Question about 70 HP Chrysler 'skipping'...

[bradw]

I just purchased a 1969 Glassmaster 15.5ft bowrider. The engine is the original 1969 Chrysler 70HP outboard. I have grown up on boats but know nothing about working on engines. The boat idles well and accelerates well. It runs well at about 1/4 - 1/2 throttle. However, at full throttle and sometimes during acceleration the motor seems to be skipping, as if it's running out of gas, or like its sucking air or something. It's not real heavy, you can run fine with it doing it. What should I do to try to fix this problem? Thanks!

Brad

 

[bradw]

Re: Question about 70 HP Chrysler 'skipping'...

bump... any ideas?

 

[eurolarva]

Re: Question about 70 HP Chrysler 'skipping'...

I would check for spun hub on the prop first. Draw a line on the prop and on the cone. Use a sharpie or finger nail polish. When you hear or feel it slip check the prop to see if the line is still lined up. A spun prop will usually go high on revolutions when it is slipping. If engine rpms go down then fuel could be your problem. If that is the case it could be a bad fuel pump, a stuck needle in the carb or the float needs adjusting. If it is the original fuel diaphragm I would replace that first. Part number 18-7806. You can buy it from NAPA or here at iboats.

 

[mreinsmith]

Re: Question about 70 HP Chrysler 'skipping'...

are you talking about a skip in the engine? because we're in the middle of troublshooting the same problem. I can probably give you a few things to check if that's what you're experiencing?

 

[bradw]

Re: Question about 70 HP Chrysler 'skipping'...

yea, i think i would describe it as a skip... when at full throttle the boat won't go full speed because the engine is skipping. it feels like it loses power for a second. then it gets back and then loses, back and forth but you're still going about 25 mph.

 

[mreinsmith]

Re: Question about 70 HP Chrysler 'skipping'...

I guess the first question is do you have any service manuals or repair books (clymer manuals seem better overall than the seloc manual)

You'll have to forgive me If I'm simplifying this too much. If you've done all this already we can go from there.

The easy checks are as follows:

• Check Cooling - Check the temp of the water coming out of the exaust. it shouldn't be too hot.
• Clean Fouled plugs - The higher mix of ehtanol in fuel today causes the plugs to foul quicker - Some people have to check them after every trip
• Clean Fuel Filter(s) - I think you only have a filter in the fuel pump itself. But check the fuel lines from motor to tank and see if there is second one.
• Star-Tron - Add some Star-Tron to your fuel
  http://mystarbrite.com/startron/
• Check spark on each plug - Get a spark "gap" tester which allows you to set the gap and simulate the actual spark coming from the ignition. (I got mine at NAPA)

Hopefully that gets you started.

If not we can go on to the fuel system checks (best to have a book for these)

M