TOPIC:

I was riding my fuel-injected kz1000G1 "Z1 Classic" and was shocked to have the bike die on me again.

I had a new fuel filter to install so I decided "this is a good time to install the new gas filter."

THIS FILTER IS HUGE -- no junk from the gas tank will get by this stock fuel filter, I can say that with 100% confidence:



I looked at the fuel pump and the hassle of removing it from the bike in order to inspect it. "Surely that would be a waste of time, look at the huge filter Kawasaki put in the gas line, surely only *clean* gas is getting to the pump. I don't feel like yanking something that I *know* must be fine."

So let's have a look, maybe that old huge gas filter is clogged, and that's why the bike is still dying.

I removed the old huge inline gas filter and poured the gas left inside into a cup -- there was no junk in the gas left in the filter to imply a clog in the filter.

So the old filter is not clogged up, the gas ran out of it fast, and no sediment came out with the gas. Guess I don't need to pull the fuel pump, hassle saved. I turned the old filter upside down, I shook the old filter, I tapped it hard to try to get any loose stuff that might show the old filter was clogged.

The old filter was clean as a whistle.

There's that fuel pump. "I know that sucker's clean. After all the old gas filter is spotless, so no junk got into the fuel pump."

But I had nearly exhausted all other causes of this bike suddenly dying like it still does.

I yanked the fuel pump.
I pulled off the gas line that goes from the output side of the big gas filter to the Input side of the fuel pump.

And I found a filter screen inside the inlet nipple of the fuel pump.

This little filter screen was not mentioned in the fuel pump troubleshooting steps anywhere in the manual.

I called the Kaw shop and asked if they sold this fuel pump's input screen, and was told that "the parts diagram does not even show the input screen -- the Kaw parts list shows the fuel pump as one part, as in 'No User-serviceable Parts Inside.'"





I had to remove the 4 screws on the fuel pump input side and remove that black input cap that has the input gas nipple in order to push the filter screen out of the fuel pump.

That input screen was filled -- with crystallized gas.

I'm not certain but I suspect that clogged input screen was starving the fuel delivery.

I would not have found it except for the highly indignant and rabidly vengeful state of mind I have towards this bike. It's like that hot cheerleader I thought I was dating in high school -- she was a real tease.

Well the filter was stuck solid in the fuel pump's input nipple. I pushed and it collapsed and fell apart:



This input screen is about 1" long and was 1/2 full of hardened gasoline crystals.

If the fuel pump's inlet was clogged -- that would explain why the bike kept stalling as if it lost spark in all 4 barrels simultaneously or as if the computer shut down all 4 injects simultaneously.

I really learned something here. In the 10 years the bike set, by leaving old gas in the line, the prior owner unwittingly compromised the mission of that big gas filter, which was to prevent junk from getting into the pump's inlet. By letting the bike sit so long, the gas itself became the pump's enemy.

Of course the Kaw shop said: "The fuel pump is No Longer Available and that little input filter screen was *never* available as a separate part, you had to install a new pump."


MY QUESTION IS -- where do I go from here?

I thought about putting an extra inline gas filter between the pump input and the output of the main filter to take the place of the useless inlet strainer, but the service guy at the Kaw shop warned me about 'keeping the flow rate the same.'

Any ideas? This may ONCE and FOR ALL fix my bike.

Maybe a fine brass mesh would work, roll a piece to fit and try that,if no luck use a lawnmower fuel filter as they have a good flow rate with little restriction.

Don't even think of using one of the glass bodied fuel filter as too many horror stories are told of fires being caused by the glass filter breaking.

how about some fiberglass or aluminum door screen rolled into a tube and pushed up in there?bj

Does the pump have the manufacturer's name and any numbers on it? If so, try putting all that in your favorite search engine (I prefer Dogpile) and see what comes up. I did that one time with a starter and came up with several companies that sell and service them. You never know...

Had same issue of periodic fuel starvation on Honda riding mower which persisted even after installing new "factory part" rubber fuel line (it's pre-shaped).

Discovered that the fuel line itself has a skinny pre-installed strainer-type filter inside the fuel line at the end where it attaches to the fuel tank outlet nipple (there's no petcock).

Tossed the little trouble-maker, which completely resolved the problem, and now rely solely on the much larger oem style in-line filter.

Yes, it's a carb without fuel pump involvement.

I thought about putting an extra inline gas filter between the pump input and the output of the main filter to take the place of the useless inlet strainer, but the service guy at the Kaw shop warned me about 'keeping the flow rate the same.'

A strainer is just that, and I suspect a brand new one offers very little if any resistance to flow.

Would suggest tossing the little clogged strainer and running without it.

Imo, it's the clogged little strainer that's preventing "keeping the flow rate the same."

The service guy is likely referring to inline fuel pressure.
I doubt an unclogged strainer type filter would affect the flow rate to any significant extent.

I may be wrong, but thinking it won't hurt anything to try.

Good Fortune!

TexasKZ wrote:

Does the pump have the manufacturer's name and any numbers on it? If so, try putting all that in your favorite search engine (I prefer Dogpile) and see what comes up. I did that one time with a starter and came up with several companies that sell and service them. You never know...

It says 'JECs JAPAN' and I'm glad to see I'm not the only one who has grown to like Dogpile! Been using Dogpile for years, it is the best 'mother of all search engines of search engines' around.

www.hitachi-automotive.co.jp/en/products/com/01.html

JECs got bought out by Hitachi. I could send them an email to see if they stock parts for this pump, thanks Texas for the advice there.

Meanwhile being pretty golldarned impatient to see if my hunch was right about fuel starvation, I got me one of these today at RoadRider bike shop:



Based on Patton's advice I will for now run without the pump's strainer which is KO'd and put this just outside the front door of the fuel pump. I got to talking with the guys at RoadRider and we agreed that since this was the low-pressure input side of the fuel pump, and is just gravity-fed right from the gas tank, added to the fact that this inline filter has like zero resistance when you blow into it, we agreed it will be fine as a standby for the pump strainer without causing a restriction or reduction of flow.

Tomorrow I will hook her up and then get to the injectors. I was very surprised to find so much junk in the input of the pump today -- if the gas crystalized over the 10 garage years at the pump inlet I'd not be surprised if the injectors have some too.

I don't blame the prior owner for not finding this clogged pump, despite all his effort to fix this bike. I aimed a flashlight into the pump's inlet today and saw NOTHING unusual. I had to remove the air filter, the airflow sensor box then disconnect all the fuel lines and unbolt the pump just to get at it. I put a small blade down the inlet side and pulled up a couple crystals. I kept digging and more and more came out.

I personally have never seen crystallized gasoline. It was weird looking.

After fixing the bad throttle position switch, and now this problem, for now I'm putting aside any idea that I'm home free. Could be more issues after this latest fix.

As fa r as replacing the pump, the Bosch part # should be on the outside of the casing, you will have to remove it from the mount.
The filters are a very small micron, I don't think I've ever seen them offered separate from the pump.
That said, why don't you "Bench Test" that pump? Make sure it can produce not only the operating pressure but block off the out put, briefly, and see what the dead head pressure is?It is great to be able to use an Oscilloscope, with a low amps probe and get a pattern of the commutator, but you probably don't have that.
Expect around $50-100 for a pump.
But one of the common failures is the relay, called Double Relay, as this controls both the power to the control unit as well as the fuel pump. ! side handles the pump, while the other does the Control Module.
Also possible to just be loosing voltage to the system via the main fuse, or ignition switch, etc.

Looks real close to a pump for 74-78 280Z Nissan/Datsun, which fits other models as well. It has the 90 Degree inlet fitting. You could use a pump that is "Straight" and re-plumb the inlet.

This has been a long and twisted path to find a few gasoline crystals. Nevertheless, we should all be thankful that Kawi chose Bosch instead of Lucas

TexasKZ wrote:

This has been a long and twisted path to find a few gasoline crystals. Nevertheless, we should all be thankful that Kawi chose Bosch instead of Lucas

boy HOWDY is that an understatement. My trouble was I have never even known what parts go into a fuel injection system. I had a bunch of new-to-me parts and no way to know which was more likely to fail than any other. Thus the roundabout.

On the + side I learned a lot.
Bug dang if will do the same process next time I work on a fuel injected bike thats been setting.

You know what made me never suspect the fuel pump?

1) I pushed the starter button early on to make sure the pump was working, and I always saw gas rush into the big paper fuel filter that sets behind the left sidecover. (the reason any gas was flowing at ALL is that the crystals were not 1" deep in the pump inlet, only about 1/2" deep, so *some* gas was getting by, but flow was being restricted.)

2) THAT BIG FILTER *SURELY* WOULD STOP ALL JUNK GETTING TO THE PUMP!


When it came down to my troubleshooting procedure, due to my lack of knowledge of fuel injection, I had a bunch of different parts in front of me that could be bad.

I had no way to predict which of the parts was more likely to be bad than others since I have no prior experience to draw on.

And then it was just lucky I had the gumption to extract the pump out of the bowels of the frame so I could get it where I could see into it and find the clog.

But I feel stupid about it. Because there WAS one sign that was a HINT:

- whenever the motor stalled, I got into the habit of pulling the left side cover to see if there was gas in the big fuel filter

- I noticed that sometimes, the big fuel filter had 1/4 full of gas, sometimes 1/2 full, sometimes all the way full

So what was happening was this:

1) the clog on the inlet of the pump was sometimes letting fuel into the pump but not a consistent amount

2) and every so often for whatever reason the clog tightened up and blocked the fuel into the pump

3) so the injectors got starved

4) and the suction wasn't enough to pull more gas into the big filter when the clog went to 'low flow' condition

5) that would explain why the big fuel filter would sometimes be 1/4 full, sometimes 1/2 full, and sometimes all the way full. The clogging action was intermittent.


At first I thought this behavior was either the petcock (so I pulled it and made sure it was clean). Then I figured a sharp kink in the gas line intermittently starved the filter.

After I removed the kink I noticed the big fuel filter still was not consistently full, it would go to 1/2 full, 1/4 full.

So I gave up and thought "I'll stop worrying about the fuel level in the filter there, that must just be the way the fuel system works."

But it was probably that clog on the inlet side all along. WE'LL SEE!

We feel your pain, we've all been there. Anybody who has spent any time wrenching on old bikes or cars could write a book called, "Why the Bleep Didn't I See That?"

This has been a good education for us all and I really hope this was the whole problem.

newOld_kz1000 wrote:

...Any ideas? This may ONCE and FOR ALL fix my bike.

Can you please stop saying this. Not only is it absolutely impossible, it jinxes everyone!!!

Cheers.

TeK9iNe wrote:

newOld_kz1000 wrote:

...Any ideas? This may ONCE and FOR ALL fix my bike.

Can you please stop saying this. Not only is it absolutely impossible, it jinxes everyone!!!

Cheers.

I guess I really AM learning a lot, more on this one bike than any other I've worked on.

The output side of the fuel pump is not putting out any gas.

Recall I had to remove the pump then discovered the clog on the input side. Well I had to let all the gas out of the pump in the process to avoid a huge mess.

This pump had LOTS of fuel in it -- first, a lot of gas came out of the input nipple. I up-ended the pump and waited until the input-nipple-side stopped letting out any fuel.

"Okay, pump empty" I says.

NOOOOOOO.

I then had gas coming out the OUTPUT nipple too.

I don't know why the input nipple ran dry, but the output nipple side of the pump was still full of gas.

I up-ended the pump and let the OUTPUT nipple-side of the pump run dry of gas.

Okay -- now back installed on the bike, the input side is pulling gas real good from the input fuel filter.

NO GAS COMING OUT OF THE OUTPUT NIPPLE.

Now I *know* this pump was working on the output side -- I put at least 150 miles on her or more since buying her 4 wks ago.

What is UP with my fuel pump? I cranked, I cranked and cranked the starter today, thinking 'maybe the output side needs to fill up with gas first and it just TAKES a long time because I completely emptied the pump."

Any advice?

(ever see that movie with Nick Nolte and Julia Roberts called "I Love Trouble"? that movie SUCKED.)