Engine Issue or Out Drive Trim Issue ? Help requested

sfm5089 · **Joined:** Mon Jul 20, 2015 10:14 am **Posts:** 22

Good Afternoon All,

I own a 2001 Horizon 200 5.7 Merc. The boat has around 120 hours. I was out on the lake this weekend and this was the first time I had it in the water and docked. I had the boat out multiple times no issues at all. I was out on thursday with 6 people plus towing one wakeboarder. Had plenty of power and planed off like normal. I docked the boat for the night came back to the boat and went back out in the lake and all of a sudden I couldnt get on plane. I confirmed my trim was the entire way down at the time as well. It was like I was not getting the power I needed to do anything. The strange thing was after a while the boat came to plane and the RPM's rose like normally to around 4200. The boat does have a hydrofoil on the outdrive. I spoke with my tech and he is saying its the trim on the outdrive but the outdrive is going the entire way down to the normal marks. The motor did struggle to start twice this weekend but overall no knocking or misses.

Here is what I tried:

1) Thought maybe bad gas - Replaced gas with a known good fuel source.
2) Replaced the Fuel filter as well
3) Confirmed the outdrive was completely down.

Any Help would be great.

GottWhat · **Posted:** Mon Jul 20, 2015 1:14 pm

When was the last time you changed the cap, rotor and spark plugs? I recently had a rough running problem which became a no-start issue. The cap and rotor had some corrosion. The spark plugs were also a bit fouled. Swapped them out and she runs perfect now.

Be sure to disconnect/connect one plug wire at a time.

sfm5089 · **Joined:** Mon Jul 20, 2015 10:14 am **Posts:** 22

I couldn't tell you the last time it was done. I got the boat last year around August and the guy did not know when the last time it was done. The boat absolutely does not have a miss or anything. Ill start there and get plugs and wires and cap tonight and get that taken care off.

GottWhat · **Posted:** Mon Jul 20, 2015 2:36 pm

When you get the cap, make sure you get the rotor as well. I assume yours does not have points.

jontmiller · **Joined:** Thu Jul 26, 2012 8:16 am **Posts:** 296

Lou will Chime in but he is aware of a fuel starvation issue somewhere around the fuel tank? just a thought.

sfm5089 · **Joined:** Mon Jul 20, 2015 10:14 am **Posts:** 22

Something about a antisiphin value ?

Thanks for all the help. Soon as I get home I am heading to advanced for parts.

I'll wait for Lou to chime in

deafwish · **Posted:** Mon Jul 20, 2015 4:03 pm

Fuel pump issues are common on older injected boats.

sfm5089 · **Joined:** Mon Jul 20, 2015 10:14 am **Posts:** 22

How do you go about testing the fuel pump ? Could someone explain a "weak" fuel pump problem to me ? I thought if the fuel pump went out the boat would not even run. All or nothing.

LouC · **Posted:** Mon Jul 20, 2015 9:37 pm

Yes you can have a fuel starvation problem caused by the anti siphon valve on the tank, it is where the line to the fuel pump is hooked up to the tank fitting. Spring loaded valve that opens under fuel pump suction and closes when the engine's off. To keep gas from leaking into the bilge if that line ever leaks.
Fuel pump issues are common on older EFI boats.

sfm5089 · **Joined:** Mon Jul 20, 2015 10:14 am **Posts:** 22

Louc,

How would I go about pointing my finger to replace the pump. Where is the fuel pump located ? On the engine block or in the tank ? Thanks for all the help.

LouC · **Posted:** Tue Jul 21, 2015 2:29 pm

I have not owned an EFI boat as of yet so I can only give general advise. That said here's how I'd proceed:
See if you can get access to a Merc shop manual for your engine package; it's always better to start with the manufacturers specs and troubleshooting procedures.
I would find out how to measure the psi that the fuel pump is putting out before replacing any thing. Learn how to diagnose the cause; do not replace parts because because it seems logical .
I like to check the ignition sys first as a matter of course. I had mentioned the anti siphon valve in past discussions because many are not even aware it exists and the trouble it can cause. I learned this after checking every cause I coukd think of and found nothing definitive . My mechanics knew right away. Funny thing is it's not even mentioned in my OMC shop manual...

sfm5089 · **Joined:** Mon Jul 20, 2015 10:14 am **Posts:** 22

Well took the anti siphion valve out and tested it again today. Sluggish to get on plane with 2 people. I am giving up here and going to take it to the local shop and let them have at it. I am going to tell them the next step I would do would be the fuel pump. Now I am thinking it might be spark related. But who knows.

GottWhat · **Posted:** Tue Jul 21, 2015 5:08 pm

Did you replace the cap, rotor and plugs? Or at least pull the cap and a few plugs to see how they look?

sfm5089 · **Joined:** Mon Jul 20, 2015 10:14 am **Posts:** 22

Yes I did. They all look normal to myself. It goes in the shop on Monday. I'll be sure to update this post because it seems like I am not the only one with the problem.

sfm5089 · **Joined:** Mon Jul 20, 2015 10:14 am **Posts:** 22

Well guys I have pin pointed the problem. Even when my boat was at full throttle my boat would only do 4250 rpm. This by my fact finding is way too low with my motor. If you add in more weight and tow a wakeboarder this problem would get worse and worse. I am running a 23 pitch right now. I am going to drop down to a 19 or 21 and give it hell this weekend.

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Engine Issue or Out Drive Trim Issue ? Help requested

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