Z Died On Me

[DuoWing]

So I've been getting back to work more and more on my 280ZT lately as the weather has been pretty decent. The car sometimes will have a hard time on the first cold start, sometimes it will start immediately, and sometimes it will start then die, then immediately start up on the next crank. When driving around town I have no issues with it it seems to run perfectly fine. Today I took it on a much longer trip than normal just because I haven't driven it very far and after about 15-20 miles of freeway driving I kicked the car down into 4th and got on it to pass a semi then it started sputtering going back and forth between power/no power until finally I was stuck coasting onto the side of the freeway. Electrical seemed to all work, was still getting spark, thought maybe my fuel line/filter got hit by something and was leaking, they were fine. My gauge on the rail was showing fuel pressure, but I could not get the car to start. After messing with it for a bit I realized I hadn't turned the headlights/parking lights back off. I turned those off and kept messing around. I disconnected the battery for a bit. I finally was about to give up, but tried cranking it some more and finally after some pulsing the pedal it started, but was sputtering then died. I did this probably two more times, then finally it was idling, but not the best. I was able to rev it up fine, so I tried to get back on the freeway and as soon as I got on the throttle the car bogged down and started acting up again, but didn't die. I then tried again and just going easier on it I got up to speed, got to the next exit, turned around and started heading back with what seemed like no problem. Made the whole trip back plus going further to home with no issues. When I got close to home I got on the car hard again to see and was having no issues. The only difference I did on the drive back was not turn on the parking/headlights. It was bright enough out that I didn't need them. The way I was previously heading was getting dark/stormy. I have a Walbro 255lph pump or at least it's supposed to be. I bought it through ebay and I'm not really sure if it's an actual Walbro. The only other thoughts I have is maybe a wiring issue, I was finding later when I drove it back to where I stored the car at night that there were some fuses in the fuse box that were getting pretty hot, I'm not sure which ones as it was dark and I couldn't tell. Also one of the connectors that goes to the parking/headlight switch gets pretty warm when running with the parking lights on. I'm not sure if these could cause a problem and cause things to freak out? I've only really had twice now where the car freaked out and both were when I was driving with lights on. The other time was at night at for a moment the tach freaked out but the car seemed to keep running fine. I didn't really drive that much longer after as I was almost home anyway.

 

Also my Brake light on the Speedometer never turns off, I'm not exactly sure how to get that to turn off. Also when sitting at a stop with the turn signal on I notice that brake light will go dimmer/brighter with the blinker as well as the voltmeter will bounce with the blinker. I don't know if this is normal?

 

I'm running the HID kit from the group buy so that's going through relays and everything so that I wouldn't think be causing a problem. A few years back I had the gas tank completely cleaned, blasted, and refinished. I'm also running a filter before the fuel pump. I need to pull that and check to see if that's getting clogged, I wouldn't think it is, but you never know.

 

Any suggestions on where to start? Or any more info you guys need? I'm running an L28ET with a P90 head, N/A "A" Cam, 1988 Z31 N/A ECU modified with Nistune so I can run the larger stock O2 sensor. 78' 5-speed tranny, ACT Street clutch, Fidanza Aluminum flywheel, etc.

[Cannonball89]

Sounds like an electrical problem. Check to make sure that your alternator belt is really tight. When I first did my turbo swap, the alternator belt was slipping under boost and making the car cut out. The datalogs revealed that, when the belt started slipping it the voltage would drop to below 11V. Also make sure that your battery is in good shape. The stalling after cranking could be due to the battery being too tired. The hot fuses would indicate low voltage as well. On my 240z I actually had to run a jumper directly from the alternator + to the battery +, but your 280z wiring is probably better and this might not be nessesary.

 

So measure some voltage readings, check that alternator belt, and get that battery tested.

 

EFI does not like low voltage!

[DuoWing]

Hmm those are some good thoughts, I'll look into it. I forgot to mention I've done the Maxifuse conversion which did help as some of the fusible links were getting pretty warm and after the conversion I seemed to eliminate that issue. I made up new 4 gauge Battery cables yesterday and I grabbed some 10 and 12 gauge wire to run more grounds around the car. Next up I'm gonna replace all the fuses in the fuse box and I ordered the parking light harness relay kit. Like I said my headlights should be fine since I'm running the HID kit that runs them through the relays and ballasts.

[Indey]

This sort of sounds like the issue that I have currently with my Z, my ecu tends to "fall asleep" for lack of a better term. It's random when it happens, but when it does I lose power and I can get it to attempt to stay on but wants to die out. Even if I get it to restart sometimes it will still be sputtering and wanting to die. However when this happens I just tap on my ecu it with my foot and it "wakes up" and then it runs fine again. I need to replace my ecu, however this is just some speculation, since it sounds somewhat similar to my car.

[DuoWing]

Well I got to work on my Z a bit today. The car never seems to have any issue with these short drives. I still need to go take my battery to have it tested. Also since the last drive my Voltmeter in the car decided to stop working. Either that or there's a fuse for it I pulled out. Anyway I felt like the alternator belt could definitely be tighter as there was more play than I feel like there should be. Tightened that up, then I replaced all my fuses. Some of them were old and I think the fuse labeled flasher fell apart when I removed it. I also installed the parking light relay upgrade I ordered through MSA. Dash lights, as well as the parking/running lights are definitely brighter now. After my short drive back tonight I checked the fuse box with it running as well as the harness connectors up to the signal stalk and everything felt cool to the touch. The relay was warm, but it seems like relays normally get warm? I'm thinking that was my problem, I can see on the connectors for the parking lights that it has definitely burnt up some. That 9-pin connector was charred a bit and showed signs that it's actually heated up and burned. So hopefully these couple things have taken care of the issue. While driving back I was getting on it at times and really running it up to redline through the gears and seemed to have no issue. So we'll see how things go.

 

This sort of sounds like the issue that I have currently with my Z, my ecu tends to "fall asleep" for lack of a better term. It's random when it happens, but when it does I lose power and I can get it to attempt to stay on but wants to die out. Even if I get it to restart sometimes it will still be sputtering and wanting to die. However when this happens I just tap on my ecu it with my foot and it "wakes up" and then it runs fine again. I need to replace my ecu, however this is just some speculation, since it sounds somewhat similar to my car.

 

This sounds like what my Z used to do when I had bad grounds in the ECU harness. It would start to sputter or randomly decide to idle bad, or a number of odd things and I could reach down, shake the harness, and everything was good to go.

[DuoWing]

Drove my Z today out to a local car meet about 25 minutes away. Drove there fine, drove around and parked and then on the way back it seemed like it started doing it's sputtering a little bit when cruising in fifth gear. I kinda let off it and just kept on the throttle real easy, it seemed to do it a couple times and I just kept cruising really easy and then it seemed to straighten out and keep going. As I got back near home I got on it a couple times and it seemed ok. I'm starting to suspect possibly the fuel pump? I'm still not certain that the Walbro I have is a real one. I think it's an ebay knockoff. It just came in a package with some instructions that said it's a Walbro I don't think there's any labeling or logo on the pump itself. Also it could potentially be my fuel pump relay. I'm using an aftermarket rising rate FPR and when I got home I popped the hood and with it in neutral I was watching my pressure gauge on the rail and as I'd rev it up it didn't seem like fuel pressure was really raising. At least not like it should be. If I have the car off and run the prime cycle it'll sit at about 35-37 psi like I have it set to per the FSM/Haynes for stock turbo motor. At idle my pressure was definitely sitting at 25psi or possibly lower. I'll mess with it some more but I'm thinking either bad FPR or bad pump. I may take the little filter off that I have before the pump to see if that makes any difference. I shouldn't even need that filter seeing as I had the tank fully cleaned, and reconditioned. Also I'll have to check the engine bay filter and see if that still seems to be clean. Pulled my plugs they didn't look lean, they looked kind of orange and dry, but nothing too out of the ordinary and they looked all really even across all six.

 

Also can one of you guys point me in a good direction to buy a real Walbro pump? The more I search online I'm pretty sure mine is a knockoff.

Edited May 7, 2012 by DuoWing

[DuoWing]

Well I removed the filter between the tank and the pump. Put some 1/2" fuel line from pump feed from the tank to the pump. Started the car up. At first the pump was super quiet then after a few minutes it started getting louder, now it sounds like the thing is just always whining. When I start fuel pressure will be fine at just below 30psi. Rev it up a couple of times and it revs no problem. Fuel pressure is not rising much above 30 like it should. I take it for a drive come back and now fuel pressure at idle is as usual back to about 22-23psi. Pulled the fuel filler cap off and didn't feel any vacuum when putting my hand over that fuel filler hole. When I did take it off a bunch of air shot out like pressure was relieved. With cap off fuel pressure and pump sound still didn't change. Checked the fuel relay and it's warm, but not overly hot or anything so I think that's ok. I'm thinking it's the pump or the regulator and I'm definitely leaning on the pump. I'll post up a picture of how my pump and feed line are routed to see if anyone thinks there's an issue with the routing. I'm thinking I'm just going to buy another pump and try that. Any suggestions? I don't know if I necessarily want to stick with Walbro.

[DuoWing]

Well I found some other posts on here talking about issues with Walbros so I decided to give the Bosch 044 in-line pump a try. That will be here soon. I messed around with my car a little more to determine if pump or regulator played an issue. One thing I noticed is either I need to drive a bit or it's not until I hit higher speeds such as on the freeway that this issue decides to show up. I drove around a bit, hopped out of the car and fuel pressure was still looking normal. Went and hit the freeway for an exit or two, came back then hopped out and fuel pressure was now low again. I pulled the vacuum line off the regulator and the pressure jumped up, but not to where the regulator is set to. It went from 20-22psi up to close to 30 at idle with the vacuum line pulled. I played around with this and it seemed to do the same thing when putting vacuum line on and off. Turned off the car and did the prime cycle a couple times. It was priming lower than where regulator is set. Thought maybe this was related to removing in-line filter so I adjusted the regulator so it was priming at about 36psi again. I came back a couple hours later after everything had completely cooled and hit the prime cycle and now the pump was priming the system at over 40psi. So either this regulator goes back to normal after sitting or it's the pump that after cooling down completely is now pushing out the correct fuel pressure. Also have some more pump relays on the way in case that's an issue.

[DuoWing]

Well I swapped out the Walbro for a Bosch 044 pump and it's doing pretty much the same thing. I also changed out the relay. From what I can tell this is coming down to being a wiring issue. The black/white wire that feeds 12v voltage through the relay to the green wire that runs to the pump was getting pretty warm/borderline hot compared to the other wires. Also over where I connected it under the dash to a battery 12v line was getting pretty warm. None of the soldered connections in between where warm, and the green power wire seemed fine. Also the relay itself definitely felt a good bit warmer than any other relays in the car. So I'm going to try running a wire straight from my maxifuse blocks to the relay so it's getting pretty much the direct battery voltage off brand new wiring while still being fused. Also I found that there's some sort of wiring issue going on with my ECU/Main wiring harness, I could shake the ECU/Harness and the car would start to stumble and nearly die. I just finished swapping the 280ZXT harness ECU connectors out for the Z31 ECU connectors which should at least give a tighter/better fit at the ECU. So off to figure out more wiring issues....yay!