Fuel drain back

[JHornsby3]

The fuel drains back in the fuel system on the 1977 SRV-19 with a Mercruiser 470. I have checked and tightened everything from the fuel filter to the carb banjo. And for the life of me, it always drains back making it very hard to start. I just can't find any reason for it to do this. Can somebody shed some new light on this for me?

And yes, I know I'm trying to keep a boat anchor propelling a boat.

 

[Nater Potater]

Probably not draining back, but leaking out the bottom of the float bowl. I assume it's a Rochester Quadrajet. 'Known issue with them. There are kits to repair those with o-ringed plugs, but it does require some light machining. I have had good success with a thorough wire tooth brush scrubbing and applying JB Weld, but it has to be spotless and oil-free to work right. A Youtube search returns many examples of the problem and repair options.

 

[JHornsby3]

The 470 is a 4 cylinder based off a ford 460 single head. It uses a Rochester 2 jet like the mercarb carb. The drain back can be seen via the clear fuel filter, inline, before the water/fuel separator. It will be full while running. But by morning, its empty again and hard to start.

 

[hughespat57]

Change the anti siphon valve on the tank. Or at least clean and test.
Even if the fuel pump valves seep a bit the anti-siphon should not.

likely just getting old

 

[JHornsby3]

Change the anti siphon valve on the tank. Or at least clean and test.
Even if the fuel pump valves seep a bit the anti-siphon should not.

likely just getting old

I was afraid of it being something at the tank. Back in 77, they put the tank in the boat and put down the decking. Then glassed it in. Nowhere is there access to the tank. Just the fuel line coming out of foam, from what I can tell, looking at things from a mirror and flashlight.

 

[hughespat57]

Yuck
Yeah I looked for an hour and can’t find a parts book or any good photos to risk cutting random holes in the deck.

I would get a new anti-siphon valve a brass coupler and a straight brass hose barb. Assemble and cut the fuel line close to the opening.

Valve towards the engine of course.

 

[JHornsby3]

An hour!?! I've been looking for five years for any kind of paper for this thing. Nothing to be found. Although, I found a brochure for $45 the other day. Copied that to my printer. But doesn't say much.

I will see if I can find a valve and put in before the filter. Or a newer boat that was made after the interwebs was put into use.

 

[hughespat57]

I used the WayBack Time Machine site.
Even on the old searay sites rhe oldest documents only went to the early 80s