Fuel Pressure leak... Seriously?
 

So as many of you may know.. I have been having a fuel pressure problem for a while now. I've checked and replaced many of the rubber lines and tightened every clamp I can find. I've also up to this point now replaced the FPR and the fuel pump.

Today I installed my new Walbro pump and it definitely is a huge improvement over the stock pump because I can recreate pressure through the lines much faster however the pressure still drops off..

Now I checked today whether the pressure stays when you clamp off the return line just after the FPR and the pressure does stay. Which means the pressure leak must be between the FPR and the tank on the return line. I cannot find a single trace of a leak anywhere and I figure at the rate this thing loses pressure I'd have seen one.

Does anyone have any ideas at all that I can check. Anything I've missed? At this point I am thinking I may have gotten a second dud FPR.. but I don't know what my chances are on that. (I got the FPR as an "OEM replacement" from autoshepherd.com)

Any ideas? :confused: I want to have my car running and smogged by Friday for prom but at this rate..

If you clamp off after the FPR and pressure holds, it's the FPR. :D

Ughhhh **** me. I paid a good amount of cash for that stupid thing. I probably can't even get a return on it now it's been a few months. :075::075:

Guess I've got to order another...

Buy a good one (actual OEM or quality aftermarket) this time.

Or you could experiment with endless junk yard options.

This is the one I purchased.

Standard Fuel Injection Pressure Regulator | Fuel Rails & Regulators | Free Shipping over $50 | AutoShepherd

Unfortunately it was also $66 at the time. Now it's $18? Great!

What FPR would you suggest for a lower price. I am running out of cash!

Edit: Ooh I see a 365 day return policy. Looks like I am going to have to deal with some customer no service...

So I got the diff back into the car (Damn that thing is a pain in the ass) and it seems to be doing alright actually but I haven't been able to drive much at all and you'll soon read why. Aside from getting the diff back in I installed the new 225 lb/hr Walbro fuel pump, changed the oil (and whoever put on the oil filter last must not have lubricated it and then screwed it on as tight as possible. Took 3 of us an hour to remove it..) and set the timing to about 24.

However when running it is having a really bad bogging problem. The fuel in the tank was bad I think and last night in first gear I couldn't get it to go past 1,000rpms. Today I filled it up with new fuel and let it idle for ~30 minutes. Then I took it out and tried driving it. While it was.. better it still was barely going. I could get it up to about 3rd gear on flat ground with my foot to the floor. It would also occasionally stall when I pushed in the clutch. It did seem like as I drove it that it could have been getting slighty better but I am not really sure. It just feels like the engine isn't getting enough gas. Could this be the bad gas still? There was maybe 1/8th of a tank of gas in the tank and I filled it up with new gas so I figured it would dilute it a lot.. Or maybe it's the FPR? Is it possible the gas clogged the injectors or something..? The gas was from maybe November/December. Anything you know of I can do about this? (Sorry for all of the questions lol..)

One side note.. I seem to have developed a short somewhere or something that makes my reverse lights not work. Also when I try turning on the light on the roof, the door light on the dash turns on and the clock goes dark. Pretty sure both of those things were alright before.. Not super electrical system inclined so some tips there are appreciated also.

Sorry I constantly barrage you guys with questions. This car just has so many little problems right now that it's proving very difficult for me to get it running right.. hopefully soon.

So just going through a process of elimination I decided to clean all of the contacts I could find on the car, including checking the ecu. Unfortunately no luck there so it most likely isn't electrical unless the ecu is fried! (Which I doubt..)

Just thought I'd update you guys. Looks like I won't be driving her to prom this Saturday! :(

I am hoping this is the FPR though I don't know if it can cause an issue like this. If not, and you guys don't give me anything else to try before the time I replace the FPR I might try putting the old fuel pump back on...

Edit: Oh and when I rev up the engine not in gear it backfires quite a bit when I let off the gas. Just giving all the details I have!

So I have a small update..

I fixed the fuel pressure problem, it was a second faulty regulator. (Thanks Nismo!)

I also fixed my thermostat, yay!


On to the more serious problems though. FPR didn't fix the problem like I hoped so I ran diagnostics on my ecu. It threw 13, 14 and 23.

So that's CHTS.. which I just replaced so it must be the connector wiring. I'll redo that on Sunday or Monday it looks like.

Car/Vehicle Speed Sensor.. haven't looked this up yet but it threw this code on and off. Don't know what kind of issues it causes.

TPS which I guess could cause part of this problem? It was fine before though so I have no idea what changed. All I've done is clean it since.

It also randomly threw 21 and 22 the first time (Ignition coil, Power Transistor, or Crank Angle Sensor/ Fuel pump - tank / Fuel pump relay) but for whatever reason these went away when I did it again..

Does any of this make any sense or does anyone have any idea what the issue could be yet? :\ I am at a loss for moving on.

Essentially what I am looking for is my next step towards getting it running better. Which of these is best to test next/replace and could cause issues like this.

Yeah, I had that exact same problem about 6 months after I did the Z31T ecu swap. Turns out the stock 280zxt lowest (bottom) ecu plug was a shibby put together at the factory. A lot of 280zxt erratic problems can be traced back to those lowest wires on that bottom plug (the ground wires for the main sensors). I've talked about it in other threads too (if you want to search for more info / pics). I cut out my ecu plugs and soldered in Z31 plugs, which allowed me to keep the Z31 wiring color codes for the new wires in the Z31T ecu swap.

FYI... the speed sensor is needed to do the MAF burn cycle.

Thanks for the tip Nismo, I'll definitely search for it.


So I went through and did the diagnosis fully this time(after reading some information on how to do it..), and I also repaired the CHTS wiring this morning.

It still threw these codes

14 - Car/Vehicle Speed Sensor

23 - TPS

I thought i'd add that the idle sits really low at about 500rpm right now and barely keeps up.

So do either (or both) of these fit kinda what issues I am having? Or should I go for one first and wait to see if it makes a difference.

The speed sensor is only used for the cruise control, and the MAF burn off cycle on the Z31 ecu.

Have you tested the tps? Set it to idle position?

I have no idea how to do that but I will search around :wink:

Haynes manual pgs 114-115.

FSM section EF&EC-56, EF&EC-83-84.

:D

Haha you're the best as always. Making my life too easy! (as if :P)

Hopefully I'll get it checked out within a few days. Got my Eagle Board of Review tomorrow (Boy scouts haha) so wish me luck!

Just thought I'd say.. I earned my Eagle Scout!

Not sure if it means much to you guys but it was a huge deal for me. It was a lot of work but the best experience of my life. The board of review was probably the most nerve wracking thing I've done though :103:

Congrats! I'm an Eagle Scout too. :D

How's the car?

No wonder you're such a great guy! :048:

And unfortunately I didn't get a chance to check anything out this afternoon. I don't get home from work until 6 and then I had dinner and went to the Board of Review.

Tomorrow though, I plan to clean and check the MAF and test the TPS. Also I realized I haven't checked/set the timing since fixing the CHTS wiring so I'll be doing that also. I'll give you an update then! :D

Yea the reveiw sucks. . . . I started my project late since I live in a very rural area and pretty much need a truck for the project anyway I turned 18 before I was done. Filed an appeal to texas but yea kinda got burned. Great program though! Still looking into the OA which I belong to give back to my old camp=)

That sucks I am sorry. Glad you're still involved though! It's a good program.


Also on another note... She lives!

My car is running now and pretty well actually. Turned out that once I fixed up the CHTS wiring I needed to readjust the timing.. a lot. But now that I have I can drive!

To clear something up.. I set the timing without the TPS plugged in because of something I read. Is that what the normal practice is?

The car backfires a little bit coming down in rpms, but it still does have a pretty big exhaust leak at the manifold so I can maybe associate it to that? We'll see. That'll be the next big project and I'm sure it'll be tons of fun. :D

My car does run a bit hotter than I expected though. It sits about 3/4 of the way up the gauge (maybe a tiny bit more) and it worried me. My fan clutch might be a bit bad but I don't think that's causing that big of a difference especially at highway speeds..

Edit: Oh and I think I experienced that vaporization of fuel in the rail for the first time. Car wouldn't stay started and then I heard a huge amount of noise coming from the gas tank. Then it started up and ran fine haha.