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Discussion Starter #1
I have on '03 VTX1800S, all stock (now). Last year my bike started cutting out on me. It started out feeling like an occasional miss. They became more frequent and longer duration over time as I tried to (unsuccessfully) find the problem.

- I tried switching the coils but the problem didn't seem to move.

- I replaced plugs, but it remained.

- The ground fix had been done prior to me owning the bike, but I cleaned and regreased the connections at each coil and the battery.

- The start switch has seen some heat in the past, but has a relay wired in now so the main power is going around it.
- It had a fuel injection controller on it, so I disconnected it. When I wired things back up, the bike ran fine, so I thought the problem was solved.


Earlier this week, it missed twice on the way in to work but otherwise seemed fine. It was substantially worse when I left for home. About halfway home it was running on only one cylinder. When I got home I pulled all the grounds and checked them. After reconnecting them it ran great. I rode to work and back the next day...it ran fine until about a 1/2 mile from my house on the way home when it missed once. I started it this morning and it was missing like before and within 100yds of leaving my garage it was back to one cylinder.



+ The key difference between this year and last is that I have no FI light this year, whereas before it would light up when it missed.


Any ideas what I should check?
 

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Check your oil level and smell. The Fuel Pressure Regulator or FPR, is a known fail item that fails due to age, not mileage. When these fail, too much fuel gets into the combustion chambers and the excess fuel washes down teh cylinder walls into the engine case. Change the FPR, change the oil and ride around the block, then change the oil again.

Here's a link on How To change the FPR;
https://tech.bareasschoppers.com/carbs-fuel-injection/vtx1800-fuel-pressure-regulator/
 

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Open and clean the connectors under the seat and left side cover and check your wiring if you used vampire clips to connect your fuel controller.
 

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Does the FI light come on the the fuel prime takes place???

Starter switch >> the heavy load is the headlight.

Did you check the Ground wire at the Brake Pressure control valve?

Check this>> https://tech.bareasschoppers.com/tech/melted-main-wiring/

While there, do the part to pull error codes. https://tech.bareasschoppers.com/resources/ecu-error-codes-vtx-1800/

Previously when the FI came on, were there any speedometer issues??

Vampire clips score the wire strands which will break at some time. Check carefully.
 

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Not that this is your issue but my 05 1800F started acting poorly like it was missing about every 1/3 stroke. The end result was very poor power. I took it in to get it fixed and the battery tested bad even though it showed the correct voltage. I ended up replacing it and the problem was gone. Something to consider...
 

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Discussion Starter #6
Wouldn't a bad FPR be accompanied by a declining fuel mileage? The exhaust certainly smells like fuel...I'll check the oil.


The FI2000 that was installed by the PO did use the vampire clips. I already checked the ground connections, but I'll look for broken wires as well.


The battery is new last year and has been maintained on a tender when the bike is parked.


No speedometer issues with the previous instance. FI light comes on during the prime (when all the other lights come on as well) but shuts off immediately after priming is complete and does not flash any error code when idling. No FI light when it misses or when I'm limping along on one cylinder.

I mentioned the start switch only because it is a known point on my bike where a bad connection may exist.
The two pin plug under the left side cover is in good condition.

I am unaware of a "ground wire at the brake pressure control vale." Can you point me to where that is?
 

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Check the TPS connector next to the throttle body. Mine was cutting out on exceleration. I cleaned & put a little di-electric grease on it and it's been fine for the last two years.

Sent from my SM-J337V using Tapatalk
 

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I had this problem in the past. Turns out the problem was the way my "power commander" was connected to the main wires using "vampire clips". Over time the vampire clips frays the ignition wires and causes the problem. I removed the vampire clips and connected the wires using connectors. I had to first splice in and short piece of wire to replace the frayed wire.
 

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Discussion Starter #9
Oil smells clean.


Throttle response seems fine to me...except for one cylinder not firing...and the problem occurs throughout throttle positions (idle, midrange, and high speeds). When the problem occurs, increasing or decreasing RPM has produced no change in behavior.


I'll try to check wiring tomorrow and see if I can pull any codes.
- Last year it didn't give me any, not really expecting any now, but I'll be in the area when inspecting the wires.
 

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Verify the injectors are functional.
12-13 ohms.
Better yet +12v and ground. I would pull ECM connector for test and listen for the injector click.

Black/White wire from the ESR (Engine Stop Relay) provides +12v to all FI devices when energized.

Wire colors on the ECM drawing.
 

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Discussion Starter #11 (Edited)
Verify the injectors are functional.
12-13 ohms.
Better yet +12v and ground. I would pull ECM connector for test and listen for the injector click.

Black/White wire from the ESR (Engine Stop Relay) provides +12v to all FI devices when energized.

Wire colors on the ECM drawing.

P/Y to Bk/W = 12.4

P/Bu to Bk/W = 12.9

I hear clicks on both when I power them.



It doesn't flash any error codes when the plug is jumpered, just a solid "all clear".


I left the bike at idle and tried to move the wires (where the FI2000 had its vampire clips) in every direction and it didn't produce any change in the way it ran, so I'm inclined to believe the wires are still okay.


Is there a way to confirm whether the FPR is good/bad...other than buying one and seeing if it makes a difference?
[Edit: found the writeup (https://tech.bareasschoppers.com/carbs-fuel-injection/vtx1800-fuel-pressure-regulator/) I'll confirm tonight.]
 

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Discussion Starter #12
No fuel from the vacuum line on the pressure regulator.


Used a timing light to check if the coil pack might be dead but. of course, it chose now to start running well again.


Anyone have any other ideas?
 

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Check your spark plug wires for corrosion. Remove them from the coils and take them apart on both sides and clean the contacts. Also check the wires that run to the coils where they are attached to the connectors. Your problem must be electical.
 

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Discussion Starter #15
When checking my connections, I discovered that the spade terminal on my coil has an extra wire...I have a normal Bl/W on the one and both the normal Y/Bu and an extra solid blue wire on the other. I'm not sure yet if it's related to my problem. I'll try to trace it tonight or tomorrow.


The PO installed an aftermarket cruise control, but it seems unlikely to me that that would tie in directly at the coil.
 

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Depending on the type of cruise the wire very well may run to it. I would say check the plug wires, the wires running to the coil and ground to the frame at that coil. Glad you are making progress.
 

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A (nearly) rupture of one of these tiny wires of the ECM can cause a cutting out of one cylinder. Look very carefully.
My VTX-1800 C of 2002 (about 87,000 miles) had recently 7 blinks of the MIL when the engine was warming up.
It happened to be a broken wire of the ECT-sensor. In order to be sure, I replaced the sensor as well.
I hope you can find the cause of your problem.
 

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0530 and awake.... Why?? Intermittent, difficult to find faults.
One case, 1800, a rider had problems, somehow a seat was putting pressure on the cable harness. May have been shorting on a harness clip.
Two cases - 1800 intermittent loss of a cylinder. One was blowing fuses intermittently, the other lost a cylinder.
Both were found to at the fuel injector pigtail where it comes out of the cable harness.
There is a frame/harness cable clip that cut into the wires.
Inspect carefully... Open the clip if you can, add additional tape.
 
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