So, this may be kind of a silly question but I need some help.

I have an S4 TII in an FB. Engine is a recent rebuild and from what I can measure, the compression is good.

Initially, I drove the car home and it started up fine. When I got it home and shut it off, I had a hard time restarting it. I figured that this was due to the engine being new. However, I went to go drive it the other day--for which it started up fine. Once I shut it off it did not want to restart.

I have a fuel pressure regulator that reads 35 psi when the key is first turned and the pump cycles. As soon as the pump finishes cycling the fuel pressure drops to 0. Is that normal? I thought fuel pressure should be consistent and that it should stay under pressure.

Also, when compression testing the L1, I had removed L2 and even though the fuel pump fuse was pulled, I got a smoke and fuel mist coming out of L2. I thought that was rather strange as there should not me any fuel coming out.

Anyway, thoughts? Suggestions? Could I have an internal fuel leak? I had my secondaries leaking and just got new 2,200cc secondaries. Could the primaries be leaking? Anything else I should check?

 

The Primary injectors "batch fire" so BOTH will give you fuel at the same time.So YES fuel will come out of the "other rotor housing" if the plugs are taken out.

You shouldn't be testing Compression with the fuel supply ON anyways..Bad things can happen.

2200 CC secondaries?..you got an ECU controlling those?

 

In my post above you can see that the fuel pump fuse is pulled so any fuel coming out would be leaking from the injectors or simply residual in the system.

Issue here is not ECU but in case you are wondering I am running a Microtech, GT35r and all of the supporting mods.

 

Can anyone answer the fuel pressure question? Should the pressure stay up after the pump finishes its startup cycle? In piston engines if the pressure drops it means you have an internal leak, I'm just not sure about on rotaries as I never paid that much attention to the gauge on the fuel pressure regulator except when the car was running. I never noticed if the pressure drops with the car on and but the engine off.

 

The system should hold pressure. There is usually a check valve in the pump that is responsible for maintaining pressure in the line and slowly bleeds it off (takes about a day). Not sure what you're using since no FB pump should be running a TII engine.

Leaking primaries does match your symptoms. Although, if it's draining your pressure that quickly, I'd suspect the wiring/program is holding the injector open all the time. Does it currently run?

 

I have a 944 fuel pump that is relatively new but the car has been mainly sitting for the past two years so it could have rotted out.

The car was starting and running, albeit a bit rich as I was still breaking in the engine prior to final dyno tune. I drove it to Pep Boys and it refused to start. Thought it was a hot start issue but no. Getting spark so it is not ignition. Perhaps the check valve failed.

The secondaries are brand new as my RC 1600cc secondaries failed due to RC sucking lately, but I'm pretty sure the primaries were not changed out at the same time but I need to verify that with Dave at Speed 1 who did that work.

 

Pressure bleed-off without the pump running is not a problem. It actually helps prevent hot start issues due to leaking injectors. There is even a kit available to add the feature.
Fuel Injection Pressure Bleed- Off Kit

As for normal FC function, the FC pump never 'primes'. It just turns on when the key is turned to start and/or the AFM is open. Whatever yours is doing is being controlled by your aftermarket ecu.

Start looking at hot cranking settings, cleaning primaries, fuel pressure while cranking. It's tough because there's a lot of non-stock stuff going on.

 

So, I removed the intake and pressure tesed the fuel injectors. Infortunately, they are not the issue. May be something in the tank or possibly the FPR.

I will check out the fuel pressure while cranking tonight when I test the spray of the primaries.

 

Check the fuel pump. I don't know what the flow rate is on the 944 pump, if it's not enough you might need to replace it to support your setup anyway.

 

Typo on my part, it is a Bosh 044 pump that flows plenty and has put down over 400hp. It replaced the crappy Walboro that had pulsation issues. Pump must be 3 years old with about 1,000 miles on it. Perhaps for sitting so long a check valve rotted out or an internal leak sprung somewhere.