My 98 F150 4.2L v6 has a delayed start. The time of the delay depends on the temperature of the weather. When it's 80F or higher and I turn the key to on, I can hear the FP hum for about 6 seconds.


Asked by timwell Dec 30, 2016 at 11:34 AM about the 1998 Ford F-150

Question type: Maintenance & Repair

My 98 F150 4.4L v6 has a delayed start. The time of the delay depends on
the temperature of the weather. When it's 80F or higher and I turn the key
to on, I can hear the FP hum for about 6 seconds. Then the check engine
light blinks one time, very fast. The blink is so fast, you have to be looking
right at it or you miss the blink. Once it blinks, the truck starts perfect. As
the temp. drops, the waiting time for the prime to complete takes longer.
When it's 30F or lower, I need to turn the key on and wait for up to 20
minutes before the hum stops, CE light blinks, and the truck will start. Once
it starts, the truck runs perfect, whether sitting in idle, or stomping on the
gas peddle. Before the engine light blinks, it's a crank but no start. Out of
the hundred or so "crank no start" situations I've read online, I haven't read
any of them that say anything about an extended prime time that varies
with temperature so I'm hoping by asking, someone will have experienced
this and can shorten my trouble shooting experience. As a footnote, I
bought the truck two years ago from the family of an old man that had died.
The truck had 9k miles on it when I bought it so it had done a lot of sitting
around. I now have 30k on it. The problem has existed since I bought it, but
has gone from a 5 minute wait at 30F to a 20 minute wait. The truck has a
recall on it due to corroding fuel tank straps and will be going to a dealer for
that work in a week. They said they will charge $99 for a diagnosis. After
hearing stories about dealers even screwing FP problems up and charging
k $ plus to replace them and it not being the problem, I would like to check
everything else it could be, leaving FP replacement as the only thing it
could be when I take it there. So can anyone suggest where I should begin
my trouble shooting?

5 Answers


First, bring the vehicle to a place like autozone and have any CE codes read. If the light blinks, it will set an internal code. If the key it turned to the "on" position the CE light should come on and remain on, with the other idiot lights, until the engine starts.


On a cold morning, when the condition is present, test the fuel pressure at the rail with the key is the on position. It's probably around 35 to 45 PSI if normal. Pressure should build up in a few seconds, and I do not believe the pump should run for 20 minutes. You can also check the FP relay under the hood in the fuse box if you know how, or just change it, they are not expensive.


Thank you for the response OJ. The other two relays in the fuse box with the FP relay appeared to be the same exact relay as the FP relay so I swapped each one of the other two with the FP relay and neither one of them gave me an immediate start. I take that as a sign it's good. The CE light works proper. On before start, and off upon start. It just gives that blink when it's ready to start. So would a CE at Autozone show any codes if that's the case? My local mechanic said it looks to him to be a computer problem and that I could find out from a dealer. He said if it is, 98 f150 4.2's may have a history of it, and Ford will have it on record. I also read a comment a different site saying fuel pump driver module's on Ford trucks has a history of failures. I considered dirty fuel filter and dirty pump strainer but doubt that, due to top end running when I put my foot in it. With FPDM's running around $550 for my truck, I'm hoping to find something a little less expensive before I go there...


Some codes can be stored in the computer memory for the CE light which do not keep the light lit. A check of the codes may point to a specific problem. And yes, it cam be a pcm/ecm module problem. Any auto repair shop that has a live data analyzer can test the PCM to determine if it is bad. Just ask if they have the proper electronic reading device to conduct such a check.. You may have to bring the car there and leave it, as the condition you describe occurs when the engine is cold.


Thank you for that information OJ. I'll be in the vicinity of an Advance Auto tonight. I'll stop by and see what they can tell me. And thanks for linking the PCM to the FPDM for me. I had heard reference to both and thought they were separate units. Thank God I won't be forced into a coin flip of which $500. part it is, if it comes to that. Take care OJ. I'll keep you posted.

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