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Discussion Starter · #1 ·
Hey all,
Tried to start the Duc up after the winter, got plenty of crank and spark but no boom. After much sweat and swearing, I got to the injectors. Neither sprays while cranking, hardly a whiff of whiff of fuel in the catch bottle. I put a 9-volt on the terminals and got a click, but no jet. It ran fine the last time I rode it, so everything should be configured right.

I'm not 100% sure I have good fuel pressure, but both hoses feel like they're pressureized. Is my next move to buy new injectors, or should I do some check on the pump? Suggestions?
 

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Discussion Starter · #3 ·
Nah,
Put a multimeter to leads. It jumped around, so there is signal. Plus I still should have gotten a spray when I clicked the injectors manually. So I either have a clog or no pressure
 

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or... the pressure regulator is stuck.

In any case, since you know how to activate the injectors, you are one step away from hooking up a spray can of mass air flow sensor cleaner and pulsing it through each until you have a nice pattern. Hence, replacing the injectors would be a last step, but they are not your problem anyway.

That's funny, you replied while I was typing
 

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Do you hear the fuel pump run for about five seconds to pressurize the lines after you switch the ignition on. If so, open the tank filler cap and listen/watch for fuel gurgling/swirling from an in-tank fuel line break (when the pump runs).
 

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pressure regulator is stuck

or... the pressure regulator is stuck...
my favorite subject right now on my ST4s. Do you [ or anybody here?] know if its possible to, and how to clean a pressure regulator?

Thx in advance for any advice.
 

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Discussion Starter · #8 ·
Ok. Things done/learned:
1: filled the fuel manifold with carb cleaner, then pressurized with a hand pump and clicked the injectors with a 9V (it was a bit of a juggling act). Result: injectors ok.
2: took out fuel flange. Everything is intact. Also, fuel pump runs after ignition off with no splashing or gurgling. Took everything that would come apart apart and hosed it down with carb cleaner. If I had to guess what part of it was a pressure regulator, that part looks like it's a one shot deal. Would need a new flange. Looked at what it costs, feinted for a while, now I'm going to get gas to try and spark this hog. Wish me luck.
 

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If I had to guess what part of it was a pressure regulator, that part looks like it's a one shot deal. Would need a new flange. Looked at what it costs, feinted for a while, now I'm going to get gas to try and spark this hog. Wish me luck.
Regulator is the piece at the bottom of the flange with a nipple coming off it, but no hose is attached. It comes out easy. You need cir-clip pliers to remove the cir-clip. Then it sometimes takes a bit of force to get the regulator out. There are two tight o rings at the tip that can make it hard to pull. Similar to the injectors, if you've had those out.

I may have a good used regulator. PM if interested and I'll see if I can find it, but I doubt the regulator would fail to the point of blocking fuel flow. I feel your next move should be to actually test fuel pressure. You can get pressure test gauges at most auto parts stores. You'll just need to adapt it to fit your bike. A simple T fitting at the throttle body would do it. You could get fancy and grab a pair of QD fittings for an easy under tank hook up, but that starts getting pricey!
 

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Discussion Starter · #10 ·
Ok. Got a test gauge. Is there a non-destructive way to get the hose clamps off? Looks like it needs a special tool.
 

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No. They are crimp on deals. You'll have to cut them. You can get these: https://www.amazon.com/gp/product/B00ZSADQB2/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1 and https://www.amazon.com/gp/product/B00375LRKC/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1. I have both and they are my prefered option. The next best, really just a good to be honest, thing is to get proper fuel line hose clamps like these: https://www.amazon.com/gp/product/B002AV7AXC/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1 which is what you likely have on the hoses inside the tank. They are fine, and make future work easy. Just not as tidy as the crimp on fittings.

Whatever you do, avoid the standard worm gear style hose clamps. They do not seal evenly all the way around the fitting. If you have to in a pinch, I guess. Not a long term solution, however.

This is a good time to replaced your likely OEM outside-the-tank fuel hoses. Any 8MM (5/16") fuel injection rated hose is perfect.
 

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BTW, you can get Oetiker clamps and crimpers at big box plumbing departments. They're used on pex and other stuff.
 
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