'88 Civic starting problem

Okay, just helped a buddy swap a new engine core (block and head - D15B2, if
memory serves) into an '88 Civic with dual-point PGM-FI. Kept the original
intake and throttle body, all wiring appears to be back where it belongs.
Engine was running before, but there was a big nasty crack down the block right
behind the #4 cylinder.

We're getting spark and compression, but no fuel into the cylinders - plugs come
out completely dry even after much cranking. Fuel pump is working, and there's
lots of pressure both before and after the forward fuel filter. Haven't checked
where the fuel line bolts to the throttle body, but I don't expect there's a
problem there either.

I'm guessing something is preventing the injectors from working (again, this is
the same intake and throttle body that was in the car and working previously).
Didn't have any time to troubleshoot it tonight, so we're back at it tomorrow
evening, so I thought I'd ask here for some pointers on where to check, what to
test, how to determine where the problem may lie - any wires to check for signal
or voltage, that sort of thing.

Thanks in advance!

 

Does the Check Engine light come on for two seconds when the key is first
turned to "II", then go off again?

Any codes stored in the ECU?

Did you reconnect the ECU ground at the thermostat?

At the bottom injector, find out which of the two wires is "hot" with the
key at "II" (the other one is grounded by the ECU when it wants the
injector to turn on). Remove the connector, and carefully hook up a
temporary connection from the hot wire to the hot side of the injector,
then ground the other side of the injector to the block or some body
ground. Does the injector now spray fuel?

 

Does the Check Engine light come on for two seconds when the key is first
turned to "II", then go off again?

Any codes stored in the ECU?

Did you reconnect the ECU ground at the thermostat?

At the bottom injector, find out which of the two wires is "hot" with the
key at "II" (the other one is grounded by the ECU when it wants the
injector to turn on). Remove the connector, and carefully hook up a
temporary connection from the hot wire to the hot side of the injector,
then ground the other side of the injector to the block or some body
ground. Does the injector now spray fuel?

 

The connector will need to be removed to do this since if the ECU is not
actively grounding the ground side, the voltage applied to the 'hot' side
will appear at the 'cold' side as well if still connected to the injector.

 

The connector will need to be removed to do this since if the ECU is not
actively grounding the ground side, the voltage applied to the 'hot' side
will appear at the 'cold' side as well if still connected to the injector.

 

Thanks, guys... I'll take these with me to the shop. I didn't do any of the
wiring re-connects so I can't guarantee anything just yet

 

Thanks, guys... I'll take these with me to the shop. I didn't do any of the
wiring re-connects so I can't guarantee anything just yet

 

Okay, buddy's testing it (I'm not at the shop, home with a tweaked back muscle
today)... he says there's no power on the injector wire. It does appear to be
grounded to the thermostat housing (he's checking if it's got a GOOD ground) but
he reads no power coming in.

He notes there's a cut read wire hanging under the intake, coming out of a
bundle along with one wire for the temp sending unit, and one for the oil
pressure sending unit. There's no indication where it should go.

And now he says it looks like the ground might be bad, so he's gonna fix that
and try again. Meanwhile, he thanks you for your help as well

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

 

Okay, buddy's testing it (I'm not at the shop, home with a tweaked back muscle
today)... he says there's no power on the injector wire. It does appear to be
grounded to the thermostat housing (he's checking if it's got a GOOD ground) but
he reads no power coming in.

He notes there's a cut read wire hanging under the intake, coming out of a
bundle along with one wire for the temp sending unit, and one for the oil
pressure sending unit. There's no indication where it should go.

And now he says it looks like the ground might be bad, so he's gonna fix that
and try again. Meanwhile, he thanks you for your help as well

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

 

Yeah? Then check here:
<http://search.ebscohost.com/Login.aspx?lp=login.asp&ref=&authtype=ip,uid>

log in with
username: lib
password: access

Click Auto Repair Reference Center from the menu at left.
Navigate to your car. There are wiring diagrams.

 

Yeah? Then check here:
<http://search.ebscohost.com/Login.aspx?lp=login.asp&ref=&authtype=ip,uid>

log in with
username: lib
password: access

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).

Thanks again...

 

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).

Thanks again...

 

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.

 

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!

 

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!

 

Say... you don't have a bunch of voltage between the engine block and the
chassis, do you? I'm just wondering how the fuel pump can drop the voltage
so much without blowing the fuse.

Mike

 

Say... you don't have a bunch of voltage between the engine block and the
chassis, do you? I'm just wondering how the fuel pump can drop the voltage
so much without blowing the fuse.

Mike

 

likewise....