1999 150 merc xr6

[bdp]

I have a 150 xr6 carb.engine that has been sitting for a while but i went to use and it cranked fine and ran fine for a day then i took it the next day and i runs good up to about 5ooo rpms then it starts losing power and backing down .I can get to run if i back off just a tad below 5ooo and it runs fine.any ideas.timing ,gas,or carb problem.
ps it was stored with stabil.

 

[Chris1956]

Re: 1999 150 merc xr6

The usual suspects fo that issue are antisiphon valve partially clogged, other filters clogged, weak fuel pump, deterioating fuel line.

 

[bdp]

Re: 1999 150 merc xr6

there is no antisiphon vavle in the bulb i took it out.but the hard fuel line is a little old and cracking.this problem would only come about at high rpms like that?

 

[j_martin]

Re: 1999 150 merc xr6

At any rate, the engine is starving for fuel, and that is the main cause of V6 mercs burning down. Don't run it "just below WOT" till you break it real good. Fix the fuel problem first.

If it's a new problem, most likely culprit is plugged fuel filter. That's the symptom. The question would be "What's plugging the filter.?

Another nearly equally likely culprit would be the fuel pump. Kit is about twenty bucks. Will take you an hour to throw it in the first time. 20 minutes after that. I consider it an annual maintenance item. I absolutely do not want to burn down a perfectly good XR4 for a 20 dollar kit.

hope it helps
John

 

[Chris1956]

Re: 1999 150 merc xr6

The antisiphon valve is not in the primer bulb, it is in the fuel tank. It is likely in the fuel pickup, right next to where the rubber fuel line connects. It also may be in the elbow. I recommend you check it, clean all the filters you can find and replace your entire fuel line. A lot of those motors have an inline fuel filter on the motor as well.

 

[Superjetjim]

Re: 1999 150 merc xr6

At any rate, the engine is starving for fuel, and that is the main cause of V6 mercs burning down. Don't run it "just below WOT" till you break it real good. Fix the fuel problem first.

Another nearly equally likely culprit would be the fuel pump. Kit is about twenty bucks. Will take you an hour to throw it in the first time. 20 minutes after that. I consider it an annual maintenance item. I absolutely do not want to burn down a perfectly good XR4 for a 20 dollar kit.

hope it helps
John

Some good advise above, get a fuel pump rebuild kit (check valves, diaphram and gaskets) - its simple to do and takes an hour tops. Fuel starvation will lean seize and toast a piston in 30 seconds flat..