mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

[zildjian29]

here is my problem it idles ok but if i try to accel slowly it will die but if i slam it to full throttle it will kinda plain out but will only hit around 15 to 20mph at about 4000rpms. the engine sounds ok sounds strong. has new plugs and wires and new points. i recently bought the boat so don't know the history to well. im not sure what to look at next! any help would be awesome! boat is 85 a 17ft stingray open bow. prop is correct also.

 

[Bondo]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

here is my problem it idles ok but if i try to accel slowly it will die but if i slam it to full throttle it will kinda plain out but will only hit around 15 to 20mph at about 4000rpms. the engine sounds ok sounds strong. has new plugs and wires and new points. i recently bought the boat so don't know the history to well. im not sure what to look at next! any help would be awesome! boat is 85 a 17ft stingray open bow. prop is correct also.

Ayuh,.... Check, 'n change the fuel filters,...

 

[zildjian29]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

Not sure where the second filter is I change the one coming from the fuel pumpis the other one in the carburetor

 

[alldodge]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

The other filter could be in the carb but unsure because we don't know if it has one. It would help us if we had your engine serial number, and also add the outdrive serial number, I'm thinking there may be two issues here.

 

[zildjian29]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

Its the mercarb I'll post the rest when I get home. Hope its not compression. Could maybe be hub.

 

[zildjian29]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

Think this is the serial for the out drive! 4443146. Can't find it on the mercarb

 

[zildjian29]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

Sry here it is for the out drive 6229718-c856558

 

[alldodge]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

The 6229718 comes out to a 1983 140hp 3.0 engine. Uses Merc carb 2BRL part number 9652A1 and uses fuel strainer (filter) part number 9033. Unable to determine outdrive but probably should be alpha 1.

I'm thinking you need to make sure your fuel systems is working correctly. This is done by replacing filters, checking to be sure you have clean clear fuel lines, pump is supplying fuel at correct pressure (4-8psi), you have good gas in the tank, and carb is working properly.

The second thing I'm thinking about is you said it will make it to 4000rpm but your only doing 20mph. This can be a spun prop hub or engine coupler. To check the prop hub, put it on a trailer and in gear, then try to turn the prop. If you hear clicking turn it the other dirction and really put some force on it. If the prop moves the hub has been spun and needs repair. When your doing 4000rpm do you smell burt rubber? If so the coupler is probably gone.

 

[zildjian29]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

Just to make sure I did a compression test and got 135, 130,130,130 in order 1234 so compression is good. The hub is good! Where is the coupler located? Thank you very much!

 

[alldodge]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

Just to make sure I did a compression test and got 135, 130,130,130 in order 1234 so compression is good. The hub is good! Where is the coupler located? Thank you very much!

How did you verify the hub is good?
The engine coupler is located behind the engine. The coupler connects the engine to the outdrive through the input shaft on the drive.

 

[zildjian29]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

I did what you said and the hub feels solid. I did start it and put it in drive and gave it throttle went to the back of the boat and you can hear a loud constant kinda like a fast grinding noise coming from lower unit! In forward and reverse.

 

[zildjian29]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

Lower unit oil is white and milky!

 

[alldodge]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

I did what you said and the hub feels solid. I did start it and put it in drive and gave it throttle went to the back of the boat and you can hear a loud constant kinda like a fast grinding noise coming from lower unit! In forward and reverse.

You should hear no grinding, suggest pulling the drain plug from the drive and see what it looks like. You probably need to pull the drive off and have it looked at.

Edit: pull the drive and have it looked at, it has some internal damage

 

[zildjian29]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

Its white!

 

[alldodge]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

Its white!

Your drive is damaged, pull the drive and have it looked at, it has some internal damage

 

[zildjian29]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

Thanks a bunch you have been a big help!

 

[zildjian29]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

Thanks a bunch you have been a big help! Took lower unit off all splines look great! There is a little hole on the lower unit with a small gasket that meets up with the upper. When taking unit off oil comes out of it. What is this for? I had an outboard and it didn't have this. Just curious

 

[Eric 3.7LX Alpha 1]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....



If your refeering to the Quad gasket it is how gear lube travels between the halves of the drive, fill the lower till it comes out the upper vent hole..... it travels only thru this opening.

 

[Eric 3.7LX Alpha 1]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

deleted.... double posted

 

[zildjian29]

Re: mercruiser 3.0 140hp no top end speed and dead spot whil accelerating!!!!!....

Thank you! Think I have gone as far as I can so gonna have someone take a peak. Thanks for all the help