150 merc v6 bogs down at w.o.t.

dsb said:

Hello I have a 1985 Merc 150 v-6 the problem I am having is when trying to go when in water under wot it only bogs down and does not go have had carbs rebuilt new fuel lines, primer ball, stator, trigger I am at a loss runs fine in yard runs good in low speed not when put in water at high speed thanks if anyone can help Darin

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j_martin said:

Fuel delivery problem. A small leak in the fuel line between the engine and the tank will take in air and cause this. So will something plugging up the fuel filter, or the pickup screen in the tank. A common problem is a loose or leaky pickup tube in the tank. If the fuel pump hasn't been serviced, that's suspect.

If the primer bulb sucks flat, it's a plugged screen. All the rest of the problems will just result in a bog.

DO NOT TRY TO RUN IT LIKE THAT. Just before it bogs, it's at about the right mixture to burn a piston.

Troubleshooting tricks. A piece of clear hose spliced into the fuel line to see any air getting in. A pressure gauge (15 lb) put in the fuel system. Should read 2 - 6 lbs at all times the engine is running. Each carb has 2 pipe threaded holes on the fuel rail. One is left with a plug in it, usually the lowest starboard one. Replace that with a nipple and hook up a temporary pressure gauge.

BTW, if you title your thread with something identifying the engine and trouble, like "V6 150 bogs at WOT", you will get more help.

hope it helps
John

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jmj120 said:

Who diagnosed the stator/trigger problem, or did you just swap it out. Did they test the power packs (switches)?

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jmj120 said:

I put a clear filter on mine between the fuel pump and carbs. Makes it easy to see if you're getting gas. Might be worth trying.
Another way to eliminate the gas tank would be to buy an inexpensive plastic tank and hose. Use it and see if the problem goes away.

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jmj120 said:

On my 150 (1992) I've got the filter between the fuel pump and the carbs. It might be easier for you to put it close to the bulb. I think I would put it between the bulb and engine. Just take your hose in the parts store and get the right sized filter. I bought one Friday and they are around 5 bucks. Clear plastic. Post your results.......

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jmj120 said:

On my 150 (1992) I've got the filter between the fuel pump and the carbs. It might be easier for you to put it close to the bulb. I think I would put it between the bulb and engine. Just take your hose in the parts store and get the right sized filter. I bought one Friday and they are around 5 bucks. Clear plastic. Post your results.......

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dsb said:

Tanks again I will post result do you know if there is a way to test fuel pump

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j_martin said:

On that engine the oil is mixed before the fuel pump. The filter is between the fuel pump and the carbs. It's only about the size of your thumb.

Bear in mind that fuel requirement at WOT is about 15 gph.

hope it helps
john

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nat85501 said:

Ok I am having a very similar problem so I have a few question how did you find the air leak in the fuel tank, and how do you check the fuel pump I have a 150HP 87 black max XR-2. Also what is WOT mean?

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jmj120 said:

You should still have the filter between the fuel pump and carbs, unless someone removed it.
I don't know about the leaking seams. I don't think it would cause a problem with the engine, but maybe a safety problem.

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nat85501 said:

I went back and read everything found were it said how to test I will try that tomorrow and I have a fiberglass tank but I am going to check the pickup tube and strainer if that don?t work going to rebuild the pumps they have a kit of under 20 with shipping and handling I would rather just get a new pump but I can?t find one.

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