Optimax 115 2008 model - VST rust & frozen float valve

Printable View

10-20-2019, 03:39 PM
CBryars

Optimax 115 2008 model - VST rust & frozen float valve

First post - forgive any incorrect verbage.

Brief background - raised with outboards - have not owned one in 30 years.

Brother sold me his Triton 18 before he passed away. Boat appears not to have run in 5+ years.

Replaced batteries - initially started ran 3-4 minutes. Went back and tried to start again next day or so - started, ran about 5 min then sputtered and died. Would not restart.

Tests to date:
1. Found fuel bulb would not pump up - replaced
2. Gray-orange fuel line - found excellent article on site - replaced
3. Pumped gas tank empty - put in 5 gal fresh 98 octane with 1 oz #2 mercury Fuel System cleaner. New Filter installed
4. Verified fuel flowing to Pulse Fuel Pump. Also open Pulse pump to make sure not clogged.
5. Engine tried to start - sputtered may 1-2 seconds. Then no start on repeated attempts over 2 days.
6. Check spark on each plug - all good.

So next steps:
1. Pulled VST - when draining the fuel filter was full and had so pressure.
2. There was pressure on High Pressure line.
3. Open VST in fuel filter side a little gunk but not major
4. On low and high pressure side found a lot of rust on low pressure fuel pump - including a good bit flaked off. Low pressure pump gaskets dirty and some corrosion.
5. High pressure side no rust o-ring corroded and sleeve corroded and inner part looks like maybe separating.
6. Tested both pumps and they both run - high pressure makes a putt sound at regular interval - not sure if that is an issue.
7. Now for the kicker - took float off - inlet valve would not move at all - tried to pull out - frozen in.

So any thoughts, best I can tell I need to:
1. Replace float valve and seat
2. Replace high and low pressure o-rings
3. Replace High Pressure sleeve.
4. Not sure if grommet and check valve need replacing.

Also - I removed the High pressure hose under pressure - dumb mistake - did I mess anything up?

Any help appreciated.

Thanks Cameron
10-21-2019, 07:40 AM
JOE54

vst seat not replaceable , would replace both electric pumps and pulse pump pull rail send send assy too VERY reputable inj service (Euro marine) start at tank and replace fuel line and bulb to mtr ,might want to find a good used vst may be cheaper good luck JOE
10-21-2019, 10:20 AM
CBryars

3 Attachment(s)

Joe - thanks for response. Some good fortune - used penetrating oil and got old inlet valve out. Cleaned passages. Going to get a replacement valve - so hopefully VST tank is salvageable.

Can you clarify point -"pull rail send send assy too VERY reputable inj service (Euro marine)". IS that the fuel rail? Help me understand what I damaged with not decompressing high pressure line?

Thank You!

Couple of pictures:Attachment 380464 Attachment 380465 Attachment 380466
10-21-2019, 08:07 PM
lpugh

I doubt anything in the entire fuel system is reusable looking at that mess, fuel tanks may be saved with a good cleaning. Don will be able to tell you what can be saved regarding fuel rail assy
To bad all this was not done prior to attempting to start it, might have saved some injectors
10-26-2019, 08:03 PM
CBryars

Big day Monday - low pressure fuel replacement pump arrived, final part due Monday. So will complete and give it a shot.

Mercury Tech recommended using 75 to 150 to 1 oil in fuel to help clean injectors - never heard of that? Any thoughts?

Drained tank - no residue at all. High pressure pump has no rust and screen is clear. Pumps gas from 1 container to another. Hoping this will work.

Thanks Cameron
10-30-2019, 06:01 PM
CBryars

Big day arrived - weather rain and fog. Installed new fuel pump and inlet valve. Motor started pretty quickly. Ran 5 minutes no issues. Tested forward and reverse. Shut off and restarted 2-3 times - strong start each time and fired immediately. Very happy to say the least.

Oil is 5 years old - since 2 stroke do I need to change it?

Big test once weather clears a little. Going to start off slow - test at dock then idle very slowly test out engine close to dock area. If all goes well will try a little faster for short runs - treating like breaking in a new engine.

Will report back - thanks for help.
10-31-2019, 08:37 AM
SilverFox579

Quote:

Originally Posted by CBryars

Mercury Tech recommended using 75 to 150 to 1 oil in fuel to help clean injectors - never heard of that? Any thoughts?

See this topic from the 3L FAQ (also in the 2.5L FAQ), there are many topics in those FAQs that apply to all Optimax engines - Oil, Battery, Spark Plugs, Fuel and Fuel Additive Recommendations

Quote:

In addition to the above, it is acceptable to add 150:1 mix of Premium PLUS in the fuel tank (for OPTIMAX engine models). This has been proven to benefit fuel system components by providing additional lubrication ONLY to the fuel system components (especially the direct injectors- which are often left DRY after engine shutdown.

Emphasis added.
10-31-2019, 10:00 AM
leonreno

The main thing you need to beware of is clogged injectors. I would replace the oil, clean out old oil and use Mercury/Quicksilver DFI oil.
10-31-2019, 10:34 AM
CBryars

Silverfox - thanks good articles - will give it a go!

Leonreno - thanks will try do that Friday before maiden voyage.
11-05-2019, 11:02 PM
CBryars

Took boat out - performed well. No engine issues at all, started right up. Doing break-in so varied speed. Did do a couple runs and got up past 45 mph. Very happy thanks for the advice.