Aging Man with an Aging Car -- I need help

[kcelectronics]

When the engine is OFF there is zero oil pressure the switch is closed and the wire is grounded, while the engine is being started the fuel pump is activated by the ignition switch, and after the engine starts the oil pressure comes up and opens the oil pressure switch, this keeps the fuel pump running, (along with the voltage from the alternator) if the engine cuts out the pump will keep running till the oil pressure drops to zero (only a few seconds) and the pump will stop! This is to over come the safety issue that would arise if the car was in an accident and the ignition was still ON but without the engine running if the fuel line was damaged the pump would empty the tank very quickly causing a dangerous situation.

Hope this explains the Oil Press switch issue?

Colin

[sblake01]

I knew what you were saying. I was just being obtuse. :cheeky:

[wm_e_smith]

Speaking of distributors, I recently replaced mine (a long story). Parts store only sold a generic for all 78 810's but I noticed that the part number was for a station wagon, whether manual or automatic transmission.

I haven't noticed any downfalls. My thinking was that probably the only difference in the three OEM's was the vacuum retard/advance? What do you think?

[wm_e_smith]

I haven't noticed lately but in the past, I would switch ignition off and heard a noise from the rear for a few seconds. I assumed it was a normal thing and the fuel pump was only maintaining pressure. BUT I also noticed the noise seem to be there when the fuel tank was low but that might have been my imagination.

[sblake01]

I haven't noticed lately but in the past, I would switch ignition off and heard a noise from the rear for a few seconds. I assumed it was a normal thing and the fuel pump was only maintaining pressure. BUT I also noticed the noise seem to be there when the fuel tank was low but that might have been my imagination.

You never mentioned that before. Is the car ever really hard to start when it's warmed up to operating temperature and you stop say to run into a convience store and come right out to try to start it? If so, you probably have a bad fuel pump check valve.

Oh, and I don't think the distributor would be an issue.

[wm_e_smith]

You have described a problem I've had, exactly. I became use to starting it by trying, letting it rest, then retrying with no foot pressure on the accelerator. I assumed it was the cold start valve operating when it shouldn't be operating.

As an aside, back in 1991, when I had the relay problem, the Nissan Rep told me that I needed a new fuel pump. I asked why? and he told me just because it is old. Because of the cost, I ignored him. The original fuel pump is there today.

They are available so I'll get one whenever but soon. I like your thought and once more, it shows I have very little trust in the repair people, especially the "service managers".

[wm_e_smith]

Afterthought! The check valve? I'm now assuming it's a part of the fuel pump or am I assuming wrong?

[sblake01]

Actually, the check valve itself can be changed. It's located in the outlet which screws in to the side of the fuel pump. When it is working proprely it will hold the fuel pressure. If not the pressure has to build up before the engine will start. I had that problem on my Z and solved it by simply changing the check valve. If you fuel pressure checks out okay, then I would suggest trying this. I pulled my 'new' check vave from a ZX in the junkyard. Four years ago. The problem has not reoccured since. I don't know if you can buy them seperately. The Nissan part number is 17014-N4225. If you have trouble finding one, let me know. I probably have one somewhere amongst my spare parts. It'll take me awhile to find it but when I do, it's yours for the cost of postage if you need it.

[wm_e_smith]

I've yet to test the fuel pressure. Also, Stephen, I just read a comment on another thread that you have never experienced a fuel pressure regulator failing. I had thought of replacing mine. Does yours thoughts still remain?

I'll check into the check valve situation and let you know what I came up with.

[wm_e_smith]

Also, if I buy a new fuel pump, will the check valve come along with it?

[sblake01]

The 1978 280Z and the 1979 810 and a 1981 200SX are the only cars I've owned with this system. They all have fuel pressure regulators. The 280 and the 810 are exactly the same and the 200 was similar. Not one of the three of them ever had a fuel pressure regulator fail during my ownership. Check your fuel pressure. The procedure is outlined in the FSM. If it is satisfactory, about 36-38 psi if I recall correctly, while the car is running, then your fuel pressure regulator, fuel pump, etc. are okay. When you turn the engine off and that fuel pressure drops then your check valve is bad. Under normal conditions, with all components functioning properly, the system will hold the pressure. That's why you have to release the pressure before you remove any of the fuel hoses or the fuel will spray until the pressure releases itself.

[sblake01]

The check valve should come with the new fuel pump. But like I said, you might only need to change the check valve rather than the entire pump. I'd try that first. Its simpler than changing the pump. Just pull the outlet hose, some fuel will leak but not much especially if the check valve is bad, remove the check valve (14mm open end wrench), don't lose the copper washer that's between the check valve and the fuel pump, replace the check valve, put the hose back on, and you're done. If it works, problem solved. Very little expense.