Help, 280 dies for a sec. under a load

[ScottyG]

I am unbelievably frustrated and I want to kick the dog.....But I won't.

I have had the z in storage for several years, (college= 6years).

I have not started it in about two years. I did the following and it is now running.

1.Remove and replace all fuel

2.New fuel filter

3. Remove all injectors and clean, all squirt well

4. New battery

5. new thermostat..... while replacing stripped housing, replaced thermostat housing. new one is different My original one (1976) has three "probes" that enter into the side of the housing, the new one has only two. The two that are currently connected connect with the standard nissan 2prong boot just like the fuel injectors, the third has only a one wire bullet connection.

6. New air filter

7. checked most of the vacccum lines.

8. New rebuilt distrubitor, cap and rotor

The car idles fine, revs fine all of the time, and accelerates fine when cold. When warm it idles fine, and revs fine with no load. But when am driving it after about 5-10 minutes and I step on the gas and accelerate hard the car will suddenly die and almost instantly comes back to life, jerking the car forward. It does no matter what gear.

I dont know what else to do I am totaly stumped.

Please help.

:stupid:

[2ManyZs]

Could be a lot of things....:cross-eye

I'd check the distributor first, check the mechanical advance plates to see if they move freely, or if any of the little "bearings" are not where they ought to be.

Check all the vacuum lines, can check to see if the vacuum advance on the distributor is working.

Check the rubber boots between the air cleaner and AFM as well as the boot from the AFM to the throttle body.

But, before you do all this, I'd check the timing and the condition of the cap/rotor first. You might also want to check the plugs and plug wires as well. I'm thinking it may be a timing/advance problem but you never know.....

If none of the above work, let us know and we'll come up with some of the less obvious things that could cause these symptoms....

[ScottyG]

Could it be this part? the part in the picture (top right) part that screws into the thermostat housing? What is this part called? I need a new one even if this is not the problem. Why have I not seen these on other 280's?

[Fun_in_my_z]

i may be way off but it sounds like the fuel pump.

least thats what it was on moms old chevy. hers did that for awhile.

[jlc280Z]

Check the throttle position switch. it is located on the throttle body. Use a meter to check the normally open and normally closed contacts.

Now move the accelerator linkage to full on and check the contacts again. The normally closed should open and the normally open contact should close.

One set of contacts tells the EFI computer to shut off the injectors @ 2800 rpm, for de-acceleration. If one set of contacts is corroded, the EFI thinks you are letting off the gas and it will shut off the injectors, causing a major whip-lash effect.

I had this problem after the car sat up for 6 months.

Hope this helps...

[ScottyG]

Update,

Checked the throttle position switchwith a multi meter, I believe that it is working properly. I cleaned all of the contacts, male and female connections, no change.

I replaced the fuel pump tonight hoping that this would make a difference. No change.

I have waited to try the timing until last because I will need some help with that.

I am also going to check my conpression tomorrow. My head gasket is leaking but it is hard to tell if this is enough to cause me to lose compression.

thanks again everyone for the help so far.

http://www.classiczcars.com/photopost/showphoto.php?photo=8954&password=&sort=7&thecat=500

[Fun_in_my_z]

i know you said you rebuilt the distributer but i talked to my dad about hes a mechanic. he says it sounds like the points.

you may want to try that he knows what hes talking about (sometimes) .

[ScottyG]

I completely replaced the distributor with a new rebuilt one. I also put on new cap and rotor.

[ScottyG]

I am leaking a lot of colant from by headgasket, Could this be caused by a warped head, or blown head gasket?

[frank13]

Warped Head causes blown gasket and vice-a-versa. But you said by head gasket? Not much point in tuning her right if she won't tune. You also said that it idles fine. Would not be true if you had a blown head gasket or warped head problem. The part in your question looks like a "Thermo Time" switch. Usually use in the EFI system for cold start warm up through either the Pressure regulator or the cold start injector, or both. I do not have the Shop book for your model so I am only refering to the basic Bosch J system. It also sound like Ignition misfire at a certain RPM. like stated earlier check plugs. And the wires & coil. Good luck. :devious: