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Old 18 Aug 2006, 01:17 am
Matt Ion
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Posts: n/a
Default Re: '88 Civic starting problem (SOLVED maybe)

TeGGeR® wrote:
> Matt Ion <soundy@moltenimage.com> wrote in
> news:v3REg.410737$iF6.53449@pd7tw2no:
>
>
>>TeGGeR® wrote:
>>
>>>Matt Ion <soundy@moltenimage.com> wrote in
>>>news:vINEg.420523$IK3.280117@pd7tw1no:
>>>
>>>
>>>
>>>
>>>>He's GOT a Haynes manual for this thing, which he can't find... i'm
>>>>SO much more useful with a good wiring schematic in front of me
>>>>
>>>
>>>
>>>Click Auto Repair Reference Center from the menu at left.
>>>Navigate to your car. There are wiring diagrams.

>>
>>Sweet, thanks!
>>
>>Meanwhile... he's determined there's no power to the injectors. Ground
>>is good, but no signal into them. Waiting to see if he'll actually
>>bother to check the ECM codes (I sent him the link from your FAQ).
>>

>
>
>
>
> Power to the injectors is from the line that comes from Terminal 7 of the
> Main Relay. The fuel pump and the injectors receive power from the same
> basic source, so the trouble is probably a disconnected wire between the
> Main Relay and the injector harness.


Well, I actually got my hands on the car this afternoon and, with the help of
the schematic (you ARE the man!), I think I found the source of the problem: the
fuel pump is for some reason sinking TONS of current and causing the voltage
throughout the car to drop excessively.

Specifically: checking voltage at the injectors, I get only about 8.5V while
they're activated, and closer to 5.5V when cranking. Voltage *at the battery*
drops from about 12V to just barely over 8V for a few seconds as soon as the key
is switched to Ignition, then jumps back up to 12V, nicely coinciding with the
brief time the main relay switches on the pump and injectors. Connecting jumper
cables to my running car, thus providing 14V to the system, allowed the car to
ALMOST start as system voltage dropped to about 9.5V with ignition on, and 8.5V
while cranking - it tried to catch a few times, but just couldn't quite fire up.

After a little more tracing, I ruled out the injectors and internal wiring
problems... looking at the schematic, there are only three things on that
circuit - the two injectors and the fuel pump - so I figured either there was a
"near-short" somewhere in its wire (a dead short would have blown the fuse), or
the pump was having issues... as it turned out, unplugging the pump lead got rid
of the strange voltage drop.

So I'm thinking the pump probably has bad bearings or sleeves, or is badly
gummed up, or in some other way is being prevented from turning freely, and thus
is drawing excessive current, enough to drop the system voltage too low to
operate the ECM and/or injectors, but not enough to pop the related fuse.

Lordco was closed by this time, so my buddy's gonna pick up a new fuel pump
tomorrow... but he'll be installing it on his own, as I'll be down at the
football game!

Hopefully that takes care of things... I'll let you know!
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