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Old 12-02-2015, 11:43 AM   #1 (permalink)
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93 4.3 CPI hard start

I have a 93 4.3 CPI Vortec in my Jeep. It currently has a hard start issue. In the past a set of injectors would fix the problem but this time it didn't help. I have replaced the fuel pump which probably wasn't needed, I'm showing 63 psi. I put new plugs, distributer cap and rotor button. It will crank and hit, sometimes it will spuder then once it starts it seems to run ok. Then for the rest of the day it starts fine but after it sits a few days it is hard to start again. Anyone have any suggestions?
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Old 12-04-2015, 11:08 AM   #2 (permalink)
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Tests/Procedures:
1. Check for 60+ PSI fuel pressure when cranking.

2. Check for 30 KV at a plug wire with an adjustable spark tester.

3. Block the fuel return line, check for 75-100 PSI fuel pressure when cranking.

4. Test the fuel pump amp draw, should be 5-8 amps.

5. Pulse the fuel injector by grounding the Blue wire with the Key On Engine Off (KOEO).

6. Fuel pressure should drop from 60 PSI to 40 PSI.





Heres a quick search id lean towards the fuel stuff but if your pump is new that's a weird one.

next best guess is the pickup coil is weak. unplug it and hook a volt meter to it. should have 0.7V or more while cranking.
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Old 12-05-2015, 09:01 PM   #3 (permalink)
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Thanks,
I did check fuel pressure, the regulator was bad and once I replaced it fuel pressure does read 63psi while cranking and about 80psi if I block the return line. I plan on checking compression just to rule that out. I will check the pick up coil. I replaced the ignition control module last year.
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