Losing prime

awthacker · #1 03-20-2011, 07:42 AM

We had a great boat ride last weekend... 50+ miles with no problems. Yesterday we rode about 12 miles out, anchored for maybe 2 hours. Then after pulling up the anchor and turning in, we get on plane for less than a minute and the engine dies. I restart and rev... seems okay... give it some gas and it dies. We idle in some 2 hrs at 6-8 mph. Once inside the inlet, I decide to tinker a little and find that the primer bulb is not firm. I squeeze it and the engine accelerates. Then trade places and have the wife back there squeezing intermittently while I drive and the boat runs great for the last 1/2 mile stretch. So the problem seems to be getting fuel to the engine.

After deep thought last night, I'm thinking it may have something to do with the fuel pump. I disabled the VRO pump personally by plugging the oil-in nozzle and disconnecting the wiring harness to the VRO. Could this be causing the fuel pump to malfunction?

I also plan on replacing the primer bulb and the fuel supply valve (it's a three way valve that would've allowed me to divert fuel to the kicker engine, which is no longer installed on the boat - I was going to replace it with a union, or splice because I only have one tank and one engine), but how can I check the fuel pump for proper operation? Should I plug the VRO harness back in, even though there's no oil supply to it? I remember having read that the proper way to disable VRO was to buy a new fuel-only pump rather than disable half of it.

Thanks,
Aaron

awthacker · #2 03-20-2011, 07:47 AM

The fuel filter seems clean and the water sperator is new, having 6-7 hours on it. Just wanted to rule these out as potential problems. The fuel is fresh and properly mixed at 60:1.

awthacker · #3 03-20-2011, 07:54 AM

Here's what I was thinking of regarding the fuel pump, but I don't wanna buy it just to be a parts changer.

http://www.marineengine.com/newparts...&Engine=&Model=

tsubaki · #4 03-20-2011, 08:38 AM

Seems I looked at a VRO on a 3 cylinder that would require you to keep the wires connected in order for the fuel pump to work or you would have to completely remove the VRO system, tap into the plug in the block in order to get a vacuum line and then install a regular vacuum type fuel pump.
Reconnect the wires and see if the problem disappears. Chances are there is a signal wire to the oil pump that will set off the low oil alarm, if so you may need to cut that wire.
The link to you provided to the premix pump looks like an easy solution.

Cam · #5 03-20-2011, 08:46 AM

Sounds to me like there is some sort of fuel restriction. It may be a collapsing fuel line, which has become quite common with this ethanol gas. Check all the lines and if possible, run it off a seperate (5 gallon) fuel tank to see if you get the same restrictions.

Destroyer · #6 03-20-2011, 02:45 PM

Quote:

Originally Posted by Cam

Check all the lines and if possible, run it off a seperate (5 gallon) fuel tank to see if you get the same problems.

That would be my first suggestion also. That instantly rules out all fuel lines, dirty filters, etc. Then you can make a better informed decision based on the results.

awthacker · #7 03-21-2011, 08:47 PM

Today I reconnected the VRO wiring harness, replaced the primer bulb, and bypassed a fuel shut-off valve. I brought along a 6.6 gal pony tank. The boat idled nicely through the no wake zone, then planed up nicely before dying out back to idle speed while at 3/4 throttle. My buddy pumped the bulb and it picks up again. We switched to the pony tank and have the same problem. Tomorrow I'll inspect the fuel pump for blockage.

awthacker · #8 03-21-2011, 08:57 PM

Quote:

Originally Posted by tsubaki

Seems I looked at a VRO on a 3 cylinder that would require you to keep the wires connected in order for the fuel pump to work or you would have to completely remove the VRO system, tap into the plug in the block in order to get a vacuum line and then install a regular vacuum type fuel pump.
Reconnect the wires and see if the problem disappears. Chances are there is a signal wire to the oil pump that will set off the low oil alarm, if so you may need to cut that wire.
The link to you provided to the premix pump looks like an easy solution.

There was a low oil alarm when the wiring harness was connected. But the engine still stalled. So the harness is disconnected again. I have run it this way for maybe 5 hrs prior to the problem.

tsubaki · #9 03-22-2011, 05:25 AM

And with the engine off, you can pump the bubble and it stays hard?

awthacker · #10 03-28-2011, 07:23 PM

Thanks Destroyer.

Quote:

Originally Posted by awthacker

There was a low oil alarm when the wiring harness was connected. But the engine still stalled. So the harness is disconnected again. I have run it this way for maybe 5 hrs prior to the problem.

I wanted to point out that the replacement fuel pump I installed was designed for pre-mix and therefore didn't have the VRO (oil) side to it. What intrigued me was that there was no electrical harness. So I guess fuel pumps operate simply on vacuum and not electricity?