chaseincats

Fair point - basically it won't run unless the coolant temp plug is pulled so the car runs in 'max rich' mode. You need to be VERY gentle with the throttle or it will die. After it's warm, you can plug the coolant temp ECU plug in and it will idle but will die with pretty much any throttle input. We smoke tested it and there are no vacuum leaks. It has new air and fuel filters, we adjusted the valves to factory spec, and cleaned all the contacts here except the dropping resistor.

Yikes, it's very possible that is what is going into the engine - he really should empty the tank.

Is that one of the relays located in the under-hood relay bracket?

The injector connectors have been replaced and look fine - I will let him know to check out the dropping resistor and ECU connectors. What is the connector you circled on the bottom of the chart - I don't see it labeled

Gotcha - it's getting pulse to fire, its just very weak.

We measured across the injector connector. Wouldn't that be the best place to measure it since it would isolate the plug itself?

Hey gang, My friend picked up a 75 280 and its not running all that great. We found that injectors 5 and 6 have 10.3 volts with the key in 'on' (but not running) but injectors 1-4 have something like 0.3v. According to the FSM, there are two dropping resistors, one that covers injectors 1-4, and one that covers injectors 5-6 so I'm assuming those (or the connectors) would be the problem. I have never heard of those going bad or causing problems though. I thought the injectors were supposed to get 6v after the dropping resistors - anyone know how they could be getting 10.3?

Interesting, got it. Regarding the combustion gas in the coolant, I'd guess I would see small bubbles in the coolant with the cap off if that were the case though, right? I ran it with the cap off when I changed the coolant to make sure everything was good and didn't see any with the car at 170. I can go grab the test kit and test anyway if you guys think its still possible without visible bubbles.

After I changed the radiator, I had enough coolant to fill the radiator to the top but not enough for the bottle. I figured the radiator would fill the bottle if the engine got warm enough so I didn't get more coolant. Is that not the case?

Alright, I'll give it a look. The heater core is connected - I did not turn it on while testing the temperature max though.

It has a 170 degree thermostat currently. The thermostat that was in there was a Nissan center feed 170 degree thermostat, and after putting the new 170 one with the offset valve (before changing any other part of the cooling system) I had the same issues so it shouldn't be that. I do remember it getting even hotter last year when i was sitting in traffic with the AC on so it really shouldn't be the new thermostat. Is the radiator throwing coolant into the overflow bottle the sign that things are too hot? Basically asking if I should care what the temp gauge is saying if it's not hot enough to push coolant out of the rad.

More numbers for you guyw More numbers for you. Today it was 95 and after a long drive with the AC on the whole way, with the sun directly shining on the hood, when I got off the highway it got up to 203 when I shot it with the IR temp gun when I got home. I put water wetter in it the other day for what it's worth. I took a look at the overflow bottle (which was never filled but I filled the radiator to the top of the neck and it was empty if that helps at all. Any ideas?

I'm guessing at this point its stuff hanging out in the coolant passages not the radiator. Regarding the IR temp gun, I tried that today and the gauge is indeed reading right. With the car in my shady garage it was apparently around 88 degrees in there and after running for maybe 15 minutes with the AC on and the hood closed it got up to around 195. Any thoughts on that number?

I used oreilly's generic flush chemical a month or so ago and did the low budget fix of 'the garden hose in the thermostat housing' which got a fair bit out but didn't change what the gauge had to say.

Any way to clear these without disassembling the head/block and shipping it off to a machine shop?

I believe its coolant since its white (not blue) and has a sweet smell

Good point - is there a way to check/fix that without sending the head and block to a machine shop?

Oil looks good - it's always thrown a small puff of white coolant smoke on a hard acceleration gear change though

I have an air/fuel gauge on here and it sits at 13.8 at idle which is pretty standard. Cruise is 14.2-14.7 depending on speed and WOT is around 11ish.

This was an aftermarket thermostat with an off-set valve. I'd definitely agree that could be the case but the thermostat I had in there previously was only a couple years old and a genuine nissan part with a centralized valve but after changing to this thermostat the issue didn't change.

Unfortunately the problem with the old rad/thermostat/water pump/fan clutch persists with the new rad/thermostat/water pump/fan clutch even after burping it.

I'd give that a shot but I got a new radiator and took it for its maiden voyage last Thursday when I noticed the car still had the issue

Hey gang, got an odd one for you. My car used to sit rock solid at 170 (has a 170 degree thermostat) but within the past year that's become more variable depending on if I'm sitting idle or driving. If sitting idle in 95 degree weather, it will go a little past half which I know isn't bad but the fact that it used to sit rock-solid at 170 regardless of weather tells me there's something wrong and even though its not severe it's annoying lol. I've changed the fan clutch, thermostat, water pump, checked fanbelt tightness, changed coolant, used a flushing chemical, and even got a brand new radiator but while the temperature isn't moving as much, the needle still moves depending on if idling or driving. There is definitely rust in the system because the PO used tap water and ever since I got it years ago, its been a game of 'how much rust will come out with this flush' (its always less but there nevertheless). I've also cleaned the temp gauge harness connector/sensor outlet and nothing has changed. I'd have thought it was the temp gauge if the car didn't go back to 170 like it used to while driving - but since it does, it tells me the temp gauge hasn't lost calibration and the coolant temperature really is changing. Any ideas?

huge help as always captain, thanks!

I would need to use the zx relay in combination with the zx door buzzer im guessing?