1995 150 HP Johnson Overheating Problem/Issue

Joined
Jun 8, 2015
Messages
25
I have an 1995 150 HP Johnson Motor on a 17 ft Sea Pro Model # J150ELEOM. When I first bought the boat used, the boat was having a fuel issue that lead from one thing to another. The first issue was that once the motor reached RPM speed's of 5500 it would run for just a few minutes and then die off unless it was kicked back down to 4500-4800 RPM's and then ran fine. At the time the carberators were cleaned and the screen that is at the bottom of the pick up tube that goes into the gas tank was removed from the tube with a wire that I pushed down the pick up tube line to remove it. Also I replaced the fuel wator seperator and also installed all brand new fuel lines leading from the gas tank to the engine as well. After the gas lines were replaced, changed the spark plugs out to the OEM Champion brand spark plugs, and removed the screen that is at the bottom of the pick up line that goes into the gas tank, the engine started running better at 5200 RPMS just not at 5500. For the next couple trips it worked fine until the engine started to have an even worse fuel issues. NOTE: THIS BOAT IS BEING OPERATED AT A 2 STROKE 50:1 RATIO EVEN THOUGH IT DOES HAVE A VRO, BUT THE VRO IS NOT HOOKED UP AS FAR AS THE OIL PORTION.

long story short to this date the all Fuel lines replaced from tank to engine, fuel water seperator replaced, VRO fuel pump replaced with a Non-Oiling Pump, the Red Plug thing that is on the engine for the Choke was leaking so that was replaced. Carberators not cleaned out but the mechanic stated that they were clean when they inspected the drain plug from the bowls, and also the fuel lines dont have any air leaks.

So Right now the engine at full throttle will run perfect for 2-3 minutes and then has to be shut off to cool down cause of over heating issue. If the engine is ran at 3/4 Throttle it will run great with no rpoblems of over heating. Any advise would be greatly appreciated.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,033
Are your fuel lines 3/8" ID in size? Do you have an anti-siphon valve installed in the fuel line? Have you considered inspecting/repairing the vapor pump and vapor separator?

Does the primer bulb collapse at high speed? If so, the vent on the fuel tank is suspect.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,033
OK, just saw line about overheat. It makes sense to rebuild water pump and inspect thermostats. Get that fixed first, than see if fuel issue is still acute.
 
Joined
Jun 8, 2015
Messages
25
Replaced new thermostats and the water pump has been rebuilt. The water pump works great and all so have no idea where to go with this except to sink the boat to the bottom of the Gulf of Mexico lol
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,033
OK, if she still overheats after waterpump rebuild and new thermostats, consider a leaking head gasket. Take compression and look for adjacent cylinders with low compression.
 

bob johnson

Rear Admiral
Joined
Feb 25, 2009
Messages
4,304
i'll take a stab.....maybe you are leaning out at WOT...could the high speed orifice be slightly clogged????

bob
 

jakedaawg

Rear Admiral
Joined
Jun 26, 2012
Messages
4,275
Check the lid of the VST for a leak. The screws are metal and screw into plastic. It is fairly easy to strip out the body. Be careful.
 
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