my 280z sputtering/stalling

[metrickillers]

hello friends, since i had my z, it sputters/stalls when its hot or has to work to hard. I have replaced , water pump, thermostat (im currently running with no thermostat), and even i went as far as to heat wrap my entire exhaust manifold and downpipe, the problem didn't change. my engine bay is actually insanely cool now. if its a cold night my car runs great (unless im racing).the problem has gotten worse to the point were it happens all the time, even if its been sitting in my garage for a day or two. I think i have tracked the problem to a dieing fuel pump and bad relay. Im getting a Bosch 044 pump here pretty soon. but my question is has anybody encountered this problem, what did you do?

[San Maru]

Temperature related, so look at the temperature sensor and its wiring. Instructions are in the factory manual.

[metrickillers]

my temp sense isn't hooked up but i know my engine isnt getting overly hot. i never boil over or even get close. my fuel lines don't get hot, but i think that since my pump is 36 years old and is almost dead, if it has to work hard it just shuts off and i loose pressure and velocity in my fuel lines. thats the only thing that makes sense to me. whatever the problem is its getting progressively worse so i don't know how it would be a "block" heat problem. so im replacing all the filters ( 9" or 5" inline aluminum filter), pressure regulator,new relays, and a 944 turbo fuel pump. so im hoping that will fix this.

[I'm BLUE]

Does it shut-off while driving ?

or is it a power/bog issue when warm ?

Racing ??? more than 1-minute of WOT high speed racing ... Nissan warns your catalytic converter will melt down right on the drivers side sun-visor when you flip it down lol . (on my 280zx)

 

Fuel pressure test , and Fuel volume test.

Lines are usually shit so check and replace those ... especially by the tank !

you need The $4.00 a foot stuff from auto-parts place ... if $1.50 per foot .. they are selling you wrong type !!

 

Electrical connector's and corroded connections .. are typical culprit's on these cars ( I know kicking a dead horse )

but really ... it's true ..

Many of your sensor connector's are Bosch EV-1 style if you need new ones.

You can test the harness and sensor's themselves and even injector's/ignition component's via a multi-meter and specs from the FSM at xenon.com

 

Keep in mind that mufflers can get partially clogged/clogged ... especially if you live in an area prone to rust out cars (sounds funny I know)

and catalytic converter's clog quite often these days (usually not the oem ones , but cheapo aftermarkets can burn up quite fast)

 

If you've already ordered the parts

I would strongly recommend servicing your fuel injector's (even look on you-tube how to do this .. quite easy .. make your own catch containers out of anything ... I prefer Sea-Foam or BG products Fuel System Cleaner ... if ..you can get some )

There particular injector's never really stop working ... mostly dirty if anything ...

While there check your injector connector's. If you need new ones just solder them in. Bosch EV-1 type ( there are cheap ones and nice ones ... )

 

Check your timing chain stretch ... advance the sprocket as deemed necessary per FSM specs = xenon.com

Test your AFM as well and make sure it operates/opens freely especially (multi-meter).

Check your O2 and replace for $12

Check your CHTS via multi-meter as well.

 

unless you're engine is/has been running warm you should always run a t-stat..

OEM temp preffered , but circumstantial to your region.

 

Typically vacuum hoses are cracked unless you replace them :) ( should be replaced something like every 12,000-20,000 miles ?? per FSM specs on some 280z/zx model years ). No one ever replaces them in those intervals though lol.

[metrickillers]

wow, thank you for all the info BLUE. yeah the car will sputter while driving at low RPM (not if cold) if i drive for about 45 minutes (warm temp) it will sputter then stop firing for a second backfires then start firing again and go's. the more i drive it the worse it gets or sometimes the more i drive it the better it gets. but recently it just gets worse. my cat exploded and i think there might be pieces in my pipe somewhere. tomorrow im actually taking the the pipe and cat off so i will check for blockage then. my air fuel mix is lean but i dont know how i will dig into that dino ecu to change it, so im going to get bigger cc injectors to even it out but that's a little ways down the line. the guy i bought it from said there was something wrong with M.A.S. so he replaced it, im not sure if its working properly. tomorrow i will also try a pressure/ volume test and see if there is anything abnormal, but it only happens when im driving it dose not happen when im idling or revving in neutral.

[San Maru]

With a temp sensor unplugged your ECU goes to full rich, which is fine as long as your engine is cold.

[metrickillers]

yeah its undrivable now "pump dead". you can actually hear the pump shut off when wen the car starts acting up. im sure there are many factors to this problem but after hearing the pump completely shut off i think that is the main reason. well thats what you get wen you have a old car with 97% of the parts being 36 years old. oh and i didn't buy the 044 pump yet, can you guys recommend some good fuel pumps for around $100-$150.

[San Maru]

You can get a nissan fuel pump at a parts yard for less than half that. Take a cordless drill battery to see if it runs.

[metrickillers]

i would do that but im prepping for a turbo so i would rather just do it now.

[I'm BLUE]

you're welcome !

 

I wouldn't install larger CC injector's to remedy the lean condition :)

make sure no leaks/blockages in fuel system at same time ( my fuel pickup strainer/filter's in my zx's have been blocked in the past ! )

 

Sounds like your first suspicion (I can't spell ? lol) .. a fuel relay/fuel pump. (fuel relay might be EFI relay combined into one unit on that year as well)

Ignition switches go out on these as well (mileage/age/use taxed !!) , but I'm sure you'd see some more dramatic symptom's as well lol

You can check this relay via the Factory Service Manual = xenon.com to confirm before dropping dough ;)

You might check your ignition system at the same time .. especially the module .. and dizzy guts ...

 

I was under the impression stock 280z,280zx,280zxt Fuel Pump's were all the same units ? ( maybe someone can confirm )

Unless you're planning on a larger turbo and injector's/other work ... then I understand why you want the 944 turbo pump lol :D

 

If you have a hard time starting .. the check valve inside you're fuel pump might be bad as well.

Oh yeah .. service your cold start injector the same as the rest of the injectors (just a tip) ! ... I usually just service them often enough and have never really had a problem.

 

 

 

Are you planning drive around N/A for a while longer before a L28et conversion ?

[San Maru]

Plumb in a fuel pressure gague and watch it. The zx turbo fuel pump is different but people do turbo swaps leaving the N/A pump. Most lean conditions I see on EFI/EECS are from unmetered air leaks. The first thing I have people do is check the manifold vacuum pressure. Anything below 20 and you have too many leaks in my opinion. My cars have 21 at idle. You are right, different electrical things can make the fuel pump operate funky. But most of my EFI and ECCS knowledge is from the S130s so I cant really list the things for him. He seems to have a psychic approach anyway. I gravitate to the scientific way myself. To each his own. At this point all I can do is wish him well. Hope you get it figured out one day.