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TOPIC: Mercury 500
Mercury 500 13 years 4 months ago #31197
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Idles fine, got runs ok very slow to accelerate, runs good then when you back down off throttle and rev up again stalls, restart throttle up stalls, let it sit,fire back up, runs ok and cycle repeats
Ideas? |
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Re:Mercury 500 13 years 4 months ago #31198
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Someone suggested ethanol? Really?
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Re:Mercury 500 13 years 4 months ago #31205
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Sounds like fuel delivery.When were the carbs last rebuilt? Fuel pump diaphram would be my next guess.Some pros will chime in with a better solution.Did you find a prop yet?
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cool runnings Mr 88
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Re:Mercury 500 13 years 4 months ago #31207
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I did get an oem for 160
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Re:Mercury 500 13 years 4 months ago #31217
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Ouchhh. Was the mangled one rebuildable?
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cool runnings Mr 88
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Re:Mercury 500 13 years 4 months ago #31275
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Zwarbyt wrote:
Anyone have any suggestions what to look for? |
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Re:Mercury 500 13 years 4 months ago #31278
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i had the same problem with my 50hp,after cleaning the carbs i had set the idle screw at 1 1/2 turns as a starting point but it was sluggish coming "out of the hole. i ended up adjusting the idle screw out 1/8 of a turn at a time until it accelerated properly, it idles a little rich but has enough acceleration to pull a skier. i would still replace the fuel pump diaphram{$5.00 part) and install ethanol resistant fuel lines.
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Re:Mercury 500 13 years 4 months ago #31279
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I agree back out the mixture screw , & the fuel pump kits are cheap and easy to change
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Re:Mercury 500 13 years 4 months ago #31280
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My 1970 500 was doing similar but was water in the carb filter screen... new screens and a reset of the idle screws made it clean right up..
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Re:Mercury 500 13 years 4 months ago #31536
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What oil mixture should I run with the gas? 20:1 or 50:1?
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Re:Mercury 500 13 years 4 months ago #31555
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50:1
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1970 Glastron V-142 SkiFlite
1965 Merc 500 1968 Merc 500 |
Re:Mercury 500 13 years 4 months ago #31556
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50-1 is fine but i run it 40-1 more oil is better and cheeper than more parts.
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Re:Mercury 500 13 years 4 months ago #31603
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Fuel fuel fuel fuel fuel!!! Did you replace all fuel lines and rebuild the carbs and pumps?? I'd bet it'll run all day at 1/2 throttle. If you replaced the fuel lines, a delivery line is pinched somewhere!
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Re:Mercury 500 13 years 4 months ago #31634
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did a new fuel pump kit and just got done cleaning out the filters they were full of plastic shreddings and gunk, cleaned and now im going to put in and try the mixture adjustment as you described it,
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Re:Mercury 500 13 years 4 months ago #31640
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It would be wise to take the time to purge the float chambers and clear the idle circuits with carb cleaner at a minimum before you re-assemble.
Thom |
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Re:Mercury 500 13 years 4 months ago #31649
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I would also be concerned about the "plastic shreddings" you found in the fuel filter too. Old fuel lines can crack and delaminate inside causing partial blockage inside the line itself.
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Bandit - 1959 Glasspar G3
See more G3s at www.g3owners.com |
Re:Mercury 500 13 years 4 months ago #31720
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yeah, didn't do much, still sluggish on its way to the higher revs..
only does 24 mph with me in it If you can imagine i lay the throttle forward, the revs rise with the throttle till about half throttle, once i pass half throttle the revs sloooowly build up, almost like turbo lag, about 10-30 seconds after laying full throttle the RPMS catch up... going to take the carbs apart and rebuild them, should I use this kit? www.marineengine.com/parts/additional-photos.php?item=MER1395-9262+1&mode=enlarge&p=0&g=/parts/images/mercury/139592621.jpg&title=+Mercury+Quicksilver+1395-9262+1+REPAIR+KIT-CARB+1395-9262+1 I have worked on many 4cyl 6cyl and turbo cars but have never worked on a carb before |
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Re:Mercury 500 13 years 4 months ago #31748
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I also was wondering if anyone had the procedure for checking the timing on this motor
Ordered the booknbutnit won't be here till next week |
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Re:Mercury 500 13 years 4 months ago #31799
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Not overpropped is it???
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Re:Mercury 500 13 years 4 months ago #31800
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Prop is oem
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Re:Mercury 500 13 years 4 months ago #31801
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OEM does not mean they sold you the correct one.IF they took the old numbers and cross referenced them correctly and the correct prop was in the box that they handed you then you should be good to go.Lets say you had a 13" prop and they mistakingly gave you a 15" prop you would be having some of the symptoms that you are describing.Have you compared the numbers and did it act the same way before you srapped bottom?
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cool runnings Mr 88
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Re:Mercury 500 13 years 4 months ago #31810
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Does your boat have a tach? That can give helpful info in prop selection and tuning of the motor. If not, you might consider getting one. My boat didn't come with one, so I picked up a period piece to mount in the dash.
My 65 Merc 500 gets my 14 ft fiberglass Glastron up to 30 MPH (29.8 GPS) fairly quickly. I'm running a 11 pitch prop and I'm still at the bottom of the RPM range. (5200) The lake I go to has an elevation of over 7500 feet. My motor is losing at least 10HP. |
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1970 Glastron V-142 SkiFlite
1965 Merc 500 1968 Merc 500 |
Re:Mercury 500 13 years 4 months ago #31839
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Zwarbyt wrote:
Could still have too much pitch on it, that would make the boat/motor behave like you describe. As has been said you need a tacho rigged up - even if it is only a temporary arrangement, that way you will see if the motor is being lugged down by the prop. |
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Re:Mercury 500 13 years 4 months ago #31845
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Prop is 10.75 inches by 10 pitch
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Re:Mercury 500 13 years 4 months ago #31860
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By the looks of your boat. That 10" should be about right. The hull isn't full of water?
I had that happen once. On a 66 Dorsett ski boat model. The guy I bought it from bondoed the hull and it leaked.The inner floor was very water tight. So I didn't notice it until I removed a drain plug. Traded her in. Wish I kept it now. It was a nice 15' boat. I powered it with a 66 Merc 500  |
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Re:Mercury 500 13 years 4 months ago #31902
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elgindave wrote:
I wish, boat is light as a feather, I push it round in the driveway by myself.... going to have to pull the carbs i guess and dig in deep |
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Re:Mercury 500 13 years 4 months ago #31913
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Check for any vacuum leaks anywhere on the engine. where the carb mounts are, intake manifold, anyplace that could be leaking air no matter how small. Check all you lines and replace any clamps with new ones. Old ones do not last forever. I have found many clamps that look good but leak air when they dont leak fuel. And really check around the fuel pump mounting for air leaks. It doesn't take much to lay an engine down on power. Good luck, Skip.
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Re:Mercury 500 13 years 4 months ago #32027
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Serial # of this motor is ?????----When engine is running , pull one plug wire off at a time ( insulated plers ).The RPM should drop on each one.
If not you have a cylinder not firing. This could be spark related.It could be reed valve related.It could be crankshaft / crankcase sealing related. You have of course checked compression.-Check spark to make sure it jumps a gap of 5/16" or better on all 4 . |
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Re:Mercury 500 13 years 4 months ago #32260
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compression tested perfect 120+ on all four
timing checked out ripped the carbs apart and the lower carb had a clogged tube, cleaned up and re assembled, once the rain stops i'll put in and test but I think that was it. |
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Re:Mercury 500 13 years 4 months ago #32275
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Comp numbers are great.Nice that you found the clogged jet.It also sounds like it was getting enough fuel that you did not score the cylinder wall by running it dry. Looking like Saturday may be rain free!!Hoping to get the Power Cats maiden run in this weekend as well.
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cool runnings Mr 88
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Re:Mercury 500 13 years 4 months ago #32277
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Can't wait
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