280 ZX Turbo running problems

[ChipF47]

I have had my 1981 280Zx Turbo for about 2 months . I purchased the car from a man who let it sit for about 3 years without running. I was able to start it with a jump from another vehicle and drive it home. It ran rough and to this date I have done the following:

1. Plugs

2. Plug wires

3. oxygen sensor on the exhaust

4. test fuel injectors and replace 2

5. Dist Cap and Rotor moved dist to seek best position

6. Fuel regulator

7. Fuel filter

8. Compression check no real low indications

9. Valve adjustment

After all this it still runs about the same. Won't idle and seem rough at higher RPM levels. Oddly enough it will sometimes clear up and run smooth and idle well for a short period of time and then revert to the described condition.

I am at a loss but beleive it may be some sensor or other non internal problem.

Any help would be greatly appreciated.

[LanceM]

3 years sitting means crap in the gas tank to me and of my experience it sounds like it may be your problem. Gas sitting for a long time turns to a varnish like crap that coats your gas tank, smells like holy hell too! New gas in the tank seems to slowly dissolve the varnish which will pass through a filter and gum up the works every where else. I would try double dosing a couple of tank fulls of injector cleaner and see if things get better. I'm figuring that the varnish is clogging the injectors overnight when the gas evaporates and after enough driving it gets flushed out and things run right, till the next day... Sounds almost exactly like the same problem I was having with my carbs. I would clean the jets and it would run great, let it set a day or two and crapola, had to clean jets again. Mine sat for 15 years and the tank was major $hit city, got it cleaned out and the problem is gone.

I also found in the mean time that a good dose of Marvel Mystery Oil in the gas helped things, with it there it would keep the varnish from clogging things up as it didn't evaporate like the gas did and would let the varnish blow through on the next start up... Hope this helps...

[ChipF47]

Lance

Thanks for the reply. I have been reading some of the other post here and seen where the coil has been a problem. When I was conducting the compression test, the book said to remove the coil wire at the coil. When I was cranking the engine to get readings on each cylinder, the coil was arching on itself very visably. Is this normal?

Thanks, Chip

[ZmeFly]

Just means your coil is doing its job. I had a problem though slight but it was annoying me for the longest time. It was a stumble at idle when the engine was warm

All I did was replace the hose and the PCV. Now idle is excellent and no more stumble.

You might want to try that.

Also go threw all your electrical connections, at the ECU and all threw the engine bay, clean everyone ESPECIALLY THE GROUNDS!!!

Secondly check all vacumn hoses, make sure they are in good order, if you can replace them.

Third as said above make sure your fuel lines are clear of any gunk. You can get a pressure gauges and put it inline after the fuel filter to check fuel pressure at idle. With this you can also check to see if your FPR is working properly. Should be around 37psi at idle.

Check that your plug gap is correct, timing is correct and also if you have an FSM check the CHTS(cylinder head temperature sender).

Good luck

[ChipF47]

Well, I changed the coil today and still runs like crap.

[ChipF47]

I spliced a pressure guage into the fuel line after the filter and started the vehicle. At any speed above idle , the pressure dropped to below 30 PSI. Sounds like I need to inspect the fuel lines and perhaps change the pump.

[ZmeFly]

Check your filters if you havent replaced them.

Also, remove the vacumn line from the FPR and see if pressure rises, if it does not, the FPR is shot!

Trying to save you a little money first.:classic:

[ChipF47]

Thanks for the info. I replaced the fuel filter and the FPR when I first got the car as an atempt to correct the condition. The car does not idle well and as soon as you try to increase RPMs, the fuel pressure drops from about 35 to 25 PSI.

[ZmeFly]

I would suggest upgrading it now instead of buying nos fuel pump.

A walbro would be a nice choice. If you go to summit racing's website, they have a holley for forced induction cars thats an inline pump.

It is the Walbro 255

[ChipF47]

This AM I drained the tank, blew air through all lines and momentarily ran the pump to clear out any thing in there. I looked for the Walbro pump on their site but could not find it. My pump is not in the tank and I would like to keep it that way. On the way to get fresh gas for attempt at run. Will let you know what happens.

[ChipF47]

I put fresh gas in the tank and started the car. It still won't idle and the fuel pressure drops as RPM's increase. I pulled the vacuum line to the FPR and the pressure did increase. The motor did not seem to run any better with increased pressure. When the line was repositioned on the FPR the pressure fell and acted as it has all along.

[ZmeFly]

Heres the Holley pump (which actually is a Walbro)

Fuel Pump

By the way it is an inline pump.

Hope this will solve your problems as it seems your not getting enough fuel pump.