75 HP Honda running horribly

[Jabyrd]

This may be a little long winded, but i want to make sure i give all the details i can. So here’s my dilemma- I recently bought a 2017 Carolina Skiff with a BF75D on it. Before I bought it, I took it on a 20-30 minute test ride. It fired right up and ran great. I took it out this weekend for the first family trip and it sucked. After about 10 minutes with the motor running about 3k rpm’s, it bogged down. I throttled back and it bucked a couple times and shut off. I tried cranking it for a few seconds and finally got it to fire off. I gave it some throttle and nothing. It would buck and sputter and die off. Wait a few minutes, crank it, give it throttle, and I’d be lucky to get 30 seconds of quality run out of it before it started acting up again. I limped it back to the marina and trailered it home. Once home, I drained all the gas out of it, refilled it with ethanol free, put in a can of sea foam, changed the external water separator, epmptied and cleaned the internal water separator, changed the primer bulb, replaced the fuel line between external water superstore and fuel bulb, and checked the flow of my eval canister. While I had the vent line off the evap, I blew back towards the tank. There was resistance at first but it “ burped” and let me blow into the tank. It would then vent out the air I just blew into the tank. Thinking I’d figured it out and the tank vent had been stuck, I reassembled it and put it back on the muffs. It idled well for 10 minutes or so then started missing. I pumped the primer bulb (before I replaced it, if I pumped it while it was running, it would stay collapsed. The new one would build pressure and regain shape), and it straightened up for a few seconds, then back to the way it was. I was watching the filter up by the high pressure fuel pump and I could see it fill u with fuel when I pumped ovule but as the level in it dropped, it would begin acting up. I’m at a wall. I don’t want to throw a $200+ pump at it if that isn’t it, but I don’t know where else to turn. If it matters, this is an built in fuel tank, not portable. Anybody got any suggestions?

 

[racerone]

Test run with a portable tank and hose.

 

[ahicks]

2 thoughts here-
Blowing back towards the tank very likely destroyed the check valves built into the primer bulb that allow it to do what it does (prime).

If the primer bulb "stays collapsed", generally that's a sign there's a restriction somewhere between the bulb and the fuel pick up in the tank.

 

[dingbat]

Where the fuel line connects to the tank there should be a anti-ship (check) value. It looks like a normal hose fitting, but it’s not

Did you remove or replace?

 

[racerone]

Test running with another tank would indicate if there is an issue with boat fuel tank or whether issue is something on the motor.

 

[Jabyrd]

I ran it with a portable tank as suggested. It idled fine for about 15 minutes. When I throttled up to 1/4-1/3ish throttle it started skipping and sputtering and bogged down. I believe it is the high pressure pump that is driven by the cam, correct? There is a filter bowl right before it. When I prime and start it, that bowl is full. I can see fuel running into it, but not at a pace that keeps it full. When the level in it gets low enough I can’t see what it’s doing anymore, is when it starts acting up.

 

[racerone]

No model # posted.----Some use a cam driven lift pump and a high pressure electric pump.------Fuel injected I think , so check all filters.----Check vapor separating tank ( if equipped ) with it.

 

[Jabyrd]

Sorry, it’s a BF75DK3

 

[racerone]

Clean and inspect vapor separator tank / filters / float valve.