Question about 1992 Geo Metro
After sitting for a while, it runs for a couple seconds and then dies. Only sprays fuel when it's cranking - key on, no fuel spraying and one wire reads 12V and the other open. Replaced entire top plate of the TB, so injector, injector connector, and pressure regulator have been changed. Checked EGR valve and temp sensor on the thermostat housing. Disconnected exhaust, same thing. Replaced ECU, still dumping so much fuel it floods.
This vehicle has no mass air flow sensor , it uses a MAP sensor for speed density fuel control , My self I would hook up a scan tool an see what the block learn an integrator or showing , this is same as fuel trims on OBD2 vehicles I would also look at the map sensor voltage parameter ! A bad map sensor can cause a lot of fuel to dump into the engine ! Manifold Absolute Pressure MAP Sensors
Posted on Apr 20, 2015
The ECU does all that injection. which engine 3 or 4 cyl?
the 12vdc key on, tells me the INJ resistor block, is good.
and the spraying tells me the ECU has power and is injecting
flooding has many causes. the tests are simple as is the tools to do them.. what to buy tools?
1: LOW engine compression, timing belt never changes and compression near 1/2 normal. 75psi not 150. cam is now retarded.
2: bad spark, (also now timed retarded due to #1 wrong above.
tune up time? this decade?
3: if those are ok, then and only then we attack the ECU and its inputs. (sorry cant burn fuel with no spark or dead engines)
Q1: can it start with cranking wide open throttle.?
Q2: Same as above but 5-10% throttle (right foot actions)
if yes, on Q2 then the ISC system is stuck closed.no starting air .
Q3: remove the fuel pump relay, pull it, now start engine with test fuel. it cant flood now) does it run perfect for 3 seconds and sound perfect. (it not see #1 and above using a timing light etc)
Ok it now runs on test fuel. for each application of test fuel.
when you insert the diagnostic jumper wire and crank for
5 seconds and release the key does the CEL lamp blink 12s
or other codes. if it does blink non 12s. you know why the ECU is
if it keeps flooding and the ISC is working and you have proper air flow (new filter?) to the engine. then you check the ECU inputs.
ECT read correctly ? cold? (how cold is it (alaska or key west temps)
if the EDT reads -39F (wrong) it will flood, i promise!
Dead MAP sensor.?
fuel pressure not at spec? but the pressure is 2 times normal.
if yes, bingo. the FPR is bad or the return line blocked.
what matters is pressure, not swapping parts and hoping pressure is correct.
recap. True path
keep in mind flooding is. (most cases, ill skip cam belt here....)
guessing your engine size, below is the schematic.
i have tools, and in a case like this, i do the Q1 to Q3 fast.
then check spark timing in under 5min flat.
oh my gosh, the cam belt slipped. and timing is way off.
all that in 15min and really helps , finding the true path.
Posted on Apr 20, 2015
The air flow sensor doesn't give a linear response and needs circuitry to provide correction to the output for correct fuelling. On models with a single point injection the circuit board is sometimes housed in the throttle body along with the MAF sensor.
Maybe the MAF sensor or its corrective circuitry is faulty...
If too much fuel is being injected the injector is being told by the ECU for whatever reason to inject too much fuel. Assuming the parts you fitted are correct for your vehicle and including the ECU are in good order, the ECU isn't going to inject too much fuel just for fun so it indicates it is receiving incorrect information from one of it's sensors.
An Audi/VW mechanic once told me if the MAF is faulty their engines run better with the MAF disconnected.
Posted on Apr 19, 2015
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Posted on Jan 02, 2017
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