Fuel Check valve to fix fuel pressure issue?

Discussion in 'SN95 4.6L Mustang Tech' started by Chondro, Dec 4, 2012.

  1. I've got an '01 that won't hold fuel pressure at the rail (goes from 35 to zero in about 40 seconds) and as a result I have to crank forever to get it to start, or prime with key turns a couple times but that's a pain. I replaced all 8 fuel injectors with a reconditioned set of delco injectors off Ebay because I had one injector that would act up periodically and hoped that was causing the leak down, but it didn't fix the problem so that's why I'm thinking the backflow is in the tank. I just replaced the fuel pump 6 months ago so I don't want to go in there again just for a check valve and thought about installing one in-line just outside the tank. Any thoughts on going with something like this?


    If this is a decent solution, anyone know what size line is outside the fuel tank? This product comes in 3/8" and 5/16".
  2. That's not going to fix ur problem...sounds like you may have to go into the tank again. There is a check valve on the fuel basket to help keep pressure after initial prime. If your car starts then slowly dies it sounds like a pump problem. I recently put a new ford svt pump in my car only to find it made 28lbs of pressure at wot. Sometimes you just get a bad unit. Drop tank double check connections make sure line isn't kinked going to hat. Start from there
  3. Lemme guess... Airtex pump from part store X?
  4. Actually, I took it to a mechanic and so I have no idea what may be going on in there. He told me he put in an AC Delco pump, new strainer, and a new filler neck gasket--or at least I hope that's what happened for my $640. It's been way too long to go back to him for a warranty repair so that's why I'm trying to weigh my options. Fortunately the pressure at the rail (when running) is about 35lbs and the car runs fine so I'm in no rush to get into the tank and see what's going on (I live in a condo and only have access to a garage when I visit my folks 300 miles away).

    When I do finally get into the tank, should I just pick up a new fuel basket in case that's the issue? Is the fuel basket something readily stocked at auto parts stores or a dealer only part? Since I didn't install the pump myself, is the basket universal to all pumps since I'm not 100% sure what's in there?
  5. Do you have a fuel pressure tester? Sounds like you might since you know what the pressure is when running. The one I'm talking about though, is one that connects to the fuel pressure line and not a permanently installed one.

    The reason I ask is that if you have a fuel pressure testing tool with a relief valve, you can use it to see if there are air bubbles (cavitation) in the fuel system. If you see bubbles in the fuel system then it's time to replace the pump.

    Ensure that if you replace it, that you get a Walbro or Bosch pump. No Airtex or other chinese garbage. Do it yourself. Swapping a pump is not worth $600+ dollars. Should have taken a shop 30 minutes tops to perform that job. Another 15 minutes if he had issues with rusty straps.
  6. You can buy the basket as an assembly from a parts store. Depending on mileage might be worth so in 6 months you're not pulling the tank again because your fuel level sensor went. Definitely diagnose the problem first before you just buy parts. I didn't notice if you mentioned the filter.....did they install a new filter ehen they put in the pump?
  7. Ohh...and take caution if you go in the tank yourself the wires get hard and brittle from the fuel. I broke the solder spot on my sending unit took an hour to repair...hth
  8. I do have a fuel pressure tester and when I bleed off fuel from the rail, I get a solid stream of fuel so it doesn't appear to have any air in the rail. Oh, and the $640 charge for pump replacement was the going rate in my neighborhood in Chicago (everything is expensive here). I don't believe they installed a new filter with the repair, but that shouldn't have anything to do with the failure to hold pressure at the rail should it?

    So when I drop the tank, will it be obvious where the check valve is located and easy to diagnose/replace? Are there rubber or vinyl lines in the tank that could have a small crack or bad seal with a rigid line they mate up with that could be causing the leak down as well?
  9. When you take the hat off there is a plastic line that goes from the hat to check valve. And valve to pump. Check for any cracks or leaks. Do you have a way to datalog your car? I would check your fuel pressure through the ecu through the throttle range. It fuel system should maintain a constant 40lbs give or take a very small amount. You may find if you're making 35lbs at idle at full throttle you may only be making 25 (just throwing a number out)