Fuel Injector cleaning

[samchar12]

What is the best way to clean the injectors in a ZN1300. The bike sat for 10 years and I am trying to get it running again. I am sure they are gunked up from sitting that long with just gas residue in them. Can I just sit them in cleaner or do they need to be professionally cleaned?

[Me Again]

small jewelry sonicator will do just fine.you can probably find one at wallyworld for a decent price.just soaking may make them look nice but will not get the gook out of the crevices ..
professionally done they will be done right but at a cost.

[trikebldr]

GOOD idea, Bill! I may do mine just for grins! Will definitely try it on those on my spare injector block.

[Me Again]

I have heard about it on a few occasions.One guy even figured out how to energize them to get all the crud out.

[trikebldr]

I have heard about it on a few occasions.One guy even figured out how to energize them to get all the crud out.

That's the easy part! They get pulsed 12 volts to control fuel flow, so to open one completely to flush it out, just apply 12 volts across the two 1/8" spade lugs on the injector. Some injectors have tight restrictors, though, so to get copious amounts of fluid to flush out the injector, apply a high-pressure pump to the fuel rail, with the pressure regulator still hooked up.

[samchar12]

Well took the FI system apart yesterday and cleaned the injectors. I filled the short attached hoses with cleaner and applied 12v to the terminals to let fluid run through them. The wet spots on the towel told me they are not blocked. When I put it back together I started it before the fuel system was done by mistake. Amazing thing is it started right up with nothing but cleaner in the injectors. No fuel other than what might have moved by the pump. This is where it gets weird. I put the fuel system back together and figure its happy days and to my surprise nothing. Just cranks and cranks but no start. I am thinking its the regulator not allowing pressure or something. I found one one ebay and hope that will do the trick. I know when I applied vacuum to the regulator it didn't open in either direction.

Am I going in the right direction here?

[trikebldr]

The fuel pressure regulator keeps the pressure between 33 and 36 psi. Normal steady running it should read 33psi, but when the throttle is snapped open and vacuum drops, the regulator increases the pressure to 36psi. That's to help prevent any lag in throttle response due to fuel starvation from low vacuum.

However, lack of vacuum will not prevent the regulator from providing at least 33psi if all else is OK. Like with any pressure regulator, trying to get reverse flow will usually completely block it off. You do have to have at least 33psi to get the regulator to bypass into the tank, though.

Actual fuel flow into the engine is controlled by electrical pulses to each injector by the DFI controller. The longer the pulse, the more fuel. Sorta like Morse code, but with variable length pulses and off times.

When you say it started right up with nothing more than cleaner in the injectors, how long did it run? With no pressure behind the injectors, they would not have been providing the fuel source. Might be some residual fuel from disassembly.

The DFI gets it's engine speed signal from the ignition control system. Did you maybe have your run/stop switch in the stop position? That kills the ignition.

Can you hear the fuel pump do it's initial five-second run when you turn on the ignition switch? That's the first check. Then, remove the regulator return line from the tank and see if anything is coming out during that five-second initial run. An alternative test is like what the book says to do by adding a fuel pressure gauge in the line between the fuel pump and the fuel rail. If you see 33psi during that five second period, then your injectors are just not firing. Check the code on the DFI unit to see what it tells you. Do you have the supplement manual for this bike? You almost HAVE to have it to troubleshoot anything in the fuel system. There is an extensive section on troubleshooting alone. Very detailed about how to test many things.

Sounds to me like your DFI isn't firing the injectors. Even if the regulator didn't give a full 33-36psi, and if the fuel pump were running, each injector would still drip enough fuel into the runner to make the engine burp and spit a bit.

I would hook a pressure gauge to the output of the fuel pump to see what it can do, alone. Then check the system with the same gauge to see what the pressure is being regulated to. If pressure is OK, then the DFI isn't doing it's job for some reason. It will tell you why with it's blinking code.

[samchar12]

Yes, the pump works and when I disconnect the return hose from the tank there is gas in it. I don't have a pressure gauge to test the pump.

It ran for a few seconds before I realized I hadn't hooked the fuel system up. The fuel rail was dry so the only other gas could have come from what residual was left in the pump. The switch was in the on position.

The DFI unit is the box under the seat correct? I don't see the green light flashing, but will look closer at it.

[trikebldr]

Correct. And, the trouble light is next to that big rubber boot around the wires coming out.

Some NAPA stores will loan tools and may have a pressure gauge.

I pulled my air filter to look down the throat of one intake with an inspection mirror. With the engine running you can see the fine fog of fuel coming out from that little "chute". Mine also sorta dripped fuel just before it fired up.

Does yours give even a burp when trying to start now? Even if pressure was low, if the injectors are firing there should be enough fuel to make it at least kick a bit.

[samchar12]

It sounds like its trying to start, but just can't kick over. I checked the plugs and I have spark so I don't think its coils.

[trikebldr]

Yup, sounds like lack of pressure, probably due to the regulator. Did you do cleaning on that regulator, like with the injectors? Can you blow forward through that regulator? You shouldn't be able to. 33psi is more than you can muster by just blowing. If you can, then it has failed, or is stuck too open to create any back-pressure.

As you know, there are dozens on eBay.

[Me Again]

Try the WOT method.
If all you get is spit and sputter than try this.
Turn off fuel.turn on key to run pump so your lines clear .turn off key. Hold throttle wide open push starter button then turn on key.
When it starts to fire then turn gas back on .You can safely crank for up to about 15 seconds at a time ,but no more than 3 or 4 times without giving the starter time to cool off.
Theres a good chance this will clear the cylinders and get you going.
This works about 80% of the time when valves are starting to get a little to far off.
Good Luck

[samchar12]

Will give it a try. I adjusted the valves already so I am pretty confident they are within spec. What is this supposed to clear? You think it could be flooded?

[Me Again]

Will give it a try. I adjusted the valves already so I am pretty confident they are within spec. What is this supposed to clear? You think it could be flooded?

Yes. Flooded and /or fouled. Either way ,cranking with the gas off will help clear the plugs and cylinders.

[trikebldr]

Pull out the air cleaner, if you haven't already from looking into the bores earlier, and shoot a small shot of starter fluid into the air box while cranking with just a bit of throttle open. If it runs even a few revs, then it indicates a fuel system problem. At least you'll know the cylinders are cleared.

It would SURE help if you had a pressure gauge and the supplement manual. With these 30 year old bikes you're gonna need the manual many times to keep it running well. And, if you do get a gauge, try to get one that will read both pressure AND vacuum.

[samchar12]

I have all the manuals printed out. Will look into getting a gauge.

[trikebldr]

Was trying to find a pressure and/or vacuum gauge on Amazon to recommend to you, but I was sure surprised at what I didn't find!

First, on vacuum gauges, -30in/hg is usually more than enough since most engines can't develop more than about -28in/hg. These gauges are readily available alone, or as a vacuum/pressure all-in-one gauge. Unfortunately, the pressure side only goes to 30psi on every one of them that I saw on Amazon. This won't cover what we need for the 1300 engine!

I have an old Penske (Sears) gauge from the late '60's that does go from -30in/hg vacuum to +60psi pressure. Even that one isn't enough for some of the higher pressure (70psi) injection systems out there today. I also have a separate 100psi pressure gauge for those systems.

All I can suggest is to find a nice 0-60psi gauge and add the correct 1/4" nipple adapter to work with our bikes' fuel systems. I would also suggest finding one that is liquid-filled to help damp out those pressure fluctuations that the manual says you will see when the engine is running. My 100psi gauge is liquid-filled and does a great job of smoothing out those needle movements.

[samchar12]

I picked up a pressure tester at Harbor Freight Should be able to do something hopefully this weekend and see what's going on

[samchar12]

I hooked up the pressure gauge between the regulator and pressure line from the fuel rail. It registered 20-25 psi while turning the key and also while cranking the engine.

I also noticed there was some gas in the vacuum line. Looks to me like the regulator is bad and is leaking.

Thoughts?

[samchar12]

Been a while, but finally weather nice enough to do some wrenching.

Put in a new to me fuel pressure regulator and it fired up on the second try. It is running a bit rich. The black smoke out of the pipes is a give away. Do I need to balance the cylinders to get it back to normal or could this be signs of another problem?