Vapor lock??

[zyoung]

Having issues on my '05 ZZ4 385... runs great and fuel doesn't pour out of the gas cap until it heats up. Then all hell breaks loose...

While stopped at one of our many 2-3 min stoplights here in Daytona, the bike will heat up and the fan cycles normally like its supposed to, then when pulling away the carburetor acts like its not getting any gas (it accelerates for a little bit then stops, acting like its draining the bowl in the carb) and when I make a turn (left or right), stop quickly, or accelerate quickly, it dumps gas out of the gas cap like there isn't even a cap on it.

-I have checked the overflow line and blown compressed air both through the rubber hose itself, and from the nipple up through the tank. it blows very freely.

-I am on my third set of vented gas caps... and am back to a new set of factory caps.

-I've tried running the fan constantly but it just heats up the gasoline quicker and it still vapor locks. (and dumps gas out of the cap)

-After the fuel heats up I have to switch to reserve and everything returns to normal. Except it still dumps gas out of the gas cap.

-It should be noted that a dealer put on a Napa fuel pump and when things get hot.... Anyone had an issue with this?? (even though I doubt the fuel pump would cause the fuel to run out of the top of the tank)

-The motor had a 180 fan stat switch on it I believe, and it was replaced with a 200 or 205. But I can't blame these issues on that because running the fan constantly should solve that issue. However, I've never turned the fan on from start up and left it running, only when the engine is 200 degrees and left it on from that point. Would running it from start up do any different??

-Also, it had a Big Block Radiator on it, the dealer suggested it should have a small block radiator... long story short, a new small block factory radiator was installed by the dealer in July of 2014. The issues started just about a month ago.

-After heating up and throwing a temper tantrum, not even driving 7 to 8 miles without stopping will cool the fuel down back to being able to be burned. It has to sit for a decent amount of time and cool off.

-I have one gas line that is sitting near or almost touch the bell housing..... I believe however that it is for the reserve tank. I am going to address the location of the gas lines again and make sure I'm not missing anything.

-When removing the gas cap you can physically see the hot vapor pouring out of the tank.

-It has a Carburetor Mike stage 2 quadrajet on it. Had it cleaned and gone through June 2014 (not by carb Mike). The choke has since been acting up but other than that the carb seems to be ok.

-New fuel filters July 2014.

Can't think of much else, but any suggestions would be helpful. Thanks in advance guys!!

-Zach

[Carl La Fong]

Lots going on.
First I would go back to the dealer and kick him in the nuts. A big block radiator is a common swap for small block bikes. His selling you a new radiator reeks of incompetence, greed and a lack of knowledge of basic thermodynamics. A larger radiator will not cause overheating, vapor lock, fuel dumping out of the caps, erectile dysfunction or short term memory loss. Gas pissing out of the cap sounds like a purely mechanical issue. There is a sealing problem. Are the gaskets or O rings in place and making full contact? Does your tank have a vent? Are your fuel lines tied as far as possible from the engine? It runs fine on reserve but craps out on the main tank? I'd pull the tank, remove the petcock and be sure there isn't a piece of crud that periodically blocks the outlet. I think most of the vapor lock problems are misdiagnosed. I live in SoCal and have ridden, many times, in 100 degree weather and have never had vapor lock, even with our crummy California mandated moose piss that they call "Motor Fuel"

[randy burkey]

You mentioned a line near bell housing that you weren't sure of..On my bike it has a gas tank vent line coming from a hole inside the neck of the right tank that is routed just to the rear of transmission..I assume the trikes have a similar routed vent.I would think gas should come out there instead of around gas caps..look for that line and make sure it's clear..And a big block radiator should cool a lot better than a smaller small block radiator..like Carl said..

[V-MAN]

John and Randy -

I'll jump in here to maybe help explain what Zach is trying to say, I've given him all my suggestions and I'm now standing here scratching my ass ... I'm out of "suggestions".

1) The tank is vented and the vent nipple was cleared and the vent hose was cleared (compressed air).

2) The fuel cap (Vented Kurakyn) was plugged 75%. Three of the four holes were plugged - pretty crappy QC. Barry had three, maybe four caps fail in less then a week - all Kury (falling apart inside his tank).

3) I suggested tieing the fuel lines up off the manifold and also off the bell housing to keep cooler (don't believe he has done this yet). I don't believe this would cause the issue he is experiencing with fuel pushing out the cap! The fuel if boiling should go out overflow/vent line!!

If the tank is vented then why does the cap need to be vented? If the vent is clear then why would the fuel not expand and go out the overflow ... why is it coming out of the cap?

Like I said ... I have suggested all fixes/checks I could think of. What am I missing?

[randy burkey]

The tank is vented..You do not need or want vented caps. I put on kuryakin caps and plugged ALL vent holes..Also does the fuel level have any effect on pushing fuel from tank? I know on a bike I cant fill above about 1" below filler neck because when bike is brought off side stand it will push fuel out vent hose..And I would imagine if tanks are overfilled it would push fuel out when motor heats up gas in tank..Just thinkin..

[Wild Bill]

I have owned my BH for 14 years and have traveled from Virginia to Florida for 14 years for Bike Week.

My bike runs perfectly in Virginia on 93 octane unleaded, but vapor locks every year at Bike Week. I casually spoke to several V8 dealers about this last week - everyone agrees that the FL fuel is the issue and they said that they hear of this frequently. They suggested Seafoam or Marvel Mystery Oil & said that they use it as well in their bikes.

In past years, I would use Seafoam or octane booster to solve my Florida vapor lock problem & it worked well. However, I found a non-ethanol 93 octane supply in Daytona last week & that also took care of it. I spoke to a H-D owner at those pumps last week who was in town from Ohio. He actually wrote a letter to some government agency last year to complain about this FL fuel issue.

No additive will fix the gas cap issue, but it might help you with the vapor lock temporarily until another fix is found. Seafoam additive seems to be the most frequently recommended product.

Good luck!

WB

[Iron Maiden]

Interesting thought Wild Bill but Bill and I ride all year long using 91 octane at what ever gas station is available and we have never had vapor lock. Zach and Tom, the previous owner, have also been riding in florida and this seems to be a new issue. We have to missing something. I recall a mechanic ready to pull out his last strand of hair on a V8 only to find a zip tie too tight on a gas hose. Zach any chance you recently tied up some lines/wires?

[zyoung]

So many responses! That's fantastic thank you guys.

I have not rechecked the lines under the tank to make sure the fuel lines are off of the intake. I will definitely do that soon. As far as the fuel level goes, I have always run it a little lower than the fill spout but have since started running it lower to prevent excessive amounts of fuel dumping out. I didn't add any new zip ties but that doesn't mean that there isn't one that was added July 2014 causing grief.

I really do appreciate the help with this everyone. Think it's time to pull the tank and take a look at what I've got going on under there.

I will keep you updated with my progress.

-Zach

[tjy]

We have a non ethanol station on south willamson we get gas at, Might be the way to go.

[petitemoose]

When in Daytona NEVER get gas on the Island. It's crap. Always try to fill up near 95 or inland. Can't explain why but I have never had good results with DB Fuel

[CanuckHoss]

Zach,

I have only had the issue of what you describe, the hesitation when leaving a light in warm driving, with Bigblocks...never ever a small block. And more so with a Holley than an Edelbrock.

I am with Carl on the rad change...only not quite so colourful in my words..lol

Daytona gas sucks!! I used Seafoam almost the whole time in Daytona this year. Had a couple burps and fart out of the FI low mileage trike and I am 99% sure it was fuel...Don had issues too.

I only ever get gas out the cap if I overfill and then make quick left hand turns with a trike...all the fuel goes to the right as the trike is upright versus a bike which leans left in left hand turns. Could you just be overfilling?? I can't see fuel coming up to the cap level when even 3/4 full in any kind of turn.

My carb guy will say that does not seem like a carb issue with the stalling as it is an Edelbrock style carb...fuel lines getting hot??

[zyoung]

Has to be the fuel lines getting hot. I haven't been filling it to the top since we worked on it that morning in the man cave. Next step I'd say is attacking the fuel lines. Still have the big block radiator, modifying the brackets however, could be another challenge. I don't have a welder. So for now I'll start with lines and go from there. Thanks for the help.

-Zach

[Ronald]

I have a similar problem as well, but living in South Fl never occurred to me it could be a gas quality problem, I changed my gas cap, but the gas spilling still happens but I've found out also that I'm missing like 2 gals of fuel!!, my gas tank should be 8.5 gals, when I ride on hwy, I ride hard (80-90 miles/hr), at about 100 to 110 miles, the gas level shows almost empty, when I refill, only 6 gals go in, but I'm sure the last time I got to gas station the bike was almost on fumes!! but still only 6 gal went in and it was filling up to the neck with the spilling occurring again on left turns.
The tank is vented, so now I'm just going to block the vent holes in the gas cap and see if that takes care of the problem, but my concern now is why I only fill 6 gas top instead the 8 or so gls, any ideas?
Thanks a million for the help

[V-MAN]

I have a similar problem as well, but living in South Fl never occurred to me it could be a gas quality problem, I changed my gas cap, but the gas spilling still happens but I've found out also that I'm missing like 2 gals of fuel!!, my gas tank should be 8.5 gals, when I ride on hwy, I ride hard (80-90 miles/hr), at about 100 to 110 miles, the gas level shows almost empty, when I refill, only 6 gals go in, but I'm sure the last time I got to gas station the bike was almost on fumes!! but still only 6 gal went in and it was filling up to the neck with the spilling occurring again on left turns.
The tank is vented, so now I'm just going to block the vent holes in the gas cap and see if that takes care of the problem, but my concern now is why I only fill 6 gas top instead the 8 or so gls, any ideas?
Thanks a million for the help

Ronald -

Just because the fuel gauge shows your empty doesn't necessarily mean your tank is empty ... I'm not sure how the fuel level is calculated on the newer model bikes/trikes but mine (2003 bike) was a simple float with a magnet. Each bike or trike depending on placement of magnet/float could be a little different. I suggest when your showing empty keep riding with either a back up fuel container or in a busy area with plenty of stations avail ... see what's really left. I would guess you have 1.5 - 2 gallons still avail!

Don

[Ronald]

I have a reserve tank, about 3 gal, always say will run the main tank till empty, but never dare to do so, this bike is a bitch to start when left with no gas on injectors!!
Riding back from Daytona I can swear I got to gas station on fumes, but I may be wrong, and only 6.1 gal went it, anyhow, I could also take the tank out, empty it completely and take it to gas station and see for real how many gls go in
Thanks for your input and hope to see you at Leesburg

[502wingman]

Since it is a Edelbrock carburator and you are checking your lines anyway: there is a fuel filter inside (!!!) the carburator where the fuel line goes in. The clogged filter causes some of the symtoms you are talking about. Be careful when you srew it together again, the plastic seal and the thred are easy to be damaged.

For the spilling: may your fuel pump go to reverse when hot ? Stupid, I know; just thinking. I know from other people experience that Florida fuel is often just crap.

[johnny redneck]

I had a vapor lock problem with my LS3 and mike and Maryann also with his big block, Thursday after a hard fast run up the highway from Dixie Cross Roads. It's happened 3 times to me in Florida, never though it could be the fuel, but that sure makes cents.
Johnny Redneck

[zyoung]

This particular carb doesn't have a filter in the carb. I was shocked when I didn't see one last time I had it off.

Just a quick update... just to test a theory Gina and I went out yesterday and left the fan on the entire time. Bike never got above 175 - 180. Still heated the fuel up enough that we had to use reserve to get home. Lifted the tank up yesterday and I'll be damned. Never once have I thought about the metal fuel filter..... it's sitting right on top of the intake. Was hotter than shit. Also the line that runs under the tank connecting both sides of the tank hangs pretty low and looks like it time to replace it. Getting pretty weak and rough looking. Going to replace the fuel lines directly under the tank and relocate the fuel filter to a different location. Hope this solves the issue. Thanks again for the help guys. I'll let you know of my progress.

-Zach

[Iron Maiden]

[SQ4MN]

I live in one of the hottest places in the country at certain times of the year. I got my current Boss Hoss bike in 2008 and it was at a time when 110 degrees was common, sometimes even hotter. My bike would constantly vapor lock. If I shut the engine off even to get gas the temp would rise a little and when I would leave the station the bike would sputter and quit. Back in those days it had a little stock fuel pump mounted to the bell housing. The bell housing would be way to hot to touch and so would the fuel pump. Back then Adrian was advising to use the Holley Red fuel pump so I did and I mounted it on a bracket I made behind my side cover. The same pump is still on it today and after 7 more years of some of the hottest temperatures it has never given me the slightest hesitation again. I heard that there may be better pumps now a days but the Holley Red is still doing just fine.

[zyoung]

SQ4MN. -- That is absolutely one of the roads I'm headed down. Never had the problem prior to changing it out last year after my Carter went bad. Just added it to my "Try next" list. Thank you all again for your input. Turning wrenches in the morning.

-Zach

[zyoung]

Worked on the trike this afternoon. After some bloody knuckles, $30 dollars in gas lines - filters - etc.... I think it is fixed. Going for a longer ride tomorrow but tonight during the 20 mile ride around Daytona it was running great.

Starting at the petcock, a gas line with a filter in place runs to the main/reserve switch. Which since in reserve it ran fine, everything from the switch back to the main tank was determined to be the problem.

When I took off the line to the switch and hooked it to the tank to drain it, nothing came out. Took off the filter and full flow of gas. I'll be damned, bad filter. While under the tank I replaced the cross over line between the two sides of the tank. Replaced and relocated the filters/lines that were just above the bell housing. The gas lines all looked really rough.

Hopefully the trike is all set now. Thanks again for all the input on this, gave me a place to start and I've gained knowledge from this experience.

-Zach

[Ronald]

is it working fine now?

[zyoung]

So far so good!!

[Hanginon]

So far so good!!

Hey Zach, how was your ride home Sunday?? Did the issue show its ugly face again? If so, I'll make a trip over and help you through this if needed. I'm sure it sucks. Or you can come to my shop and we'll dig into it.

Standing by,

Jim