuel pump,etc. You must realize that you will be bringing pressurized fuel, at about 7psi for a carb, and much higher for fuel injection, to the guage. Any leak from a loose clamp, chafed or cracked hose etc will spray high pressure fuel and be very dangerous. Atomized diesel will be flammable under theses conditions. My two cents is set up a schedule for filter changes, every three or six months, or what ever. Low fuel pressure could have several causes, a bad pump, kinked line, clogged pickup,sloshing fuel. The diagnostic value would not justify the safety risk, in my opinion.
Lou

[Randy]

Here is a Quote from the Racor web site,

Vacuum and Compound (vacuum/pressure) gauges and related hardware is available to monitor element condition. As the filter element slowly becomes clogged with contaminants the restriction (resistance to flow) increases. The fuel pump still tries to draw fuel (suction) but because of this restriction less fuel is delivered to the engine and instead more air is pulled from it (fuel de-gassing). These results can cause the engine to lose power and eventually stall.

I have had my Vaccuum gage installed for over 5 years as per their instructions and have great results in it,

Randy

[h]

Randy,

Can you tell by the vacuum gauge when it is nearly time to replace your filter? What was your vacuum reading close to filter replacement time?

h

[Randy]

Doug:
Right now I change it out when I draw 8 inches of vacuum. I have not really found site that tells you when to change it out per how much vacuum one draws. What I do is take the old filter out and cut it apart and see actually how dirty it is. That is the only way that I know, I do know you do not want to starve your injector pump as Keylimejay states.

Randy

[keylimejay]

Doug: My experience is that 8 inches is a good number. 10 inches is fuel starvation with loss of RPM's. I'm surprised at how few sailors use a gauge. Many say they change filters...x.....often. I wonder how much money is wasted changing filters that don't need changing.

[Randy]

KeylimeJay:

That is so true, I use to change out my 2 filters each spring just as a preventive measure. Now with the gauge I have saved a lot of money and can buy more rum:)

[Veranda]

Lou,

I think you have that a bit backwards. He's right when he writes about a vacuum gauge. Most diesel engines have a mechanical or electrical fuel pump mounted after the primary filter. So there is no pressure in that line. A vacuum gauge would be the correct choice as there's suction only.

As far as the installation goes....I have a Racor 500 series with the big Tee handle on top. Just replace the Tee bolt with the vacuum gauge. You need a wrench to remove it to change the filter from then on but at least you have the gauge rigidly mounted.

Bill
s/v Veranda

[stvbryant]

At the sailors solutions web sight under Engine Room, is a listing for a Vacuum Guage Kit with Drag Pointer and Adaptor for Racor® Turbine Series Diesel Fuel Filters. The nice thing about the drag link is that it shows you what the vacuum was befor the engine shut off so you don't have to go below to monitor Vacuum while you are at the tiller.

http://www.sailorssolutions.com/index.asp?page=ProductDetails&I...