Could be most anything at this point. When you test leakdown at the service port, you are checking the entire fuel delivery system. Everything from the check valve in the pump to the valve plate in the fuel pressure regulator, and everything in between. If the leakdown test fails, further diagnosis is necessary to determine where the leak is. Next step is to check fuel pump maximum output pressure and leakdown in the tank. It will require some "creative plumbing" with the pressure tester connection to the fuel filter outlet. All pressure and fuel flow must dead end at the tester. During pump prime, pressure must be 73psi to 108psi, and must remain above 55psi for at least 10 minutes after the pump shuts off. If it passes both of those tests, the problem is in the plenum. Post your results.

 

what are you guys building to test the pressure at the filter ? im trying to figure out what i need to test it there instead of the shrader on the rail area.

 

This is a tool that I made a few years ago. It will work on 1997 & newer 4.3L engines. (1996 & earlier require different connectors.) It connects inline at the fuel filter. It will test regulated fuel pressure and leakdown, (same thing as testing at the service port by the distributor). It will also check fuel pump maximum output pressure and is capable of isolating the fuel pump to check for leakdown in the fuel tank. Total cost... maybe $45, about the cost of a decent pressure tester alone. The brass adapters, ball valve and gauge are available at a home improvement store or a good hardware store in the plumbing department. The quick connect fittings etc are available at most auto parts stores. The rubber line must be "fuel injection rated".

 

Sorry for the long delay. I haven't found the part for the fuel pressure tester I borrowed from a friend. That was the reason I had no pressure. The pin in the schrader adapter fell out somewhere. Haven't got ahold of snap on to see if they sell replacements $$. Although after I installed the fuel pump the first time it failed the leak down test in 30 seconds. So while looking for the Schrader valve piece I picked up a regulator and installed it. Now it runs but spits and sputters and is not driveable. Seems really stinky and rich. I have a video I will try and post tomorrow.

 

Here is a link to the video. Sorry about the sound something happened during upload. It starts up rough then stumbles and backfires. When you press the throttle it stumbles until it slowly climbs up then at 4000 rpm it seems smoother. Any help would be appreciated. I am really close to droping it off at the mechanics shop and praying it doesnt cost to much.

 

So I have given up on the shop. Two days and the mechanic is still scratching his head. I will let you know what I find out.

 

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