-- 1998 F-150 4.2 V6 with 96,000 miles.
-- Plugs and wires changed 9 months ago.
-- No arcing seen in dark under hood

Problem:

On two occasions, once in early December and once in mid January, the truck wouldn't strart when I went to leave first thing in the morning. It would turn over fine, but just wouldn't start. After about ten minutes the truck started, sounded crappy (missing) for about 10-20 seconds then ran just fine with no problems.

On about 3 occasions during that time the truck wouldn't start on the first try, but then would on the second or third try. It would then run a bit rough for about 5-10 seconds then would run fine.

Last week drove through an automatic car wash and after passing through the rocker panel / underneath spray, truck gets a slight miss and does so for about 1-2 minutes while in the car wash, then returns to normal.

About a dozen or so times in the last year the truck starts fine but has a slight miss for about a block or so of driving from my house after starting it first thing in the morning.

All problems listed above seem to happen when it is damp outside. Doesn't happen all the time, and rain doesn't seem to affect it, unless there is a high content of moisture in the air.

I want to find out what the problem is now that I have had two occasions that truck would not start (for at least 10 minutes), so I can prevent the problem from worsening.

Any and all suggestions concerning what the problem may be are greatly appreciated.

Thanks,
Steve

 

When's the last time you replaced fuel filter?

 

The fuel filter was changed between 3 years ago at 45,000 miles. If it was the fuel filter, wouldn't the problems I am having be less intermittent? The problems I am having don't happen very often, but happen enought for me to feel the need to investigate further.

Thanks,

Steve

 

First thing I would do is change the fuel filter. Three years ago at 45,000mi, now you have 96,000mi. That's 51,000 miles, WAY overdue! Start with the simple maint. things.

 

Thanks,
I'll try that.

Steve

 

That would be the most obvious thing to start with regarding the engine being hard to start. Missing after the car wash was most likely caused by moisture with water being sprayed from underneath.

 

I am not familiar with the 4.2 but there have been many instances where a crank sensor failure has caused this intermittent starting problem on the 4.6 and 5.4 engines. If your truck has a crank sensor then replace it. They do not cost much and this has fixed the problem many times for others.
I say this because the discriptions like "only happens some times, only when cold, only when hot" seems to be the norm