I’ve got a ‘94 Sonoma 2X4 4.3L that was having issues with rough idle when cold. Had a code 45. Changed the bad O2 sensor, cleaned TB, nothing. Replaced fuel filter and it had dirty fuel backwashing out. Fuel pump was crazy loud and noisy always once key was in start or running. Truck had no issues starting or running. Just rough idle even cold. Dropped fuel tank and replaced with complete fuel pump assembly. Hooked everything back up but truck will not start. You can hear the pump engage when key placed in start. Removed fuel line for discharge side of filter and confirmed fuel flow. I’m at a loss for a running truck won’t start back up after a fuel pump replacement when it clearly has power and fuel flow. Fuel gauge reading just fine too. Any ideas?
Sonoma won’t starter after fuel pump replacement
- Thread starter jdomke1
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Disconnect the fuel line after the filter and place it in a bucket, turn the crank and verify flow after the initial pump prime. If that's okay (I wasn't sure by your description if you tested flow just during prime or not), then I the next thing I would suspect is the fuel pressure regulator, or the check valve is faulty.
Fuel definitely jetting out of fuel filter.
I figured it out. Summit sent me the wrong fuel pump. Apparently there are two from Spectrum for my truck. One for TBI (25psi) and another for CFI (125psi). When I bought it they only offered one option. What a tremendous waste of my time and money. Sending the wrong one back, too bad for them that it’s used. Already ordered the right one. Now that I’ve taken apart the FI system I’m going to just replace the regulator, seals/gaskets, and main supply/return lines. The individual injectors and tubing seem fine. Jetted them with carb cleaner and then compressed air. No leaks and nice flow. Either way, another week of waiting for the parts to come due to the holiday. I’ll post back when I’ve got it done and fingers crossed works perfectly.