F115 starting

[Deltatango]

I have two issues with my 2003 F115 that I think may be related.
1. The engine runs really well, but over the last 12-18 months I have noticed that the number of seconds of cranking required before it fires has noticeably increased.
2. Over the last 6 months it has developed a hot start problem. The motor starts up normally at the ramp, runs well. If I shut it down once it has reached operating temperature and I shut it down, it will not restart. I can restart it if I wait a little while, this can be accelerated if I advance the throttle. This sounds very similar to the vapour separator chamber problems described elsewhere.

I've done the basics, compression test, overhauled cables, terminals, battery, new fuel, run direct from tote tank, ring free shock treatment, new plugs all without noticeable change.

Presumably need to check the fuel rail pressure? Why would this help with the hot start problem?

Engine is due for an impellor change (programmed maintenance) wondering if some small degradation in the cooling system and possibly the return fuel cooler has lead to this problem?

Thanks in advance

Phil

[TownsendsFJR1300]

When it acts up, remove the top cowl and try it.

Sounds like fumes (under the hood) may be flooding the engine (thus the added throttle helps).

[99yam40]

some motors have water cooled fuel exchangers to help with situations like this.
I have no idea if yours does, but is something to look for.

Also running motor for a few minutes at idle to cool things down before shutting off may help

[fairdeal]

Sounds like fumes (under the hood) may be flooding the engine (thus the added throttle helps).

Agreed, symptom resembles the problem on the early F150 & F225,
the gas in the VST boiling off thru the vent into the intake silencer, making for a "flooded" restart.

You might check for restricted fuel cooler passages/hoses - although I would think you would notice a reduced flow at the telltale....

I read that your milky oil nightmare turned out to be the thermostat, running cold.

Wonder if now you are running "hot"....