Subject: [Spridgets] Airtex Fuel Pump

From: Tim Collins via Spridgets <[email-masked]>
Date: Mon, 1 Oct 2018 11:19:35 -0400

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I recently completed an autopsy on an Airtex Products fuel pump ((E8016SM,
although the picture below shows a different number). This pump failed on
me a few miles from home. I knew it was the pump because the thumpty,
thumpty sound stopped. After about 15 - 20 minutes I tried to start the car
& the thumpty, thumpty sound was back and the car started. The pump lasted
until I was about 6 houses from my home in the subdivision.

I put the pump in new in 2008 and hadn't run that many tanks of gasoline
through it. I first suspected that the pump had failed because of alcohol
laced gasoline & corrosion. However, I found absolutely no evidence of fuel
related problems. The plunger still move freely in it's bore and the
one-way-valves operated freely. No visual evidence of gum or off color
deposits. I use Shell Premium.

During the autopsy, I uncovered the circuit board and coil within the body
of the pump. Since there was no evidence of gasoline contamination, that
just left "electrical" as the problem. All the "innards" are "potted" in a
rubber like substance. Around the circuit board it could be pried out with
a knife and pick tools. The rubber around the coil is rock hard. Could it
be that the heat from the coil vulcanized or cured the potting material?

I could identify a MOSFET transistor (IRF540) which is a fast switching
transistor. I suppose it is the transistor's job to switch the electricity
in the coil so that the plunger is attracted first to one end of the bore
and then to the other, collecting some gasoline in the process to shove
along to the carbs. There is another chip, 8 legs on it, but I couldn't
find any ID markings. I suspect that chip controls the timing of the
switching. (Could be a 555 chip??). The rest of the components are standard
resistors, capacitors, & diodes.

Since everything is potted, there is very little opportunity for cooling to
take place other than the heat carried away by the gasoline which would be
the primary cooling agent. I assume the coil generates a fair amount of
heat. The coil has a measured resistance of 2 ohms. By applying 12 volts to
just the coil (not through the circuit board), the plunger made one stroke
through the coil. So, amazingly I didn't damage the coil winding while
picking rubber out of the fuel pump & and I could rule out the coil as the
root problem - unless there is some weird heat related problem in the coil.
My money is on a circuit board failure.

So, what lesson did I learn? Apparently nothing since I replaced the bad
pump with the same make and manufacturer - hoping that the first pump was
just a fluke with a bad/weak part. And I will continue to use Shell premium
gasoline. Time will tell. . .

Tim
ps: sorry if this is a second copy of the note. My mail program says the
first try wasn't sent.

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<div dir=3D"ltr"><div class=3D"gmail_default" style=3D"font-size:large"><di=
v class=3D"gmail_default" style=3D"font-size:small"><font size=3D"4">I rece=
ntly completed an autopsy on an Airtex Products fuel pump ((E8016SM, althou=
gh the picture below shows a different number). This pump failed on me a fe=
w miles from home. I knew it was the pump because the thumpty, thumpty soun=
d stopped. After about 15 - 20 minutes I tried to start the car &amp; the t=
humpty, thumpty sound was back and the car started. The pump lasted until I=
 was about 6 houses from my home in the subdivision.</font></div><div class=
=3D"gmail_default" style=3D"font-size:small"><font size=3D"4"><br></font></=
div><div class=3D"gmail_default" style=3D"font-size:small"><font size=3D"4"=
>I put the pump in new in 2008 and hadn&#39;t run that many tanks of gasoli=
ne through it. I first suspected that the pump had failed because of alcoho=
l laced gasoline &amp; corrosion. However, I found absolutely no evidence o=
f fuel related problems. The plunger still move freely in it&#39;s bore and=
 the one-way-valves operated freely. No visual evidence of gum or off color=
 deposits. I use Shell Premium.</font></div><div class=3D"gmail_default" st=
yle=3D"font-size:small"><font size=3D"4"><br></font></div><div class=3D"gma=
il_default" style=3D"font-size:small"><font size=3D"4">During the autopsy, =
I uncovered the circuit board and coil within the body of the pump. Since t=
here was no evidence of gasoline contamination, that just left &quot;electr=
ical&quot; as the problem. All the &quot;innards&quot; are &quot;potted&quo=
t; in a rubber like substance. Around the circuit board it could be pried o=
ut with a knife and pick tools. The rubber around the coil is rock hard. Co=
uld it be that the heat from the coil vulcanized or cured the potting mater=
ial?=C2=A0</font></div><div class=3D"gmail_default" style=3D"font-size:smal=
l"><font size=3D"4"><br></font></div><div class=3D"gmail_default" style=3D"=
font-size:small"><font size=3D"4">I could identify a MOSFET transistor (IRF=
540) which is a fast switching transistor. I suppose it is the transistor&#=
39;s job to switch the electricity in the coil so that the plunger is attra=
cted first to one end of the bore and then to the other, collecting some ga=
soline in the process to shove along to the carbs. There is another chip, 8=
 legs on it, but I couldn&#39;t find any ID markings. I suspect that chip c=
ontrols the timing of the switching. (Could be a 555 chip??). The rest of t=
he components are standard resistors, capacitors, &amp; diodes.=C2=A0</font=
></div><div class=3D"gmail_default" style=3D"font-size:small"><font size=3D=
"4"><br></font></div><div class=3D"gmail_default" style=3D"font-size:small"=
><font size=3D"4">Since everything is potted, there is very little opportun=
ity for cooling to take place other than the heat carried away by the gasol=
ine which would be the primary cooling agent. I assume the coil generates a=
 fair amount of heat. The coil has a measured resistance of 2 ohms. By appl=
ying 12 volts to just the coil (not through the circuit board), the plunger=
 made one stroke through the coil. So, amazingly I didn&#39;t damage the co=
il winding while picking rubber out of the fuel pump &amp; and I could rule=
 out the coil as the root problem - unless there is some weird heat related=
 problem in the coil. My money is on a circuit board failure.=C2=A0</font><=
/div><div class=3D"gmail_default" style=3D"font-size:small"><font size=3D"4=
"><br></font></div><div class=3D"gmail_default" style=3D"font-size:small"><=
font size=3D"4">So, what lesson did I learn? Apparently nothing since I rep=
laced the bad pump with the same make and manufacturer - hoping that the fi=
rst pump was just a fluke with a bad/weak part. And I will continue to use =
Shell premium gasoline. Time will tell. . .</font></div><div class=3D"gmail=
_default" style=3D"font-size:small"><font size=3D"4"><br></font></div><div =
class=3D"gmail_default" style=3D"font-size:small"><font size=3D"4">Tim</fon=
t></div><div class=3D"gmail_default" style=3D"font-size:small"><font size=
=3D"4">ps: sorry if this is a second copy of the note. My mail program says=
 the first try wasn&#39;t sent.=C2=A0</font></div><div class=3D"gmail_defau=
lt" style=3D"font-size:small"><font size=3D"4"><br></font></div><div class=
=3D"gmail_default" style=3D"font-size:small"><div><img src=3D"cid:ii_jmqftf=
ac0" alt=3D"P1070446S.jpg" width=3D"562" height=3D"422"><br></div><div><img=
 src=3D"cid:ii_jmqftph61" alt=3D"P1070457S.jpg" width=3D"562" height=3D"422=
"><br></div><div><img src=3D"cid:ii_jmqftyus2" alt=3D"P1070475S.jpg" width=
=3D"562" height=3D"316"><br></div><div><br></div></div></div></div>

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