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Discussion Starter #1
I rebuilt the engine on this quad. Someone ran it out of oil. So ,new crank, rod, piston.....etc. I got it back together and it starts up, idles high for 4-6 seconds, then dies. Repeat. I set the TPS per the manual. I didn't have the right fitting to test the fuel pump like the manual describes. But, I did undo the fuel line at the tank, and hooked up the pressure gauge. When I hit the key, the pressure goes up to about 45 like it should, but, then drops right off. I put new pump on it yesterday, and it does the same. WHere to next???
 

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When it runs for a few seconds is the fuel pressure staying high or is it dropping off.

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Discussion Starter #3
When it runs for a few seconds is the fuel pressure staying high or is it dropping off.

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Well, like I said, I don't have the right fittings to connect the gauge and start the engine. I guess I need to get whatever I need, huh? And I put a new pump on it. But, maybe there is a pressure regulator that maybe malfunctioning?
 

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I have a pressure regulator if you need one.
 

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Discussion Starter #5
Alright, thanks. IDK yet what I need. I did check the valves this evening and the ex valves were pretty tight. I went to start it and see, but the battery is dead. DOH!
Didn't you say in another thread about the same bike, that you had a fuel line from the tank to the throttle body? I patched the old one, but, I also ordered a new one, but I probably wont' get it until next month.

I have a pressure regulator if you need one.
 

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Discussion Starter #8
So, after the battery charged (slow low amp) all night, it doesn't have enough grunt to crank the engine over. It cranks, but, when it hits the compression stroke it almost stops. It has 12.8 volts at the terminals, but, that doesn't neccessarily mean anything, huh? I'm wondering (hoping) that if the battery was weak and the ex valves tight, then maybe it was losing a bit of compression, still allowing it to start, but with EFI and a weak battery, maybe that's why it would die out. IDK. Hoping its something easy like that.

Yes, I have a couple fuel lines.
 

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I may be getting older, but I refuse to grow up!
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Battery should be at least 13.5 volts. As said, try jumping from your vehicle.
Normally hard starting is caused by tight intake valves, but a low battery won't turn the engine fast enough to fire the plug.
 

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Discussion Starter #11
13.5....ok. I'll give it a shot here in a bit. The intake valves were a bit tight also. Not as bad as the ex,tho.

Battery should be at least 13.5 volts. As said, try jumping from your vehicle.
Normally hard starting is caused by tight intake valves, but a low battery won't turn the engine fast enough to fire the plug.
 

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Discussion Starter #12
No go with the jumper cables. I did have a brand new battery here in a Honda 350 rancher. I took it out and put it in the raptor and it fired right off, and then died after 4 or 5 seconds. When I tried to re-start it, same old thing, ooomph, ooomph, ooomph, it hits the compression stroke and it almost stops. I put the charger on that battery for a while and got 1 start-up out of it before it returned to the same old ooomph, ooomph, ooomph....
I wonder if the auto de-compression isn't working right.


Jump start it with jumper cables


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During the piston install did you file the rings in the cylinder? Checking that they fit correctly?
 
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Discussion Starter #15
If I'm not mistaken, that pc in the circle, due to centrifugal force, swings out and de-activates the decompression system, right? It seems to be in order here.

20200614_115015.jpg

During the piston install did you file the rings in the cylinder? Checking that they fit correctly?
 

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That part looks good, and yes I was referring to the filing of the rings on the cylinder.
 

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If I'm not mistaken, that pc in the circle, due to centrifugal force, swings out and de-activates the decompression system, right? It seems to be in order here.
Yes, it does swing out. But, there's a pin and activator in the cam.
 

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Have you tried to give it gas when it does start to see if it keeps running?

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Discussion Starter #20
Yes. It will rap up like a mo-fo. Great throttle response. Kinda like a carbed engine......but then it dies after 5 seconds. I don't rev it too high, tho. New piston and stuff...


Have you tried to give it gas when it does start to see if it keeps running?

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