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Warning: E34/E32-200 Fuel hose routing

CaptnNero

Accelerant
On our '88 E34 I just discovered that both the fuel vent hose and the filler hose are routed loosely way downwards under the cockpit sole after they exit the tank top. I think this is not good. This means that the low loop in both hoses is full of fuel. To fill the tank, the low loop in the vent hose has to burp air before more fuel can be added.

From a quick look it appears that there is room to re-route the hoses upward towards their deck fittings as they should be. Perhaps the fuel system designer wanted the proper routing but the builder didn't do it correctly.

I've had this boat for two winters. To fill it I add fuel slowly with a small siphon hose from a 5 gallon portable tank until the fuel backs up the filler hose and then I assume that the tank is full. After filling I have looked at the manual gauge on the tank but it showed half full. I thought it was broken. Anyway, each fall I top-off the tank before haul-out for the winter. This spring we've only done about 6 hours since de-winterizing with a "full" tank, but after removing the manual gauge and examining the tank I saw that it really is only half full !

One clue was that when I removed the first fuel gauge screw (with the engine off), there was a hissing sound which I determined to be from releasing a vacuum from the lift pump previously sucking from the tank. If I had just "filled" the tank, this would have been releasing pressure from the weight of some fuel in the filler hose. With the engine running, the fuel lift pump must be strong enough to lift the fuel in the vent hose and let more air in when the tank vacuum gets too high.

I removed the fuel vent hose from the tank end and could hear fuel sloshing around in the vent hose. Then I pressurized the tank end of the vent hose and there was significant backpressure from the fuel in it. When I released the pressure, fuel came out the tank end of the hose.

I noticed similar tank pressurization behavior in my last boat, an '88 E32-200 but didn't look into it or consider the consequences.

I think my next task is to re-route the vent and filler hoses continuously upwards to eliminate the problem. I also will put one of those Attwood fuel vent hose check valves in the vent hose.

Is my analysis here correct ? Any fuel system professionals out there ?

-- neal
 

Shadowfax

Member III
Check The Vent

I also have a '88 E34 and do not have the problem you described. When I fill my tank the vent overflows before the fill overflows. I suspect the fuel vent line is clogged. Spiders especially seem to like to crawl into the vents and I have a clogged waste vent story that is beyond gross.

The fuel gage should not be affected by a pressurized fuel tank as it floats to the level of fuel. If it is showing a full tank and upon inspection you have a half tank, I would begin to suspect the gage itself.

Moving those lines around has to be a major project.

Good Luck
 

Geoff Johnson

Fellow Ericson Owner
When I changed my fuel cap (having dropped the OEM screw top overboard), I had to crawl into the lazarette hatch and lying on my back, wrestle the fuel hose off the barbs . . one of the most difficult things I have had to do on the boat.

Now I fill the tank only from 2.5 gallon jerry cans connected to the fuel inlet with a short piece of hose. Like filling a water bottle, a sudden increase in pitch tells me the fuel has started to climb the fuel hose. Even on my sometimes rocky mooring I can avoid spilling diesel all over. As for fuel consumption, I normally go by engine hours; I assume 1/2 gallon per hour for my M25 (which is a little high, I think).
 
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CaptnNero

Accelerant
Actually it's showing half full when it's half full. The confusion was that when I used a small siphon and a 5 gallon tank to fill it, the fuel backs up the fill hose faster than the fuel in the vent hose can be displaced by the increasing air pressure.

I tested the vent hose and it is not clogged; it just has fuel filling the lower dip in the hose which prevents air from flowing freely. If I siphon the fuel out of the vent hose, it will work fine until it gets choppy and the fuel spills down into it again.

On the project aspect, I need to empty the starboard cockpit locker and remove the inboard wall panel. Then I can see if I can lift the hoses and attach them to something.

Thanks, I think I'll need the luck you mentioned !

-- neal

Shadowfax said:
I also have a '88 E34 and do not have the problem you described. When I fill my tank the vent overflows before the fill overflows. I suspect the fuel vent line is clogged. Spiders especially seem to like to crawl into the vents and I have a clogged waste vent story that is beyond gross.

The fuel gage should not be affected by a pressurized fuel tank as it floats to the level of fuel. If it is showing a full tank and upon inspection you have a half tank, I would begin to suspect the gage itself.

Moving those lines around has to be a major project.

Good Luck
 

CaptnNero

Accelerant
M25XP fuel consumption

I did some careful measurements on the M25XP for a season on our E32-200 before we got the E34. It came to about 0.45 gal/hour at 2400 rpm. Then I knew to add 5 gallons every 11 engine hours. We do about 60 hours per season.

On the 32-200 I once started to replace the fuel filler deck fitting but couldn't get the hose to budge off of the barbs. At the time I didn't feel like cutting the hose and having to replace it too. Those 1 1/2" wire reinforced hoses are tough. When I replaced all of the head plumbing it was quite a chore. When I was done there were quite a few sawed through black hose pieces.

-- neal

Geoff Johnson said:
When I changed my fuel cap (having dropped the OEM screw top overboard), I had to crawl into the lazarette hatch and lying on my back, wrestle the fuel hose off the barbs . . one of the most difficult things I have had to do on the boat.

Now I fill the tank only from 2.5 gallon jerry cans connected to the fuel inlet with a short piece of hose. Like filling a water bottle, a sudden increase in pitch tells me the fuel has started to climb the fuel hose. Even on my sometimes rocky mooring I can avoid spilling diesel all over. As for fuel consumption, I normally go by engine hours; I assume 1/2 gallon per hour for my M25 (which is a little high, I think).
 

Tom Metzger

Sustaining Partner
Not a great idea

I think my next task is to re-route the vent and filler hoses continuously upwards to eliminate the problem.

There are a lot of E-34's out there that fill their diesel tanks without a problem, so I doubt there is a serious design problem with venting. I am inclined to go with the spider theory, but a kink is also possible. If you have checked the vent hose to be clear the tank will vent regardless of trapped fuel.

Having changed the diesel fill hose I can say with authority that rerouting hoses is not an easy job. They run behind the plywood bulkhead of the sail locker and are well secured with clamps. This bulkhead can't be removed without removing the holding tank. Since there are hose clamps behind the holding tank it is obvious that the hoses went in early in the construction process. I am inclined to think the boat may have been built around the hoses. :devil:

To replace the fill hose I cut an access hole in the plywood bulkhead using a Roto-Zip bit in my Dremel tool so I could control the depth of the cut. This is important as there are other hoses back there. I removed the hose clamps I could reach and used brute force to remove the one I couldn't reach. I wouldn't recommend this for the vent hose as it is not as solid as the fill hose.

An easier way to empty the vent line of fuel would be to sail on a starboard tack. Not only will this empty the line, it will give you the right of way. :)

If you want to talk about design problems, lets talk about the fill hose that makes a too small radius "U" turn. Mine split on the bend. :boohoo:
 

CaptnNero

Accelerant
There are a lot of E-34's out there that fill their diesel tanks without a problem, so I doubt there is a serious design problem with venting. I am inclined to go with the spider theory, but a kink is also possible. If you have checked the vent hose to be clear the tank will vent regardless of trapped fuel.

This spring I siphoned the fuel from the vent hose and only then did it work properly, until filled with fuel again while under way. Spiders were not the problem. Since both the vent and the filler hose are routed downwards from the tank, the tank becomes airlocked and will not fill properly. I've seen an overflow condition on both my 32-200 and the 34 ! When I checked the level by removing the fuel sender the fuel was inches below the top recessed point where all of the hoses attach to the tank. Also I don't like the idea of leaving the fuel sitting in those hoses long term.

Having changed the diesel fill hose I can say with authority that rerouting hoses is not an easy job. They run behind the plywood bulkhead of the sail locker and are well secured with clamps. This bulkhead can't be removed without removing the holding tank. Since there are hose clamps behind the holding tank it is obvious that the hoses went in early in the construction process. I am inclined to think the boat may have been built around the hoses. :devil: ...

Tom, thanks for the gory details. When I was working on the tank last spring it did not look like it was going to be easy. I'll be relocating the CNG tank and replacing the head hoses so removing the holding tank will be a no brainer at that point. I expect to be doing all this when I replace the fuel tank this winter.

If you want to talk about design problems, lets talk about the fill hose that makes a too small radius "U" turn. Mine split on the bend. :boohoo:

Oh boy, I guess that's another thing to correct this winter. ;)
 

Captron

Member III
Fueling issues

I have an 83' model E38 ... constant problem fueling from marina fuel pumps ... both hoses sag enough on their way up to the fittings that it makes it hard to fill the tank. Part of the problem is the routing of the hoses. Part of it is design ... the hoses exit the tank such that proper routing would run them through the aft end of the quarter berth. I should be able to correct this when I replace the lines next time ... The PO or the folks he hired didn't do it right... lines sag too much. So with most marinas we have to be very careful and pump very slowly to avoid spills. Generally though, if we go slow enough, the vent burps before the main fill line. Of course, we're running near on 20 minutes to get our 40 gallons or so... that tends to piss off the power boats waiting on us. Not to mention that if we go too fast, the main fill tube burps about a quart before it stops. There's no such thing as too many paper towels in that case.

Also the fill tube exits through the side of the coaming, maybe 2 inches higher than the transom vent ... I suppose this is to keep spills outside the boat ... if the fill was in the top of the coaming it would gain another two inches on the vent and it would be easier to access ... otoh ... spills might dribble into the cockpit.

The main issue is that marina fuel pumps are designed to load 70 foot plus power yachts that carry upwards of 10,000lbs of fuel ... the hoses are 1.5 or 2 inch and they can probably top off a 747 in 15 minutes.

Also my vent line is only 5/8 inch or so ... probably should be larger given the fill is 1.25 inch.

It never ends ...:0305_frow
 

CaptnNero

Accelerant
I have an 83' model E38 ... constant problem fueling from marina fuel pumps ... both hoses sag enough on their way up to the fittings that it makes it hard to fill the tank. Part of the problem is the routing of the hoses. Part of it is design ... the hoses exit the tank such that proper routing would run them through the aft end of the quarter berth...

Captron, thanks for checking in on this. I gave up using fuel pumps to fill when we had the 32-200. Since then I've been filling from jerry cans using one of those "magic" siphons with the slug in the hose for priming. The thing fills slow enough that I don't end up with a spill with the burping of the vent and fill hoses.
 
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