Jump to content
SAU Community

Recommended Posts

Hey guys, I did a smoke test this week chasing vacuum leaks and found two leaks which I fixed up... Now having a weird issue where it starts and at idle after a few seconds the fuel pressure suddenly goes to 0 and stalls.. if I blip the throttle, it will regain pressure and keep going though. I put a new fuel filter on and drained the old fuel and put new fuel in but maybe thats stirred up some crap in the fuel tank and blocked the intake or something??? Any other ideas? FPR stuffed?

EDIT: Also, when it stalls, the pump primes and pressure goes back up and it starts again as per normal and happens all over again.

Edited by Tim32
1 hour ago, Tim32 said:

Hey guys, I did a smoke test this week chasing vacuum leaks and found two leaks which I fixed up... Now having a weird issue where it starts and at idle after a few seconds the fuel pressure suddenly goes to 0 and stalls.. if I blip the throttle, it will regain pressure and keep going though. I put a new fuel filter on and drained the old fuel and put new fuel in but maybe thats stirred up some crap in the fuel tank and blocked the intake or something??? Any other ideas? FPR stuffed?

EDIT: Also, when it stalls, the pump primes and pressure goes back up and it starts again as per normal and happens all over again.

Check your FPCM. What happens if you bypass it? The ECU will bypass it during prime + initial start, then the FPCM kicks in and slows the pump down.

If you've been mucking with vacuum lines, start there, and check you have your vac line on properly, and on a vacuum line that isn't flowing air, it's just a vacuum source.

 

When you measure your fuel pressure, are you measuring absolute fuel pressure, or gauge pressure compared to the inlet manifold?

Hey guys, thanks for the replies! (We are noobs so sorry if some of this seems obvious or is completely wrong)

@joshuaho96 I did go looking for the FPCM (after googling) but it's an old drift car so I think that has been bypassed already, the fuel pump is wired directly to the battery.

@MBS206 OK I'll double check vacuum lines. I'm just looking at the FPR gauge, shows around 40PSI while priming and idle, until instant drop to 0, not even a slow drop, like instant.

 

1 hour ago, Tim32 said:

Hey guys, thanks for the replies! (We are noobs so sorry if some of this seems obvious or is completely wrong)

@joshuaho96 I did go looking for the FPCM (after googling) but it's an old drift car so I think that has been bypassed already, the fuel pump is wired directly to the battery.

@MBS206 OK I'll double check vacuum lines. I'm just looking at the FPR gauge, shows around 40PSI while priming and idle, until instant drop to 0, not even a slow drop, like instant.

 

How is the Fuel pressure gauge connected, show photos, what's it referencing etc.

 

Get photos of how the fuel pump is wired.

I'm assuming there's a relay triggering it, if so, measure what the signal wires are doing. From memory the ECU pulls to ground, so find the coil wire that goes to the ECU and measure resistance to ground.

 

If it's an old drift car, what ECU is in it?

9 minutes ago, Tim32 said:

Here's some pics, ECU is stock. thanks again.

IMG_3128.jpeg

IMG_3127.jpeg

That wiring looks like it was done by a 12 year old with a methamphetamine addiction. Start by redoing that disaster. What you're describing has nothing to do with your FPR vac source. 

  • Haha 2

I gotta agree that FP wiring looks, interesting.

And questionable.

 

I'd be doing some probing to see what circuit is shutting off.

It actually sounds like FPCM wiring is partly in use.

Priming, starting are all at full power from memory, then a few seconds later drops to half strength, and it looks like that signal isn't getting to your FP, as a hypothesis that is.

 

Needs more probing on a multimeter being done.

1 hour ago, MBS206 said:

I gotta agree that FP wiring looks, interesting.

And questionable.

 

I'd be doing some probing to see what circuit is shutting off.

It actually sounds like FPCM wiring is partly in use.

Priming, starting are all at full power from memory, then a few seconds later drops to half strength, and it looks like that signal isn't getting to your FP, as a hypothesis that is.

 

Needs more probing on a multimeter being done.

This is exactly what I was thinking, I just wasn't expecting whatever that hackjob was. Skyline owners never disappoint.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • A few small updates since the previous post and lessons. I decided to do a little interior light upgrade on the 110. I quite like the iilumo items, even if they're a bit of a premium over other brands. You'll also note the Stedi Fogs, that will go into the S15 fog lights as I needed to match the bulbs since I got the new ones earlier. I hope they fit as the body is quite a bit longer than your normal bulb.  Annoyingly, I managed to trip the fuse, which normally wouldn't be an issue until I located the fuse. I can't say I've ever come across this. I had lucked out that someone nearby had a spare, but oddly enough Toyota dealerships seem to keep this in stock. I ordered some to keep in my stash and as luck would have it, someone else nearby tripped the same fuse so I passed on the favour.  I also did a little service on the 110 ahead of some additional work coming up. It's been annoying that Goleby's stopped carrying this particular HKS filter for the 110, so now I need to keep them on order from Japan. I also took the opportunity to install a bash plate and number plate riser. The plate riser is such a cheap but nice fix to help really tidy up the car. I'm tempted to now also replace my headlights, on this car. Both items were from Project Aero.    I also needed to replace the rear tyres on the 110, and after trying to get it aligned learnt that I need to replace some bushes in the front end, so that's next.  Closing out this update with a nicer picture as always! 
    • Yeah mate, never miss it.
    • Any going to watch World Time Attack at SMSP this year?
    • Appreciate the correction on the "ground", that will make a huge difference to looking at this. That makes complete sense about AF70/AF71 which is what I had come down to being the issue, one of these. I'll have another look in the ignition wiring when I get a chance next week. I'll also make up a jumper wire for running that AF73 test.  ECU is fine, relay itself is fine, pump harness is fine and the pump itself is fine. I am going to upgrade the Walbro 255 anyway with a DW300 I have since I need to replace the fuel sender and I'm going to upgrade the FPR with my chasebays kit ready for new plenum/injectors/dbw, but I'll get this working first. That's why this is so frustrating. 
×
×
  • Create New...