1990 150 Johnson GT Loss 0f Power

[Alpinegold]

I really need some guidance on my issue. Bought a 1989 Nitro 19' with a 1990 150 Johnson GT. The motor bogs down on hole shot and will not plane up. Originally had a 4 blade shooter prop 25" pitch and replaced with a 3 blade prop with a 21" pitch. The boat also has a jack plate which is fixed and can't adjust it while on the lake. When I first bought the boat in October 2013 the boat would plane up but noticed the bow would come up rather high when planing although I was trimed down on my motor. ( Prior to the nitro I had a v178 Ranger with a Johnson 115 motor and it would come out of the hole like immediately. ) When coming out of the hole the motor sounds bogged down and now it will not plane up at all? A friend of mine tells me he thinks it could be a leak in my manifold gaskets. I have a Johnson service manual and going through it the cause of power loss could be a ton of things that I'm not technically competent on 99% of.

Also having live well issues which is resulting in a lot of water going into bottom of boat even though I repaired hole in recirculating hose and cant identify where all the water is coming from. If anyone knows the livewell system Nitro was using back in those days I sure would like to talk to you regarding this subject.

Really could use some advise as I have already spent over $ 1000 on new water pump, aerator pump and timer switch and leaking vro pump. Vro was disconnected prior to me buying it.

Alpinegold - I'm really pulling hair and teeth at this point.

 

[emdsapmgr]

Check for spark on all 6 plugwires when you have the engine under load. Possible you are only running on 5 cyls. The livewell system is a complete system of plumbing under the deck of the boat. When floating, all of this plumbing is usually underwater and will fill with lake water as soon as the boat is floated from the trailer. The system can develop any number of leaks, including, a leaking hose, cracked pump housing, cracked elbow fitting, etc. You can do a test. Fill the boat with water when on the trailer and see if water comes out of the livewell suction port at the bottom, stern of the boat. If so, you've got an internal leak in the system somewhere.

 

[keefallan]

When is the last time you had a tune up? There is the simple things to check for. 1) do a compression check. The numbers should be around 95 -100 lbs. 2) do a resistance check on the plug wires. They should all be in the same ohm range. If not replace the offending wire(s). 3) Do a resistance check on the coils. They should all be in the same range to. Make sure that all your contacts are shiny clean too. Buy new plugs and install. 4) When is the last time the carbs have been cleaned? If the midrange jets are clogged, it won't come out of the hole at all. A quick way to check for that is this: when you are out on the water, nail the throttle and as it's bogging down push in the primer/choke. That will put more fuel in and the boat should come out of the hole. Then you know that you have a fuel issue. There are other possible problems, but this is the simplest problem to talk about and usually gummed up carbs are the first place to look.

Truth be told, your 150 should leap out of the hole. It is a low ported motor(lots of torque!). I love them. I have a couple of them in various tunes(stock to ported).

I'm not going to ask the question that water may be adding the weight to cause the bogging? Wait..........I just did.