Here is the saga for what it?s worth is as follows.
I installed a Yaesu FT900 in my 1991 Mazda Navajo (this is really identical
to a Ford Explorer). As soon as I fired it up and ran the car the fuel pump
noise was unbearable. It was about S7 on 20m. I confirmed it was the fuel
pump and not something else by turning the key on but not starting the
motor. The pump would hiss for about a second then stop. After starting the
engine the hiss was continuous. It was the weekend before Dayton so I
decided to wait till after I came back to tackle the problem. While at
Dayton I went into the Ford both and talked to their representative. He
said they were aware of the problem and had a fix for it under warranty but
since my truck was out of warranty all he could do is give me the number of
the Technical Service Bulletin TSB and I would have to deal with the dealer.
I called my local dealer he looked up the TSB found the part number and had
the part waiting for me. $20 bucks later I had a fuel pump relay. This did
not seem right so I went to the service dept and had them look up the TSB.
They printed me a copy and I discover that this TSB referred to an audible
clicking noise but nothing about RFI. I remember a post on this reflector
about this problem so I searched back and sure enough I found it. Ford?s
Technical Service Bulletin, TSB-93-15-6. They offer a fuel-pump filter that
installs in the tank, right next to the in-tank fuel pump. The part number
for the filter is F1PZ-18B925-A. Some small trucks have TWO fuel pumps --
one in each tank.
I went back to the service dept and they looked up the TSB. It referred to
RFI noise and almost every Ford product since 1990 and gave a part number
for a filter to be installed in the fuel tank in series with the fuel pump.
I ordered the part for $60 from the parts dept. A week later it came in. I
proceeded to take the tank out of my truck. This is not an easy task and if
you haven?t worked on cars all our life you might not want to even begin. At
57 it is getting harder and harder for me to crawl under and do this but I
did. It was not an easy task and hours later with many cut knuckles I had it
on the ground. In the process I managed to bust the old fuel pump. I had the
manual but it failed to describe how to take off the lines with the new
clips. So $160 for the new fuel pump, I put it all back together and you
guessed it. NO IMPROVEMENT AT ALL!!!!! I then tried a shorter ground. Maybe
a slight improvement. I tried a .01 across the leads to the pump it got
worst. I tried a .1 it still was worst.
I tried 10 turns of wire on a powder iron core in the positive lead no help.
Then I wound 10 turns of both leads around the core (common mode) and the
noise just about disappeared. I wound another in series with the first and
it was gone. I used an Amidon T-200-6 core. It would probably have been
better with a ?2 core but I didn?t have one.
I have talked with a guy who said the filter from Ford fixed his problem but
he had a metal tank mine is plastic. I know of another friend with Ford van
and the dealer installed the filter and it helped some. I talked to another
ham on the air who said he replaced the Ford pumps with Lucas or some other
English pump he wasn?t sure and cured the noise that way. I think Ford
solved this problem on one of their cars and thought it was done. If you
own a late model Ford with an in the tank pump be ready for some
experimentation. I hope this helps someone.
73 Steve W8GAZ from Minnetonka MN
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