Twelve days ago I replaced the old Perko fuel filter with a new Racor 230. The Racor is much larger than the old Perko. Prior to this I never had a problem with the engine quitting in the six years I owned the boat. The engine is a Yanmar 3GMF. The old Perko was lower than the tank and in direct line with the fuel pump on the engine (tank - Perko - fuel pump - secondary). The Racor is too large to fit in the same place. So for ease of maintainance I placed the Racor "higher" than both the fuel tank and the engine and therefore needed to "double" the length of the fuel line. Since then I can't keep the air out of the top of the Racor. The pump on the Racor is not strong enough to pull the fuel to the top when I bleed it so I must remove the bleed screw and fill the Racor to the top and then bleed it. Once the engine is turned off it seems the fuel drains out of the Racor back down the fuel lines to the level that's in the tank. Is the Racor too high? Would a small 12 volt pump on the engine side of the Racor be of any benefit? I'm thinking the small fuel pump that's on the engine is not strong enough to pull the fuel all the extra distance (I doubled the fuel line legnth at least) and up as high as the filter is located. Should the pressure or prime remain after I shut off the engine or is it gravity that's allowing the fuel to drain back down the lines (remember the Racor is higher than both the tank and the engine). Looking for advice. Thanks in advance. Joe Mullee
I need help with the Racor
- Thread starter Joe Mullee
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Filter Problems
The fuel never drains out of the lines when the engine is off unless there is a leak somewhere that is letting air in. If there is a leak, you should be shooting fuel out when the pump is running. Most boats are set up with a electric pump at the tank and a manual pump on the engine. It sounds like the air is coming back thru the manual pump when the engine is off. I would find another location for the filter that is lower.
The fuel never drains out of the lines when the engine is off unless there is a leak somewhere that is letting air in. If there is a leak, you should be shooting fuel out when the pump is running. Most boats are set up with a electric pump at the tank and a manual pump on the engine. It sounds like the air is coming back thru the manual pump when the engine is off. I would find another location for the filter that is lower.
You no doubt have a small leak in the line
that allows the fuel to drain out of the lines and be replaced with air. Because the line from the tank to the fuel pump is on the suction side of the pump you won't see a fuel leak but because you keep getting a bubble in the filter you have a small leak.
that allows the fuel to drain out of the lines and be replaced with air. Because the line from the tank to the fuel pump is on the suction side of the pump you won't see a fuel leak but because you keep getting a bubble in the filter you have a small leak.
I think you answered it yourself...
yes, your new racor is too high...so you have to mount it lower. Don't screw up the proven design with extra pumps...however, you might consider a outboard squeeze bulb between the fuel pump and the secondary filter this really helps the bleeding process. Good luck.
yes, your new racor is too high...so you have to mount it lower. Don't screw up the proven design with extra pumps...however, you might consider a outboard squeeze bulb between the fuel pump and the secondary filter this really helps the bleeding process. Good luck.
Joe:
I've been thinking about this problem since I left your boat on Friday. I do think the problem has something to do with the new Raycor you installed recently. I believe that perhaps one of the fittings is not sealed completely and may be letting a little air into the system. I re-read Calder's book "Marine Diesel Engines," and on pg 59 (bottom right)he discusses the problem as follows: "If any of the fuel lines have a high spot, however, a bubble of air may remain at this point and be extremely hard to dislodge." That seems to describe the problem. Calder also discusses how to deal with "Persistent Air in the Fuel Supply" on pg 63. He suggests a couple of tests to perform to find leaks between the tank and the lift pump. I can loan you this book if you don't have it. But I do think the culprit here is the Raycor as we could not bring fuel up and out the bleed screw no matter how many times we pumped the Raycor pump. We could bring it out the large screw next to the bleed screw and that suggests to me that there is a leak somewhere preventing suction. Finally, let me know if you need the phone number of a mobile diesel mechanic who I used some years ago. He was cheaper than the guy who showed up late Friday. Good luck with all this.
I've been thinking about this problem since I left your boat on Friday. I do think the problem has something to do with the new Raycor you installed recently. I believe that perhaps one of the fittings is not sealed completely and may be letting a little air into the system. I re-read Calder's book "Marine Diesel Engines," and on pg 59 (bottom right)he discusses the problem as follows: "If any of the fuel lines have a high spot, however, a bubble of air may remain at this point and be extremely hard to dislodge." That seems to describe the problem. Calder also discusses how to deal with "Persistent Air in the Fuel Supply" on pg 63. He suggests a couple of tests to perform to find leaks between the tank and the lift pump. I can loan you this book if you don't have it. But I do think the culprit here is the Raycor as we could not bring fuel up and out the bleed screw no matter how many times we pumped the Raycor pump. We could bring it out the large screw next to the bleed screw and that suggests to me that there is a leak somewhere preventing suction. Finally, let me know if you need the phone number of a mobile diesel mechanic who I used some years ago. He was cheaper than the guy who showed up late Friday. Good luck with all this.
The height should have had nothing to do with it, BUT
Joe, Given the fact that you have an electric fuel pump, the "sealed" system should maintain itself, based on the basic rules of physics. There's a leak somewhere, and if it's not in the lines or clamps, then try what a friend discovered a few months ago: after all sorts of air problems, he found a poor gasket seal between the filter and the housing, and also a ding in the side of the filter (from the factory that he hadn't noticed). He put a new filter in, and the problem was solved. Also check the tightness of the vent on the top of the Racor housing. I swapped filters a while a go, and didn't close the vent properly. My fault, but it happens. With the (I assume) electric fuel pump, there should be absolutely NO need whatsoever to ever have to use the dumb hand pump on the top of the Racor housing (been there, done that, have the fingers to prove it). Think of it this way: plenty of boats have fuel tanks way below their engines and filters. All boats do NOT have gravity feeds where the tank is above the engine. If higher fuel filters were a problem, NO ONE would have a fuel tank below the filters, and that's just not the case. Let us know how it turns out. I hope Warren's references are not required. The "high point" idea has merit, but once that bubble is cleared, there shouldn't be any more problems, unless there IS actually a small leak. Stu PS, just reread your post, Joe, and it seems I misunderstood your "pump," since you said: "Would a small 12 volt pump on the engine side of the Racor be of any benefit? I'm thinking the small fuel pump that's on the engine is not strong enough to pull the fuel all the extra distance (I doubled the fuel line length at least) and up as high as the filter is located." It appears the pump you mentioned is NOT an electric fuel pump, and that you had a gravity feed with just the engine fuel pump doing all the work. Here's a source for an electric fuel pump, just wire it into your ignition switch: http://c34.org/bbs/index.php?topic=2515.0 The route should be: tank, Racor, electric fuel pump, engine driven fuel pump, secondary engine mounted fuel filter The engine driven fuel pump just isn't hacking the pressure drop in the length of fuel hose, and didn't seem to be designed to do that. That's why we have electric fuel pumps. On our C34s, the tanks are above the engine. From full to about half empty the fuel level is higher, and even without the electric pumps, fuel will siphon to the engine. It's only when the tanks get less than half full does the pump do its job, even though it works all the time. Unused fuel just gets bypassed by the injectors anyway. I recommend an electric fuel pump for you, rather than redoing your last project. It's a simple job to just tack it in-line.
Joe, Given the fact that you have an electric fuel pump, the "sealed" system should maintain itself, based on the basic rules of physics. There's a leak somewhere, and if it's not in the lines or clamps, then try what a friend discovered a few months ago: after all sorts of air problems, he found a poor gasket seal between the filter and the housing, and also a ding in the side of the filter (from the factory that he hadn't noticed). He put a new filter in, and the problem was solved. Also check the tightness of the vent on the top of the Racor housing. I swapped filters a while a go, and didn't close the vent properly. My fault, but it happens. With the (I assume) electric fuel pump, there should be absolutely NO need whatsoever to ever have to use the dumb hand pump on the top of the Racor housing (been there, done that, have the fingers to prove it). Think of it this way: plenty of boats have fuel tanks way below their engines and filters. All boats do NOT have gravity feeds where the tank is above the engine. If higher fuel filters were a problem, NO ONE would have a fuel tank below the filters, and that's just not the case. Let us know how it turns out. I hope Warren's references are not required. The "high point" idea has merit, but once that bubble is cleared, there shouldn't be any more problems, unless there IS actually a small leak. Stu PS, just reread your post, Joe, and it seems I misunderstood your "pump," since you said: "Would a small 12 volt pump on the engine side of the Racor be of any benefit? I'm thinking the small fuel pump that's on the engine is not strong enough to pull the fuel all the extra distance (I doubled the fuel line length at least) and up as high as the filter is located." It appears the pump you mentioned is NOT an electric fuel pump, and that you had a gravity feed with just the engine fuel pump doing all the work. Here's a source for an electric fuel pump, just wire it into your ignition switch: http://c34.org/bbs/index.php?topic=2515.0 The route should be: tank, Racor, electric fuel pump, engine driven fuel pump, secondary engine mounted fuel filter The engine driven fuel pump just isn't hacking the pressure drop in the length of fuel hose, and didn't seem to be designed to do that. That's why we have electric fuel pumps. On our C34s, the tanks are above the engine. From full to about half empty the fuel level is higher, and even without the electric pumps, fuel will siphon to the engine. It's only when the tanks get less than half full does the pump do its job, even though it works all the time. Unused fuel just gets bypassed by the injectors anyway. I recommend an electric fuel pump for you, rather than redoing your last project. It's a simple job to just tack it in-line.
Racor
I had a very similar problem. I'm using a Racor and it is higher than the tank. After changing filters I developed and air leak. It turned out to be the F500 Racors drain petcock. I had opened the drain to clean the bowl out and it never closed properly after that. I popped in a new Racor F500G and it fixed the problem. I am getting a new bowl petcock for the first filter and I will run both filters so one can be changed while the other is in operation. Regards, Big Joe
I had a very similar problem. I'm using a Racor and it is higher than the tank. After changing filters I developed and air leak. It turned out to be the F500 Racors drain petcock. I had opened the drain to clean the bowl out and it never closed properly after that. I popped in a new Racor F500G and it fixed the problem. I am getting a new bowl petcock for the first filter and I will run both filters so one can be changed while the other is in operation. Regards, Big Joe
If the old Perko worked why did you replace it?
Here is an example which validates the old adage, "If it ain't broken, don't fix it" Constant upgrades is not a law of physics. You have an air leak in your system or did not bleed it properly.
Here is an example which validates the old adage, "If it ain't broken, don't fix it" Constant upgrades is not a law of physics. You have an air leak in your system or did not bleed it properly.
Benny, Benny, Benny
You must have too much time on your hands to be so opinionated. As I'm sure most know-it-alls like you know Perko no longer makes the old filters that Hunter used on the early 80's boats. In fact the elements that are used in those filters will also be phased out according to the Perko rep I called at their home office. Since I plan on longer sailing trips in more challenging waters this summer I decided it was time for a better filter, not just a water seperator whose element will be difficult to obtain. So as you can see my decision wasn't based on your limited knowledge of the situation. Thanks anyway for your encouraging words of advice. Peace! Joe Mullee
You must have too much time on your hands to be so opinionated. As I'm sure most know-it-alls like you know Perko no longer makes the old filters that Hunter used on the early 80's boats. In fact the elements that are used in those filters will also be phased out according to the Perko rep I called at their home office. Since I plan on longer sailing trips in more challenging waters this summer I decided it was time for a better filter, not just a water seperator whose element will be difficult to obtain. So as you can see my decision wasn't based on your limited knowledge of the situation. Thanks anyway for your encouraging words of advice. Peace! Joe Mullee
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