06 F60TLR possible vapor lock ???

[Fred Pittman]

Thanks for chiming in, Rodbolt. I'm just doing the best I can to keep my boat. If I can't make it idle at *****ing speed on the water, It's useless to me. Wifey says I've already overspent on this thing and if it won't fish it has to go....It's running with 5 lbs. pressure between the lift pump and the VST. the small filter between the lift pump and the VST is new (did the same on the old filter), The fuel hoses from the gas tank to the VST have all been replaced. The fuel filter before the lift pump is new also. All the spring clamps that Yam put on this motor have been replaced with screw clamps. It only messes up on the water, never here in the yard. You say to fix the leak/restriction between lift pump and tank? What else is there that I could possibly fix???
Thanks. Fred

[Fred Pittman]

Could it possibly be an electronic/electrical issue here that shuts down the VST pump at random?

[rodbolt17]

could it be? maybe.
but if it was then pumping the primer would have no effect.

all the primer does is reprime the vst and lift pump after maint.
if you never needed to refill the VST the primer would be unnessasary.

[Fred Pittman]

I only know I'm not imagining things... Do you know what happens when you have 8 rods out pulling crankbaits with braided line 60 ft. behind your boat in a crosswind when your motor suddenly shuts down? Anyone interested in a restored 24 ft. sun tracker with an f60 that won't *****?

[pstephens46]

Sounds like you have narrowed this down with others help. VST not getting enough fuel right? Find a master tech in your area and let em know where it stands....what are you fishing for btw?

Your time and aggravation can be assigned a dollar value as well...

[99yam40]

Only thing I can think is to put it in the water and run it until it has problems while monitoring the press and vac to see what happens.

In my opinion, If the VST stops filling then either the lift pump is not pumping or it is sucking air.
strange thing is you put a different type pump in series and it still did it.

at least you would know if the pressure stays up from lift pump or not when it dies.

If the lift pump keeps the VST filled, then it would be time to see if the HP pump is still running when the problem shows up

[99yam40]

Sounds like you have narrowed this down with others help. VST not getting enough fuel right? Find a master tech in your area and let em know where it stands....what are you fishing for btw?

Your time and aggravation can be assigned a dollar value as well...

apparently you did not read his posts. he has the fish finder on simulate while he runs the motor on dry land because he is bored as this trying to get the problem show up is taking so long

[pstephens46]

I'm sure he has a fish in mind. Never said he would catch it.

[Fred Pittman]

*****ing in Mississippi for crappie with bandit crankbaits

[rodbolt17]

did you verify the fuel cooler is functioning?
typically at high speed the VST ia self cooling by the incoming fuel.

at low speed 90% of that fuel, compressed at 45 PSI(heated) is returned to the VST.

if the VST overheats it can and will(about the only time) vaporlock and shut down.

the fuel will tend to boil in the suction side of the pump and now it pumps air not fuel or the pump locks up.

[Fred Pittman]

Thanks, Rodbolt.... I removed the hose at the bottom of the fuel cooler that tees into the telltale line and blew through it...it seemed to be clear of obstruction. When the barrel water was cold the fuel cooler temp was running cool also. As the barrel water heated up, so did the fuel cooler, always remaining a few degrees warmer than the water in the barrel and much cooler than the surrounding parts ( as much as 25/30 degrees). I think we possibly may be onto something here though. I just wish the VST was easier accessible as the ones on the Mercs.... I'm thinking now that If I use some thermal paste and exhaust pipe tape,I can tape a probe to either the side of the fuel cooler or the VST itself and attach it to my grill/smoker temp monitor and can monitor either the vst temp or cooler temp remotely from the helm and even set a temp alarm there ! My next trip to the water will be interesting for sure. I'll have vac. gauge in the inlet hose. press. gauge on the press. side of the lift pump, and temp gauge on the fuel cooler....

[Fred Pittman]

One more thing of note, Rodbolt, that may be of some importance here. I thought it rather insignificant at the time. I haven't had the boat on the water to test it since I first removed the thermostat and the thermocouple probe, but I noticed when I first removed the thermostat cover that the rubber seal on the thermostat was not seated properly around the thermostat, but the seal (at 4 o:clock position was sort of pushed outward which would possibly allow some water to bypass the thermostat. Also, possibly , for some reason, the temp alarm wasn't working until I removed the thermocouple and reinstalled it.
My line or thinking here is that possibly the out of place seal interrupting correct water flow, allowing for overheat at idle speed, alarm not functioning, allowing for higher engine temps at constant and continued idle speed possibly setting up a vapor lock situation that a few pimps of the primer could overcome ?????
I know that sounds rather far-fetched but for sure something weird is going on here and we're gonna find out just what it is.... Thanks for the help....Fred

[rodbolt17]

it is rather farfetched.

but the cooling system MUST work at peak efficiency or the VST can overheat and the fuel boil.

remember at low speed the lift pump pumps very little fuel.
any minor airleaks will result in no fuel.

myself I would take it to the river,idle it while monitoring lift pump pressure and rail pressure.
running on muffs or barrels will be a boring waste of time.

[Fred Pittman]

Do you see a problem with my splicing the schrader valve adapter into the high pressure line and leaving it there permanently? I can tuck it in so it won't rub against anything when the cowling is in place. Will use high pressure band type clamps instead of regular screw type hose clamps....I can't afford to buy that $142 adapter....

[Fred Pittman]

OK, guys...I took the boat out this morning for one last run with the cowling on. Cranked right up and ran great, all speeds, then I slowed it down and ran at 1500RPM's and it stalled and died after 10 minutes. Quick pump up of primer bulb and it fired, up, ran for 3 minutes, then died again. Pumped it back up and ran it back to the trailer. Planning to go back to the water tomorrow with cowl off. It's sitting here holding 10 lbs. pressure in the line between the lift pump and the VST with no sign of a fuel leak around any fitting. ( not running)....
I've plumbed in a fuel pressure gauge into the high pressure line feeding into the rail, and have a vacuum gauge inline between primer bulb and engine. Should know something tomorrow....Fred