Question about 1996 Geo Prizm
Fuel pump act like it went out
cranks perfectly, full cranking speed, not 1 rpm but nearer 300.
ever do the 60k tuneup in the book.?
assuming the service was done and all cyl. are over 150PSI (WOT)
then we check spark first, not fuel..
The ECU brain cuts fuel (by design) any time spark is gone.
here is the proper flow:
1: throw, wild guess?, compression is good,. cam belt slip??????
is cam shaft turning,? look down oil fill hole. is it?
2: i check spark it's bad. (fix spark)
2a: i check spark its good', on all 4 cylinders not just 1.
3: spark was good. cam spins, pray compression is ok....
4: i connect scan tool, i crank for 5 seconds and see RPM rise ,good
i see ECT at say 50f (garage temp) and might see DTCs get thrown as i crank? , i see P0340 or p0355 ( one is dead CKP and other is CMP)
in my case no DTC thrown cranking , and i have spark and ECU
communicates. (key point) we alway s do that ,the tool is $9 (ask)
5: i then look at spark tips, they are:
1: soaking wet, its flooded, (spark was good but they are 10 year old.
2: dry, no fuel all spark tips day.
your engine has 4 cylinders, and all four most not flood or run dry.
i can listen to any cold start and hear gross misfire. but.....
if they are bone dry, i check voltage to the fuel pump.
it must be 12vdc cranking , 1/2 the cars you must crank. to get the pump to run ,(ECU hard logic!)
say I have 12vdc cranking
i check he fuel pressure, its not 30psi, its 5 psi (bad)
i rap the side of the fuel pressure regulator and it now is 30psi.
car starts. the reg was stuck wide open(its bad)
ok, still no start. or good pressure. Good is 30.
let say it was 60psi, i find i forgot to replace my dirty and packed up fuel filter
at the 60k mile service point. ( did i save $10 ? , no)
pretend filter is good..... pressure way low.... (examples)
so i read my FSM and it shows this shunt test, i then block (pinch)
the Fuel return line at the Fuel press. regulator.
i see 60psi, the pump is good. (do only for 5seconds ) (2 man test)
i see 10psi, the pump is bad ( of i have 12v at pump cranking,.....)
all this are pump tests there are 6 tests. not counting the injector balance test.
this is my order you can do it backwards, but will most the time have to start over, and cuss a $200 pump change , in vain.
here is the scotty way.
wont start, spark is good, tuneup done. sparks all 4 are wet
this is called flooding, the operators guide, says.
crank with the throttle open (WOT) car starts, it was flooded.
can happen in N.Canana (especially summer fuel in tank)
now car runs find and fresh fuel , 10 x better.
if no , post car keeps flooding, we can work that too.
is fuel pressure at 60psi, bingo, ask.
Posted on Nov 29, 2013
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Posted on Jan 02, 2017
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