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| Another 1988 48hp won't idle |
| Author |
Message |
    
JOHN ROLLINS
New member
Username: jrollinssr
Post Number: 1
Registered: 06-2009
| | Posted on Tuesday, June 30, 2009 - 02:59 pm: | 
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I bought this boat/motor that had been sitting several years. First off I cleaned fuel system throughly. Have rebuilt or gone through the carbs several times with new kits as needed. Have removed and cleaned jets, removed leaded plugs to clean fixed jets and orifices, have replaced one carb. There's is never any signs of debris or grunge in float bowls or jets.You can keep the engine on a fast idle by pulsing the choke or spraying carb spray in either carb. One's as good as the other. Float bowls levels are good, fuel pump puts out good before and after new fuel pump kit. Compression approx 145psi each, good strong spark on new plugs. The engine will go at higher speeds if you can get it in gear without dying. There are no mixture screws to play with. I have inspected the reed valves, ok. ??? Anyone ever heard of crankcase seals causing this? Or hopefully a simpler solution. JR |
Tony Delio
Senior Member
Username: tonyob
Post Number: 1478
Registered: 05-2001
| | Posted on Tuesday, June 30, 2009 - 06:37 pm: |
|
Anything that can cause a loss of vacuum could cause a bad idle, crankcase seals is one possibility. Sometimes an engine needs a slightly larger idle jet. You will find a number stamped on the jet. This is the jet size. You could try a larger jet and see what happens. |
John Rollins
New member
Username: jrollinssr
Post Number: 2
Registered: 06-2009
| | Posted on Wednesday, July 01, 2009 - 08:54 am: |
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I have checked for vacuum leaks and have run a slightly larger drill bit through the jets. The problem is fairly severe in that it doesn't kinda idle but dies immediatley even with the fast idle lever up unless you keep pulsing the choke/primer. There is a crankcase vent hose that goes to the aircleaner plate that I'm unsure of. It seems to be clear of dirt daubers etc...Should that draw a vacuum or have a pressure pulse? Another post mentioned bad things happen if you adjust the timing advancer rubber tipped screw. I don't remember doing that but it made me think. I bought this boat/motor from someone who couldn't get it to run either maybe they played with it. Do you check timing with a light? |
Morten Ringvold
Senior Member
Username: haffiman37
Post Number: 3867
Registered: 04-2006
| | Posted on Wednesday, July 01, 2009 - 09:13 am: |
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' run a slightly larger drill bit through the jets.'
Most definitely not the way to do it!
Start by doing a de-carb with Engine Tuner or Sea Foam.
Then do a complete synch of ignition and carbs according to the ORIGINAL manual. |
john g
Member
Username: johng1974
Post Number: 20
Registered: 05-2009
| | Posted on Wednesday, July 01, 2009 - 09:21 am: |
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yep drilling jets is a no no.. they often dont have a straight thru cross section inside anyway, more like a small venturi IIRC... by drilling you are making some wild changes I would say.. sorry...
John |
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