GT40 won't start

Oh, the last time I replaced the filter, when I reassembled it, one of the wires came off the top of the canister where they plug in. After I unplugged each pump plug to hear the other one, I could hear it wasn't running, so opened it back up and found the loose plug.

If it is running (you can hear it) and still no pressure and you are ready to buy a new one, there's probably no harm in putting the pump in a bowl of water and running it to see if it pumps water. I don't like the idea of putting a good pump in water to test, but if you think it is not pumping, might as well do that last test. If it pumps water, then there's something else going on.

If nothing is coming out of the schrader valve when you run both pumps and you've taken the valve out, then there is a problem with the high pressure pump/lines. The high pressure pump is the one in the fuel canister; the low pressure pump is below bolted to the front of the block.

One point of failure is the hose that suspends the high pressure pump inside the canister/filter. In my case, I had a black hose (gas line hose) that was original. It developed a pin hole that got progressively bigger and bigger to the point that the gas would just flow back into the canister instead of the fuel rail and the engine would eventually starve. In your case, it was running and now isn't, but if either the hose has some sort of break or is loose (not tightly clamped to the pump and to the top of the canister), you won't get flow out to the rails.

When you've tested the pumps, did you unplug each one separately (since they are on the same relay) to re-confirm that both are running? I'd unplug the low pressure pump just to be sure you can hear the high pressure pump is really running.

As for testing pressure at the schrader valve, run down to Harbor Freight Tools or an auto supply place and pick up a fuel injector pressure tester gauge. You just screw it onto the schrader valve and then can do all sorts of tests (pressure, pressure regulator, bleed down, etc.). Still, if you are not getting any gas to come out with the valve out, nothing is getting to the rails, so I'd go back into the canister (after unplugging the low pressure pump to make sure just the high pressure pump appears to be running).

Open the canister again (it will be full since you heard the splashing at the tank signifying that the low pressure pump is filling the canister with the excess flowing back to the tank). I'd double check that hose to make sure there isn't a split, etc. The two things I can think of (if it sounds like it is running) is that the hose split or the hose slipped off the top of the canister when you were replacing the filter), or the pump just happened to go bad. I'd suspect the hose or the clamping first.

I suspect that since we have always had ethanol in our gas here in California since we got our boat in '96, it just ate away at the pump hose. So now every time I open the canister to replace the filter, I replace the hose at the same time.

If the hose and the clamping at both ends is secure, then I would say the pump has a problem. Not sure the best way to test it out of the canister since you want to see if it is pumping liquid but I certainly wouldn't put it in an open container of gas either.

Bottom line guess is it is the hose/clamping. Just make sure everything is tightly connected inside. And I'd watch very carefully about pulling the valve out and then turning the pumps on. You're going to get a ton of gas all over the place if everything is working properly. I'd get the pressure gauge and plug it onto the schrader valve before trying that test again......   :)

I agree that you should put a pressure gauge on the schrader vavle; that will tell you a lot. In addition, if there is fuel pressure, I'd recheck the safety tether. My switch finally died a few months ago. I had to jump it. Also, there is a way to jump the pumps so that they go on continually even if the engine isn't running. I'd have to look it up, so let me know if you'd like to do that.

Also, depending on the fuel level in your tank, if you do run the pumps with the jumper (so that they keep running), you should hear the splash of the gas returning to the tank after it's round trip. I always hear that splash, telling me the low pressure pump is working. Then measuring the pressure at the schrader valvue tests the high pressure pump.

Ok, one more thing, if that doesn't help. This is an old thread:
http://nautiqueowner.com/forum/forum_posts.asp?TID=19630&PID=241519&title=poor-running-after-fuel-filter-change

The other guy, don't really know him because he never came back after that thread, said that Vince at Skidim mentioned something about pushing the filter all the way down until the bottom O-Ring on the filter fitted against the fuel cell snuggly. Be sure to check that as well.

1997nautique wrote: Yes, I took out the fuel tank, so yes I had the gas lines disconnected.

Wait, you took out the fuel tank? To change the filter? Or for something else. Yup, if you push down on the tire valve looking thing, you should have fuel there, and that should help let out air pockets.

Just a quick check, before you go too deep. Does this have a safety tether? That's definitely connected, right?

It would be nice if you could check what pressure you are getting at the fuel rail.

Did you have to disconnect any of the fuel lines?

If there is air, and this is just a theory, you'd have to push down on the fuel rail shrader valve to release the air/check to see if fuel is getting up there.

Did you have any problems before? Is this an Fuel Control Cell type filter/pump? If so, did you unplug anything near the FCC to get the filter out?

Did you give it enough time to get fuel all the way through the system. I'm thinking flooding is less likely than an air pocket you've got to work through.