fuel rail and pressure regulator suggestions-78 280Z

[Captain Obvious]

On ‎11‎/‎20‎/‎2019 at 9:21 PM, Yarb said:

Well that did the trick it’s idling now!!!

Excellent! Glad you got that one issue knocked off the list. Now on to the next one!

[Yarb]

And all the others patiently waiting in line!!!

[Captain Obvious]

LOL. Of course they are!  

What's next in line?

[Yarb]

 And all the others patiently waiting in line!!!

[Yarb]

Dave WM has graciously offered to help speed up the process by going over some tuning procedures with me and hopefully getting Her back on the road after a 12 year Z nap....I’m fortunate we live fairly close.

[Dave WM]

here is the current plan

fuel pressure test

cyl pressure test

timing check

vacuum hook up for test run

Temp check

CTS at operating temp check

have spare AFM and ECU if needed.

 

[Zed Head]

What's wrong?  Not really clear what the problem is.

[Dave WM]

fouling plugs was the main issue.

We met up and I went over the system. New plugs get black and wet pretty fast (minutes of running). However this is just a start up and idle (extended long enough for the T stat to open) and a few short burst, so the rich look may just be due to no extended normal use to burn off the start mix. I did the remove the oil cap test after the car warmed up, it would increase in idle speed and increase the vacuum (indicating a rich mix). A check of the FP looks good, 36-38 engine off, 30 at idle with a vacuum of just about 16inhg. The AFM had broken glue gobs so I assume it had been messed with at some time in the past. I brought my known good AFM from my test engine, We swapped it, and the vacuum deepened and the remove the oil cap test resulted in a drop in idle, worsening running. This lead me to believe the AFM was suspect. 1st I opened up the  orig AFM bypass to allow more air to bypass the flap. this helped (deepned the vacuum) but did not lean enough to get to the point of lean enough to pass the oil cap test. I could improve the idle with the AFM by holding the flap more closed (lean) so we proceeded to tighten the clock spring about 3 teeth total. Reinstalled it and the orig now adjusted AFM, reset the bypass. Now removing the oil cap results in a marked decrease in idle performance.

For some reason I never check the CTS resistance after warm up so that could be an issue (I just forgot, duh), but I discount it since the spare AFM I brought seemed to work so  well. I am not sure the orig AFM is optimized, its better but I did notice a small backfire (exhaust) just as we were wrapping it up for the day (goose the throttle, left off, minor backfire thru exhaust). I suggested just reinstall the airfilter (it was missing) and stop any further work on the EFI until a road test can be conducted to test under actual driving conditions (could not test today).

Aside from the possible rich fouling (which may not be an issue at all once a more comprehensive drive test is done) the engine sounded great. smooth, all injectors clicking away, no miss, no excessive valve noise. We had a temp fuel supply setup (gas can on elevated platform to simulate correct fuel level). as the tank is not yet installed.

I suggested checking with a local marine store about a prefilter (not the G3 fram but a 100 micron designed for prefilter use). This as a precaution against any large particles fouling the OE pump screen. I am running such a filter and have had no issues with fuel starvation. I noted on the G3 my pump would make noise, not so with the large as designed prefilter.

After its ready to get on the road we will check and see about a fine tune of the AFM. For now his efforts will concentrate on getting the temp gauge/fuel pressure gauge to work. We tried shorting to ground the temp sensor wire, and inconsistent results, sometimes ground would work some times it would not. Odd. I suggested getting a new sensor and fitting for mounting since I was having a very hard time getting a good ohm reading direct off the center terminal to chassis ground.

The oil pressure was a bit more confusing the sender seemed to be working 90ohms engine off 0 ohms engine on (that seemed odd but I tested it to my car and I got the same results). Clearly the sender is doing something yet the gauge was not even coming up to zero key on. I check the voltage at the oil pressure harness. I expected to see a wide flux in the voltage on my digital meter as the built in VR on the gauge duty cycles the supply. This is how my gauge works, 0 to over 10v constantly changing. I should have brought my simpson 260 which I think would be a better meter for reading this VR voltage. Anyway on Yarbs car the voltage was very stead right around 2.6-2.8 volts. I suspect a VR issue or some other problem with the gauge it self. Ground the oil pressure lead from the harness had no effect on the gauge.

He is going to need to resolve this gauge issue both for the temp and oil pressure before getting the car on the road.

the rest of the car looked very rust free. he only has a couple small areas that will need attention, but the area under the battery, the floor pans, around the wheel arches all looked very good. The frame rails look good as well. I am pretty sure it had the orig paint, so it would show its problems.

Oh and checked the timing, set to 10bdc and confirmed the mech advance was working (visual it would advance with rpm).

 

 

 

 

 

 

[Yarb]

 Dave, I really appreciate your time and effort today. Thanks for documenting today’s events which will come in handy when we revisit the AFM in the future. Once it’s back on the road I believe we will have a better idea on dialing it in. I think you. Accomplished quite a lot today just seeing the car for the first time. At this point as you documented earlier to focus on the gauge issue for now and move on to the drive train swap. Thanks to everyone for the guidance in order to get another Z back on the road. I’m looking forward to the next challenge ahead.