fuel pouring on the ground like a garden hose
 

FD hasn't been started in at least a year. I push it out of the garage and it starts easily. I let it idle for about a minute and then as it continues to idle fuel begins pouring off of the bottom of the front sub frame. expecting a burst fuel line hose or leaking fpd I turn it off, 2 days later pull the uim and jump the f/p and ground terminals on the diagnostic connector turn on the ig switch and go back to under the hood to turn on my battery disconnect, and I can hear the fuel pump run and feel the turbulence of the fuel running thru the fuel line at the rear of the secondary fuel rail, but there is now no leak or fuel odor. I let the fuel pump run longer than I had the engine running. I was wanting to see the leak before I pull off the solenoid rack- is there anything that would cause this kind of fuel leak only when the engine is actually running rather than just running the fuel pump? Any ideas?

Good call on jumpering the fuel pump diagnostic connector. I wonder if supply voltage is low enough with the engine running on battery alone such that it won't build enough fuel pressure to cause the leak.

Possible, but it was pouring on the ground so rapidly I expected to see a huge tear in a hose. Battery is an Odessy PC680 with enough juice to start the car, maybe I'll put a full size battery in parallel with some jumper cables but for that size leak i don't know if it would make a difference. There is a slight chance that YEARS ago when I installed the remain that is in there now that the fuel feed and return lines were reversed (doubt it), but the car has run for years since then with no problem and I don't know what could develop even if the lines were reversed that would cause this (or if the car would even run like that). Maybe someone here knows if an injector top o ring seal failure would only show up when the injector is triggered? Otherwise I would expect that it would be leaking whenever the pump is on...

Pull the upper intake manifold and jump the diagnostic connector (fp to gnd). Have a helper key on while you look around the engine bay for leaks. Should be pretty obvious. Don't get splashed in the face.

I did that....did you read my first post?

What is your fuel setup?

When I bought my FD the prior owner ran a -6 feed and then used one of the old feed lines as a return line leaving two lines from the tank open on the firewall by the brake booster. I filled the car up and had fuel pouring out of one of those lines. I capped it until I pulled all the stock fuel line out. Basically asking if you have any open lines?

it has the stock fuel system, a couple thousand miles driven in its current configuration with no changes before sitting in my garage under cover for about a year.

i think your battery swap is a good idea, and then just let the pump run. if you don't see any leaks in ~20minutes, start wiggling fuel lines.

it maybe is possible there was a stuck injector and it filled something (the engine) with fuel, and it found a way to leak out.

it maybe is possible there was a stuck injector and it filled something (the engine) with fuel, and it found a way to leak out.

I have had this happen.

Injector stuck open, engine ran pretty rough and fuel literally poured onto the garage floor out the exhaust/turbo area and ran out the garage door.

check the fuel pulsation damper. I had a small pin hole in mine and it dumped fuel everywhere.

If it's not a hose then you are left with fuel pulsation damper and the injector o-rings. The o-rings can look great but still let a lot of fuel through them.

Was on mobile so hard to read. Where was the leak?

Will do the battery parallel thing & let the pump run tomorrow. Good idea about the stuck injector, though the engine was idling fine while the fuel was leaking out and the dip stick oil level is right where its supposed to be. I suppose if it is a stuck injector the result of this trial will be somewhat dependent on the position of the rotor in the engine. what I DONT want to do is fill the exhaust system with gasoline! (I hope I haven't filled it already with my limited fuel pump run so far....) I guess I need to pull the plugs and rotate the engine to have the intake port and plug open to each other then run the pump?

Been a while since I had one of these engines opened up, but Im not sure its possible to have the intake port open at the same time the same slice of volume is open to a spark plug hole, so I guess I'll have to let the pump run with the exhaust port on the opposite side of the apex seal then rotate the engine to dump any fuel that may accumulate out the plug hole. orrrr, might just be easier to just crank the engine with the starter with the plugs out while the pump is running. but then I'd be getting normal injector pulses and might not be able to tell if its normal fuel or not. Ack, dunno what to do here...disconnect the injectors maybe while doing that....

Pull the upper and look into the lower with the diagnostic box jumped and see id you see anything leaking.

yes, that will work. I'll try tomorrow

ran the pump for a few mins no output from (visible, outer runners) injectors into the manifold from the top fuel rail, I can't see the bottom ones (inner runners) bc they are further down but I wasn't able to hear, see or smell any fuel from there or the others while the fuel pump was running. I'll be repeating with a full size battery in parallel with the small one. I see the system has a 2 speed feature that I may have to address later....
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Ran the fuel pump again while inspecting the area all along the injectors, under the rats nest and inside the LIM with a bore scope, while moving the 2 rear hoses I could touch. Still no leaks and everything is dry. I'm going to put the UIM back on and crank the engine & see what happens, car on ramps, garden hose and halon extinguisher nearby, with help. If it leaks it won't have a chance to get warm enough to ignite before it gets shut down, and at least I'll be able to see whats going on...I have a strange feeling that this problem will mysteriously disappear.. Do stuck injectors stay stuck or sometimes unstick?

I would recommend doing a test something like this:

https://www.rx7club.com/3rd-generati...1/#post5978887

This will basically test the assembly of the fuel system and the integrity of the seals. It won't let you know that the injectors are working 100% correct, but it will let you know if they are stuck open (i.e. the injectors will not be open for this test so any fuel leaking is a problem).

If this test passes (i.e. no leaks), then your injector spray pattern may be incorrect (i.e. too much fuel). However, my bet is that you'll see a leak using the above test.

That would do the job for sure, hoping to test without removing the whole works. If I get any leakage on the next run I'll remove the lines, plug the return and pump the feed line with a bike pump. if I can't locate the spot then next step would be to remove the whole system and test it like in the link.

This may be a dumb question but why not just replace all the feed and return lines instead of going through all this trouble?

what if the problem isn't a hose?

the first step in diagnosing a problem is to duplicate the complaint. if you do this, then it is often obvious what part(s) to replace/adjust.

it is a bit weird (and probably frustrating) that the car is not repeating the problem, but that would suggest something that isn't a hose, hoses usually are not intermittent.

the last step in a repair (or anything BTW), is to verify that it fixed the problem, which is why its important to be able to duplicate the problem in the first place.

I fully agree, but I guess I would look at it as the vehicle is over 20 years old, it would be a good safety item to replace the lines anyway.

Just ran the car after having reassembled everything, no leaks, no smell. I can only guess it must have been a stuck injector. For the moment my co-driver is a very large CO2 fire extinguisher! I do get a CEL now, will check for the code tomorrow. Possible I forgot a connector under or near the UIM when I put it back on...