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Discussion Starter #1 (Edited)
Hi guys,

My F4 stranded me. I start it and it fires right up, but idles low and dies after a short while. Any throttle kills it immediately.

It did the same thing to me last week, I saw bubbles coming from the hose off the filter, and changed the hoses and filter this weekend. Being that she's got new correct submersible hoses and a new OE filter and that there's no bubbles this time, I'm stumped. The bike was running yesterday, and I can hear the fuel pump prime before start and run when the bike is idling (before it dies).

Seems to me like a fuel pump usually either works or it doesn't. Struggling to figure out what else the problem could be.

What do you think?
 

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no fuel?

check the quick disconnects, bet an O-ring/junk is plugging one, probably the pressure side

remove the fuel pump plate, disconnect the John Guest connectors at the fuel rail, reconnect the quick disconnects to the plate, this opens the valves inside, disconnect the fuel filter

blow through the John Guests with an air hose......you will get less air through the return side because of the fuel pressure regulator
 

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Does the fuel pump prime and then shut off when you turn the key but before you hit the starter, or does it keep running?

I think it is something related to the work you did. Everything is hooked up correctly, right? filter oriented in the correct direction? The vent hoses and over flow hoses connected correctly?
 

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+10

Does the fuel pump prime and then shut off when you turn the key but before you hit the starter, or does it keep running?

I think it is something related to the work you did. Everything is hooked up correctly, right? filter oriented in the correct direction? The vent hoses and over flow hoses connected correctly?
What he said.:)
 

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Discussion Starter #8
Either you're right that I screwed something up, or I just didn't fix the right problem in the first place. It started and died before I worked on it, and it started and died after. Same symptoms. When it did it the first time, I saw bubbles in the tank and saw that the hose was 3/16ths instead of 5/8ths, so I figured correct, tightened hose and problem solved. Maybe not.

Pump primes and stops. Filter is oriented correctly. Same with vent and overflow. No kinks in the hoses. Pump works, wires have no shorts. All checked and double checked.

This is one of those problems where I need to figure out why it happened just as much as I need to get it fixed. Don't want to put the bike together, have it run, and stall out next week too.
 

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fuel starvation.....

Caliautobahn;
the line between the fuel pump and the injector rail is clogged/blocked or the pump is screwed.....

if it won't take throttle its not getting fuel:stickpoke
 

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Discussion Starter #11
Ok, went through the system this morning, got full pressure with a pressure tester plumbed in-line. Bike started, ran, no problems whatsoever. These are the kind of problems that either you find something definitively wrong, or it'll happen again, so I went to test to failure.

Rode the bike, warmed it up, and managed to kill it. My house is on a hill and I test-rode up, so I coasted back down to the house. Result? Fuel pump whir's and primes, but the bike doesn't start and nothing comes out of the return hose. Almost certain it's the metal quick disconnect connectors, unless the pump is pushing so low of pressure it won't open the pressure regulator....will order a new set asap.
 

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plugged fuel lines?

And what have I been saying about these damn things Knurl ?:stickpoke
well Caliautobahn, did you buy the CPC ones from CAG or the Chink shit on line?

i'm sending out a complete fuel system less injectors for testing tomorrow with all new O-rings and filter
 

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Discussion Starter #16
Bought a set of new CPC disconnects. No Chinese ebay coke can junk. Expensive, but cheap compared to towing the damn thing again.

Wondering if the defective ones I have now are CPC or counterfeit - they do have the CPC logo on them...

I'll test them against the old ones once they're in and report back.
 

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Discussion Starter #17
Found the problem. The internal o-rings on the female quick disconnects had both swelled to double their original size, cutting off fuel flow. Ethanol? O-rings that weren't fuel compatible? I don't know. But it's something to be on the lookout for.

Problem solved. Thanks guys!
 

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CPC from CAG

Bought a set of new CPC disconnects. No Chinese ebay coke can junk. Expensive, but cheap compared to towing the damn thing again.

Wondering if the defective ones I have now are CPC or counterfeit - they do have the CPC logo on them...

I'll test them against the old ones once they're in and report back.
if you buy them from CAG, Carl, you get the real deal, not some internet/Chinese BS

i told Carl where to get them because he was a Forum sponsor

I BUY them from Carl:drummer:
 
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