Help/ Turn the car on, but turn off by itself

[kingofswords]

Hi guys,

My car (q45, 1991) keeps turnning off by itself. At first on the second try, the car would start, and I was able to drive it. Now sometimes it will start, and keep running , and sometimes it will turn off a few seconds after. It seemed that when it was cold, the car wouldn't keep running, but just yesterday, was driving it for a while, and I stopped to pick up my wife from work (didn't turn it off though), and it satrted shaking a little then engine stopped running. I took it to a repair shop, and the guy change the gas pump & filter, and the air filter. He said that that would solve the problem, which obiously it didn't, so I got my money back. Anyways, the problems is still there, and I have no idea what could this be. I don't want to take it to another repair shop, because I don't what to get rip off. Any ideas?

Thank you in advance,

[Jesda]

Does it happen when hot or cold?

[maxnix]

Welocme in to the most information on the G50 on the web.

This post might get moved to the Infiniti Online Mechanic Forum, where it is more appropriate.

If your mechanic replaced your fuel pump and filter without charge, he is very generous. Is you heard a buzz from behind the back seat that you don't hear now, then it needed replacing anyway. You didn't give mileage (nor location in your profile), but I would suspect the ignition switch at that age. Problem is, without a maintenance history, there are many things in combination that could be the problem, making it most difficult to diagnose over the internet.

[kingofswords]

It used to happed when it was cold, but yesterday I was driving it, and it was hot, and after a while it turn off (I had it parked but it was running). Today I drove it to work, and it ran fine, but when I first turned it on it seemed like it didn't want to accelerate.

[maxnix]

Your description indicates more than one problem.

Was the fuel pump new OEM?

[kingofswords]

I'm living in Hawthorne, near Los Angeles. And the mechanic charged me $200, but he told me that this would take care of the problem...but it didn't, so I got my money back. I had just recently replace the fuel pump, but he said that it was plugged, and so I trusted him.

The car has 166000 miles.

When I do get the car to keep running, it does not accelerate. Even if I step in the accelerator, the car goes very slowly, and if I'm lucky it will eventualy "catch up" and accelerate normaly.

[elwesso]

sounds MAF related, but i dont think changing the fuel pump was futile.

[maxnix]

Was the fuel pump new OEM?

So was it a new fuel pump? Did you check the terminals of the FPCU?

Were there particles in the bottom of the tank? Did you clean out the fuel lines? REplace the rubber? How long since fuel filter changed?

Any history of BG44K? Plenum, EGR, IAC valves and lines all pristine? Rail slush ever performed? Check the resistance on you injectors? How about the KS?

What does the ATF look like? Any maintenance?

Accessing the oil filter from the top will eventually ding the MAF connector.

So much we need to know to help.

[kingofswords]

I'm sorry, but to be honest I don't know what's oem means. I do know the pump was new.

[maxnix]

OEM = Original Equipment Manufacturer

i. e., Nissan

[kingofswords]

I bought the car afew months ago. The only thing I have done/change to the car is the oil, oil filter, gas pump, gas filter, spark plugs, and air filter. I was about to do the transmmision oil/filter change, but his came up.

What do you suggest?

[kingofswords]

Oh,Ok. I don't think it was an original part. I know it didn't came from a dealer, and it looked a bit different then the one it had...but then again I'm not for sure.

[elwesso]

Id buy a used MAF out of our classifieds, wil cost about $50 andyou can install yourself, only takes a few mins.

[kingofswords]

What's a MAF?

[johngalt]

Mass Air Flow sensor.

I had a post here that had a nice writeup linked describing the MAF, in this post.

[elwesso]

Mass Air Flow sensor. Spend some time on Q45.org. We are here to help, but not to hand it to you on a silver platter...

[kingofswords]

Thanks for the tip. I don't know much about cars. I just know that my car is not operating correctly, and wanted to get some ideas on what could be causing this problem. I'm very sorry that I don't know the terminology, and I don't expect you to teach me. Please don't get offended. I'll try to check out this wed site.

Thanks,

[kingofswords]

Thanks I check this out. I think this will help a lot.

Thanks again,

[squeefoo]

You must check the Fuel Pump Control Unit (AKA FPCU) ground pin to circuit board before you spend any money.

My car did the exact same thing when I bought it, and the pin to board solder joint was melted. Easy fix. Do a search on FPCU+pin+solder in this forum.

[maxnix]

Yeah, and I would be real suspicious of a non OEM fuel pump.

Test the MAF connector first by wiggling it while the car is running.

Spend a few evening reading the previous posts, including all by Q45tech. You will understand a lot more when you finish, and will be better able to diagnose your problems and ask the right questions.

[elwesso]

Thanks for the tip. I don't know much about cars. I just know that my car is not operating correctly, and wanted to get some ideas on what could be causing this problem. I'm very sorry that I don't know the terminology, and I don't expect you to teach me. Please don't get offended. I'll try to check out this wed site.

Thanks,

No one here is offended, so your OK. We are here to help you fix your car and help you learn..... Just spend some time reading on Q45.org......

I am willing to talk withy ou about this problem on the phone, email me if you want my phone number.