f150 vapor lock kit ?

[biglars57]

I have a 2005 F150 that I acquired two years ago that has always started hard when warm after sitting, which I have confirmed from rail pressure (or lack thereof) is from vapor lock. I found a vapor lock kit on ebay for $400 and bought it last week. (I actually looked on boats.net for the kit but couldn't find it) After acquiring the bulletin related to the kit/repair I have found out the the kits for 04 and 05 motors are different as the ECU is different from 04 to 05. All other parts are the same.

Anyone know what changed in the ECU from 04 to 05 and if the 04 ECU would work in the 05 motor? And does the canister without the updated ECU do any good?

I have learned that Yamaha is now supplying the kits for the 04 and 05 motors for over a grand........so if this one would work I'd give it a try.

In going through the bulletin it looks like the canister provides some back pressure to the VST which I believe restricts the vapors from escaping??? Not sure what had to be changed in the ECU.....but I would think the canister without the ECU should do some good.

Thanks

[boats.net]

Need to take it to your local Yamaha dealer, it may be covered under warranty and not cost you anything.

[biglars57]

I called Yamaha and my dealer and both said that the motor is too far beyond the warranty for Yamaha to fix the problem.

I've heard different explanations...........but what exactly happens when there is vapor lock in the f150s?? My motor starts fine when cold, but after it's been run for a while and shut off it can be hard to start. Is there back pressure to the pump in the VST??

[boats.net]

When shuts off the engine heat increases and gas begins to boil causing air voids in fuel supply.

[rodbolt17]

also vapors from the VST are vented into the air box.
this will create an excessivly rich mixture.
thats what the canister and vapor shutoff valve is for.
if by slightly opening the throttle helps hot restarts then you need the vapor kit.
EFI engines rarely have vapor lock issues as the vapor seperator is just that and the rail is under pressure.

[biglars57]

The last time we used it I put it on the lift and let it sit about 15 minutes, and then tried to start it and it wouldn't fire right up. I did advance the throttle about half way and turned it over for a while and that didn't work. I put it back in top center neutral and cranked for a while and it eventually caught on one cylinder, sputtered a bit and then ran fine.

I know in looking at the instruction bulletin for this kit that the vst is vented to the canister instead of the intake, and a second hose from the canister is hooked up to the ISC. So there must be some fumes from the ISC that they want vented also.

I have two F115s (about 2003 vintage) on a boat down in FL that due to ethanol issues I got pretty familiar with changing VST and injector filters. I have run that boat a lot and never had a problem starting the F115s when warm. I know the intake/VST on the F115s is on the port side and the intake/vst on the F150 is on the starboard, but other than that the intake/VST and plumbing to injectors looks very similar. Is there more heat on the starboard side of the F150 that causes this problem to occur?

I'm still a bit confused on this..........is the VST heating up and "boiling" all the fuel out of it's bowl and then being empty not able to feed fuel to the rail?? Or is the heat causing a rich/flooded situation that something in the computer may be making worst?? Because if it's the VST running dry I don't see how this kit could fix that??

Thanks for all the replies - Dan

Also....Rodbolt17, you mention a "vapor shut off valve"........what/where is that??

[Popeye4949]

biglars I have the same problem with my 2005 150f. Could you post a link to the bulletin. This problem just started this summer. If I let it sit for 15 mins or so it usually starts right up, however it appears to be getting worse. I have just over 130 hrs on this motor.

Thanks

[biglars57]

biglars I have the same problem with my 2005 150f. Could you post a link to the bulletin. This problem just started this summer. If I let it sit for 15 mins or so it usually starts right up, however it appears to be getting worse. I have just over 130 hrs on this motor.

Thanks

I had a dealer email it to me, so if you want to PM your email to me I can send it. I never found it on Yamaha's site.

[rodbolt17]

lets look at vapor lock.
vapor lock is fuel boiling in the lines.
typically associated with carbed motors.
fuel under a vacum tends to boil at lower temps.
however the inverse is true.
fuel under pressure has a raised boiling point.
thats why we dont see vapor lock with EFI systems.
that VST holds about 1-1.5 qts of gasoline.
the pump is submerged in it.
the rail is under pressure.
however the VST IS vented to the intake manifold on older engines.
this can lead to an overrich hot start.
open the throttle too far and it shuts the injectors off,flood clear mode,thats why the vapor shutoff valve and the carbon cannister,just like the automotive world, came to be on outboards.
before you jump on the internet bandwagon spend some time studying how and why things work.
makes troubleshooting much easier.

[biglars57]

"before you jump on the internet bandwagon spend some time studying how and why things work."

Not sure what you meant by that, but I can assure you that being an engineer by training, I have researched this issue much more than I would like.......but I will add that when reading your responses to other Yamaha outboard questions, your replies have demonstrated a deep knowledge of these outboards.....so I am appreciative of your expertise and willingness to share it.

I currently own 3-F250s, 2-F115s and 1-F150. All of these motors are fuel injected by similar VSTs, pumps and injectors, but the F150 is the only motor that demonstrates this problem. And as I know the F115s vent their VSTs to the aribox also, I'd simply like to know what's different about the F150 that causes this problem, given I burn the same fuel in all the motors?

You mentioned the vapors causing an overrich hot start, but the repair bulletin from Yamaha for this problem states: "Cause: High ambient temperatures coupled with highly volatile fuel may cause a lean condition during warm engine starts". (direct from the bulletin)

I called Yamahas technical assistance line and the technician told me he was very familiar with the Vapor Recovery kit. As we were discussing my motor he told me to check water and fuel fllow through the cooler......and asked how old was my gas...etc...etc...and I could tell he was telling me that I had an old motor. I finally just asked him........"in brand new 05 and 04 motors that had this problem, that this kit was designed to fix, just exactly was the condition that caused the motors to not start.....and he said he didn't know.

So please excuse me if I seem ignorant and am beating a dead horse......but after I spent a couple grand on the F115s having a mechanic change VST filters that I now can easily change myself....I'd like to understand what this problem is before I drop another grand+ at the local Yamaha dealer....the same dealer that when I asked about this kit/problem, they didn't know it existed.

Thanks - Dan

[rodbolt17]

then lets go back to what EXACTLY vapor lock is.
if the fuel boils in the rail something got way hot.
easy to check with a fuel rail pressure tester.
boiling fuel will raise fuel pressure at engine shut down.
let it sit and watch the gauge.
then turn the key on and pressure should return to normal.
when you turn the key OFF you should hear the ISC reset to 100% in anticipation of the next start cycle.
a sticking ISC or a missadjustment of the link and sync,or carbon in the shutter bores will also cause a hot restart issue.
I have installed a few of the kits.
never saw the vapor lock.
have seen overrich intake conditions cause hot restart.
thats why the later model engines use a vapor shut off valve.
this valve routes VST vapors to the cannister at engine shut down by closing of the VST to intake vent line.
at engine restart the valve is held closed for about 20 seconds the gradually opened to allow the vapors to be removed from the cannister and burned through the intake.
dont have an engineering degree,
do have an equivalent in the US Navy's electronics program for an associates in electronics.
but it doesnt hurt that I also have about 30 years experience in the marine and automotive field.
only time I have ever seen what may be considered a vapor lock is when the VST fuel cooler clogs.
typically that complaint is stalling after extended *****ing.
fuel will boil in the VST at low speeds but typically enough fuel is being replaced at high speeds to keep the VST cool enough to operate.
this applies to mercruisers,volvos and all other non return to tank liquid cooled vapor seperators.

[biglars57]

Thanks for your replies Rodbolt17........I'll do a bit more testing with my fuel pressure gauge to see how the pressures act over a longer period of time.

I have probably read every post you can find on the internet related to F115 VSTs and F150 vapor lock. And quite honestly the reason I posted on this site was the responses and advice you have given on the posts I've found was clearly the best I'd seen and it was obvious that you have a lot of experience with these outboards!! So as I stated before I am very appreciative of your willingness to share what you know!!

[rodbolt17]

on the F150
listen for balancer whine.
and when it stumbles at off idle throttle up, there is a cure.