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Discussion Starter #1
Hi All,


A couple weeks ago, I was riding to work and the bike shut off. Was dripping gas out of the carb. Would run, but only 1/4 throttle or above.



I tore it apart, and replaced the needle/seat with an All Balls racing one. New gasket, etc. I decided, given mine is a 2003, this would be a good opportunity to ditch the fuel pump. So I bought a new 3/" fuel line, took one of the thin heat shields off the other lines and ran it from the petcock, across the top of the motor to the carb inlet. Used about 18" of fuel line. I'm a little worried about the fuel flow when I get down to reserve level, but we'll see.





Well I took it for a ride, it was fine for about 10 minutes, then it started cutting out and actually died. I was doing about 70mph, when I pulled the clutch in, it died, I let it out, and obviusly it would bump start again. I pulled over, and all I could find was the vent hose from the right side of the tank was unplugged. I plugged it back in and decided I'd try and limp it home (about 10 miles). It ran fine. So I then went for broke, got back on the highway for 10/15 miles and kept the rpms up (trying to burn fuel in case the bowl was going dry). Never hiccuped.



There is about a mile long steep grade and I went Wide Open in 5th from before the hill through the top, she runs out of steam at about 105/110, but she didn't buck, sputter, or cut out in the least. It was a solid mile WOT, and if there was a restriction



Could the unplugged vent from the back right of the tank caused some sort of positive pressure or something in the tank causing fuel to not flow with gravity? I can't explain why it did what it did, looking for some insight.
 

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Vent plugged or unplugged should not cause any issue unless a bug went into it.
Verify the vent is functional.

18" hose over the engine.?!??

It is 10" from the fuel petcock to the back of the air box.
From petcock due east aka right then dropping to carb inlet.

It would seem that you took the long route.
Try the more direct route.
 

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Discussion Starter #3
Vent plugged or unplugged should not cause any issue unless a bug went into it.
Verify the vent is functional.

18" hose over the engine.?!??

It is 10" from the fuel petcock to the back of the air box.
From petcock due east aka right then dropping to carb inlet.

It would seem that you took the long route.
Try the more direct route.

Thanks for the help. I'll remeasure just to be sure. Is this how the fuel line was routed from the factory on 2004+ bikes?

How can I verify the vent is functional?
 

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More than likely it is functional or you would not have ridden that long after..

Put a piece of hose on the vent tube and then:: blown into it or suck fumes from it.

Look at the 2004 parts fiche for the fuel hose. The fuel port faces to the back so a 90 degree turn there.
Since 2003 fuel port faces engine it should go across and downward to the carb.
 

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Discussion Starter #5
More than likely it is functional or you would not have ridden that long after..

Put a piece of hose on the vent tube and then:: blown into it or suck fumes from it.

Look at the 2004 parts fiche for the fuel hose. The fuel port faces to the back so a 90 degree turn there.
Since 2003 fuel port faces engine it should go across and downward to the carb.

That's how mine is routed, but I'm definitely running out of fuel. I can almost repeatably get the bike to bog out and die, if I'm in 5th gear and go WOT for more than 10 seconds, it's like the bike is pulling more fuel than gravity can fill the bowl.


This is a theory, because it only repeatably does it in 5th gear with a long throttle open. I can run 15 miles on the highway in 3rd gear doing 75/80mph and it doesn't phase it.
 

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I did a fuel flow check once many years ago on the vacuum petcock. The gasoline stream was as large as the ID of the fuel port.
IF you have a good fuel flow than vent should be good. Fuel cap latched in place. Test it!

I had limited top end when my slide valve diaphragm had too many holes in it.

Has the fuel tank been sealed/coated??

Did you disconnect the FP relay???
 

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Discussion Starter #7
I did a fuel flow check once many years ago on the vacuum petcock. The gasoline stream was as large as the ID of the fuel port.
IF you have a good fuel flow than vent should be good. Fuel cap latched in place. Test it!

I had limited top end when my slide valve diaphragm had too many holes in it.

Has the fuel tank been sealed/coated??

Did you disconnect the FP relay???


I don't have a vacuum petcock. The 2003 came factory with a fuel pump and a standard petcock. So I routed a new line from the standard petcock, straight to the carb.

There is a vent on the back side of the tank where it tapers down, on the right side. How would you like me to test it?

I don't think the tank has been sealed or coated. It was a brand new tank from Honda 3-4 years ago. I didn't have this problem when the fuel pump was connected. I saw many people talk about getting stranded with them when they died, and for the $300-$400 replacement and the pain in the as* they are to change out, I figured while I had everything apart it's good preventative measure.

I traced the two wires coming from the fuel pump, and I disconnected one of them. I figured that would prevent it from running.


I've had the diagpram off a couple of times in the past few months, there wasn't a single hole/tear/slit it in.

I don't have a limited top end. If I hold the throttle open in 5th for a 1/2 mile or so, (even if I start at 60mph and let it slowly wind up, the bike get to a point where it just spits and sputters. Its the same thing if you turn the petcock off and run the gas out. There's some restriction or "vacuum/pressure/blockage" from the change of the new fuel line causing it.
 

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I know about the FP and manual petcock.
I have been telling every 2003 1300 owner about this for years.
Just saying what my fuel flow looks like.
Did you ever remove the petcock?

Remove the fuel filter.
It has been proven that some fuel filters do not work on gravity flow.
Thinking about this last night and remembered someone tried a fuel filter. It did not work on gravity flow.
A filter made for gravity flow is suggested, not one used on a FP.

https://www.vtxoa.com/forums/7-vtx-1300-riders-board/353330-fuel-filter.html#post3773706
 

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Discussion Starter #9
I know about the FP and manual petcock.
I have been telling every 2003 1300 owner about this for years.
Just saying what my fuel flow looks like.
Did you ever remove the petcock?

Remove the fuel filter.
It has been proven that some fuel filters do not work on gravity flow.
Thinking about this last night and remembered someone tried a fuel filter. It did not work on gravity flow.
A filter made for gravity flow is suggested, not one used on a FP.

https://www.vtxoa.com/forums/7-vtx-1300-riders-board/353330-fuel-filter.html#post3773706
I don't have the fuel filter connected. I had bought a 3/8"line from the store, and ran 12/13" from the 2003 petcock to the carb. Last night, I took it all apart and checked for a kink in the hose. While I didn't find one, it's a softer type of rubber hose than the factory style hose. I could pinch it with my fingers. So I took one of the hard rubber factory lines, cut it to length and ran it direct from the petcock to the tank.

It seemed better, but bike does buck a little WOT in 5th, but there's definitely an improvement. Obviously it's kind of hard to test WOT in 5th gear on public roads safely, but I coudn't get it to do it on reserve, and it only happened last night on On.

So maybe there's a problem with the fuel filter in the petcock, or maybe it's a pressure thing. I'm not sure.
 

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Replace the gas tank petcock. There is a screen inside and when I removed mine it was corroded and falling apart. With the new petcock the motor has more pep. That was my fix.

G
 

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Discussion Starter #11 (Edited)
Replace the gas tank petcock. There is a screen inside and when I removed mine it was corroded and falling apart. With the new petcock the motor has more pep. That was my fix.

G

I'm thinking at least replacing the screen. It's listed as a separate part. My tank was replaced 3/4 years ago, I assume they would have replaced the screen at that time, but who knows. The previous owner is a good friend of the family, I'll have him look at the old tank and see if the old petcock is there.

I can't see a petcock screen getting plugged up in 4 years, but maybe they didn't replace it...


Maybe my petcock is misaligned, what I mean is, maybe in the "ON" position, maybe it's not fully open, preventing full flow. I guess I can drain the tank, remove it and take a look.

God this bike it's just one thing after another.
 

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Discussion Starter #12
Replace the gas tank petcock. There is a screen inside and when I removed mine it was corroded and falling apart. With the new petcock the motor has more pep. That was my fix.

G

So I took the line off the petcock last night and put another line onto it, into a bucket, the flow is fine. There is no discernible difference between the flow rate from RES vs ON.

When the fuel level gets lowers, approx 1.4/1.5 gallons, sure, it flows a little slower, but it's still a solid stream.

So I think I've ruled out the petcock screen as far as a culprit. I don't have a big enough Metric open end wrench to get it out (my set stops at 20mm) so I also put a mechanic scope into the drained tank and looked, and the filter is white, and there is no sign of rust/heavy corrosion.

Obviously the scope can't pick up on debris, but the flow rate shows there's not a big clog.

I can't honestly say if this was happening when I had the fuel pump attached or not, it only happens when I run WOT in 5th. I'm guessing it didn't, but if the 2004+ bikes didn't have a fuel pump, there has to be a fuel delivery issue here. But the line runs direct from the petcock, across the top of the engine, right to the carb. It's not pinched or restricted anywhere.


There seem to be quite a few threads from back in the day about this happening. Bikes bucking, sputtering, or dying out at WOT Was there ever a mainstream fix?
 

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Discussion Starter #14
>>>> Provide links>>>There seem to be quite a few threads from back in the day about this happening. Bikes bucking, sputtering, or dying out at WOT Was there ever a mainstream fix?


What about the strainer in the carb hose fitting??
2003 parts fiche shows it..
30 SCREEN, FUEL STRAINER 16176-MW3-A80

https://www.partzilla.com/product/honda/16176-MW3-A80?ref=2cf5dc919d3620e3b1d977dc181a558e76d3ae06
Here's two threads:

https://www.vtxoa.com/forums/7-vtx-1300-riders-board/451377-not-just-another-cutting-out-w-o-t-post.html


https://www.vtxoa.com/forums/7-vtx-1300-riders-board/316801-bike-cuts-out-heavy-throttle-2.html?amp=1

My 2003 didn't have that fuel strainer. I looked very carefully when I first took the carb out. I haven't put another one in. The parts fishe show it, but the 2003 had an inline filter under the seat before the fuel pump too, I don't know if they were actually there.
 

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Unscrew bowl drain screw.
You are using the manual petcock, check fuel flow from carb bowl.

Usually when the Main tank fuel runs out I get a lean out pop.
If I pay attention I can hear the difference as it starts running lean.

About 3 weeks ago I forgot that I changed to trip B. I felt it running rougher and gave it throttle.
Squirt from accelerator pump was good for a few milliseconds but loud fat backfire from dry main jet.

105/110 MPH, VTX speedo or GPS. GPS than that is about it... Out of HP
 

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Discussion Starter #16 (Edited)
Unscrew bowl drain screw.
You are using the manual petcock, check fuel flow from carb bowl.

Usually when the Main tank fuel runs out I get a lean out pop.
If I pay attention I can hear the difference as it starts running lean.

About 3 weeks ago I forgot that I changed to trip B. I felt it running rougher and gave it throttle.
Squirt from accelerator pump was good for a few milliseconds but loud fat backfire from dry main jet.

105/110 MPH, VTX speedo or GPS. GPS than that is about it... Out of HP

Unscrew drain screw and what? Check for debris?


As I noted above, I did check fuel flow from the tank. Same strong steady flow "ON" or "RES".

That's 105/110 indicated on speedo. I don't think it's the speed. It's the 6/7 Seconds in 5th gear at WOT that's causing the problem. No other gear can I hold it open that long. But in 5th, I can start at 70mph and romp on it, and hold it there. It's like I'm sucking the fuel bowl dry. I don't trust the bike to ride very far, like commute to work, etc. (I don't want to have a problem and be late to work).

This weekend, I'll take it out and ride it around normally, get on it, etc. I don't expect the bike to be a race bike, and I know 6/7 Seconds at WOT in 5th really isn't what this bike is designed to do. My fear, is this is a symptom of a problem that might get worse, and i'd rather fix it now.
 

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Discussion Starter #17
Just wanted to bump this thread.

I'm starting to wonder if I either need to re-connect the fuel pump, OR get a vacuum actuated petcock. Maybe the vacuum line to the petcock helps "suck" the fuel through the hose under high load engine situations and prevents the carb bowl from running dry.

But $100 for a petcock, or $100 for a new fuel pump, I mean it's kind of a what do I do situation.
 

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It doesn’t
Then why does my bike run out of fuel in 5th at WOT without the fuel pump?
Don’t know.
But I DO know the vacuum petcock doesn’t help “suck” fuel. The vac just opens a plug. It’s a safety thing. That's it.

I have been running a vacuum-less petcock on mine for 10 yrs. no issue.

Have you pulled the petcock to check the screen, checked the diaphragm with a bright light behind it?

Could also be non fuel related, corroded common electrical ground at front coil can cause the bike to cut out.
 
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