EFI - periodic rough idle and shut down

[Sailor Bob]

I have been getting a periodic hesitation when under load for the past year or so. From time to time it will provoke a roadside stall. It is grossly inconsistant and once done, all symptoms disappear for several hundred miles.

Since I removed her from storage I have had the problem severely on two occasions.

Symptoms: sputtering over three grand that works it's way back down to idle speed - leaving me on the side of the road billowing dark smoke from the exhaust while missing like a son of a bitch. The smoke has a very strong smell of gas (according to the guy following me). She will konk out after a while and eventually starts and may even run fine.

The manual places me checking voltages pretty quick. I am thinking it may be a dirty fuel issue, as befor I had the worst episode I inadvertantly ran the tank quite low - next day - trouble.

Any thoughts - similar experiences?

[webdawg1]

I'm thinking gas tank as well... Have you had a good look around inside the tank recently?? Has the tank been redone or is it OEM to the car? (I.E. - Original tank that came with the car from the factory) Pretty much sounds like it's sucking up trash/crud from the bottom of the tank when you run it really low on fuel...along that same vein of thought you might want to change the fuel filter if you have not done that recently...

webdawg1

[DatsunZsRule]

Always a joy trying to track down an intermitten problem :classic:

I'm guessing this happens when warm only correct? I doubt your going to be pushing your RPM's 3,000 or higher on a dead cold motor (At least I hope you wouldn't )

Sounds like something is messing up the fuel mixture and causing it to flood out severely when warm. If it were me, I guess I'd start testing things like the coolant temp. sensor, Thermotime Switch ect. any component like those that could cause a fuel mixture problem like that when faulty.

Good luck with it

[turbo 260]

Could be a sticky fuel pressure regulator.

Jim

[240 Al]

Bob I'd take a good look at the temp sensor and connnections. The connections corrode and get resistive. The ECM sees the higher resistance as the engine being colder than it is and richens the mixture. If your not concerned about originality you can replace the connector to it with early 90's taurus 3 liter v6 injector connectors. They have a seal that helps keep the moisture out. The coolant temp sensor is about $33 from Courtesy parts.

Don't mistake it for the temp sending unit which has a single wire. It could also be that the sensor is changing value intermittently so ohming it out may not show it to be bad.

It could be other things like the fuel pressure reg. or sticky airflow meter. If you think it's the cold start valve, you can pinch off the fuel hose to it to see if it stops.

Car fiche.com has a fact. manual you can down load. there's also 280z electronic fuel injection book that explains it in plain english. I can direct you off line on that book e-mail me. 240 Al

[Sailor Bob]

Thanks guys for the excellent tips - I think am going to have to look at the tank anyway (after trying a few of the tips) - it is the original and to my knowledge has never beeen cleaned. It may take a while (as I am back at work right now), but I will advise you if and when I find the problem.

I may start a new thread on gunk found inside a gas tank.

[geezer]

I'm having trouble seeing how gunk in a fuel tank can cause an extremely rich condition to the point of choking out the engine and causing it to stall. The opposite seems more likely. It wouldn't hurt to check the condition of the tank. lines and filters but I wouldn't throw a lot of money at it without some further diagnosis. Take 240 Al up on his offer and get the information needed to logically narrow down the list of possible reasons this is happening. Better than needlessly throwing money at it.

[Sailor Bob]

You are right Ron - Spent a half hour last night reading the manual, prodding and jiggling wires. Seems that my EFI harness is a little on the brittle side with some repairs evident from the past.

It looks like the water temperature sensor connector is the same type as for the injector. I am thinking new connections might do the trick, but thinking I will end up doing all connections as the injectors all need to be done as well.

My harness has some splices in it already - wondering if it is more practical to replace the entire harness.

[m4xwellmurd3r]

replacing the whole harness might be a bit of a chore. I haven't tried yet, but there are lots of wires and I don't like wires.

I found a kit online on ebay for a touch over 20 dollars to replace all 6 injector plugs. it comes with instructions and shrink wrap. it's put together very nicely and the seller is an AWESOME guy (we had problems with USPS, he sent me a new set as soon as he found out I didn't get it. then once I got the old set, I just wrote return to sender.)

[Friar-Tuck]

Injector Solenoid Connector

Check out these guys for injector connectors.

Go to delcity website and type in 73522 in the search window....

Voila.. (and there is only a one item minimum.)

Beware, you can spend Hrs. looking through this catalogue!

Tuck\o/

[sblake01]

Those will work but they look pretty much like the OEM connectors and will probably get brittle a crack just like the OEM ones. Plus, you know how difficult they are to remove with the way the clips are designed. We talked about a better solution in this thread a couple of years ago. There's a smattering of useless information n there as usual, however. Look at the connectors in posts #21 and #30.

[Sailor Bob]

Got her running fine again by cleaning the water temp. sensor conection and the injector connections with electrical contact cleaner and an air blast.

The connections all feel loose to the touch, the boots are shot and the harness is rough looking but apearently the entire setup is still functional. So although it is running fine now - I will still look for a replacement harness. Z car source has one listed but they seem to be offline for a while.

Thanks all for your assistance.