Runs well and then stops, will not start then does.

[CINNALOCKS]

I have a 94 Q.....had to go somewhere a couple of weeks ago....had been making a few runs and all was good. No humming in the rear and no other unusual noises. Came out and nothing it was 4 in the afternoon and over 90 degrees. It was like the battery was dead, but that radio and air came on before I even noticed the car did not start. Had to have it towed home. Later around 10pm it started. Same thing happened a week later, had it towed to the garage and left it.
Put it on the computer and they are saying it comes back as a MAF PROBLEM caused by loose pins and a bad air duct.

While that may be an issue I am not buying it as THE issue. I am thinking it is the fuel pump itself. I checked the module and all is good. Besides if it were the module it would crank... but not fire, it does not even crack. He said he found no problem with the fuel pump but he would go back and recheck flow and pressure. While I am willing to replace the MAF and Air Duct....some how I feel as if this will not solve my issue.

[maxnix]

Do check the MAF connector and wiring.

Not cranking is a head scratcher. Fuel filter replace within last year?

What usually happens is the FPCU overheats and melts the solder, which solidifies when it cools. You must get FP readings at idle and under load. Cold and warmed to operating temperature.

[qship96]

No crank at all? Look at the starting system first, especially the starter relay.Located up near the windshield on passenger side, typical nissan blue relay,exact same ones {same part numbers too} that regularly fail in the traction control system.Sometimes when this relay starts to fail, it is intermittant, like you are experiencing.

No crank rules out fuel pump,controller,filter,and MAF as primary issue.

[CINNALOCKS]

No have not changed the fuel filter in a year but am doing it now. I know my air duct from the manifold to the maf is bad and have been looking to replace it but that would not keep it from cranking would it? I will have them recheck the FPCU, but when I last looked it was looking good no burnt spots or obvious bad wiring. Last time I had a control issue it still cranked, so I was able to by pass it by using an alligator clip and a paper clip. But it cranked. No when it stops I only get a hum in the rear when I turn the key.

[CINNALOCKS]

Qship no crank when it gets warm. First thing in the am or when it cools off then starts with no hesitation and runs fine till it stops again....never know when. Then no crank only a hum in the rear when I turn the key. If it sits over night it always starts the next morning.

[qship96]

replace the relay first, as it is only $17. If problem persists,look into starter,maybe the selenoid {sp} is going bad?

[CINNALOCKS]

Had them replace the air filter, fuel filter and the fuel components fpcu and fuel pump read well. Will have them replace the relay tomorrow before I bring it home. Then I will clean the maf completely as describe here in the forum and grease the connections, cleaning with a qtip. Then I will leave it running at my house in the heat. At least then if it happens I will not be stranded or need a tow. If that does not work, I will look at the starter,replace the maf the hose and the connectors. All stuff that probably needs to be done anyway. The Maf is used and 2 years old as is the starter. A new MAF is about $490....I would prefer to have a new one but only if I cannot a good used one.

Thanks for the quick responses gentlemen. It is calming to come here among friends, car shops are beast!

[CINNALOCKS]

Brought the Q home. Cleaned the MAF and connections. Had to special order the Air Duct and the Starter Relay. The temperature is over 100, so I am not risking driving it until I at least get the Starter Relay. Too hot for me to be out doing anymore work until Monday when the high temp is predicted to be 84. The Starter Relay is due here on Wednesday. When the new Air Duct shows up I am taking the old one off and doing some repairs on it. Intend to use foam insulation to seal the inside and provide resistance to the heat then on the outside use plumbers tape to reinforce the cracks..The guys at the shop had the same issue with a Honda Duct and could not find a new or good used one. They tried this method and it has been working for over a year.

[djwarner]

One thing no one has menioned is the neutral/park switch on the gear selector. I've had two instances of this several month apart. Moving the gear shifter out of park and back into park solved it.

[maxnix]

Just idling won't raise the current draw enough to melt the solder on the FPCU board. Can you safely race up and down the street in front of your house?

[CINNALOCKS]

Thanks Maxnix, I could if it would start. Came home from the shop and cleaned it up. Could not get it to crank again, the relay appears to be dead. I am hoping to get the new starter relay today( 8 days later due to the holiday and the weekend) and snap it in.

[CINNALOCKS]

Dammit......Got the starter relay and snapped it into place. Nothing changed. Will not even crank. Battery is strong. I have no clue where to go from here. Drove it home from the shop last week and have been able to get it to crank since. I am at a loss and in a garage that does not accommodate a tow truck to get it to the shop. Would the starter cause this kind of issue and is there a way for me to rule this out without a diagnostic tool.

[Rex]

If you're sure your battery is strong, check the ground wire and it's termination.

When it gets in the "no crank" condition, will it jump?

Have you tried tapping the starter? (sorry, I'm an old guy)

[qship96]

Again, the fuel pump control module condition has absolutely zero to do with the starter not even cranking,none. Check voltage at starter while someone else turns ignition key to the start position....if you are getting proper voltage, I would say you have a failing starter.

[jnever1]

My 95 did this to me last year. The exact same symptoms. I just replaced the starter with a cheap-o from autozone (that happened to be a refurbished nissan part) and the battery cables since they were original and quite corroded, especially at the ghetto ground point by the passenger wheel well. All has been well since.

Also, noticed that you hear a noise from the trunk when attempting to start. You may have heard that fuel pumps in our generation Q's make this noise in their twilight years. Mine hummed for 4 years before I finally got around to replacing it (easy job). No more noise! No more tows!

[maxnix]

Again, the fuel pump control module condition has absolutely zero to do with the starter not even cranking,none.

I think we all realize that. But it could contribute to the lousy running after it is warmed.

The other thing to consider if all systems are truly viable is the ignition and/or neutral switch. Lots of keys on the key ring will wear the switch prematurely.

[CINNALOCKS]

Maxnix.....I was referring to running the car in an idle in the heat to get the starter relay to react and stop the car when I turned it off and tried to restart. Not in reference to the fcmu.

I would agree with Qship96 if it does not even crank it is not the fcmu nor the fuel pump. Besides the readings for the voltage and flow on the pump was good. I thought we already decided it would crank but not fire if it were the fcmu and would could by pass that with a paper clip attached to a ground and the unit anyway.

Rex the ground is good and the battery is strong. Does not react to a jump. That was the first thing we tried prior to the original tow. The raps with a hammer are on deck.

Jnever1 I am not at all sure anyone actually checked the starter but I will look into it as soon as I can figure out how to get it out of the garage (I am in a hi rise condo and no tow truck can get inside). Battery and cables are good. Actually the starter was replaced with a used on two plus years ago....this time I will look for a reman or a new one. Also have to find someone work with me the voltage check or wait til I get it to the shop two blocks away. In the meantime I will give the starter a couple of raps with a hammer and see if it makes a difference..

[jnever1]

It may seem silly, but I used a DC/AC convertor with a digital voltage readout to test my alternator output.

For example, when plugged into the cig lighter receptacle, I would observe 10~12V, sometimes lower, on my convertor's readout with engine running. Battery would drain, car wouldn't start/crank/etc as a result. After new cables and alternator (and a slow charge on the battery), minimum voltage I get from receptacle is 12.1V @ ~650 RPM. At 5000 RPM... lol >15V (and my convertor shuts off for safety). Surprising results since the wires and connectors are more than 17 years old.

Also, I ran heavy gauge wire from the battery terminals into the cabin for 500W convertor usage versus 100W usage from the cig receptacle. Voltage results mirrored receptacle results.

While not the preferred multi-meter method, this device offered equivalent service for my needs.

Just something to keep you thinking outside the tool-box. :-)

[kevindanielk]

Have you tried shifting into neutral and trying to crank, when it does not want to crank in park? djwarner mentioned that the neutral safety switch might be malfunctioning but I didn't see any response from you, to his post.
Shift to neutral and while holding key in crank position, wiggle the shifter slightly up towards reverse and then slightly down towards drive, all while trying to crank. Had my neutral switch shift on me a while back and I had to set it back right.

[CINNALOCKS]

Yes Kevindanielk, I did try that and it was not the issue. Called AAA to tow it to an electrical shop. Battery was low so we charged it, to no avail, still did not turn over. Pushed it out the garage and it started. Drove to the shop the lot was full with an Advanced Auto next door, I pulled into their lot and had the alternator, battery and starter checked. They told me it all was in specs no indication of any issues. Went to leave would not start.

Got it to the electrical shop, when started 30 minutes later..... Replaced the starter, the battery and cables. Runs fine. Hard to believe it has taken so long and so much effort. These are the drawbacks of not being able to work on the car, living in a high rise condo, no work can be done on the premises and there is no room. Sure do miss having Wes being available to see me if I made the trip to Anderson.