Fuel Pump? UPDATE

dodger29 · **Posted:** Fri Jan 01, 2016 8:35 pm

Hi All,

New to boating (and this forum) and recently (Nov 2015) purchased my "new to me" 2006 Horizon 260 with a 6.2l V8 Mercruiser.......

I got a pre-purchase inspection done and the report said everything was good and within limits for a boat of that age and use (300hrs)

Over Christmas, I noticed that coming out of cruising speed (3,000rpm) down to the regulated waterways of only 6knots, the boat would stall and after putting it back into neutral, she would start up again and we would continue...... this happened 3 times over 3 times out with the boat.

Finally yesterday, she does not start.... the motor turns over, but doesn't fire up.

My mate told me to listen out if the fuel pump is cycling when I turn on the ignition, but as a newbie, not really sure what to listen out for.....

With the engine hatch open, I am just not sure what to look/listen/smell for when trying to diagnose the problem.....

Does anyone have any suggestions? I called my mechanic but he seems to still be on holidays!!!!

Many thanks......

UPDATE

Firstly, thanks to all who have responded to this thread with helpful insights/tips....

Well, my mechanic came out yesterday and found this......

http://village.photos/images/user/55359 ... fd8c4c.JPG
http://village.photos/images/user/55359 ... f0a614.JPG

A fried/melted relay which prevented power going to the fuel pump...... he called his marine electrician to come out tomorrow and replace the relay. He couldn't answer my question as to why this would melt BEFORE the fuse going.....hopefully the electrician will be able to shed some light on this and perhaps uncover a deeper underlying issue at play......

Will give an update once the electrician does his thing tomorrow.

Cheers,

Dodger29

acguy · **Posted:** Fri Jan 01, 2016 8:43 pm

Hello, and welcome

When you turn your key on to the accessory position. you should hear the fuel pump power up and prime the system my Volvo is loud enough to hear with the engine hatch open. Listen for a hum type sound. Sorry don't have a merc so I can't tell you where it's located

dodger29 · **Posted:** Fri Jan 01, 2016 8:52 pm

thanks very much....will head down to the boat now and see if I can hear anything.....

Perfect day....boat just sitting there! new toy! aaaarrgghh!

alex8q4 · **Posted:** Fri Jan 01, 2016 9:20 pm

Here is a link to a similar motor to yours. After the beep from the ignition you can here the fuel pump until about the 6 second mark.

Good luck.

https://m.youtube.com/watch?v=ia0xFQH5kTg

dodger29 · **Posted:** Sat Jan 02, 2016 2:20 am

Thanks for the link...I don't hear the hum of the fuel pump.....

Mechanic is coming Monday morning to assess the issue....

thanks to those who replied to my post! I will update, for the benefit of others, once mechanic has a look and gives me a report.

TX H210SS · **Joined:** Thu May 27, 2010 9:10 am **Posts:** 1488

Let us know. . My money is on something simple like the engine kill switch interrupt switch the stalls the motor when going into neutral or fuel filter. ...may even be the fuel vent. If the fuel pump was going out you would have been hearing a high pitched whine...at least I did on mine and you can't help but here it. ...like a tea pot whistle. Hope it's an easy fix

230 Mike · **Posted:** Sun Jan 03, 2016 1:32 pm

I agree with TX. However, note that just because a fuel pump powers up doesn't mean it's producing enough pressure to operate normally. There can be debris clogging the pickup, the pump itself can be weak (but still running), etc.

weather · **Posted:** Sun Jan 03, 2016 6:02 pm

On the Volvo's there is a 20A breaker on the engine that is for the fuel pump - might want to see if the Merc has the same.

dodger29 · **Posted:** Sun Jan 03, 2016 6:53 pm

thanks for all the advice on things to look out for...... will be passing all this onto the mechanic when he arrives.......

will def. be interesting to find out what the issue is.....

Cheers,
Roger

Raft61 · **Posted:** Mon Jan 04, 2016 4:02 am

Hi Dodger29,

Hope you've got your problem fixed. Yes, you should hear the fuel pump "buzz/hum" for about 7-10sec once you turn the ignition on, while it is building up pressure in the fuel lines. You could also check that you have fuel pressure at the fuel bleed valve. See this thread http://www.smwebhead.com/phpBB3/viewtopic.php?f=5&t=11917. If the fuel pumps not running you'll have no fuel pressure.

Fuel pump is a separate (box shaped) module on the starboard side of the engine right down near the bottom of the engine. It should also have water hoses connecting to it (for cooling).

In a Mercruiser your age, the symptoms you describe could also be one of...
1) Mercruiser had dodgy fuel pumps (circa 2002-2006) which would corrode and block the cooling waterflow causing vapour lock on hot motors. Also had painted internals which would flake off and block fuel flow. see this thread http://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=12001
2) A faulty IAC valve (Idle Adjustment Control), which would first appear as stalling at idling, and difficulty in starting. Try starting with throttle wide open in neutral (Throttle back immediately if it starts). If it starts like this, your IAC valve is faulty. It's very easy to replace yourself.

Cheers.

LVChris · **Posted:** Mon Jan 04, 2016 12:22 pm

I had a very similar problem when I bought my Vista. Mechanic checked fuel water separator, checked and cleaned anti-siphon valve and checked power to fuel pump...turned out to be faulty fuel pump replaced and she was good as new.

http://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=10192&start=0

dodger29 · **Posted:** Wed Jan 13, 2016 2:20 am

Well,

Replaced burnt out relay and all seems fine........ (see update to original posting)

thanks to all who responded.....

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