CONTINUOUSWAVE

I replaced my fuel hose years ago. I do not remember the brand [of the replacement hose], but the hose was blue.

This spring (2019] the engine was cutting back once [the engine accelerated] to about 4,500-RPM.

I found the liner [of the unknown brand fuel hose installed as a replacement years ago] had bunched up on the inlet to the external fuel filter, creating a narrowing of the passage. The liner did not disintegrate, but enough had peeled away from the cut end of the hose to restrict fuel flow.

I may have exacerbated this by disconnecting the hose to facilitate waxing [the boat hull], then, in the course of reconnecting the hose, the liner peeled and bunched up as it was pushed on the barb. The liner remained in one piece.

Replace the entire hose. Modern hose does not use a liner since it was prone to degrading and clogging the engine.

Look for it to be stamped alcohol resistant marine hose and its not grey in color. Trident is a good brand.

When fixing a hose to a barbed fitting, use only one hose clamp. Position the clamp so in presses the hose onto the clean portion of the fitting behind the barbs. Putting a clamp on a hose so it bears onto the barbed portion of the fitting tends to cut into the hose itself, which can lead to problems like permeation, leaks, damage to the inner liner, and cracking.

jimh wrote:When fixing a hose to a barbed fitting, use only one hose clamp. Position the clamp so in presses the hose onto the clean portion of the fitting behind the barbs. Putting a clamp on a hose so it bears onto the barbed portion of the fitting tends to cut into the hose itself, which can lead to problems like permeation, leaks, damage to the inner liner, and cracking.

I'm not a fan of hose clamps on fuel lines due to the unequal clamping force since they tend to "flat spot" under the worm gear housing and can also pinch the fuel line. People also tend to over tighten them. For these reasons, you will never see a motor come from the factory with a hose clamp and they use spring clamps or better yet Oetiker clamps.

Here's a pic of the 3 types - Oetiker style, spring style and hose clamp (with my pencil pointing at the area of concern).



I know on hose clamps used for water lines and though hull fittings it's common practice to use 2 clamps and they are placed 180 degrees in relation to each other.

D-

BOB--I think you are categorizing "hose clamps" to mean only worm-gear hose clamps, or Jubilee Clamps, as they are called in the U.K. I see plenty of them used on fuel lines. But "hose clamp" is really a generic name for any sort of clamp used on a hose.

The Oetiker clamps are used on Evinrude engines, and probably many others. There is an informative discussion at

http://continuouswave.com/ubb/Forum3/HTML/020693.html

I see the spring-style clamps used on lots of water hoses under the hoods of automobiles. But I have never tried using one. Is there a special tool for compressing these spring clamps during installation?