esfishdoc
Well-known member
Hey Folks... haven't been posting for awhile but I've been lurking and boating and fishing and trying to get to the bottom of a problem that has been around for a year now. I've posted this over on The Hull Truth... here is the cut and paste:
http://www.thehulltruth.com/boating-for ... -f225.html
In my explorations to try and fix an annoying problem that has been present for a year I've resorted to monitoring the running of the low pressure fuel pump by installing a remote voltmeter to track its on/off cycles. The Yamaha manual suggests the pump runs 10 seconds on and 20 seconds off when rpm's are under 1200 and continuously when over 1200. I find this to be the case with mine when running on the muffs. It also works just fine on the water..... until..... Out on the water there are times after continued operation at cruise speed for say 20 minutes and then dropping back down to idle the pump will stay running. Sometimes it does and others it doesn't. The importance of this is the only time the engine will stall out is after this change is noted. I might drift for 10 minutes after cruising and then the engine dies out a fuel starved death. Or I would be idling along and when calling for power up I might get to 3000 rpm and it sags and starves. The only way to restart at this time is to squeeze the primer bulb a few times (which suggests to me the VST tank was empty). After a few squeezes... ( sometimes 3 to 6 before meeting resistance) There is always fuel in the bulb. (The bulb has been replaced and is vertical. I've used an aux. Tank and it does not fix the problem. All filters are new. VST tank and all filters in it have been checked and replaced. The low pressure fuel pump was replaced early on.. which did not fix the problem... fuel is good.... the engine never falters at running cruise speed... I could run the tank empty and it would not stall )
This problem goes back a year and has been intermittent and unfix-able. It seemed that over the winter when going out in temps under 50 the problem did not occur which makes me think it might be temp related. That.. and the fact it only seems to happen after running in the water under a load (causing higher operating temps?) and not on the muffs. I keep chipping away and trying this and that trying to find the problem.
What is the normal operation of the low pressure fuel pump and what systems if any feed info that can alter the normal operation?
Is it a fuel flow problem causing the pump to run out of specs or is it electrical?
My local Yamaha dealer/mechanic ran the motor on land and checked the computer and says everything checks out OK and they can't get it to malfunction. They also said they've never heard of a problem like this. Fortunately it only cost 130 for that assessment.
Suggestions?
Questions?
I'm looking forward to getting this fixed.
Thanks for your help in advance.
Richard
Saturday I jumped my first ever Eastern Shore tarpon out of Willis Wharf... broke a 9/0 hook in the process... but that's another story...
http://www.thehulltruth.com/boating-for ... -f225.html
In my explorations to try and fix an annoying problem that has been present for a year I've resorted to monitoring the running of the low pressure fuel pump by installing a remote voltmeter to track its on/off cycles. The Yamaha manual suggests the pump runs 10 seconds on and 20 seconds off when rpm's are under 1200 and continuously when over 1200. I find this to be the case with mine when running on the muffs. It also works just fine on the water..... until..... Out on the water there are times after continued operation at cruise speed for say 20 minutes and then dropping back down to idle the pump will stay running. Sometimes it does and others it doesn't. The importance of this is the only time the engine will stall out is after this change is noted. I might drift for 10 minutes after cruising and then the engine dies out a fuel starved death. Or I would be idling along and when calling for power up I might get to 3000 rpm and it sags and starves. The only way to restart at this time is to squeeze the primer bulb a few times (which suggests to me the VST tank was empty). After a few squeezes... ( sometimes 3 to 6 before meeting resistance) There is always fuel in the bulb. (The bulb has been replaced and is vertical. I've used an aux. Tank and it does not fix the problem. All filters are new. VST tank and all filters in it have been checked and replaced. The low pressure fuel pump was replaced early on.. which did not fix the problem... fuel is good.... the engine never falters at running cruise speed... I could run the tank empty and it would not stall )
This problem goes back a year and has been intermittent and unfix-able. It seemed that over the winter when going out in temps under 50 the problem did not occur which makes me think it might be temp related. That.. and the fact it only seems to happen after running in the water under a load (causing higher operating temps?) and not on the muffs. I keep chipping away and trying this and that trying to find the problem.
What is the normal operation of the low pressure fuel pump and what systems if any feed info that can alter the normal operation?
Is it a fuel flow problem causing the pump to run out of specs or is it electrical?
My local Yamaha dealer/mechanic ran the motor on land and checked the computer and says everything checks out OK and they can't get it to malfunction. They also said they've never heard of a problem like this. Fortunately it only cost 130 for that assessment.
Suggestions?
Questions?
I'm looking forward to getting this fixed.
Thanks for your help in advance.
Richard
Saturday I jumped my first ever Eastern Shore tarpon out of Willis Wharf... broke a 9/0 hook in the process... but that's another story...
