96 150hp fuel vacuum warning check-engine

[VTXMatt22]

Sorry about the confusing title.
I replaced my 110 hp with a 1996 150 OceanRunner last year. The engine ran great, but gave me a check engine warning at WOT. Determined that the check valve (anti-siphon) at the top of the fuel tank was probably undersized, so I removed it (since the tank is below the engine). That seemed to cure the problem, but the boat started to develop a hard starting issue, so I did a de-carb, but the problem persisted. I then figured out that fuel is backflowing to the tank, so I have a lack of fuel at startup.

So I replaced the primer bulb and checked all the fuel lines yesterday. It started much better and the bulb seems to be holding fuel better. BUT, my check engine alarm at WOT came back on yesterday. It only seemed to come on above 4500 rpm, which I don't often go above, so it's not critical, but I might be selling the boat to a friend next year and want to make sure it is right.

All the fuel lines are 3/8". I tried a vacuum pressure gauge on the fuel lines, but the needle bounced around alot so it was hard to get an accurate reading, but was close to where the alarm should have sounded. (before I removed the anti-siphon valve)

Any advice would be appreciated.
thanks
Matt

 

[ezeke]

Re: 96 150hp fuel vacuum warning check-engine

Just a few thoughts:

saw a fellow pull a 100 gallon tank, only to find that the tanks small vent screen had corroded shut;

the fuel pickup screen can get gel or debris over time and reduce flow;

in-line fuel filters should be replaced often;

and, full sized water separating fuel filters are the best option.

 

[VTXMatt22]

Re: 96 150hp fuel vacuum warning check-engine

thanks,
I do have a full size (1/2" npt fittings) on the fuel/water seperator. The fuel tank was replaced about 3 years ago, so I would think it would be clean. How would I check or clean the screen in the tank? It seems like the likely culprit.

Matt

 

[ezeke]

Re: 96 150hp fuel vacuum warning check-engine

Most tanks have a three or four screw surface plate with the pickup directly below it. The screen is at the bottom, horizontal. The anti-siphon valve and fuel line connection would normally be at the outside top of the surface plate.

I would not expect that pickup filter to be clogged on a relatively new tank, but you never know.

 

[VTXMatt22]

Re: 96 150hp fuel vacuum warning check-engine

The only opening on the tank is for the fuel gauge pickup, but it is next to the outlet tubing, which is welded. The anti-siphon valve was removed. Would the tubing size and overall tank setup, be THAT different for a 110 hp vs a 150 hp?

 

[Chris1956]

Re: 96 150hp fuel vacuum warning check-engine

The setup for the two motors is not different. Most tank fuel pickups I have seen unscrew for replacement or cleaning. I would remove the fuel pickup screen, if you have one.

BTW, I have the same motor and same issue you have, except I only have it during hard acceleration, not high RPMs. I recommend you make sure all fuel line connections and fittings are airtight.