Fuel pump issues

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Fuel pump issues

Postby helix2 » Sat May 11, 2019 5:43 pm

1998 Honda Helix 16,000 miles. Was running great until I went to start it one day and it would not. Starter turns, has fire at the plug, I could tell I was not getting gas to the carb. Removed the line at the carb, engaged starter and no fuel coming from line. Plenty of fuel in tank. I rode the bike the day before. Line from tank to fuel pump not blocked. I then tried the test in the manual. I jumped across the wires and went straight to the battery. Pump worked and put out plenty of fuel. It will not pump with the starter engaged. All fuses good.

What am I overlooking?

Thanks
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Re: Fuel pump issues

Postby birdmannn101 » Sun May 12, 2019 4:46 am

helix2 wrote:It will not pump with the starter engaged. All fuses good.

What am I overlooking?

Thanks


Are you sure that you checked the 5 amp fuse in the glove box?

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Re: Fuel pump issues

Postby zozman » Sun May 12, 2019 5:42 am

Blocked fuel filter or line?


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Re: Fuel pump issues

Postby helix2 » Sun May 12, 2019 6:50 am

Thanks for the replies. Yes, I did check the fuse in the glovebox. I replaced it with a new fuse just in case. I wondered about a blocked fuel line as well. When I hooked the pump up manually, I left all lines in place. I only removed the line going to the carb. When hooked straight to the battery, it pumped fuel out of the tank like normal.

What is it that "tells" the pump to work? It seems like when I bypass the systems, it does work. Maybe bad CDI? The funny thing is, when everything is hooked up, I can spray a little start fluid in the carb and it will run. I just can't get gas to the carb.

Still working on it, thanks for all suggestions.
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Re: Fuel pump issues

Postby zozman » Sun May 12, 2019 8:50 am

More troubleshooting:

1. Unscrew the gas cap.
2. Pour a small amount of fuel into the cylinder, install plug and attempt to start. If the engine starts, but stops soon, you may have a faulty fuel pump. (just because it pumps fuel, doesn't mean it is pumping the volume and flow rate it should). There is a flow test in the manual (20-10).
3. Find the ICM (Ignition Control Module. Rap the ICM with the butt head of a screwdriver as you attempt to start the scoot. What happens?

Report back your findings.


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Re: Fuel pump issues

Postby helix2 » Sun May 12, 2019 12:06 pm

Thanks for the help first of all. I tried the tapping on the CDI box and it did not help. No fuel coming out of the pump. I also tried the pump test listed in the manual and it seems to be pumping correctly, but only when hot wired straight from the battery. It will hit and run on starting fluid. One other thing that just happened, as I was cranking it the 5 amp fuse blew in the glovebox.

How does the connector come loose on the CDI?

Thanks again
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Re: Fuel pump issues

Postby zozman » Sun May 12, 2019 1:04 pm

helix2 wrote:... I also tried the pump test listed in the manual and it seems to be pumping correctly, but only when hot wired straight from the battery... as I was cranking it the 5 amp fuse blew in the glovebox....


Run the test on the starter relay for possible short.


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Re: Fuel pump issues

Postby helix2 » Sun May 12, 2019 1:33 pm

I happened to have a new starter relay. Tried it and no luck.
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Re: Fuel pump issues

Postby zozman » Sun May 12, 2019 7:35 pm

Next step: Change out the ICM (Ignition Control Module).

There is no fuel pump relay. The fuel pump is usually controlled by the ignition control module. When it is switched on will provide current to the fuel pump so that it may function. A faulty ICM may be sending erroneous signals to the fuel pump. Any faults with it can cause issues with the fuel pump, which can cause startability problems for the scoot.

We keep changing stuff until we find the culprit.


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Re: Fuel pump issues

Postby Phil » Sun May 12, 2019 8:50 pm

Sounds like it could possibly be a ignition control module. I would also check to make sure the fuel pump has a good ground. And then back track the positive wire going to the fuel pump as far back in the electrical circuit as possible with a digital volt meter on the continuity checker setting. Just to make sure there isint a broken wire or a short.
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Re: Fuel pump issues

Postby GrahamH » Mon May 13, 2019 9:14 am

Suggestions on how to trace the fault…...

If the engine will run by using starter fluid then power must be getting to the coil. The Black/yellow wire to the coil should be connected to the fuel pump BL/Y. A continuity test here would be useful or simply add a jumper wire from coil to fuel pump.

The white/green wire at the fuel pump looks to be connected to the fuse (among other connections) again perhaps try a jumper wire directly from fuse to fuel pump.

And of course a third jumper to ensure the green earth from the pump goes to a good earth.

There is a connector just before the fuel pump with W/G, BL/Y and G going in but with an additional BL wire coming out to the fuel pump. This wire I believe should be connected to the W/G. Maybe a jumper across the fuel pump terminals will have the same effect.

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Re: Fuel pump issues

Postby Dan_Lockwood » Mon May 13, 2019 9:41 am

helix2 wrote:I happened to have a new starter relay. Tried it and no luck.


Lots of good suggestions thrown out on this for you.

Here's another one. JUST to make sure it's not the fuel pump, check for voltage to the power lead on the fuel pump when cranking. If no power then as others have said, back track the wiring until you find you have power when cranking. If you track the output from the ICM for the fuel pump and it's dead, that's a clear sign the ICM is faulty. If you get power from the ICM for the fuel pump, than track in the direction of the fuel pump until you find the drop point.

This all just takes time and as I understand, some of the wiring is not easy to follow due to harnesses etc.

Good luck and let us know what you find to fix your issue.

Have a great week!
Dan

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Re: Fuel pump issues

Postby zozman » Mon May 13, 2019 10:17 am

Here's another....

Check for proper ground. The main ground is on the frame left side of fuel tank behind your left foot heel as you sit on the scooter.

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Re: Fuel pump issues

Postby scootcat » Mon May 13, 2019 11:34 am

Hey this is good read, thank you so much !
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Re: Fuel pump issues

Postby helix2 » Mon May 13, 2019 7:40 pm

Latest update. I will check the ground but I am in agreement that it could be the CDI. I tried the test the manual said and these are the results; Checking the wires with the key and shutoff switch as per manual checks good, exciter coil check on the CDI 50-250 ohms reads 100 ohms. Ignition pulse generator check on the CDI 50-170 ohms reads 0 ohms.

I'm guessing at this point that the ignition pulse generator side of the CDI box has control of telling the fuel pump to pump?

Thanks to everyone for the responses. Great forum that I hope I can add to!!! I will make a check of the ground but feel like a new CDI is in my near future. It will take a few days to get, but I will post the results.
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