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Premium Member
1978 280Z 4 original owner
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9 Posts
Discussion Starter · #1 ·
I have a 78 280Z original owner. Just completed a fairly thorough restoration. A lot of FI problems have started which I need help with.
New to the forum and trying to figure out how to go about getting the questions to the right area for assistance
Any advice?
 

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2,784 Posts
Hello Geoff,

Were you having any of these FI problems prior to the restoration? If not and these are now new, then chances are you've done something wrong or installed something incorrectly post resto.
Start with the easy stuff first. So, which is the first issue, or at least the one that is bothering you the most? Is it something like the engine simply won't start, or starts then dies, or fuel pump
not kicking on? In my experience with fuel related issues, its usually something small and minute, but then you start thinking its more than that and even more complicated.

Please refer to both the factory service manual for the 78 and the fuel injection bible for reference and to help diagnose these issues.
you can download them for free at www.xenonzcar.com and Datsun Factory Service Manuals - NICOclub


Bon
 

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Premium Member
1978 280Z 4 original owner
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9 Posts
Discussion Starter · #4 ·
Hey Geoff, try to break it out symptom by symptom, although that can be difficult. The better you can identify symptoms, the more we may be able to help.
Hey Guys thanks for the response.
Here is the history
Before the body restoration I removed the fuel tank and had it restored by Z Car source.
Replaced the fuel pump, fuel filter, replaced injectors.
It ran fine for a month or so after getting it back from the body work
The first problem was stumbling /losing power during acceleration. I spoke with a mechanic on the mainland {I live in Hawaii} he recommended cleaning the contacts on the throttle switch which alleviated the problem.
After a 40 mile drive as I was entering my driveway it started stumbling and stalling at idle. Also noticed blue smoke from exhaust.
Spoke to the mechanic in CA he recommended installing an oem fuel pump. I installed the new fuel pump, the problem did not go away.
Yesterday I cleaned the connectors on the Air Regulator, Thermotime Switch, Water Temp Sensor, Heat Temp Sensor, Gauge Sensor, Throttle Switch.
None of this worked and I noticed considerable blue smoke from the exhaust.
Note. I noticed a slight gas smell in the oil from the dipstick
Next I checked the plugs and found them to be black and moist with gas. I replaced the plugs {NGK} with a heat range hotter
Still stumbling, stalling and lots of blue smoke.
I hope this timeline helps. {I did download the Z car fuel injection manual/bible and used that for reference}
Any help would be greatly appreciated
 

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Super Moderator
8 / 71 240Z, HLS30-40031, L24-052899, Sunshine Yellow
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300 Posts
Does it have an automatic transmission?
If so, the vacuum modulator, that controls down shift, can leak at the diaphragm.
If that happens, vacuum will suck trans fluid into the intake manifold.
I have seen them cause a real smoke screen.
 

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Premium Member
1978 280Z 4 original owner
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9 Posts
Discussion Starter · #6 ·
Hi Dave,
Thanks for the reply. No it is a 4 speed.
Was told by the guy who has been helping me out from CA that I should replace the water temp sensor. I have the part ordered.
He feels the problem is excess fuel and the new sensor will alleviate that. I do think some of the smoke is caused by oil seeping in the cylinders. Possibly the valve seals are bad?
It has always smoked a bit in the past. The car has 82K original miles and has been meticulously maintaned since I bough it new. It has sat for extended periods over the last 43 years
maybe the valve seals dried up if that's possible.
Again any other suggestions would be appreciated.
 

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1983 280zx n/a 5-speed t-tops
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57 Posts
I had a similar problem with a friends car recently. It turned out to be the Fuel Pressure Regulator. The internal diaphram developed a leak which allowed gas to dump into the manifold through the vacuum hose. That extra gas caused symptoms very similar to yours.

You can check the FPR by 1) using a vacuum guage pump to see if the FPR will hold vacuum, or 2) remove the vacuum hose from the FPR while the car is running to see if fuel comes out the hose nib. Its best to check with a vac guage tho.
 
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