Obscure starting problem

[240jojo]

My setup and relevant parts: sr20det, walbro255, DENSO 550cc injs, AFPR, newish (look fine, get spark) spark plugs.

Okay, to detail what is going on:
-Walk out to car after sitting for 1 day, engine turns over but will not start
-Jump start doesn't help
-Freshly charged battery will start car
-Runs great once it is running
-Engine will "start" if fuel pump fuse is removed, (dies due to no new fuel)
-Putting fuel pump fuse back in during above case results in running car
-Plug #4 was wet when I pulled it to check spark on each plug after unsuccessful starting attempt
-FPR gauge shows pump holding 40 psi steady pressure when car is on or running

I'm leaning towards some sort of fuel problem, but not 100% sure due to it working if the battery is freshly charged.

Next time I get a chance to work with it, I'm pulling the fuel rail to see how the injectors behave with the ignition on and running, separately. What else should I look for?

[Corey121]

Sorry read the thread then posted something stupid, have you replace the battery or are you just recharging it to get the car to start? After sitting for a day does the car turn over slow or fast?

[240jojo]

I've charged the battery, had it tested as good, and used a known good battery.

I only noticed that for some reason it will start up no problem if the battery had recently been fully charged. Though I suppose it's possible that this COULD be because the battery just wasn't in the car for a while, and that affected it somehow.

When trying to start the car after it has sat for a while, it takes just a second to get to full speed, but then turns over just as fast as it ever has.

When it starts with the fuel pump fuse removed, it starts up on maybe the second turnover.

[Sileighty_85]

Sounds like either a bad Fuel injector O-Ring or a leaky injector

[240jojo]

Sounds like either a bad Fuel injector O-Ring or a leaky injector

Yeah, that's definitely where I'm leaning. My guess is that cylinder #4 is filling with fuel while it sits and flooding. Pulling the fuel rail tonight to see what I can see.

Does anybody know how fuel pressure in the lines should behave all the way from turning the ignition on to shutting the car off?

Mine goes like this:
0psi and off
40psi and on
~40psi and running
40psi and off
goes back to almost 0psi over the course of maybe 2 hours.

[Sileighty_85]

think it depends on the regulator,
my FP drops off pretty quick after the engine is shut off.
I have a SARD.

[240jojo]

Replacing the walbro255 with a skyline pump I had sitting around seems to have fixed the problem.