I need Help with a VP 50 GXI engine issue

"Hi I have a 2002 VP 5.0 GXI e

"Hi I have a 2002 VP 5.0 GXI engine that I just changed the raw water impeller on. It's the kind that mounts on the crankshaft. I did put muffs on it and everythng seemed like it was working fine there was no leaks or anything! I put it in the water today and everything seemed ok but after I whle I noticed the boat seemed to be runnng waay to cool under power and it wouldn't let me go full throttle without the engine cutting in and out, acting as if it was too cold for that throttle position. When I let the boat sit and idle in the water I noticed the engine temp was climbing up and as soon as I would start driving it again it would go down really quick! I know I put the impeller in the right direction it's rubber and didn't have any curve to it at all. I'm pretty positive that I put the 2 hoses that connect on to it on the right parts of the pump. What do you think is wrong. It runs hotter when standing still idling and too cool when it's under power! Please help me out!"

i maybe wrong but i think they

i maybe wrong but i think they have a thermastat fitted and it may be missing or stuck open this is the only reason it would run cold same as a car.. it sounds like it running in choke mode

if that's the case would i

if that's the case would it also cause the engine to run hot when just idiling or would it be cool no matter what the engine is doing? because right now the temp goes up quite a bit when just idiling.

if its running hot what do you

if its running hot what do you mean is it over heating? it will run hotter same as if you in traffic jam yes and cool when running or cruising yes whats the temp when idle and when you open the oil filler cap is there any signs of a creamy sludge?

"It's not overheating, or

"It's not overheating, or at least I didn't sit for a long time in the water in neatral with it idiling otherwise it's possible that it might have. The temp guage went up a good 20 degress just sitting for a couple of minutes idiling in the water and then when I was driving again the temp went down very fast a good 20 degrees."

it sounds like a thermastat pr

it sounds like a thermastat problem i take it the water on idle is flowing fine? if water flowing fine and impeler is good i would check the thermastat is working or even there

"ok so what if I accidently sw

"ok so what if I accidently swapped the 2 hoses going into the impeller pump unit, do you think that it would be acting this way?? Just curious."

you could try this but i would

you could try this but i would say no it would over heat or get very hot quick and get hotter but with out seeing the engine and setup its hard to say i take it water is flowing out of the engine fine on idle?

When it's idling in the wa

When it's idling in the water there is bubblng occuring at the transom of the boat. This is my firs time out for the season with it so It's hard to remember if it's bubbling anymore or less that it usually does. When I ran it on the trailer with the muffs on it appeared to be operating normal with the water exiting out of the front bottom portion of the drive. There are no buzzers or anythning going off I just notice the temp guage and the fact that it is cutting in and out when trying to go full throttle whch is by design when the engine is too cold and not warmed up. After I let it idle a little and the engine temp went up it would let me hit full throttle for a little bit without cutting out until the engine temp dropped down again and then it started cutting in and out again!

the bubbling could be exhaust

the bubbling could be exhaust rather than water flowing out just on the off chance you dont have any wires shorting out giving you the cutting out and also false readings on the guage??

The boat isn't that old an

The boat isn't that old and since the engine is performing according to the temp guage I trust that they are both working properly. The cutting out is a built in feature so you don't do any engne damage to the engine if it is not fully up to operating temp. It will only let you give it 75% throttle until the engine has reached normal operating temp. Yes it could just be the exhaust making the bubbles it's really hard to see where the water exits out of the boat when the boat is sitting still at idle. I really need another boat to follow behind me when I'm on plane to see if the water is flowing out properly from under the drive. I need to get a cooling system shematic and make sure that I have the 2 hoses attached properly to the impeller pump unit (upper and lower).

in that case i would just fit

in that case i would just fit a new thermastat as a service part to new sesson they are not major amount of cash that way it a peice of mind then check other things yes do try the pipes round the other way from my experience the left hand pipe as you look at the impeller is always the inlet and the impeller should rotate from left to right this way you know the pipes are right and if its rotating anti clock wise then the inlet will be the right hand one hope this helps in your case the lower one on the impeller will be the inlet

ok so here's what I've

ok so here's what I've done so far. Last Friday I replaced the thermostat it ran a little warmer under power but still is running too cold. Today I went and took the raw water pump apart again to check everything over. The impeller is the exact sime size as the old one was. I do have a question about the mounting plate the impeller housing bolts on 2. It spins pretty freely and the holes only line up a couple different ways. Should that mounting plate be moveable or somehow locked in a fix position. I know that it doesn't rotate when the engines running but was just curious about that. So bottom line is afer all that I still am having the same issue. Anyone have any other ideas??

"Two things come to my mind: t

"Two things come to my mind: thermostat of wrong temperature range, or thermostat housing in bad condition.

Is your thermostat rated for 160ºF?"