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Discussion Starter · #1 · (Edited)
2007 VTX 1800F lose power when hot, Please Help!

Hi, I purchased a 2007 VTX 1800F Spec 3 a month ago. It only has 4K miles. I love the bike but I have run into an issue I can not figure out:

Shortly after the bike gets hot from riding, the bike lose power above 3000 RPM's on all gears. At 3000 RPM's in neutral, give the bike some throttle and the bike seems to choke to idle RPM range but experiences a horrible idle: sputtering, popping, jumping...... Release the throttle and the bike idles clean and throttle clean up to 3000 RPM's.

If I allow the bike to cool for a little, this behavior stops for a short period until the bike heats up again.


I have tried to recreate this behavior by letting the bike heat up in from cold to start in idle but it only happens when the bike heats up under power.

Other things I have noticed: The bike reeks with the smell of gas after it runs.


I cant get the bike to stall and I haven't been able to get any error codes from the bike. This model doesn't carry oxygen sensors or a fuel pressure regulator.


I initially thought the fuel pump may be failing but I would like to be sure about that before I spend $400 on an OEM pump for this bike. I haven't performed a fuel pressure check because this behavior doesn't just happen on the bench.


Has anyone had this problem or know what it may be?
 

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Welcome to the board!
Take a few minutes to familiarize yourself with the forum. At the top of every board there are threads that are tagged as "Sticky" These threads are "Sticky" because they contain very important/valuable information about the VTX and everyone should read them.
The thread at the top of the 1800 tech board called, "Air, Fuel, Motors..." will answer most of the performance questions...
http://www.vtxoa.com/forums/73-how-...motors-missives-article-updated-1-3-06-a.html


Bookmark or save to your favorites folder, these websites, http://www.vtxoa.com/forums/73-how-step-step/
This is the NEW VTXOA Garage, a sister site to this message board and contains all your How-to/Tips/Tricks/Why’s and links to other helpful sites for your new VTX. http://www.bareasschoppers.com/ A fellow VTX Riders site that has many write-ups on “How-To” do work on the VTX.

There is also a helpful Search icon in the users Toolbar just under the VTXOwners Association banner

Click the “Advanced Search” button

Now, click "Search Single Content Type" and add you keyword to search
Select 1, and only 1 "Forum" to search in at a time, or at all.
For example, "Best airbox" I would only search in the "1800 Tech Board"

That's the basic way, you can limit further by using some of the other "Drop-Down" menu's like if you know the thread you are looking for is only a week or so old, etc....

The purpose of the "Search" is to offer a member the opportunity to research his/her question better. There is so much information from past threads that you may never see because that member is no longer here, or doesn't see your new post, or just won't respond to the same question. So use it to your advantage and enjoy the board! View this funny and informative film about posting and searching…
How To Use This Forum, Click Here

Also, update your Profile to include where you live and what type X you have to your Signature line. I.E. 1300/1800/C/F/N/R/S/T
 

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Check the coolant level at the radiator cap on the thermostat housing.
The ECT maybe showing Hot to the ECM so the ECM is putting into Limp Home Mode. You should pull codes from the ECM. I was trying to get a link from Bares pages. Web hosting place had "Gateway error"..
http://tech.bareasschoppers.com/resources/ecu-error-codes-vtx-1800/

Reseat the ECT connector, it could have oxidation from sitting soooo long.
31MB download of an early service manual. Engine is the same. You have 2nd generation ECM and TS flasher.
circuit. Same engine fault codes.
http://dl.dropbox.com/u/6530962/Bike Stuff/Honda VTX1800 RS 02-03 Service Manual ENG By Mosue.pdf
 

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Discussion Starter · #5 ·
Diagnostic Results

I attempted to pull fault codes just as described in the manual, the same steps shown here: http://tech.bareasschoppers.com/reso...odes-vtx-1800/

* There where not any fault codes stored on the ECM.

* I checked the coolant level which was OK. I also did a manual check to make sure the thermostat isn't getting stuck. I let the bike sit in idle for a while and warm to normal operating temperature. While warming I touched the top radiator hose, If the hose become hot quickly, the thermostat is stuck open; This didn't happen. During the check, the top hose did not feel hot, but it did start to warm; This could mean the thermostat is stuck closed. I'm not sure if I let the engine heat long enough and I didn't run it enough to get it into the "limp" mode. I'm going to perform this test again before I pull the thermostat out for a bench test.

* While I had the seat off, I decided to check and make sure the MAP sensor was not the issue. The "limp" mode definitely seams as if the fuel is not being commanded as it should. This test only opened up more questions....... The results MAP sensor circuit test makes it seem like I have a short somewhere, and I cant get any output voltage from the specified ECM wire harness connectors (B7+ and A22-) during the MAP sensor performance test. Anything below 2.7 volts cause for a replacement of the ECM.

Before I dig too deep into trouble shooting the MAP sensor, Im going to reassemble the bike, run it until the the "limp" mode begins, then make a judgement call about the thermostat and move on from there.
 

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Discussion Starter · #6 ·
Diagnostic Results

I attempted to pull fault codes just as described in the manual, the same steps shown here: http://tech.bareasschoppers.com/reso...odes-vtx-1800/

* There were not any fault codes stored on the ECM.

* I checked the coolant level which was OK. I also did a manual check to make sure the thermostat isn't getting stuck. I let the bike sit in idle for a while and warm to normal operating temperature. While warming I touched the top radiator hose, If the hose become hot quickly, the thermostat is stuck open; This didn't happen. During the check, the top hose did not feel hot, but it did start to warm; This could mean the thermostat is stuck closed. I'm not sure if I let the engine heat long enough and I didn't run it enough to get it into the "limp" mode. I'm going to perform this test again before I pull the thermostat out for a bench test.

* While I had the seat off, I decided to check and make sure the MAP sensor was not the issue. The "limp" mode definitely seems as if the fuel is not being commanded as it should. This test only opened up more questions....... The results MAP sensor circuit test makes it seem like I have a short somewhere, and I can’t get any output voltage from the specified ECM wire harness connectors (B7+ and A22-) during the MAP sensor performance test. Anything below 2.7 volts cause for a replacement of the ECM.

Before I dig too deep into trouble shooting the MAP sensor, I’m going to reassemble the bike, run it until the the "limp" mode begins, then make a judgment call about the thermostat and move on from there.
 

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