150 Merc bogs in slow speed

[Dead Eye]

I am having a problem in idle speed. The moter is a 1988 150 Black max. The boat runs great at WOT. It is only when i get to a no wake zone it bogs down. I take it out of gear before it stalls and it idles fine. I noticed when it is ready to stall the bulb gets soft. Anyone have an answer?<br /> Thanks, Dead Eye

 

[gregmas99]

Re: 150 Merc bogs in slow speed

Try a blocked fuel filter or a crook plug lead

 

[rickdb1boat]

Re: 150 Merc bogs in slow speed

Could be weak fuel pump at low speeds. Not enough vacuum to pull fuel to motor. Just a guess.. Others more familiar with the Merc. system will have more answers.

 

[mellowyellow]

Re: 150 Merc bogs in slow speed

primer bulb goes soft? start there, new bulb.

 

[rickdb1boat]

Re: 150 Merc bogs in slow speed

But why would it run at full speed if the bulb was bad? Just curious.. But good idea, anyway!!

 

[mellowyellow]

Re: 150 Merc bogs in slow speed

maybe at full speed it has enough suction to<br />compensate for bad primer bulb Rick?

 

[gregmas99]

Re: 150 Merc bogs in slow speed

Thats why I said fuel filter, if its upline of the bulb and pretty blocked, at idle the pump will draw the fuel out of the bulb and make it go soft, but at WOT the pump whould have more suction to overcome the resistance of the blocked filter.

 

[profish00]

Re: 150 Merc bogs in slow speed

Good answers i would start there....

 

[nickantanies]

Re: 150 Merc bogs in slow speed

Hello, I also have a 1988 merc Blk Max, what size prop do you have on and what type of boat is it?? I'm having trouble finding the right size for mine. and whats your max speed at wot....<br />thank you<br />nick

 

[Dead Eye]

Re: 150 Merc bogs in slow speed

The moter is on 1988 wellcraft fisherman. I don't have any answers to your the prop size {the boat is in storage}. As to WOT no speedo yet. I only had the boat 1/2 season . I am still tring to get the kinks out. The boat was in storage for 2 years before i got it. In the comming month i'll try to get you the answers.<br /> Dead Eye

 

[chumbucket]

Re: 150 Merc bogs in slow speed

Nick,Have a 150 Merc on 20 Grady,here are prop #;s original 48-78118-17 stainless 48-79794-17. What ever those numbers mean ???? 15x17 Those number's are out of original motor book .1982 Merc 150.

 

[gss036]

Re: 150 Merc bogs in slow speed

The bulb has checks valves in it for one way flow, so they could be leaking. DON'T buy an off brand, buy a good Mercury factory bulb. That is why yours has lasted fot 16 years, off brands will need replacing a lot sooner. If your filter was really clogged, I would think you would get some surging around 4000 rpm, fuel starvation? Should start with a new water seperater/fuel filter every spring. The water stays at the bottom and rust the metal.