Jump to content
HybridZ

Recommended Posts

hey guys, i have a 77 280z and i recently replaced my fuel pressure regulator with a cheap adjustable aftermarket one to see if would fix a other problem "stupid move". this regulator said adjustable but it really wasnt so it was running around 50+ psi.. i never really ran it on that kind of psi but the otherday i had to move it out of my driveway for a second and it seemed to be running normal then all the suddin it started running insanly terible. it seemed to idle ok but when you touched the throttle it would instantly sputter. whell after a while of trying to solve this problem i fell unsuccessful and put it back in the garage. a few days later i try to start it and it will barly start and sounds like its only running on 3-ish cylinders and does not idle. still cant figure it out, a day later i go and try agian and then it fires maybe once for one or two cylinders and dies. im not sure what this problem could be. my best guess is that because of the high psi it has broken or jammed some or all of the injectors.  today i replaced the regulator with the stock one and banged on all the injectors to see if they would come un-stuck. i did have some breif success, it started and ran on 3-ish cylinders agian. if you guys have any idea of what this could be please let me know, thank you .

 

sorry for the long ass story.

Share this post


Link to post
Share on other sites

If it were my engine i would remove all the spark plugs and see if they are all wet. Clean them up with some carb or brake clean spray and dry them off. Remove the coil wire from the coil and crank the engine over to clear all the cylinders of any fuel that might be in them. Install the cleaned up plugs, plug the coil wire back in and fire it up. Should be ok once you get it running in my opinion.

Share this post


Link to post
Share on other sites

Thank you for the replies, i will try all of the things suggested. and @NewZed the problem is that my fuel pump keeps shutting off and my engine would stop firing for a second so i thought that it would help but i didnt, i will let you guys know tomorrow what the end results are from the trouble shooting.

 

Share this post


Link to post
Share on other sites

Sounds more like ignition, maybe the ignition module or just the distributor cap and/or rotor, wires, magnetic pickup coil maybe, etc. 

 

Could be any of those, but your description is a lot like how my 76 ignition module went bad.  It would do what yours is doing after a run up above 3,000 RPM, but would fix itself with a restart.

 

Edit - forgot to say that "fuel pump shutting off" might not be happening, and it's really ignition module shutting down.  Another sign. 

 

The injectors rarely get stuck, expecailly if they're used regularly.  If they do stick, it's usually a small leak, not a big hairy one that would give your symptoms and not all of them at once.

 

 

One thing, also rare, that might hold the injectors open though, is a bad ECU.  Try banging on it and see what happens.

Edited by NewZed

Share this post


Link to post
Share on other sites

If you can get it started again watch the tachometer needle.  When the ignition module goes bad it typically causes the tach to read high and the needle to jump all over the place, much faster than actual engine speed.

 

I know you can link to youtube or add embed code.  Don't know if the site hosts the files, probably not.  Easiest to youtube it and link it.

Share this post


Link to post
Share on other sites

Ok,  Today the car wont even start. tried kicking the ecu "no change" and checked it out to see if anything had fallen off but it was fine. i havent checked the plugs or wires but im sure that plugs or wires dont just instantly go bad, unless they were fouled by a instant change of Air ful Ratio but it was running like usual, lean.

Share this post


Link to post
Share on other sites

Fuel pressure is high, it flooded the engine. Fix that first. Put your old regulator back in.

Pull the plugs, dry them off dry out the cylinders.

 

Disconnect your CSV, both electrically and clamp off the fuel line.

 

Try it again.

Share this post


Link to post
Share on other sites

TD, he said that he put the stock regulator back on, in his Post #1 text-device based word dump (it's sad that I barely care about the crappy grammar and formatting anymore).  The adjustable FPR was an attempt to "stop his fuel pump from shutting off" (the other problem). 

 

Two vey basic things to do would be to check for spark while cranking the engine over, and to measure the fuel pressure.  If one of those is missing, it needs fixing.  If you have both of those, then flooding is a likely problem, assuming that no plug wires have been removed and replaced, or something unusual has happened (did you move or remomve the distributor while working onthe FPR?).  If you've removed and replaced the plug wires while you were working on the FPR, make sure they're not in reverse firing order.  The engine will run like you described with them backward.

Share this post


Link to post
Share on other sites

Fuel pump shutting off is either oil pressure switch issue or contacts in the AFM. But not necessarily an AFM issue, if hte car stalls, the flapper closes and the fuel pump shuts off.

 

Odd as it is to say, what solved that on someone's car I worked on was a valve adjustment. Car would barely idle and then get into hysteresis because the engine would rev, then stall, pump shut off, but 'recatch' and start to rev up again (pump then comes back on), but due to fuel starvation engine dies (fuel pump shuts off) repeat....

 

Car go real smooth after valve adjustment, fuel presure dropped 5PSI! Vacuum at idle went from 8"hg to 18" HG. There was a timing adjustment as well since the guy had advanced the timing to 'isle up' the engine because turning the (fouled with PCV CRAP) idle adjustment screw didn't do anything.

 

Really, go to the basics before starting troubleshooting. Do a full proper mechanical tune up with the car and make sure all settings are correct....THEN start diagnosis. The 45 minutes - hour you take doing this may annoy some...but the time it saves later in diagnosis as you spend time finding symptoms, finding the issue, repairing it...then having something else jump up...

Share this post


Link to post
Share on other sites

thank you @tony D, i haven't been able to work on my car because of some personal problems, but as soon as i can i will pull the plugs and see if they are wet, and show you what they look like. As a note i have had the car for about a 1 1/2  and put about 5,000 miles on it and haven't changed the plugs or wires but the guy i bought it from said they were brand knew.

Share this post


Link to post
Share on other sites

Many times you can reclaim these plugs by burning off the fuel with a propane or MAPP gas torch. I go till the ground electrode is glowing red an no more orange flames are present.

 

Then I move to the next plug. Bare handed. It shouldn't take that long to burn em off...

 

Usually at that point, I put a flame blast into each plug hole and usually get a healthy "woooshbop!" out of a few.

 

Then I screw em in and fire it off post haste!

Share this post


Link to post
Share on other sites

"update" after i put the new plugs in last night the z started right up and idled, but sounded like yet again it was only running on 4 or 5 cylinders. This morning i drove it to my school shop and we did some testing. after a plug, compression, wire test etc. we came to the conclusion that cylinders 1 and 4 were not firing, and the injectors that belong to those cylinders were stuck open.  I only got that far today but i will still continue to update you on this situation. thanks guys.

Edited by Metric Killerz

Share this post


Link to post
Share on other sites

So they weren't stuck open, they were simply closed from lack of an electrical signal to make the solenoid coil work.

 

Hardware stores or places like Home Depot and Lowes, sells crack pipe lighters that you may be able to use to burn off the fuel. I just usually use some brake kleen or carb cleaner from a spray can to clean spark plugs up. 

 

Not having one of those in the glove box makes searches during traffic stops go much faster...

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...