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Discussion Starter · #1 ·
What are all the signs of a bad crank seal? If one is bad will it make the fuel pump not work? Our 86 indy 400 will not stay running,it runs for 30 seconds then dies,usually fouling the pto plug. Sometimes it will run for a couple minutes but idles up to 3000rpm then down to 1700 then back up to 3000. It also seems to run good at 3/4 to WOT throttle. All I can really think of is that it needs a fuel pump or a crank seal,wanted to see if anyone else has had these issues or can help narrow it down.
 

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Unless I'm mistaken, while idling, spray carb cleaner on the crank seal (only works for the PTO seal since the MAG can't be reached). If the motor revs up, the seal is bad.
 

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You can do the mag side also, just spray in the recoil hole and thats how i was told to, buy a person i trust with my sleds motor. Wooohooo i added something of value before 8am.
 

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Discussion Starter · #5 ·
I have tried spraying the pto seal with no luck,have not checked the mag side though. I swapped out the carbs as well as trying a different CDI I had and the symptoms never changed. I will probably replace everything on it to find out its a simple $1 fix or something.
 

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If the crank seal goes it will cause a lean condition on that side. Fouled plug says you are getting too much fuel. If the fuel pump diaphram goes it usually causes fuel to fill the crank through the impulse line. I believe on the 400 that the impulse runs off of the pto side. To check the pump verify that the impules fitting on the pump will hold pressure (4-6psi) indefinitely. You should be able to get a rebuild kit for the pump for about $10
 

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I agree with mhawk. It sure seems to be a fuel related problem. I would definitely investigate the fuel pump. As mhawk said a crank seal with cause a lean conditon. Bad reeds can cause the motor to flood out, but I think the 400 is piston port. So that's out of the picture.
 

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Discussion Starter · #8 ·
That makes sense Mhawk,I have noticed a little fuel in the crankcase when I pulled the drainplugs. I will put a new pump on and see what happens.
 

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RMK-KING said:
That makes sense Mhawk,I have noticed a little fuel in the crankcase when I pulled the drainplugs. I will put a new pump on and see what happens.
Just buy a rebuild kit.
http://your_addresshttp://www.shadetreepowersports.com/cgi-bin/A54952E2/mac/template.mac/loadHtmlPage?htmlPage=snow/engine/fuel-pump.html
 

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Discussion Starter · #11 ·
97SKS700 said:
it wont idle
keeps fouling plugs on the PTO
What are you referring to?
 

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Discussion Starter · #12 ·
The top diaphragm on the fuel pump had a small crack in it,so it was sucking fuel through the impulse line into the crankcase as mentioned earlier. Works good now!
 
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