so frustrating.....

[bunky2004]

so after chasing ghosts left and right with this darn thing, I am at a complete loss. After carb rebuild, engine timing, new ignition system (complete) and thorough cleaning, the engine runs fantastic......on the trailer while on muffs. Good acceleration, great idle, all is well. I put it in the water and it bogs down under load so much that I cant seem to get it above 1700 to 1800 RPM. Any thoughts? Mercruiser 2.5 with rochester 2 jet

 

[bunky2004]

one thing i forgot to add was that prior to all the work I did, it took off like a raped ape and had good power as well as speed. Reason for everything to be redone was that it would spit sputter and die after 15 to 20 min

 

[Fun Times]

What year is it?
Did you replace the fuel pump and pump gasket at all?
​What design fuel pump do have, FUEL PUMP AND CARBURETOR(NEW DESIGN) ​
FUEL PUMP AND CARBURETOR(OLD DESIGN)

 

[bunky2004]

its the old design. year is 1987. I didnt replace pump or pump gasket. I had good pressure prior to all the work and there werent any leaks so i didnt think i needed to.

 

[Fun Times]

its the old design. year is 1987. I didnt replace pump or pump gasket. I had good pressure prior to all the work and there werent any leaks so i didnt think i needed to.

Probably no need to change it then. I was just thinking if you did, then sometimes the thickness of the pump mount gasket changes the fuel pressure if it's a different size then what you had/what was working in the past.

​Another thought would be to ensure your exhaust system isn't clogged up all the way down to the stern drive as sometimes the water shutter in the exhaust pipe could fall and clog up the outlet. See item number 6, http://www.mercruiserparts.com/bam/subassembly/30903/963/230

Here's your parts catalog if needed, http://www.mercruiserparts.com/2-5l-gm-153-i-l4-1987-1989-0b531854-th

 

[bunky2004]

the exhaust seems to be clear of debris, and functioning correcrly

 

[bunky2004]

So just a quick update. I finally had time to really sit down with it and spend some good time with it. Come to find out all cylinders are working correctly except for cylinder 3. my confusion is that it has an entirely rebuilt ignition system. I have swapped spark plugs and wires with other cylinders and have no change. Do you think it is possible that I may have gotten a bad distributor cap out of the box? Or could there be a different issue that I'm overlooking?

 

[bobkat1864]

Recommend trying a spark tester on the plug wire of no. 3...if no spark then the cap is suspect, especially if you have spark to the other wires. Any chance you still have the old cap?

 

[bunky2004]

i do have it

 

[bobkat1864]

Try swapping back to your old cap and see if the problem goes away?

 

[Scott Danforth]

the spitting/sputtering after 20 minutes sounds like the fuel vent.

check your cap tower, sometimes there is molding flash preventing connection to the plug wire.

does this motor have points? if so, did you set the dwell prior to timing?

 

[bunky2004]

Hey everyone, I have been so busy with work and home lately that I haven't really had a chance to get back on here. I did swap back to my old cap and rotor and all was well as far as the misfire went. So, I guess it would appear that all is well and I'm ready to hit the water. Except that upon one final inspection of all fluids and performance I found that I seem to have gear oil coming out of the "**** hole" on my outdrive. Seemed a little strange so I check the dipstick on the top (OMC Cobra outdrive) and it looks pretty milky. Guess its time for a new post, only in the OMC cobra section. Thanks for all the help guys! You have all been a big help in the diagnosis of this beast. Being a mechanic, I kind of thought that this 2.5 would be the same as any other 2.5 in cars and trucks from the 80's. Boy was I mistaken!

 

[thumpar]

Yea, the 2.5 was only put in the nova II in the 60's for a couple years. The more common car version is different. They are good motors though.