Hey @Tamir check the pressure while cranking, it will give an exact data.
I have a FAST Pressure Drop in the Fuel Hose 2 sec After Switch ON (Engine OFF) - It's Normal OR Problem?
An Updating
The answer: This is a problem!
The Normal Situation: After 2 seconds, and if you do not start the engine, the pressure drops ONLY to 38PSI. From here a very slow pressure drop continues which takes an hours. Even after a few hours the pressure still maintained and above 10PSI.
In case the pressure drops in a minute to O(PSI), engine off, it means there is a fuel leak in the system.
In my case the leak was internal, from the pressure relief valve (located inside the fuel tank, part of the pump structure), a leak back to the fuel tank. A leak from the pressure relief valve is a hidden leak, a leak that cannot be smell or seen or heard it.
The repair required a NEW pump-motor and NEW relief-valve.
Usually the entire pump will be replaced as a set (16700-KYJ-901).
For the rest of the details click here:
www.cbr250.net
Thank you for your help and support!
====================
I have a problem, a difficult in engine starting.
Usually I only get good starting in the second try.
I checked the parameters of the fuel pump:
1. The pressure in idle is 43PSI, which is OK.
2. I checked the fuel flow in 10 seconds, on and off five times in a row (2 seconds each time), the volume: 200 ml, when the minimum required is about 70ml, so that is also OK.
Oddly, in Haynes book and Honda technical book, both do not mention a drop in pressure before starting ( 2sec After Switch ON). It is a problem?
I was taking a video, and that's how my "problem" looks like:
I found the Partzilla excellent video (link below):
Another excellent video[Rocky Mountain ATV MC] that explains how to test the fuel pump I found at the following link :
According to this explanation, starting at 5:20, I have a problem with the one-way valve.
In the CBR250R there is a one-way valve on the fuel line?
And there is also this great video [Ignite Moto] that explains how to disassemble and assemble our fuel pump (CBR250R):
Where is MY problem and what to do to fix it?
Thanks!!!
The answer: This is a problem!
The Normal Situation: After 2 seconds, and if you do not start the engine, the pressure drops ONLY to 38PSI. From here a very slow pressure drop continues which takes an hours. Even after a few hours the pressure still maintained and above 10PSI.
In case the pressure drops in a minute to O(PSI), engine off, it means there is a fuel leak in the system.
In my case the leak was internal, from the pressure relief valve (located inside the fuel tank, part of the pump structure), a leak back to the fuel tank. A leak from the pressure relief valve is a hidden leak, a leak that cannot be smell or seen or heard it.
The repair required a NEW pump-motor and NEW relief-valve.
Usually the entire pump will be replaced as a set (16700-KYJ-901).
For the rest of the details click here:
I have a FAST Pressure Drop in the Fuel Hose 2 sec...
An Updating The answer: This is a problem! The Normal Situation: After 2 seconds, and if you do not start the engine, the pressure drops ONLY to 38PSI. From here a very slow pressure drop continues which takes an hours. Even after a few hours the pressure still maintained and above 10PSI. In...
www.cbr250.net
====================
I have a problem, a difficult in engine starting.
Usually I only get good starting in the second try.
I checked the parameters of the fuel pump:
1. The pressure in idle is 43PSI, which is OK.
2. I checked the fuel flow in 10 seconds, on and off five times in a row (2 seconds each time), the volume: 200 ml, when the minimum required is about 70ml, so that is also OK.
Oddly, in Haynes book and Honda technical book, both do not mention a drop in pressure before starting ( 2sec After Switch ON). It is a problem?
I was taking a video, and that's how my "problem" looks like:
I found the Partzilla excellent video (link below):
Another excellent video[Rocky Mountain ATV MC] that explains how to test the fuel pump I found at the following link :
In the CBR250R there is a one-way valve on the fuel line?
And there is also this great video [Ignite Moto] that explains how to disassemble and assemble our fuel pump (CBR250R):
Where is MY problem and what to do to fix it?
Thanks!!!
1 - 20 of 30 Posts
An Updating
I switched to an OEM new fuel pump motor, No Change: After 2 second switch ON, there is a dramatic drop in the fuel pressure, until it reaches to zero.
I checked the parameters of the NEW fuel pump:
1. The pressure in idle is 42PSI, which is OK.
2. I checked the fuel flow in 10 seconds, on and off five times in a row (2 seconds each time), the volume: 145 ml, when the minimum required is about 70ml, so that is also OK.
Is this a problem? OR this is how it should to be ???
![44808]()
I switched to an OEM new fuel pump motor, No Change: After 2 second switch ON, there is a dramatic drop in the fuel pressure, until it reaches to zero.
I checked the parameters of the NEW fuel pump:
1. The pressure in idle is 42PSI, which is OK.
2. I checked the fuel flow in 10 seconds, on and off five times in a row (2 seconds each time), the volume: 145 ml, when the minimum required is about 70ml, so that is also OK.
Is this a problem? OR this is how it should to be ???
I have not found any information in Honda's technical literature. Thanks for the encouragement. You also understand that there should be no pressure drop (switch ON, engine off). I'm was not sure I'm was looking for a real problem, so the problem is real, OK. I was replacing all O-Rings in the pump structure, but did not investigate with a magnifying glass if there a crack in the plastic structure ...
Well, now as your advice, I will check the fuel injector, and we will see what I will find there. Thanks!!!
Updating
I made a tool and I will wait 24 hours for the glue to dry ...
P.S. To allow accessing to the screw it was necessary to remove the IACV as well.
I do "actuating the injector", I intend to give the injection a 9V battery voltage.
Yes, a good thought
.P.S. For that test you need to catch the injection with a zip tie.
The execution got a little complicated for me. The IACV needs to be removed so that the injector screws, the on screw "up", can be accessed. So I took IACV out. When IACV was outside, I assembled everything except two connectors:
1. The fuel injector.
2. The IACV.
And like this the computer did not supply voltage to the fuel pump. At this point, when the injector was in my hands, I preferred to clean it.
Updates
So I cleaned the injector, it was not dirty, nor did it appear to be leaking.
And before final assembly I tried your offer again, this time
1. The fuel injector full Connected.
2. The IACV NOT Connected.
The experiment was successful
, the injector does not leak, BUT still, immediately after those 2 seconds a fast pressure drop begins.See the video attached below:
Thanks!
DannoXYZ a drop in pressure before starting, 2sec After Switch ON, engine OFF, It is a problem???
Yes, a good thought
.
Hey @Tamir my bike rpm also goes up to 2000rpm sometimes in normal whether condition and sometimes when I park the bike for couple hours it again takes some time to settle down like cold starting (to ~1400rpm which is specified in service manual).
As you have checked the wires and there is no short circuit to ground or themselves, so connection is OK. I'm attaching the IACV diagnosis procedure in case if don't have,
![44817]()
And I'm sure that will be OK, but still checking it few times can eliminate the fact that 'there might be chance that it get stuck sometimes'.
And at last I'm still confused about the sudden pressure drop result.
As you have checked the wires and there is no short circuit to ground or themselves, so connection is OK. I'm attaching the IACV diagnosis procedure in case if don't have,
And I'm sure that will be OK, but still checking it few times can eliminate the fact that 'there might be chance that it get stuck sometimes'.
And at last I'm still confused about the sudden pressure drop result.
Don't worry about pressure when engine is OFF. Measure pressure when you push START button. What is that pressure?Thanks!
DannoXYZ a drop in pressure before starting, 2sec After Switch ON, engine OFF, It is a problem???
Yes, a good thought
The whole idea of preliminary pressure, is to assist to starting, because the pump takes a few seconds to build up pressure. If you wait more than 2 seconds(After switch ON) and the pressure drops till zero, then all the "preliminary pressure assist" no longer assist, and the engine starting is more difficult.
There is no information about "preliminary pressure assist" in Honda Technical Book (Or in the Haynes Guide). I know that the pressure should be maintained (TO assist...), there should be a one-way valve that keeps the pressure from falling until the moment the ignition button is pressed.
See the video here.
starting at 5:20
But perhaps low-volume motorcycles like CBR250R do not have a one-way valve?
I ask because I do not know
???The START button activates the pump and the pressure rises.
When my engine is running the pressure is stable and normal 43PSI
1 - 20 of 30 Posts
