Throttle issues and now car won't start

[Blinkerfluid22]

Today I replaced a leaky fuel pump and installed an inline fuel filter pre-pump. I got the car back together and drove to the gas station. During this drive the car hesitated a lot from 2000-3000 rpms. After filling up the car was much better and reved more freely, but the throttle seemed to stay open on deceleration while stopping.
After the car warmed up I reved to about 5500 and then something happened. The car started stumbling and would shut off unless I gave it throttle, it also sounded like it wasn't running on 6 cylinders. Now the car cranks and begins to fire but it doesn't start. There are just a few pops from the exhaust, which are only sustained for 2-3 seconds, rpms are very low during this as well around 500rpm. I thought maybe the new fuel pump dislodged something in the fuel line that maybe clogged the filter. So I unplugged the line from the fuel filter and cranked the car, and it shot out fuel, so no blockage.
Any suggestions here? What should I focus on next? Plugs?injectors?afm? The car is a 76 280z, I just picked this up last weekend so I'm trying to work out the kinks. The guy i bought if from said it had an aftermarket cam, but no specific information about which one. Other than that the motor appears to be stock with the exception of a 6-1 header.

Edited April 28, 2015 by Blinkerfluid22

[EuroDat]

Welcome to the forum. Noticed its your first post.

You might want to start by explaining what model and setup you have. SU's, tripples, efi? You could be talking about a mustang for all we know.

Members find it easier to reply when they can relate to the problem. Now you have to many variables. The fuel system changed a lot over the 8 years they produced the S30. I know enough about the EFI system to keep me out of trouble and maybe help others, but little about the SU's.

The throttle staying open on deceleration could be typical for worn linkages on the SU setup. But then Im presuming your running SU's.

Don't be put of by my comments. Just add a little more detail about the setup, any alterations, background information etc.

Chas

[Blinkerfluid22]

Welcome to the forum. Noticed its your first post.

You might want to start by explaining what model and setup you have. SU's, tripples, efi? You could be talking about a mustang for all we know.

Members find it easier to reply when they can relate to the problem. Now you have to many variables. The fuel system changed a lot over the 8 years they produced the S30. I know enough about the EFI system to keep me out of trouble and maybe help others, but little about the SU's.

The throttle staying open on deceleration could be typical for worn linkages on the SU setup. But then Im presuming your running SU's.

Don't be put of by my comments. Just add a little more detail about the setup, any alterations, background information etc.

Chas

 

Thanks for the advice Chas, I have updated the OP

[Blinkerfluid22]

I have a 10 day temp registration to get the vin verified, so any help is welcomed.

Edited April 27, 2015 by Blinkerfluid22

[siteunseen]

He's got EFI, AFM, injectors in the next to last sentence. Check your air filter housing for rodent's nest. Have you replaced the metal fuel filter up front?

 

Chas, I'm sorry if that sounded bad, I was on my phone waiting at the drug store.  It's a pain typing with these stumpy fingers.  Forgive me.

Edited April 27, 2015 by siteunseen

[Blinkerfluid22]

He's got EFI, AFM, injectors in the next to last sentence. Check your air filter housing for rodent's nest. Have you replaced the metal fuel filter up front?

Yes, I checked the air filter, it looked new. I didnt replace the fuel filter up front, but I tested to see if it was blocked and fuel came shooting through exit side so i presume its good.  

[FastWoman]

It sounds like your throttle linkage is sticking, for one thing (won't come down to idle when you remove foot from gas pedal).  All the linkages are mechanical.  You can watch what pushes, pulls and turns when you step on the pedal (with the ignition off).  You should clean and lube the entire mechanism, from the gas pedal, to the pivots on the firewall, to the throttle body.  And make certain your return springs are strong enough to close the throttle.

 

As a newbie, you should download a copy of the beloved Factory Service Manual (actually written by Nissan).  You can download it for free from xenons30.com in their reference materials section.  It is very thorough and very well written.

 

I would change all fluids and filters.  When you change the fuel filter, shake it out to see what falls out of it.  If you see a bunch of debris, you may have rusty gas tank issues.  You may also have rust in your injector rail, as those filters apparently don't last forever.

 

Oh, and... Welcome!

[siteunseen]

Read up on the BCDD.  When I first bought my '77 it would hang up around 2,000 RPM for a few seconds then drop back down.  They're adjustable so I got mine working.

 

Also there's a throttle stop rod that pops out to keep the throttle from smashing down too soon.  It's under the plastic white thing with a hole in it.  Manual trans only, autos didn't have it.

 

Here's something you'll find yourself using quite a bit, http://atlanticz.ca/index.php/tech-tips.html

 

Go to "electrical" then to "electrical connection cleaning".  It's an easy way to get familiar with your car and doesn't cost much but makes a heck of a difference.

 

And WELCOME aboard the Z Train.

 

Cliff

Edited April 27, 2015 by siteunseen

[Blinkerfluid22]

It sounds like your throttle linkage is sticking, for one thing (won't come down to idle when you remove foot from gas pedal).  All the linkages are mechanical.  You can watch what pushes, pulls and turns when you step on the pedal (with the ignition off).  You should clean and lube the entire mechanism, from the gas pedal, to the pivots on the firewall, to the throttle body.  And make certain your return springs are strong enough to close the throttle.

 

As a newbie, you should download a copy of the beloved Factory Service Manual (actually written by Nissan).  You can download it for free from xenons30.com in their reference materials section.  It is very thorough and very well written.

 

I would change all fluids and filters.  When you change the fuel filter, shake it out to see what falls out of it.  If you see a bunch of debris, you may have rusty gas tank issues.  You may also have rust in your injector rail, as those filters apparently don't last forever.

 

Oh, and... Welcome!

Thanks for the link FW, i will replace the filter and blow some air through the rail.

[EuroDat]

Just to add to FastWoman's post. If you scroll down the xenons30 page you will find the 280Z/ZX Electronic Fuel Injection Guide, 3.8MB PDF File. Its well worth reading and the trouble shooting guide is good for finding faults.

 

As for your starting problem: You could have problems with flow and low fuel pressure. A simple pressure gauge will tell you a lot about the system.

I used a fuel gauge to iron out some problems I had.

[EuroDat]

And btw if it has a really old filter chances are its failed and allowed a lot of crap through to the injectors and FPR. They could be bloked and or the FPR could be stuck open with crap in it.

I changed my old filter when I got the car. The car was sitting for a long time. This is how it looked when I cut it open.

 

[Zed Head]

 During this drive the car hesitated a lot from 2000-3000 rpms. After filling up the car was much better and reved more freely,

 

but the throttle seemed to stay open on deceleration while stopping.

 

 something happened. The car started stumbling and would shut off unless I gave it throttle, it also sounded like it wasn't running on 6 cylinders. Now the car cranks and begins to fire but it doesn't start.

The first thing sounds like the fairly typical lean spot in the AFM.  A potentiometer in the coolant temperature circuit might help that.

 

The second one could be sticky linkage, as noted, or stuck dashpot (the little thing with the "Sorry" game piece on top - not a vacuum fitting), or loose throttle return spring, or gummed up throttle blade/body.  My 76 had all four of those problems.

 

The third one sounds like either an ignition module gone bad, or an ECU, or ECU connection, going bad.  If you have good spark it might be the second, if not, the first.  Check for spark, and check the ECU connection.  Could also be the coolant temperature sensor connection.  It would run well cold, the flood when it got hot.

 

Check plug quality, check for spark.  If they're clean and you have it, try starting fluid.  Watch the tach needle, if it jumps all over the place, that might be a module problem.