1972 Merc In-line 6 Question

[BigBoatinOkie]

Hey guys. My brother asked me a question that I don't know the answer to, so i'm asking here. He's working on a 1972 IMP with a 165 mercruiser staight 6 for a friend of his. The engine runs if they pour gas in the carb, but they are not getting fuel from the tank. May be the pump or a clog somewhere, but he said that there is some little aparatus in the fuel line between the tank and the fuel pump that has wires going to it. What is it? I know it's not much of a discription and I don't have a pic at the moment, but I thought I'd go ahead and ask anyway.

 

[Bondo]

Re: 1972 Merc In-line 6 Question

Ayuh,... My Guess is,... a P/O plumbed in an electric fuelpump...

 

[Fishermark]

Re: 1972 Merc In-line 6 Question

I agree with Bond-o. I suggest removing it completely and replacing the mechanical pump if it is bad. You might also need to check the anti-siphon valve in the tank, but my money would be on a bad pump that someone tried to jury rig.

 

[BigBoatinOkie]

Re: 1972 Merc In-line 6 Question

This thing is only about 1" in diameter and 2" long. Are there fuel pumps that small? Anyway, my bro is gonna post up a picture hopefully when he gets off work this evening.

 

[BiggerBoatinOkie]

Re: 1972 Merc In-line 6 Question

Thanks, Bro, for starting this thread for me.
And thanks for the replies. Like my brother said I would be posting a pic or two of the device that he has asked about. So here you go. Thoughts?

 

[cr2k]

Re: 1972 Merc In-line 6 Question

Could be a fuel pump. I would guess so if there is not a fuel flow meter on the dash. I don't like the screw in the side of it to ground it. Looks like it could damage some internals or leak.

The copper fuel line and single flare brass fittings look dangerous too. That stuff can crack from vibrations.

If you are gonna replumb your fuel system and NOT use steel lines and double flares then at least use marine inboard fuel hose. B1

 

[Joshua Nichols]

Re: 1972 Merc In-line 6 Question

That is weird looking thing... Kinda strange they left the mechanical pump on it when they put the electric on... Is there voltage to it?. It does kinda look like a little electric fuel pump...

 

[Bondo]

Re: 1972 Merc In-line 6 Question

It does kinda look like a little electric fuel pump...

Ayuh,.... Because it Is...

 

[Adirondack]

Re: 1972 Merc In-line 6 Question

Isn't that just the cutest little thing. All it needs is your trash can. Looks like someones low budget fix to a bad fuel pump. A nice new mechanical marine pump, and some nice plumbing work and your running problem will probably be solved.

 

[Adirondack]

Re: 1972 Merc In-line 6 Question

As an afterthought I have to wonder when it became good practice to use a fuel line as a ground for electrical components.

 

[BigBoatinOkie]

Re: 1972 Merc In-line 6 Question

Well there ya go brother. I told you my boys here on iboats would point you in the right direction. Survey says.........toss that junk! Even if it did work, that set up looks pretty sketchy to me. I'd go with a new mechanical pump and hose.

 

[Fishermark]

Re: 1972 Merc In-line 6 Question

You have to wonder why it was installed in the first place however. Sometimes people will install something like that to "fix" a problem they are having.

I agree you need to remove it as it is unnecessary and unsafe... but before simply replacing the mechanical pump, it might be a good idea to read this article in the DIY section at the top of the page first.

 

[BiggerBoatinOkie]

Re: 1972 Merc In-line 6 Question

Thanks everyone for the quick responses. Not sure when I'll get a chance to do the work but I'll let everyone know what he outcome is.

 

[HT32BSX115]

Re: 1972 Merc In-line 6 Question

Those old boats frequently used copper fuel lines and compression/flared fittings from the tank.

Also, back in those days, anti-siphon valves weren't required (by USCG regs)

If the tank is in the bow (and/or higher than the engine and/or fuel line) you should add an anti-siphon valve at the tank to prevent fuel from siphoning out of the tank in the event of a leak.

If you developed a leak and the boat was in your garage or barn etc, ALL the fuel would siphon out of the tank into the bilge..................one little spark........and BOOM


you can buy the A1 USCG approved fuel line and anti-siphon fittings etc at West Marine and other marine supply places.


Cheers,


Rick

 

[BiggerBoatinOkie]

Re: 1972 Merc In-line 6 Question

The tank is just forward of the engine compartment and the top of the tank is at or below the pump. Hopefully I can tear into it this weekend. I'll probably take out the copper line and install rubber fuel line.
Thanks again for the help.