Fuel pump sight glass

[pschauss]

A mechanic told me that the sight glasses on my mechanical fuel pumps (Mercruiser 454 engines) are now illegal and should be replaced my a vent tube running to the carburetor. A google search turned up an ABYC document from 2011 which lists a requirement for either a vent tube or a sight glass. ( https://www.uscgboating.org/assets/1/As ... 002.01.pdf) Has there been a change since then?

A Federal regulation document that I found from 2019 states only that the pump must not leak if the primary diaphragm fails. (https://www.govinfo.gov/content/pkg/CFR ... num183.524),

[scenarioL113]

Can you post a pic of what you have?

I read it same as you and it looks like your sight-glass is what they are recommending as the fail-safe component. It should only have fuel in the sight-glass if the fuel pump fails.

I have not had gas-inboards in many years and dont remember what my old Mercruisers had to be honest

[Bruce]

They were actually filter housings in the past with glass to see debris. Filters became hard to get and with the advent of better filter seperators like racor, people never replaced once removed.
It's against the law for boat manufacturers of new boats, but not boat owners of older boats to have. But it's not wise to have glass below decks or in enclosed engine boxes with gasoline in them.

If it's a bottom filter, buy a metal housing replacement. If it's a side fitler just unscrew and discard.

[Tony Meola]

Bruce

If I remember correctly, when we had the big blocks, there was a device that had a glass bowl. It was not part of the filter set up. It was located right by the fuel pump, and if I remember correctly it had a tag on it that said if fuel is in the glass bowl, to check the fuel pump. I believe it was supposed to let you know the diaphragm in the fuel pump went bad.

Don't know if it worked, because every time we had to replace a fuel pump, I never saw any fuel in the bowl.

[pschauss]

That’s the one I’m talking about.

[scenarioL113]

I am not sure if it is "illegal" in a vessel of this vintage. It "may" be but I am not sure. I think your mechanic is pointing out something that should prob be upgraded to a safer device.

I just upgraded my raw water intake thruhulls to modern "seacocks", I did not "have" to do it but I wanted to make my boat safer. (hopefully I did a good job...we will find out next week).

[Bruce]

There was instead of a tube to carb on early engines glass bowl for just that reason Tony.
Surprised that you still have that feature after all these years Peter. Most of those pumps have been replaced long ago.

[Tony Meola]

Bruce

Thanks. You know I don't remember if changing out the fuel pump eliminated those bowls. Must be getting old.

[Rawleigh]

Newer fuel pumps just have the tube to the carb, right?

[pschauss]

Mine came with a plug screwed into the hole where the sight glass was supposed to connect. I took out the plug and installed the sight glass from the old pump. Since the manuals that I have show the sight glass and explain its purpose I assumed that was what I was supposed to do.

[Tony Meola]

Peter

From Bruce's post you would have the option to do that but it is not needed and probably not a good idea just incase it does trap fuel.

[Bruce]

You can leave them if you wish, but if you have insurance coverage you might want to check with them or read your policy as it relates to gasoline inboat boats and if they have any specific things on fuel systems.

I know my business liability policy coverage excluded me from using glass or clear bowls on any gasoline filters, pumps, tanks or what have you below decks or in enclosed engine boxes when I did work. I could use clear bowls on an outboard boat in a transom well, but I could not put that same filter say under a back seat next to the well.

Many older boats because of how things were done before lawyers and insurance companies got involved in losses, I had to be carefull just what to upgrade to modern standards or could leave alone.
Boat owners aren't under many of the same requirements as service centers or manufacturers are.