Odd problem

[Pomorza]

Hey guys.

About two weeks ago I did the timing chain on my 280z. I'm not sure if this has anything to do with the problem but, since then I've had two times where I have lost power in the Z. The last time was this past afternoon.

I just left Nissan and got on the road. Upon start up the car drove fine for a bit but then for about five or six seconds I lost power of the motor at 2.5k. No matter what I did I could not regain power. The engine then regained power as if nothing happened. It did this once before.

On that occasion I started the car in the morning I was about halfway down the car refused to go beyond 3k on the tach. When I floored it, it sputtered and acted like it was getting no gas. Got to the stop sign down the street from my home and the tach dropped to 500 or below then went up to 750 then down again. I started driving again and within a few seconds all was good. Power returned and all was right with the world. I drove the car about 20 miles afterwords and nothing of the kind happened again.

I added a third of a bottle of seafoam to the tank before doing the cam chain and all. Since then I've filled up so I'm not sure if that has anything to do with it. My car has a top end rattling noise which could be a lifter I have been told but I'm not sure how that can play into this.

Thanks guys

Jan

[WingZr0]

Sounds like eradict fuel pressure issue. Had a similar problem once but don't know what it was since the engine was rebuilt to solve that and other issues at the same time. Let me guess, your driving along, everything's fine then all of a sudden quite. Your pumping on the gas, nothing is happening then it just revs on back alive like normal. There was a bunch of other VERY bad things wrong with my car but even after the rebuild my mechanic who did the engine still said there was a lack of power and fuel pressure at around 2500RPM untill about 3000 or so then the pressure came back. He saw it with a fuel pressure gauge. Look at the fuel pressure regulator and fuel damper by fuel pump first, if damper is leaking then there you go. Keep in mind that when the diaphram in the damper goes out it does not always constantly leek so put your hand up in there while the engine is running and feel around for wet gas. Also keep an eye on it for awhile to spot and smell for leaking gas. How old is the fuel pump itself.

Edited March 30, 2010 by WingZr0

[WingZr0]

To also note after the rebuild I never had that issue again. Not that this lack of pressure was ever noticeable but 600 miles or so after the rebuild while still in the engine break in phase it seemed like that problem was coming back though it never stalled. Just seemed like it was slow to respond a couple times trying to accelerate in 2nd gear. The second occurrence being worst than the first. Thats when I finally noticed the Fuel Damper was leaking after smelling gas from the back tire, seeing the leak drops but never catching it in the act untill investigating with the engine running. Once the damper was replaced I finally had 100% solid power back and no more "stalling" related issues. Hope this helps.

Edited March 30, 2010 by WingZr0

[Pomorza]

Your description is dead on. I'll be driving along and bam out of nowhere the car just looses all power for a second and then gets it back the next. I'm not sure how old the fuel pump is but by the looks of it (rusty, dirty ect) I'd guess that maybe a five years to a decade. (just an educated guess). The pressure regulator is pretty new as it was replaced a few months before I bought the car. I'm not getting the smell of gasoline but I'll go back there sometime soon and feel around for gasoline.

I have an inline fuel pressure gauge and it holds rather steady at idle. Its rather hard to see when I'm driving (as its under the hood) but I'll try to reproduce the issue with the car just standing (revving the engine).

Thanks for the information

Jan

[WingZr0]

Your welcome. As mentioned the damper sort of leaks inconsistantly so look at the bolt on top of it and see is there are any drippage lines or marks coming from the bolt, thats where the leak occures. Took me about three tries of starting the car and watching before gas finally started to spill out from the bolt, so if you don't see it the first time keep checking. Don't tighten the bolt to try stoping the leak, you'll just back up the fuel line and gas will start leaking from the nearest / weakest hose clamp. Easiest way to remove it is to remove the fuel pump clamp and let the pump hang by the fuel hoses, then remove the hoses off the damper then unbolt that entire mounting plate that has the damper attached to it from the under carriage. Replace the damper on the plate then reinstall. You'll need pliers to hold the dampers lock nut when you take it off the plate btw. MSA sells a great all metal, non bolt version by UNISEA JECS. Has a rubber plug instead of a bolt. Just bolt it on and go

Edited March 30, 2010 by WingZr0