2003 f115 txrb stalls/low idle

[3RDCOASTGUY]

The Problem: Dies when going into and out of gear after its warmed up. I can launch the boat in the water, fire it up and it will idle all day long with no issue while I'm getting my crap together at the ramp. Leaving the dock shifting in and out of gear and idling is still not a problem. Once underway and cruising for 20-30 min ill throttle down and try to go under 1000 rpm`s it will begin to stall and has a long re-start. If I don't get the RPM`s above 1000 quickly it will die again. Once everything cools off the cycle starts all over again. Motors run great other than this issue.

Things I have done and changed: new ICV, new thermostat, checked TPS voltage, cleaned VST, new shift position switch (was actually bad), good fuel pressure @ key on and running. compression was 145-150 on all 4.
removed injectors and soaked and cleaned the best I could. I did what the service manual said and I could hear the clicking sound while running. This is my last ditch effort before I take it to a mechanic. Any advise or troubleshooting steps would be great. Thanks

[pstephens46]

Getting warm and running rich? Wonder if the relief valve is stuck?

[fairdeal]

throttle down and try to go under 1000 rpm`s it will begin to stall and has a long re-start.
If I don't get the RPM`s above 1000 quickly it will die again. Once everything cools off the cycle starts all over again.

good fuel pressure @ key on and running.

Won't be surprised when Rodbolt tosses off the answer to this immediately -
but I certainly am puzzled.

Idle control valve already replaced...that would have been my best guess.

Have you had the pressure gauge on the fuel rail while this was happening? that would be helpful to know of course



won't restart because the VST has run empty?

have you tried "pumping the bulb" when it is dying?


or because the engine is "flooded"?

tried advancing the throttle when trying to restart?

[pstephens46]

The vst has to be vented to the intake, right? Can't see it on the diagram. Trying to see if there is a relief valve on that line. Where ever it is. Maybe it's the iPhone. Or my eyes.

[fairdeal]

[QUOTE=pstephens46;137440]The vst has to be vented to the intake, right? Can't see it on the diagram. Trying to see if there is a relief valve on that line. /QUOTE]

top of the VST has TWO vents - of course

and yes, a "relief valve"

[pstephens46]

I saw that relief valve but does that line terminate at intake?

The child's drawing for the F150 is a little more clear with the tube with relief valve dumping into intake.

[3RDCOASTGUY]

I havnt checked rail pressure when this happens because I assumed the low idle would cause an erratic fuel pressure reading. should I still have a good fuel pressure reading regardless of how it's idling?

[boscoe99]

Is this one of those models with a stupidly simple speed density system?

Compression checks are teats on a boar hog.

[tarheel53]

Compression checks aren't ALWAYS tits on a boar ........ I've pulled many a plug and stuck a thumb over the spark plug hole while cranking ...... quick check for burnt valve, holed piston,etc ...... of course that was back in the old days working in an ESSO station ;-)

[fairdeal]

Is this one of those models with a stupidly simple speed density system?

Compression checks are teats on a boar hog.

good start on standing in for Rodbolt

[3RDCOASTGUY]

So what your saying is.......wait, what are you saying....? Teets on a boar are possibly good for a kinky boar though right? Guess I'll dole out some more cash on another tool I'll only use once😳. Sucks to be poor

[99yam40]

I havnt checked rail pressure when this happens because I assumed the low idle would cause an erratic fuel pressure reading. should I still have a good fuel pressure reading regardless of how it's idling?

rail pressure should be steady, that is what the pressure regulator is for.

Some motors pressure will spike when accelerating, but as long as RPMs are steady the pressure should be steady.
anything below spec means there is a restriction or other problems

[pstephens46]

Compression checks aren't ALWAYS tits on a boar ........ I've pulled many a plug and stuck a thumb over the spark plug hole while cranking ...... quick check for burnt valve, holed piston,etc ...... of course that was back in the old days working in an ESSO station ;-)

Esso station....brings back memories. People back in the 60s and 70s actually had brand loyalty towards fuel purchases. Dad had an Esso credit card when we lived in Charlotte.

[3RDCOASTGUY]

rail pressure should be steady, that is what the pressure regulator is for.

Some motors pressure will spike when accelerating, but as long as RPMs are steady the pressure should be steady.
anything below spec means there is a restriction or other problems

. Well, that's just it the idle is sorta all over the place. Between 6-800 rpm fluctuating before it just dies. it cranks back up every time but I have to go into gear quickly. Would a compression problem cause this?

[99yam40]

Fuel pressure should be steady, is it or is it not?

if you are moving the throttle it will very due to vacuum changes.