Leaking Air Somewhere?

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Thompy_04

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I have a 1960 18 hp Model FD-14 and am having some issues. The motor starts fine in 2 pulls and will idle for about 20 seconds then die. If you pump the primer bulb it will stay running. If you start to open the throttle it just sounds as if its bogging down untill you pump the primer bulb. Has absolutely no WOT capabilities even if the bulb is pumped. Carb has been rebuilt, getting great spark, fresh gas, new plugs, new fuel line connectors, running outta possabilities here thats it. Thanks guys.
 
kenmyfam

kenmyfam

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Re: Leaking Air Somewhere?

Thompy_04 said:
I have a 1960 18 hp Model FD-14 and am having some issues. The motor starts fine in 2 pulls and will idle for about 20 seconds then die. If you pump the primer bulb it will stay running. If you start to open the throttle it just sounds as if its bogging down untill you pump the primer bulb. Has absolutely no WOT capabilities even if the bulb is pumped. Carb has been rebuilt, getting great spark, fresh gas, new plugs, new fuel line connectors, running outta possabilities here thats it. Thanks guys.
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Air leak in the lines somewhere or fuel pump come to mind. Air leak is #1 right now as even keeping the bulb pumped you are getting no WOT.
 
A

a70eliminator

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Re: Leaking Air Somewhere?

If you pump the primer bulb and get fuel leaking at the motor connection then you have an air leak, the o-rings in the fuel quick connectors can be replaced. Does you motor require the pressurized fuel tank with the extra fuel line? If not then you may have to inspect the fuel pump, a piece of dirt will mess them up.
 
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Thompy_04

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Re: Leaking Air Somewhere?

No fuel is leaking anywhere when the primer is pumped and both connectors are new as is the fuel pump.
 
kenmyfam

kenmyfam

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Re: Leaking Air Somewhere?

Is the bulb on the right way around ???
Is the fuel pump same as the old one and connected correctly ??
 
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F_R

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Re: Leaking Air Somewhere?

Great spark, huh? OK, I gotta ask, did you pull the flywheel and check the coils? Bad (cracked) coils are the norm in those motors unless they have already been replaced. They are the great deceiver. You would swear it is a carburetor or fuel problem, but it isn't. A carburetor cannot work properly if the engine is not running properly. And yes, it is common to have "good" spark with cracked coils. As I said, the great deceiver.
 
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Thompy_04

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Re: Leaking Air Somewhere?

Yeah I know the coils are good, replaced them when I first acquired the motor a couple years ago. Points gapped at .20 that are new, and new condensors. I was out today looking around today as it ran noticed some oil under the armature plate still. Could a leaky top crank seal cause this problem? I've always wanted to change the seal just because the visable oil
but the motor never gave me any trouble so I didn't bother. Could this be a crucial air leak?
 
wbeaton

wbeaton

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Re: Leaking Air Somewhere?

It sounds more like coils or carb to me. Did you do the plugs and plug wires at the same time?

If you suspect the top seal then start the motor and spray WD-40 under the armature plate. Some folks use propane from an unlit torch. If it revs up when you spray the seal area then you know that's your leak. Also spray all the seems of the powerhead in a sysmtematically looking for the same result. I've had a couple 18's of that vintage with bad seals and they both acted more like lean carb issues with lots of sneezing.
 
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Thompy_04

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Re: Leaking Air Somewhere?

Yes wbeaton the plugs, wires, and coils were all replaced at the same time. the electrical system was replaced completely. The carb is freshly rebuilt that was my first thought was a gummed up carb but it was doing this before the carb rebuild but not as severe. The sneezing discribes how it runs perfectly. Pump the bulb and it runs smooth as ever, stop pumping and in 20 seconds it starts to sneeze again. One more thing wbeaton where would all the seems of the powerhead be where it sits on the leg, correct?
 
wbeaton

wbeaton

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Re: Leaking Air Somewhere?

If pumping the bulb fixes the problem then its likely fuel related. Try another tank and line. If the leak is on the motor end then spray the joints (seems) between all the components after the carb. These include where the carb meets the air intake, intake meets the crankcase, the crankcase halves, top seal and the base gasket.
 
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Thompy_04

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Re: Leaking Air Somewhere?

Thanks will do and get back atcha, gotta be something simple as forementioned. I do know the tank and lines are good I plugged up all the line up to the carb and the bulb would stay hard and not leak anywhere. I know the gasket between the carb and intake is good on the account that I replaced it after the carb rebuild, but after that its up in the air. Thanks again for all the tips.
 
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Thompy_04

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Re: Leaking Air Somewhere?

Replaced the top crank seal today, still no luck. The seal was shot anyway so no harm done. Checked all the seems and still no leak. I did however pop the flywheel today and find a frayed ground wire from both coils. Is there a way I can test the coils? Its not blown or bubbly I've seen that out of this engine before. I do have a multi-meter though.
 
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freddyray21

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Re: Leaking Air Somewhere?

I just scanned this, but saw no mention of a fuel pump rebuild or check. A small hole in the diaphram will cause this problem. If pumping the bulb keeps it running fine then pumping the bulb is acting as a fuel pump. keep it simple.
 
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Thompy_04

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Re: Leaking Air Somewhere?

Fuel pump is brand new freddyray21. I'm thinkiin' they're right, most likely a coil or two, or spark plugs. AC Delco's in there, and I know where that might lead me.
 
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