masterhufflpuff

Hey guys, I have another fuel related issue. Car is a 1983 280zx Turbo with the z31 ECU swap. Drove the car to school today no problem, just put in a new throttle body and TPS so I was working on adjusting the TPS because the car would backfire at WOT, but when I went to start the car not even a half hour later, and noticed my fuel pump was not priming, and the car wouldn't turn over, i checked the fuel filter for plugs, nothing, tried several different relays in place of the one under the passenger side dash, nothing. When I ran a line straight from the battery to the fuel pump i was able to get it to pump non stop, but obviously that wouldn't work for running conditions. So i'm wondering if it's possibly the ECU, since it's not the pump, it's not the relay, So at this point, if it is the ECU, which I think is the last option, from what i've seen there's two different options. 1) open up the ECU and try and figure out what fried, or 2) I know a few people have bypassed the ECU portion when they had this same problem, specifically JfairladyZ. I think the 2nd option is what I would like to try, but I don't understand where to splice in, and to which wire. I bought the car with the z31 ECU already done, so i'm not entirely ready to try and pick apart the horrible mess the previous owner created, although I should...

Thanks Everyone!
-Huff

Edit: I should note that it sounds like the fuel pump relay does still click once initially when the key is turned, and then once again after several seconds, as though its still causing the pump to prime

masterhufflpuff

Looks like it could possibly be a fusible link as well? the one labeled Br under the hood and next to the battery?

NismoPick

Sounds similar to this guy's problem which turned out to be a burnt section inside the ecu: https://www.zdriver.com/forums/300zx...ed-help-40079/

masterhufflpuff

Went back out this morning, first thing I checked were the fusible links next to the battery, they were getting power going in and out, all of them. Then I took apart the ECU to see if there were any spots that were blown, nothing noticeable, a small spot had some corrosion but I cleaned that up easily, plugged it back in and still got nothing. Re checked the wiring and couldn't find anything. tried jumping the relay, which is getting power, but couldn't get the fuel pump to turn on.
Are there other fusible links? other Relays? It doesn't make any sense to me if the wiring is good, the relay is good, the fuse is good, and the pump is good. It's defeating me.

NismoPick

Is there power at the pump? Is the pump grounded correctly?

masterhufflpuff

Nismo, the pump is indeed getting power, I think when I originally checked it i must have had a bad ground with my meter. So does that mean that the Pump is grounded poorly? Can that happen over time?

Although I was able to get the pump to work by running a line straight from the battery to the pump, could that mean the terminal where the power is going into the pump needs cleaning?

masterhufflpuff

I found closure. Went through all the lines one more time with the voltmeter and was finding constant power all the way up to the pump, so I checked all the grounds to make sure they were good, and they all checked out. So the last thing left to do was to clean up the port connection on the actual pump, and that did the trick. Although now I'm not getting any spark. On to the next adventure! thank you for the help all.

NismoPick

The stock fuel pump electrical terminals are covered with plastic caps... assuming yours were left open to get dirty / corroded?

masterhufflpuff

if the terminals are supposed to be completely covered by plastic caps...then yes, there weren't any caps at all over them...not a good combination.

Zuphoria

No caps? Just get some liquid electrical tape and lather them up! I love that ****!

masterhufflpuff

I haven't heard of that before, I might just have to look into it, thanks for the tip!

masterhufflpuff

Alright, the chain continues, I fixed the fuel pump problem, regained spark to the plugs, thought I was good to go, the car started up, but the idle was surging and wouldn't go past 2000 rpm's. Well I figured out that the idle connection wire from the TPS had just been disconnected, so I reconnected that and it idled well, but anytime I gave it gas it would cut off at 2000. All threads point to the TPS, so I ran the tests.

First I took an air compressor and blew out the connections incase any moisture had accumulated within, that didn't work. Then I checked continuity throughout the two points, and it was fine. I tried adjusting the TPS, but even when I had the adjustment correct, it would still cut out. When I unplug the TPS it runs worse because it's not being told it's at idle as well.

Then I went to the ECU, the FSM says to check continuity between pin 18 and 25, and when the throttle is depressed there should be no continuity, that's what my meter read. When the throttle is released there should be continuity, which is what my meter read. So that wasn't it either.

I tried unplugging the CHTS, no change there, ran worse. Same with the o2 sensor, and the MAF.

The MAF was my original thought because when unplugged the car isn't supposed to rev above 2k, but I checked continuity and grounds on that and it read all fine, and the car ran better with it plugged in.

One thing I did notice about the TPS that seemed off was the voltage. It was getting 9.45V which seems low for a Z car, checking in the FSM i didn't see anything on voltage, can anyone confirm that it is supposed to get around 9V?

As well am I missing anything major that would be staring me right in the face? It's not adding up to me, but maybe I'm checking all the wrong things here.

Car is a 1983 280ZXT with the z31 ECU swap

NismoPick

The TPS requires no specific voltage. It's just an on-off switch, that is all. What is your timing set to?

masterhufflpuff

I haven't yet checked the timing, I have the CAS at the same position it was when it was running correctly, but I suppose it could've changed or moved? To check the timing I need to open the head up and see where the timing chain is at, correct? set that to TDC? Is there anything I need to do on the distributor? Timing is something I've never done before so it'll be a little bit of a struggle here. I will need to use a timing light I presume?

NismoPick

Well you just start with a timing light (gun). Go from there.

masterhufflpuff

Alright, I will get back to you within the week with results. Thank you!

masterhufflpuff

Ok, here's what I found. there is a white mark at 20 on the timing marks, and another white mark on the pulley. When the car smoothed into idle after start up the white mark on the pulley was resting at around 6 or 8. (idle is somewhere in-between 750rpm and 1000rpm). Is that a good sign or a bad sign? i thought the TDC was supposed to be at 20 +/- 3. Am i supposed to check this at a certain RPM?

Skully

I do believe...that you are in the zone chief. At idle, it should be around that 8 ya.

Edit
Oop you are turbo, ya that 20ish...

masterhufflpuff

so in that case 8 is way off?...

Skully

Seems to be that way, you are for sure on #1 (closest to the rad).

masterhufflpuff

Yes sir, on the one closest to the radiator. So what would cause it to be so far off? I'm wondering if somehow I did my test wrong? It doesn't seem like it would be able to idle at such a drastic difference, but it idles smooth, exhaust smells a little rich I think.

NismoPick

You know you can easily adjust the timing, right? Loosen the two 10mm bolts at the base of the distributor and rotate while shooting the gun at the timing mark. Adjust to desired location, turn off, tighten down.

I'm going through the same thing right now with an 81 turbo I just acquired. The previous owner didn't have a clue what he was doing. The car has been running uber rich, so I towed it home. Upon inspection, he installed those gimmicky E3 spark plugs, and incorrectly installed the HEI ignitor (I'm no longer a fan of this "upgrade"). I'll be installing new NGK plugs and a Z31 ignitor and the 82-83T distributor.

masterhufflpuff

ya i've found out how to adjust it, I just want to make sure that at idle (somewhere between 750-1000) that white mark is indeed supposed to line up at 20. Is that correct?

Nismo, how many Z's do you/have you had? if you don't mind sharing, and which one has been your favorite?

NismoPick

24* is the official setting per the 83 FSM. I have mine set at 25*. I've owned 20-something Z cars... mostly S130's, but a few S30's. I kinda regret selling my 280ZT ( https://www.zdriver.com/forums/240z-...c-heavy-30516/ ), but I love my grey 81 2+2 turbo swap. It's always been my Z.

Here's the new 81T I bought last week.

masterhufflpuff

alright looks like i'm off to go adjust the timing, I will let you all know how it goes! thank you!

Nismo, you certainly keep yourself busy don't you! I'm jealous, no wonder you're such a master with these cars, the Yoda of Datsun.