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Old 11-05-2002, 07:15 PM
Senior Member
Join Date: Sep 2002
Posts: 2,486
You need to check the fuel system pressure before replacing anything. From what you've described it sounds like the system isn't holding pressure when not running. This would cause long cranking and/or rough running following start-up because the pump(s) need to build up lost pressure before the engine can start and run smoothly. I honestly haven't seen too many happy endings after using fuel additives. A worn injector that's leaking down over night or a fuel pump check valve that's leaking internally needs to be replaced. Simply connect a fuel pressure guage and verify the correct pressure(s) with the engine running. If everything is OK shut it off and monitor the pressure(overnight if necessary) to see if it drops below spec. From your description I think you'll see a pressure loss within an hour or two if, indeed it's fuel-related. Also, don't overlook the ignition suppressors. They're easy to test and cheap to replace. If it's an LH-SFI 119 engine have a look at the caps and rotors too. I've tossed hundreds of them in the trash over the years. A little bit of green stuff inside the cap is all it takes to cause a running problem. Good luck
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