91 rs 3.1 no start - Team Camaro Tech
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post #1 of 5 (permalink) Old Dec 28th, 10, 02:02 PM Thread Starter
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Chuck
 
Join Date: Feb 2001
Location: norman,oklahoma
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91 rs 3.1 no start

Ok guys. Never thought I would post a running issue on here, but i am at my wits end, and not sure where to take from here. I have no codes, car is hesitant to start, but will run for about 3 seconds if I flood start it. After that it is as if someone pulls the coil wire off, and the car just dies.

Here is what I know.

Had no power when my dad was driving home, and would want to die on anything over partial throttle.

Upon testing got weak signal from TPS... ranged .9- 4.1 volts...not horrible, but changed anyway.

changed MAP....had good vaccum to sensor 16 inches i think.

changed the usual.... plugs wires cap rotor....

verified coil with the one off my 67. no change

replaced pickup in dist....also tested module with extra from another car.

verified compression.... averaged 176 per cyl

replaced ECM.

Fuel pressure was constant at 40-45 dependant on load.

also replaced Pressure regulator.

So I am about out of ideas....car has 345k miles...35k on new motor.... Only things left to check would be injectors (replaced when motor was installed...) and wiring harness, but am no longer at a shop to access test specs. I have also ohmed out TPS and MAP wiring to ecm. verified no open or shorts. Anyone know of a common harness failure that could cause this. I am frustrated at this point, and any advise would be appreciated. If you need more info feel free to ask.

Thank you in advance,

Chuck

67 rs/ss
381 sbc 11:1 AFR Heads Holley 950 EFI
DSE Quadralink

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post #2 of 5 (permalink) Old Dec 28th, 10, 02:45 PM
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Re: 91 rs 3.1 no start

Injector harness has one wire with battery power from a relay from a fuse(?) with IGN on, black wire? The other inj wire goes back to the ECM and it places a low on this colored wire to open inj to dispense fuel.

Your TPS voltage is good, no holes from idle to WOT.
Seems like you've checked everything else. No dist module = no spark and no injectors.
Might check EGR valve making sure it is seated and the TBI gasket to manifold for sealing.

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post #3 of 5 (permalink) Old Dec 28th, 10, 03:23 PM Thread Starter
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Chuck
 
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Re: 91 rs 3.1 no start

great ideas everett. I verified with a genisis tool egr opening and shutting. seal is in tact, and does not have a tbi. I am getting fuel on plugs, so that rules out injectors if thats the case. That only leaves 2 things... injectors stuck open and flooding, cuz i just pulled a plug and its soaked. or I have a loss in spark, which i dont understand. I have fire.... replaced or tested with known good part on everything. Maybe I will just punch myself in the face repeatedly till this thing starts!!! LOL! (It may have a chance of working!!!!) P.S I have had 2 issues with this car constistantly.... EGR code since 20k miles on car and CTS replaced like 6 times. 1 prom and 2 computers later....no fix. Havent had the code since new motor, but well you never know. Wiring to both has also been checked and verified. Looks like I may throw some more money at it and just buy a distributor...(crossing fingers..)

chuck

67 rs/ss
381 sbc 11:1 AFR Heads Holley 950 EFI
DSE Quadralink

"From what I have replaced in pursuit of more, I could have built another one."
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post #4 of 5 (permalink) Old Dec 28th, 10, 04:46 PM
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Re: 91 rs 3.1 no start

Have you used timing light to see spark arrive at the right time?
Disable ign by unplugging brown/white wire at firewall, could be inside kick panel, takes out ECM control of advance.

If plugs are dripping wet with fuel, they will never fire/ignite/spark. Dry them off.
Plugs wet, means coolant sensor is sending cold to ECM and ECM is choking the engine with fuel as in choke plate closed. Usually, holding pedal to the floor cleans up a flooded condition.

Does ign switch have IGN voltage in RUN/IGN position?

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post #5 of 5 (permalink) Old Jan 10th, 11, 06:19 AM
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Shannon
 
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Re: 91 rs 3.1 no start

Some of those engines also have a Cold Start Injector in addition to the six Cylinder injectors and are prone to sticking because of the jet size and duration of opening.

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