Fuel Ventilation Problem..? Or fuel filter?

[SenecaLakeJunkie]

Hi all, my old 89' Maxum 1900 SR with a 3.0 Mercruiser, that I use mostly for fishing now, but not nearly enough (the source of most problems, likely) has run fine for me in my third year with it (previous owner was the town boat mechanic!), but occasionally, with no consistency, except possibly after a long run time before incidence, just bogs and dies like its out of fuel. About 15 mins of floating and fishing and it always restarts normally. Then its fine, but mostly, of course I tend to head in after that or move to the troller. But its run long enough again to get me back to ramp when worried about it every time. NOW, this year I was fueling up for the first time with only about 2-3 gals left in since October; gas spilled back out port after only a couple gallons, and also, stuff started spilling out from the tank ventilator thing (one the left side of the outdrive on my boat), with some sort of residue; I figured it pushed most out, but I still had it later when trying to add just a few more gallons. The boat was stored in an open field.

SO: Could this be a fuel filter problem..? I haven't replaced them since I've had it. Or, does it seem related to my intermittent fuel supply problem that resolves itself..?! i.e., does ventilation also effect fuel supply to the lines- and how does one thoroughly clean the ventilator thingy to make sure it breathes well and doesn't clog? Does anyone have a schematic for this boat's fuel system?

I am away from the boat again, so I duck taped the ventilator in the meanwhile to keep critters out. Gonna start it up again next week.

Thanks for any insights any might have!!
Happy Boating!

FingerLaker
'87 Bayliner Capri/85 H.P. Force on the Big Muddy Potomac
'89 Maxum 1900SR/Mercruiser 3.0 on Cayuga's Shining Waters (NY)

[mmwjr]

Insects are know to build nests in the vent fitting. A clogged vent can result in fuel starvation as you need to replace the fuel used with air else a vacuum is created which restricts fuel flow.

[SenecaLakeJunkie]

Thanks sooooo much, Mike. Yeah, that makes perfect sense with the symptoms, it takes 10-15 mins for the vacuum to relieve itself, and I run for a while again no problems. It just didnt seem like a fuel/filter issue otherwise.. Sitting in the open field, I should be taping over the vent I guess, which i did last year after I had a hunch, but the problem seems to be persistent from the stuff left in there from 2020. I am going to look up some info on blowing the line out with air, I think. Thanks again for help with confirming this. Have a great season!

[mmwjr]

Originally Posted by SenecaLakeJunkie

Thanks sooooo much, Mike. Yeah, that makes perfect sense with the symptoms, it takes 10-15 mins for the vacuum to relieve itself, and I run for a while again no problems. It just didnt seem like a fuel/filter issue otherwise.. Sitting in the open field, I should be taping over the vent I guess, which i did last year after I had a hunch, but the problem seems to be persistent from the stuff left in there from 2020. I am going to look up some info on blowing the line out with air, I think. Thanks again for help with confirming this. Have a great season!

Next time it acts up try opening the fuel fill, if you hear a rush of air and the engine runs you got it.

[wiigelec]

If you haven’t changed your fuel filter in three years you may consider doing so.

[SenecaLakeJunkie]

Ah, good to know.. its pretty bad, so will at least try to really solve the clogging issue. Thanks again, Mike!

[SenecaLakeJunkie]

Thanks, wiigelec, yeah got one already in the onboard tool kit, should be able to do that next after this issue is resolved.