motor missing at high rpm HELP!?!?!

[C YENSEN]

well it was the first night out for my 84' V20 (470 merc. I/O. 2 barrell) and she started fine, and ran great for about 5 minutes, then she started to miss while we were running at 3900*rpm. we backed it down to 2000 rpm and ran ok, she idled around 900 to 1200 rpm. so we gave her a ten minute break and then when i tried to take it back up to 3900 she would not go over 3100. after talking to a few people we think it is water in the gas (condensation build up). the previous owner stored it with only 20 gallon of gas last winter, and i put a fresh 25 gallon in last night before the ride.

so i got a new filter and a couple bottles of dry gas, hopefully that fixes it.

a mechanic i know said it may be a points problem

any advice or suggestions would be awesome * ???


thanks *

ps. how do i attach an image?

[macojoe]

Well it could be the points??

When were the plugs changed last??

As for the gas the best thing would have been to drain the old then add the new.

If you know a little about motors you can kind of tell when it is gas and when it is electrical.

If plugs are ok and not fouled, this would be from points not opening. Check the coil also.

Being that it is fine when slow and breaks up at high speed I no think the gas.

But that said I be willing to bet you have a restriction in the gas line some where??

Are the vents clear?? Take air hose and blow all lines out including vents. Add new filter

Could be a weak fuel pump??

Check vaules on the fuel tank could be all gooped up from the old gas and getting stuck??

Add some Gumout to the gas and spray the Carb all down to make sure it is all clean.

[joeithaca00]

sounds like you have an ethanol problem.

Try and get a sample of the gas from the tank, put it in a clear container and see if you have little bubbles in the gas (little melted butter like substance).

If it is an ethanol problem and you put dry gas in there you could make the condition worse. I had an ethanol problem at the start of the year, drained 30 gallons (put it in my truck) and refilled the tank (+changed the fuel filter). Ran fine after that. Be careful of the additives, you're just adding more alcohol into your fuel system.

[C YENSEN]

well i know they are dark but here are a couple of photos

[chumbucket]

Nice clean looking '84 ya got there.


Welcome. ;D

[C YENSEN]

why thank you ;D

as soon as i get this motor miss thing figured out i will be a hell of a lot happier.

[Mac_Attack]

You'll get it figured out and then you'll be close to heaven! What a ride! Bill Mc ;D

[C YENSEN]

how many gallons of gas does my 84 I/O hold?

i think 60 buy not sure.

thanks

[reelapeelin]

You're right about the 60... ;) :)...