WOT RPM's too low?

[Kenny8906]

88 XP150 Model E150STLCCA

I am running a 14.5 x 22p prop and is only hitting 5000 RPM's @ WOT. Is this normal? The motor seems to run fine just hard starting. It does drink the gas very badly. I'm just wondering if I have an ignition issue or something else, since my prop isn't really considered big.

[shuppa00007]

im going through the same thing slow out of the hole and top end rpms low I just installed new power pack and waiting for new coils to come in yours could be the same thing .

[ELGIN]

Check compression, decarb, check cylinder head temps 140-160 at idle, a cold running engine will be hard to start and drink fuel.
On the GT-XP 150s if you have a rough idle or stalling issue you may need to replace the recirc valves.

[DoferGofer]

What size boat, or how heavy is your boat? You may have too much prop. My engine would handle a 14.5X21 on a 17.8 run a bout, but could not turn the same prop on my 19' center console. Finally, end up with a 14.5X19 on the center console.

Just a thought.

[Kenny8906]

The boat is an 17'8" bass boat. I believe hull weight is 1260lbs. The boat idles good, and comes out of the hole good.

Elgin, I do need to check the head temps because after making a run it will sometimes not idle well when shifted in neutral, and sometimes dies. The other night when I was strapping it to the trailer I noticed the water coming out of the motor was pretty warm. If my heads are getting hotter than normal would it be a thermostat issue since I do have good water pressure.

[DoferGofer]

Kenny,

Your engine should turn a 14.5X22 without any problem, as mine had no problem with a OMC SST 14.5X21+ on a boat in that weight and size. As for the actual reason you are not gaining the WOT RPM's you are seeking can be many. I am sure the pros here will steer you in the right direction. I worked a long and hard to get my XP up to snuff. But, I will tell you this, I don't care what anyone say or do, It's going to be a gas hog. Mine has been a gas hog since I bought it spanking new in 1985.

Good luck,

Melvin

[Kenny8906]

Melvin, Thanks for the help. I'm going to pack the GPS tonight just get an idea of my fuel consumption. Unless I'm way off its geting less than 1 mpg now, and most my running is less than WOT.

Just another thought, would my motor being too low cause it not to reach the peak RPM's?


Modified by Kenny8906 at 12:17 PM 6/18/2009

[DoferGofer]

You should get more than 1 mpg. I raised my motor to the top hole on my boat. BUT, be careful if you choose to raise your motor. I would only raise it one hole at a time and watch your water pressure as you move it up. I think I could raise mine even higher but I am not getting in the jack plate scenario. The next time I am out, I will give you some feedback as to my mpg but my boat is much heavier than yours. My boat dry weight is 1600 + lbs, with three large batteries, riptide trolling motor and sixty gallons of gasoline.