95 blazer crank or knock sensor
fam_mechanic
01-11-2006, 12:28 PM
If the crank or knock sensor goes bad what does it do?Does it turn the spark off to the engine so it wont start?Or maybe the fuel?Is the crank and knock sensor one of the same?Is there a way i can use my meter to check it?
blazes9395
01-11-2006, 12:37 PM
I assume you mean crank_shaft senor and knock sensor. They are two different types of sensors. If the crankshaft sensor goes bad, you will have no spark, and a no-start condition. If the knock sensor goes bad, you will have a SES light come on, but the truck will still run. the crankshaft sensor and knock can be tested/observed through a scanner, or by actually probing the sensors, each in their specific ways.
fam_mechanic
01-11-2006, 04:37 PM
thanks Blaze but I still have spark so i guess it rules out the crank senor
blazes9395
01-11-2006, 04:41 PM
Do you have a no start?
fam_mechanic
01-11-2006, 04:45 PM
Do you have a no start?yea she will turn over but it wont start only with starting fluid new fuel pump 2 days ago because of same problem.installed pump truck fired up ran 2 days now im back at square one. nut kit and cpi replaced also
dmbrisket 51
01-11-2006, 06:08 PM
crank sencor= no spark, if you have spark, next question is are you getting fuel, you said a new pump fixed it for a day or two, do you still hear a prime, maby you disrupted an intermitten short haven the tank down and now there is a dead short again, check the fuses? bad signel wire to pump? do you have fuel to the rail?
blazes9395
01-11-2006, 06:28 PM
Yeah I agree with dmbrisket. Check for pressure at the engine. If the pressure is low, even if theres pressure but still under acceptable minimum, it won't fire because the pressure cannot overcome the poppet nozzles for it to fire. Check pressure and see where its at.
fam_mechanic
01-11-2006, 06:39 PM
Yeah I agree with dmbrisket. Check for pressure at the engine. If the pressure is low, even if theres pressure but still under acceptable minimum, it won't fire because the pressure cannot overcome the poppet nozzles for it to fire. Check pressure and see where its at.
More news.I just sprayed the shit out of it with starting fluid to get it home.The truck fired up and ran fine,I returned to the house,shut it off and it wont start.I sprayed it again to get it started and it sits and runs smooth just dont shut it off.at this point i have to says the truck runs but only if started with starting fluid.
More news.I just sprayed the shit out of it with starting fluid to get it home.The truck fired up and ran fine,I returned to the house,shut it off and it wont start.I sprayed it again to get it started and it sits and runs smooth just dont shut it off.at this point i have to says the truck runs but only if started with starting fluid.
dmbrisket 51
01-11-2006, 09:20 PM
then i would say cold start problem; bad/no prime, maby something in the iac, maf, map, or baro. reading. once pumping the pump may have just enough umph in it to keep going, but not enough for the inital fire after 2 second time out. where was the new pump from? personally i prefur (after started working as machanic, i realy see why, all aftermarket pumps are shit) the oe pumps, we have suppliers here in muskegon mi, that let us get the original a/c delco pump but not from the dealer, what your going to want if you didn't is an original equipment A/C Delco fuel pump, and then again your regulator could be taken a shit, not likly but possibly a vaccume leak/...
fam_mechanic
01-12-2006, 08:58 AM
then i would say cold start problem; bad/no prime, maby something in the iac, maf, map, or baro. reading. once pumping the pump may have just enough umph in it to keep going, but not enough for the inital fire after 2 second time out. where was the new pump from? personally i prefur (after started working as machanic, i realy see why, all aftermarket pumps are shit) the oe pumps, we have suppliers here in muskegon mi, that let us get the original a/c delco pump but not from the dealer, what your going to want if you didn't is an original equipment A/C Delco fuel pump, and then again your regulator could be taken a shit, not likly but possibly a vaccume leak/...
general motors fuel pump and cpi unit installed.about 62 psi.Good spark at the coil and more the 1 plugwire.Runs fine just wont start without the aid of starting fluid.sounds like a fuel problem to me,but its all new except for the lines from the tank to the fuel rail
general motors fuel pump and cpi unit installed.about 62 psi.Good spark at the coil and more the 1 plugwire.Runs fine just wont start without the aid of starting fluid.sounds like a fuel problem to me,but its all new except for the lines from the tank to the fuel rail
rlith
01-12-2006, 11:07 AM
general motors fuel pump and cpi unit installed.about 62 psi.Good spark at the coil and more the 1 plugwire.Runs fine just wont start without the aid of starting fluid.sounds like a fuel problem to me,but its all new except for the lines from the tank to the fuel rail
It may not be a hard enough spark to kick it... Have you thought about the ignition module attached to the coil?
It may not be a hard enough spark to kick it... Have you thought about the ignition module attached to the coil?
fam_mechanic
01-12-2006, 12:02 PM
It may not be a hard enough spark to kick it... Have you thought about the ignition module attached to the coil?
Yea done swapped the module out with one from my other blazer (the good one).guess I'm gonna try coil now.
Yea done swapped the module out with one from my other blazer (the good one).guess I'm gonna try coil now.
Southern Comfort
01-13-2006, 07:25 AM
NO START-ENGINE CRANKS OKAY (4.3L, 5.0L, 5.7L & 7.4L)
NOTE: Before performing the following tests, check battery
condition, engine cranking speed and for adequate fuel in
tank.
General Inspection
1) Ensure proper starting procedure is being used. Visually
check vacuum hoses for splits, kinks and proper connections, as shown
on Vehicle Emission Control Information label. Check ignition wires
for cracking, hardness and proper connections at both coil pack and
spark plugs.
2) Remove spark plugs. Check and replace as necessary. In
very cold temperatures, ensure oil is proper viscosity and not
contaminated with gasoline.
NOTE: VCM data is deleted when using scan tool CLEAR INFO function.
Before clearing DTCs, use scan tool CAPTURE INFO function to
record FREEZE FRAME and FAILURE RECORDS data.
Ignition System
1) Perform On-Board Diagnostic (OBD) system check. See ONBOARD
DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate G - TESTS W/CODES
article. After performing OBD system check, go to next step.
2) Attempt to start engine. If engine starts and continues to
run, see appropriate H - TESTS W/O CODES article. If engine does not
start, go to next step.
3) For "P" series, go to next step. On all models except "P"
series, install scan tool. Monitor VTD FUEL DISABLED parameter while
cranking engine. If VTD FUEL DISABLED parameter is active while
cranking engine, diagnose anti-theft system. See appropriate ANTITHEFT
SYSTEMS article in ACCESSORIES/SAFETY EQUIPMENT. If VTD FUEL
DISABLED parameter is not active while cranking engine, go to next
step.
4) Using scan tool, monitor Throttle Position (TP) sensor
voltage with throttle closed. If TP sensor voltage is greater than 2.5
volts, go to DTC P0121. See appropriate G - TESTS W/CODES article. If
TP sensor voltage is 2.5 volts or less, go to next step.
5) Using scan tool, monitor Engine Coolant Temperature (ECT)
sensor. If ECT sensor value is less than -22 F (-30 C), go to D
TC P0118. See appropriate G - TESTS W/CODES article. If ECT sensor value is -22 F (-30 C) or greater, go to next step.
6) Using Spark Tester (J-26792), check for spark at 2 spark
plug wires while cranking engine. If spark is present at both wires,
go to next step. If spark is not present at both wires, diagnose
components and power, ground and signal circuits related to ignition
system. See appropriate wiring diagram in L - WIRING DIAGRAMS article.
Also see BASIC IGNITION SYSTEM CHECKS. Repair as necessary.
7) Turn ignition off. Reconnect spark plug wires. Connect
fuel pressure gauge. Turn ignition on with engine off. Observe fuel
pressure. If fuel pressure is 55-60 psi (3.9-4.3 kg/cm ), go to next
step. If fuel pressure is not as specified, diagnose fuel system. See
BASIC FUEL SYSTEM CHECKS (GASOLINE ENGINES).
8) Turn ignition off. Disconnect fuel injector harness
connector at intake manifold. Using a test light connected to ground,
probe each fuel injector feed circuit while cranking engine. See
appropriate wiring diagram in L - WIRING DIAGRAMS article. If test
light illuminates for each circuit, perform fuel injector coil test.
See FUEL SYSTEM (GASOLINE) in appropriate I - SYSTEM/COMPONENT TESTS
article. Also, check for any engine mechanical problems. Repair as
necessary. If test light does not illuminate, diagnose fuel injector
circuit. See FUEL SYSTEM (GASOLINE) in appropriate I -
SYSTEM/COMPONENT TESTS article.
Fuel System Electrical Circuit
1) Perform On-Board Diagnostic (OBD) system check. See ONBOARD
DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate G - TESTS W/CODES
article. After performing OBD system check, go to next step.
2) Turn ignition off. If fuel pump runs continuously, go to
step 26). If fuel pump does not run, go to next step.
3) Inspect ECM B fuse (20-amp), located in underhood
fuse/relay center. If fuse is okay, go to next step. If fuse is open,
go to step 21).
4) Turn ignition on. Install scan tool. Using scan tool,
command fuel pump relay on. If fuel pump operates, go to IGNITION
SYSTEM. If fuel pump does not operate, go to next step.
5) Remove fuel pump relay. Using a fused jumper wire, jumper
fuel pump positive feed circuit to fuel pump relay ignition feed
circuit at fuel pump relay connector. See appropriate wiring diagram
in L - WIRING DIAGRAMS article. If fuel pump operates, go to next
step. If fuel pump does not operate, go to step 7).
6) Using a test light connected to ground, probe fuel pump
relay control circuit at fuel pump relay connector. See appropriate
wiring diagram in L - WIRING DIAGRAMS article. Using scan tool,
command fuel pump on. If test light illuminates, go to step 8). If
test light does not illuminate, go to step 9).
7) Using a test light connected to ground, probe ignition
feed circuit at fuel pump relay connector. See appropriate wiring
diagram in L - WIRING DIAGRAMS article. If test light illuminates, go
to step 10). If test light does not illuminate, go to step 11).
8) Using a test light connected to battery positive, probe
ground circuit at fuel pump relay connector. See appropriate wiring
diagram in L - WIRING DIAGRAMS article. If test light illuminates, go
to step 12). If test light does not illuminate, go to step 13).
9) Check for an open or short to ground in fuel pump relay
control circuit. Repair as necessary. After repairs, go to step 31).
If circuit is okay, go to step 14).
10) Reinstall fuel pump relay. Disconnect fuel pump harness
connector. Using a test light connected to ground, probe fuel pump
positive feed circuit at fuel pump harness connector (body harness
side). See appropriate wiring diagram in L - WIRING DIAGRAMS article.
Using scan tool, command fuel pump on. If test light illuminates, go
to step 15). If test light does not illuminate, go to step 16).
11) Repair open in fuel pump relay ignition feed circuit.
After repairs, go to step 31).
12) Replace fuel pump relay. After repairs, go to step 31).
13) Repair open in fuel pump relay ground circuit. After
repairs, go to step 31).
14) Check for poor connections at VCM. Repair as necessary.
After repairs, go to step 31). If connections are okay, go to step
17).
15) Using a test light connected to battery positive, probe
ground circuit at fuel pump harness connector (body harness side). See
appropriate wiring diagram in L - WIRING DIAGRAMS article. If test
light illuminates, go to step 18). If test light does not illuminate,
go to step 19).
16) Repair open or short to ground in fuel pump positive feed
circuit. After repairs, go to step 31).
17) Replace VCM. Perform VCM relearn procedures. After
repairs, go to step 31).
18) Check fuel pump positive feed and ground circuits at fuel
pump harness connector for poor connections. Repair as necessary.
After repairs, go to step 31). If connections are okay, go to step
20).
19) Repair open in fuel pump ground circuit. After repairs,
go to step 31).
20) Replace fuel pump. After repairs, go to step 31).
21) Turn ignition off. Disconnect fuel pump harness
connector. Remove fuel pump relay. Using a test light connected to
battery positive, probe fuel pump positive feed circuit at fuel pump
relay connector. See appropriate wiring diagram in L - WIRING DIAGRAMS
article. If test light illuminates, go to next step. If test light
does not illuminate, go to step 23).
22) Repair short to ground in fuel pump positive feed
circuit. After repairs, go to step 31).
23) Using a test light connected to battery positive, probe
ignition positive feed circuit at fuel pump relay connector. See
appropriate wiring diagram in L - WIRING DIAGRAMS article. If test
light illuminates, go to next step. If test light does not illuminate,
go to step 25).
24) Repair short to ground in fuel pump relay ignition feed
circuit. After repairs, go to step 31).
25) Check fuel pump positive feed circuit in fuel pump wiring
harness (tank side) for a short to ground. Repair as necessary. After
repairs, go to step 31). If circuit is okay, go to step 20).
26) Remove fuel pump relay. If fuel pump continues to run, go
to step 30). If fuel pump does not run, go to next step.
27) Turn ignition off. Using a test light connected to
ground, probe fuel pump relay control circuit at fuel pump relay
connector. See appropriate wiring diagram in L - WIRING DIAGRAMS
article. If test light illuminates, go to step 29). If test light does
not illuminate, go to next step.
28) Replace fuel pump relay. After repairs, go to step 31).
29) Repair fuel pump relay control circuit for a short to
ground. After repairs, go to step 31).
30) Repair fuel pump positive feed circuit for a short to
power. After repairs, go to step 31).
31) Using scan tool, clear DTCs. Attempt to start engine. If
engine starts and continues to run, go to next step. If engine does
not start, go to step 4).
32) Allow engine to reach normal operating temperature. Using
scan tool, check for DTCs. If any DTCs are present, diagnose DTCs. See
appropriate G - TESTS W/CODES article. If no DTCs are present, system is okay. I don't know if this will help,but I thought I would send it to you any way. I hope it helps. Sometimes we get a little frustrated and over look some simply little thing. When I get to that point, I back up, clear my head and then go back to the basics.
Thanks
SC
NOTE: Before performing the following tests, check battery
condition, engine cranking speed and for adequate fuel in
tank.
General Inspection
1) Ensure proper starting procedure is being used. Visually
check vacuum hoses for splits, kinks and proper connections, as shown
on Vehicle Emission Control Information label. Check ignition wires
for cracking, hardness and proper connections at both coil pack and
spark plugs.
2) Remove spark plugs. Check and replace as necessary. In
very cold temperatures, ensure oil is proper viscosity and not
contaminated with gasoline.
NOTE: VCM data is deleted when using scan tool CLEAR INFO function.
Before clearing DTCs, use scan tool CAPTURE INFO function to
record FREEZE FRAME and FAILURE RECORDS data.
Ignition System
1) Perform On-Board Diagnostic (OBD) system check. See ONBOARD
DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate G - TESTS W/CODES
article. After performing OBD system check, go to next step.
2) Attempt to start engine. If engine starts and continues to
run, see appropriate H - TESTS W/O CODES article. If engine does not
start, go to next step.
3) For "P" series, go to next step. On all models except "P"
series, install scan tool. Monitor VTD FUEL DISABLED parameter while
cranking engine. If VTD FUEL DISABLED parameter is active while
cranking engine, diagnose anti-theft system. See appropriate ANTITHEFT
SYSTEMS article in ACCESSORIES/SAFETY EQUIPMENT. If VTD FUEL
DISABLED parameter is not active while cranking engine, go to next
step.
4) Using scan tool, monitor Throttle Position (TP) sensor
voltage with throttle closed. If TP sensor voltage is greater than 2.5
volts, go to DTC P0121. See appropriate G - TESTS W/CODES article. If
TP sensor voltage is 2.5 volts or less, go to next step.
5) Using scan tool, monitor Engine Coolant Temperature (ECT)
sensor. If ECT sensor value is less than -22 F (-30 C), go to D
TC P0118. See appropriate G - TESTS W/CODES article. If ECT sensor value is -22 F (-30 C) or greater, go to next step.
6) Using Spark Tester (J-26792), check for spark at 2 spark
plug wires while cranking engine. If spark is present at both wires,
go to next step. If spark is not present at both wires, diagnose
components and power, ground and signal circuits related to ignition
system. See appropriate wiring diagram in L - WIRING DIAGRAMS article.
Also see BASIC IGNITION SYSTEM CHECKS. Repair as necessary.
7) Turn ignition off. Reconnect spark plug wires. Connect
fuel pressure gauge. Turn ignition on with engine off. Observe fuel
pressure. If fuel pressure is 55-60 psi (3.9-4.3 kg/cm ), go to next
step. If fuel pressure is not as specified, diagnose fuel system. See
BASIC FUEL SYSTEM CHECKS (GASOLINE ENGINES).
8) Turn ignition off. Disconnect fuel injector harness
connector at intake manifold. Using a test light connected to ground,
probe each fuel injector feed circuit while cranking engine. See
appropriate wiring diagram in L - WIRING DIAGRAMS article. If test
light illuminates for each circuit, perform fuel injector coil test.
See FUEL SYSTEM (GASOLINE) in appropriate I - SYSTEM/COMPONENT TESTS
article. Also, check for any engine mechanical problems. Repair as
necessary. If test light does not illuminate, diagnose fuel injector
circuit. See FUEL SYSTEM (GASOLINE) in appropriate I -
SYSTEM/COMPONENT TESTS article.
Fuel System Electrical Circuit
1) Perform On-Board Diagnostic (OBD) system check. See ONBOARD
DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate G - TESTS W/CODES
article. After performing OBD system check, go to next step.
2) Turn ignition off. If fuel pump runs continuously, go to
step 26). If fuel pump does not run, go to next step.
3) Inspect ECM B fuse (20-amp), located in underhood
fuse/relay center. If fuse is okay, go to next step. If fuse is open,
go to step 21).
4) Turn ignition on. Install scan tool. Using scan tool,
command fuel pump relay on. If fuel pump operates, go to IGNITION
SYSTEM. If fuel pump does not operate, go to next step.
5) Remove fuel pump relay. Using a fused jumper wire, jumper
fuel pump positive feed circuit to fuel pump relay ignition feed
circuit at fuel pump relay connector. See appropriate wiring diagram
in L - WIRING DIAGRAMS article. If fuel pump operates, go to next
step. If fuel pump does not operate, go to step 7).
6) Using a test light connected to ground, probe fuel pump
relay control circuit at fuel pump relay connector. See appropriate
wiring diagram in L - WIRING DIAGRAMS article. Using scan tool,
command fuel pump on. If test light illuminates, go to step 8). If
test light does not illuminate, go to step 9).
7) Using a test light connected to ground, probe ignition
feed circuit at fuel pump relay connector. See appropriate wiring
diagram in L - WIRING DIAGRAMS article. If test light illuminates, go
to step 10). If test light does not illuminate, go to step 11).
8) Using a test light connected to battery positive, probe
ground circuit at fuel pump relay connector. See appropriate wiring
diagram in L - WIRING DIAGRAMS article. If test light illuminates, go
to step 12). If test light does not illuminate, go to step 13).
9) Check for an open or short to ground in fuel pump relay
control circuit. Repair as necessary. After repairs, go to step 31).
If circuit is okay, go to step 14).
10) Reinstall fuel pump relay. Disconnect fuel pump harness
connector. Using a test light connected to ground, probe fuel pump
positive feed circuit at fuel pump harness connector (body harness
side). See appropriate wiring diagram in L - WIRING DIAGRAMS article.
Using scan tool, command fuel pump on. If test light illuminates, go
to step 15). If test light does not illuminate, go to step 16).
11) Repair open in fuel pump relay ignition feed circuit.
After repairs, go to step 31).
12) Replace fuel pump relay. After repairs, go to step 31).
13) Repair open in fuel pump relay ground circuit. After
repairs, go to step 31).
14) Check for poor connections at VCM. Repair as necessary.
After repairs, go to step 31). If connections are okay, go to step
17).
15) Using a test light connected to battery positive, probe
ground circuit at fuel pump harness connector (body harness side). See
appropriate wiring diagram in L - WIRING DIAGRAMS article. If test
light illuminates, go to step 18). If test light does not illuminate,
go to step 19).
16) Repair open or short to ground in fuel pump positive feed
circuit. After repairs, go to step 31).
17) Replace VCM. Perform VCM relearn procedures. After
repairs, go to step 31).
18) Check fuel pump positive feed and ground circuits at fuel
pump harness connector for poor connections. Repair as necessary.
After repairs, go to step 31). If connections are okay, go to step
20).
19) Repair open in fuel pump ground circuit. After repairs,
go to step 31).
20) Replace fuel pump. After repairs, go to step 31).
21) Turn ignition off. Disconnect fuel pump harness
connector. Remove fuel pump relay. Using a test light connected to
battery positive, probe fuel pump positive feed circuit at fuel pump
relay connector. See appropriate wiring diagram in L - WIRING DIAGRAMS
article. If test light illuminates, go to next step. If test light
does not illuminate, go to step 23).
22) Repair short to ground in fuel pump positive feed
circuit. After repairs, go to step 31).
23) Using a test light connected to battery positive, probe
ignition positive feed circuit at fuel pump relay connector. See
appropriate wiring diagram in L - WIRING DIAGRAMS article. If test
light illuminates, go to next step. If test light does not illuminate,
go to step 25).
24) Repair short to ground in fuel pump relay ignition feed
circuit. After repairs, go to step 31).
25) Check fuel pump positive feed circuit in fuel pump wiring
harness (tank side) for a short to ground. Repair as necessary. After
repairs, go to step 31). If circuit is okay, go to step 20).
26) Remove fuel pump relay. If fuel pump continues to run, go
to step 30). If fuel pump does not run, go to next step.
27) Turn ignition off. Using a test light connected to
ground, probe fuel pump relay control circuit at fuel pump relay
connector. See appropriate wiring diagram in L - WIRING DIAGRAMS
article. If test light illuminates, go to step 29). If test light does
not illuminate, go to next step.
28) Replace fuel pump relay. After repairs, go to step 31).
29) Repair fuel pump relay control circuit for a short to
ground. After repairs, go to step 31).
30) Repair fuel pump positive feed circuit for a short to
power. After repairs, go to step 31).
31) Using scan tool, clear DTCs. Attempt to start engine. If
engine starts and continues to run, go to next step. If engine does
not start, go to step 4).
32) Allow engine to reach normal operating temperature. Using
scan tool, check for DTCs. If any DTCs are present, diagnose DTCs. See
appropriate G - TESTS W/CODES article. If no DTCs are present, system is okay. I don't know if this will help,but I thought I would send it to you any way. I hope it helps. Sometimes we get a little frustrated and over look some simply little thing. When I get to that point, I back up, clear my head and then go back to the basics.
Thanks
SC
fam_mechanic
01-13-2006, 02:22 PM
I removed the upper half of the intake,and pulled out a poppet nozzle.I put poppet nozzle in a small cup.I turned engine over a few times.No gas from nozzle.Have 60psi.and fuel up to the test port.I hace pics id like to show but do not know how to up load them to here.there is fluid that lays in bottom of intake.Could this be left from the starting fluid i was using?Remember the cpi unit was replaced in september.I just want to visibly see gas coming out of poppet nozzle.Intake look washed out but could it be from the last cpi uhttp://i41.photobucket.com/albums/e297/fam_mechanic/060113031142.jpghttp://i41.photobucket.com/albums/e297/fam_mechanic/060113031142.jpgnit?
dmbrisket 51
01-14-2006, 03:09 AM
the 'hotter' (more flamable is hot, less flamible is cooler) a product is the quicker it evaporates, ether (starting fluid) is extreamly hot, it would evap. at room temp in a matter of min. in a pile that size, looks like you need a lower intake, that looks like oil
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