Anyone ever heard of a porous fuel line. Service guy says this is keeping my genset from running..

quote:

Originally posted by Dave Bowers:
Anyone ever heard of a porous fuel line. Service guy says this is keeping my genset from running..

Short answer: Yeah, sort of.

Long answer:

Any rubber fuel line on the suction line of a fuel pump can be a problem if it deteriorates. My own experience has been that tiny cracks form from age and brittleness. These cracks can allow the pump to suck air instead of gas. The normal failure mode is to suck a mixture of air and gas for a while before it progresses and sucks mostly air. Porosity would be another way of describing this, rather than small cracks.

These things can be difficult to trouble shoot when the hoses are hard to access. A fuel pressure gauge is not always revealing, as it will read air pressure in the line produced by the pump. My own trouble shooting is to first lay my fingers on the pump or listen through a tube or stethoscope. Pumps vary, but a typical electric fuel pump will have a different feel and sound when it is trying to pump air than when it is pumping pure gasoline.

For a more positive test, you can also run a hose from the suction side of the pump to a fuel can. If the genset runs OK that way, but not connected to the RV, the problem is on the suction side of the genset fuel line.

It could be something so simple as a clamp that needs tightening. Other trouble shooting has involved putting a clear vinyl tube in the fuel line. Run the pump and look for bubbles in the clear section. The bubbles that are the result of breaking the line for installation should go away after you purge the line into a bucket or let the genset run for a while. I do not recommend clear vinyl fuel line for permanent installation, however, as it deteriorates quickly and could become a fire hazard. I use a clear fuel filter for observation purposes.

Having said all that, any old RV should have new fuel line. The introduction of alcohol into our gasoline has accelerated the deterioration of fuel lines. My own preference is to use Weatherhead H077 Fuel Injection hose with a burst strength of 900 psi. Pretty tough stuff. Or Goodyear fuel injection line from Kragen. It has a Hypalon®. cover which resists environmental and heat-induced aging effects, and a Fluorel® liner which resists alcohol and old/bad gasoline.


The line is marked SAE 30R9. A lower spec line is OK, but the FI line is able to stand higher pressures, and has the liner that resists deteriorated old gas, so should last longer.

Always, ALWAYS be sure you are getting SAE-rated fuel line. I have had all sorts of counter clerks cut me off the wrong hose. Even the BMW dealer put transmission hose inside the tank on my bike.

The proper size FI clamps form a truer circle so are less likely to leak later than worm drive clamps. Even with FI clamps, I tighten them down tightly on a socket of a little smaller diameter than the hose first to be sure of a perfect circle. My V12 Jag has a bad combination of too many injector clamps and way too much underhood heat. and has forced me to learn a lot.

I also prefer the squeezy-springy clamps made from flat spring stock rather than worm drive clamps on non-FI fuel lines for reasons of constant tension and perfect circles. These clamps are typically supplied with new in line fuel filters. I don't think they have enough tension to do the job on the stiff Weatherhead FI lines, but they do fine on the Goodyear FI line. Corbin clamps provide constant tension on the Weatherhead FI line, and that combination is what I am presently using between the steel chassis fuel line and the engine. I am not aware of the constant-tension worm drive clamps in a small enough size for fuel lines, but would use them if I could.

I have seen both the neoprene hose crack and the steel "dip tube" that drops into the fuel tank develope leaks. It is easier for air to flow through the hole instead of fuel and you end up with a fuel starved genset. To quickly check the fuel line between generator and the fuel tank, remove both ends, plug one end with a fitting and apply about 10 psi of air pressure to the other end. Using a solution of dishwashing liquid and water, spray the entire run of the line and look for bubbles. If you don't see any leaks, while the line is still capped, apply about 15 inches of vacuum to the line with a mighty vac or similar hand vacuum pump. If it holds vacuum for a 3 minutes then you can eliminate that section as suspect. Concentrate on the generator fuel pump and the fuel tank dip tube. The genset fuel pump should draw a solid vacuum too. Unfortunately you must drop the fuel tank to service the dip tube. A task best left to someone with equipment and knowledge to handle the tank.

quote:

Originally posted by billyt53:
Unfortunately you must drop the fuel tank to service the dip tube. A task best left to someone with equipment and knowledge to handle the tank.

Having just done that on my pickup, I believe I might just cut a hole in the floor above the tank connections. If I were younger or smaller, I might even consider reaching up in there to do the work. All Barths are a little different, but mine seems to have a fair amount of room for a small flexible person.

So, Dave............what's happening on your fuel line?

BTW, I edited my first post to add a little more information that could be helpful.