TOPIC:

Kawasaki Automatic Inventory Turnover (KAIT)
detail showing "Sure-2-Fail" (tm) wiring
harness fail point

I bought a fuel injection pressure testing kit ($15 at Harbor Freight).

The Clymer manual says the fuel pressure at idle should be from 31 to 34 psi, and from 34 to 37 psi when revved.

Well, the gauge is jumping all over, the needle will not sit still but it shows up in the range called for in the manual. I'm assuming the needle jumps because:

1) the injector solenoids are opening/closing the injectors as the engine's running, thus affecting (dropping) the fuel pressure when the injector opens and sprays its shot of fuel

2) plus the darn thing does not idle at all, ie. same 'under 3000rpm rough running' issue. The rpms are not steady at idle nor when I rev it.

But I did see pressure on the dial reach as high as 40psi+ so to me that means the pump output is okay.

I want to test every other thing I can before I cut the factory seal on the air flow switch so by the time I do so, I've eliminated everything else.

Does this sound okay for fuel pressure?

If you can reach Larry Cavan, he might have some pointers about the FI system.

For me, your fuel pressure sounds correct, as mine is 33 PSI at idle going up to 35 PSI when the throttle is moved even a little.

MFolks wrote:

If you can reach Larry Cavan, he might have some pointers about the FI system.

For me, your fuel pressure sounds correct, as mine is 33 PSI at idle going up to 35 PSI when the throttle is moved even a little.

On your bike, does the needle stay in one place, ie. at idle on your bike, does the needle on the pressure gauge hit 33psi and rest there, or does it move around a bit?

It will fluctuate with normal idle and opened throttle movement as the injectors open and close like yours does.

About the only way I see to reduce the pulsations would be to install a surge tank or restrictions to the gauge.

Your fuel pressure regulator should have 3 hoses, correct? 2 fuel lines, in & out, and 1 vacuum line. Remove the vacuum line at the regulator and plug off the hose. Pressure should then be stable at the higher value.

Motor Head wrote:

Your fuel pressure regulator should have 3 hoses, correct? 2 fuel lines, in & out, and 1 vacuum line. Remove the vacuum line at the regulator and plug off the hose. Pressure should then be stable at the higher value.

Okay thanks MH, I will give that a try. It's really hard to read and make sense of the gauge with the needle jumping around by 20psi in either direction.

Also today I'm pulling the air flow switch also and I'll post pictures after I make some headway -- by the way, your youtube video mentioned that getting that cover off the 1st time is not easy but didn't show how to do it or explain it, any advice about removing the black plastic cover on the air flow switch? I think the video said to be careful the first time or you might damage the switch.

20 psi? No it should not do that! That is a problem, first if HF is close by return the gauge and get another, just to be sure. Second, do a "Dead Head Test", that is to pinch off the line some the pump makes full pressure, that should be and hold like 80 psi or close with no fluctuation. You may well have a faulty pressure regulator, again this would be available from other supplies and not just Kawasaki.
Those covers are silicone glued on, so you have to get under the lip with a Exacto knife or small razor blade and cut from the bottom all the way around to loosen it. Then while carefully prying around to get it loose. They can be broken, but normally will come up.

So if the regulator has any fuel at what is the vacuum line, it is shot, broken diaphragm, or if it jumps 20 psi it probably has a broken spring inside. This is if the Dead Head Pressure checks out.

Motor Head wrote:

20 psi? No it should not do that! That is a problem, first if HF is close by return the gauge and get another, just to be sure. Second, do a "Dead Head Test", that is to pinch off the line some the pump makes full pressure, that should be and hold like 80 psi or close with no fluctuation. You may well have a faulty pressure regulator, again this would be available from other supplies and not just Kawasaki.
Those covers are silicone glued on, so you have to get under the lip with a Exacto knife or small razor blade and cut from the bottom all the way around to loosen it. Then while carefully prying around to get it loose. They can be broken, but normally will come up.

So if the regulator has any fuel at what is the vacuum line, it is shot, broken diaphragm, or if it jumps 20 psi it probably has a broken spring inside. This is if the Dead Head Pressure checks out.

On the 'Dead Head' test, which of the 3 lines that lead to the regulator should I 'pinch off'?
In the diagram, there are 3 lines leading to the regulator:

1) to the return valve on the gas tank
2) to throttle valve
3) the fuel distribution hose

In the 'dead head' test which one of these should be pinched off to raise the pressure to 80psi?

Also,by 'pinch off' do you mean squeeze shut with finger pressure, or actually pull one of those 3 lines and block it off?

Squeeze the line with a pair of plies, tight enough to collapse the line in against itself causing blockage. You should have the gauge Tee at the point coming out of the pump going to the fuel rail, or distribution pipe they might call it. Squeeze at the point just after the fuel rail before the regulator, the pressure will rise instantly, and with the excess fuel the motor will probably die. You can Jump the pump and run the test without the motor running. The regulator is then plumbed into the return line to the tank. The small hose should be the vacuum to the throttle body/ manifold vacuum.


The inlet to the regulator is the top one, the outlet is the one on the left. Squeeze the outlet/ left one.

Here is what I have in the 81-83 FSM,

Okay, excellent that clears it up about how to run the test -- thanks MH.

My Clymer manual doesn't say this, but in your picture of your FSM, right under the "Table 9-9 Fuel Pressure" it says:

"The gauge needle will oscillate. Read the pressure at the *average* of the maximum and the minimum indications."


Sheesh I'll stop worrying about the jumpy gauge needle!
If I take the average I'm right around 31-35psi.

Now, the other thing that was happening yesterday during my fuel pressure test is the 'rough idling' symptom had returned. The motor would die so I had to keep revving the motor to keep it from dying during the test.

So if the manual says 'the needle will oscillate' under *normal* running conditions, I'm sure the fact that my motor's RPMs yesterday were jumping up and down and up and down as I tried to keep the motor running had a LOT to do with the extra-jumpy needle on my test gauge.

I have my air flow meter now and have set about testing it once more before I crack it open.

One thing I forgot to mention: I previously reported that the throttle response was sluggish, I said that I did not have a smooth increase from 1200rpm when I opened the throttle to get the bike rolling from being stopped to moving in 1st gear. There was like a delayed reaction when I opened the throttle to get the bike underway. The RPMs would not pick up as fast as I thought they should when I opened the throttle, and I had to gun it a little bit to get the revs up to slip into 1st gear. THAT IS NOW GONE.

I didn't mention that before, and I thought I'd bring it up for continuity's sake, the sluggish/delay in the throttle and the revs building disappeared after I removed that big clog from the fuel pump's intake. Little by little as I find and fix these little gotchas, this Kz1000 is becoming more and more like what we all expect a garage-kept 20,000 mile Z1 should run like.

Also, today I found and fixed a loose connection that was supplying power to the entire wiring harness used in the Fuel Injector system. After that the bike ran normal. I'm not going to say anything more than that on this one for now.