1990 Q45 wont start please help

[aoktech]

Ok hered my dilemma car was running great got up in the morning to find out my car wont turn over it just cranking. Im getting spark and gas to the fuel rail and air it will turn over with starter fluid but doesnt stay on maybe 2 sec the most please help

[black g50]

Got a spare MAF?

[aoktech]

No I dont but when I pulled the line from the fuelrail it no squirting out more like pouring out like when you turn on the water hose on but not all the way so im thinking its the fuel pump but please let me know something because I would hate to buy a fuelpump and that not be it

[yodawill2000]

Need to check fuel pressure.
If low it could be the FPU, or the pump. Toasted FPU usually has burn marks on the connector Ive heard.

FYI:
Pulling the ECU codes can take the "Guesswork" out of it .

[aoktech]

i don't know how to pull the ecu code is there anyway to show me how to do it cause i need this car back on the road

[Q451990]

ECU probably isn't going to tell you much. The usual failure is the fuel pump control module burns out due to a worn out fuel pump pulling too much current. You can ground a certain pin on the connector to troubleshoot it. The picture at the end of the thread is the best one I can find. wont-start-t505283.html

Did you hear something like a hive of bees buzzing just behind the back seat at idle - especially when the fuel was below a 1/3 of a tank full? The pumps usually get noisy before they take out the controller.

If you find that grounding this pin allows the car to run - then it's time for a new pump and controller. The controller usually goes for about $50 used.

Good luck!

Heath

[aoktech]

After futher research I found out that the fuel pump was recently replace but I looked at the fpcu and notice that in the connector it was a little burnt could this be the problem. I pulled the pump anyway to inspect it everything look ok i checked the oms and it was 0.6-0.7 specs say it should be 0.5 is this a problem for the fpcu

[aoktech]

I also grounded the as discussed and it still wouldnt start I changed fuel filter im still experiencing low fuel pressure but cant test the pressure due to not haveing a test port on fuel rail

[trobbinsfromoz]

When you ground that pin (pin 4) of the FPCU, it grounds the negative end of the fuel pump and so the pump gets full battery voltage across it.

[aoktech]

I can hear the pump sounds like it got stronger when doing this but the pressure from what I see is an adequate enough and because I don't have a test port I don't know how to check the fuel pressure

[aoktech]

When you ground that pin (pin 4) of the FPCU, it grounds the negative end of the fuel pump and so the pump gets full battery voltage across it.

When I grounded the pin out I dont hear a different in punp speed

[Q451990]

You're grounding the pin on the harness connector - not the control unit, right?

Do you know what kind of pump was used when it was replaced?

Heath

[aoktech]

that's correct I'm groundingthe pin in the harness not at the control unit I know that they got the new pump from the Infiniti dealership but for some reasin im leading towards it being the pump

[aoktech]

ok i just replaced the fuel pump today on the car and still a no go still my fuel pressure is not there what could the problem be please i would hate to have to junk this car i put a lot of money into it to get it going and would hate to see it go please help

[OwnerCS]

Where are you located? We might have members near you or can recommend a good shop that knows how to fix the issue. Your fuel pump should put out between ~34 and ~44 pounds of pressure when starting the engine. There will be an immediate surge over ~40 lbs for a couple of seconds then the pressure will settle back to ~34 lbs while the engine is turning over.

Here's a picture of me testing fuel pressure on my 91 model.

[Q451990]

You can buy a fuel pressure gauge kit for about $25 at Harbor Freight. Even better, AutoZone (and probably other parts stores) have them available as loaner tools. You technically "buy" it, but if you return the tool in the condition you took it - they give your $$ back.

http://www.autozone.com/autozone/access ... 913437_0_0_

Also, just for fun, be sure the fuel hose from the filter is going to the forward fuel rail tube as shown in the above picture.

Heath

[goody90q45]

After you replaced the fuel pump did you put the fuse back in the correct slot? There should be an empty slot above the fuel pump fuse. Are you using a known good fuse? Sometimes burnt fuses can be hard to spot except with a magnifying glass.

[aoktech]

I live in neptune, nj ive checked autozone amd a couple pf other places they dont carry that fuel pressure tester they only carry the 1 that uses the test port on the fuel rail which I don't have. I know my pressure is not between those levels because I pulled the line off the fuel rail in just poured into a gas can like I'm drinking out of a water fountain instead of shooting in there. I replace the fuel filter and fuel pump and grounded out the fuel pressure control module harness.

[aoktech]

After you replaced the fuel pump did you put the fuse back in the correct slot? There should be an empty slot above the fuel pump fuse. Are you using a known good fuse? Sometimes burnt fuses can be hard to spot except with a magnifying glass.

I believe the fuse is good because the pump does run when I crank and turn the ignition on, I never pull the fuse I pull my battery out to charge you because after a while the battery went dead from me cranking the car and it sitting

[aoktech]

could a faulty fuel pressure regulator causes this issue

[Q451990]

could a faulty fuel pressure regulator causes this issue

I don't think so, because it's on the other side of the injectors. It regulates by increasing flow to the return line - so basically letting more or less fuel out of the "back door" vs. controlling how much comes in the front. I'm assuming the correct fuel filter is being used, and it's been replaced recently? I can't imagine one being so blocked as to prevent the car from starting, but maybe?

[aoktech]

right now I'm grasping for anything, I replace the fuel pump 2 days ago from someone that was parting out there Q 45 on this forum, still no pressure, I bypassed the fuel pressure control module, replace the fuel filter, car still cranks but won't start I don't have ideals fuel pressure to start a car I believe. the way it happen is I drove my car night parking in my driveway for the night came out to start in morning nothing

[SanCarlosQ45]

It sounds like your injectors aren't firing. I got an ECU from a member on the forum that when I put it in it would crank over without firing. Of course after I put the original back it it was fine.

First thing to check is if the CEL light comes on when you turn the key to the on position. The next thing is to check the codes, with mine all I got was a solid red light. If you can check the codes than more than likely its not the ECU. The problem is that these early ecu's have a very small trace on the board for main power supply. This failed on mine as well as a capacitor. It looks like it could have been from use combined with a possible surge.



This is a 94' ecu, the 90 ecu has the same diode and capacitor just in different positions. The failure point is the trace between pin 45 and that diode. If you have a soldering iron you could solder a wire between the pin and the diode.



Its worth a look, its the only thing I can think of.

[Q451990]

the way it happen is I drove my car night parking in my driveway for the night came out to start in morning nothing

Did you drive it for a while the night before, or maybe just moved it a short distance without warming the engine up? These cars have a tendancy to flood if they're started in cold weather and then aren't allowed to warm up to normal operating temperature before turning them off.

Heath

[texasoil]

It sounds to me like 1) the fuel injectors are not firing for some reason. There should be an error code set in the ecu for this fault. I opine this cause because you said it will run on starting fluid which it would not do if the fault was ignition. Why aren't they firing? Bad harness connection, bad fuse, crank angle sensor not working (should still start in 'limp in mode' Check all the underhood wiring connections and harnesses.

The fuel pressure controller is a simple coil spring loaded restricter valve that is pulled open by manifold vacuum, allowing more fuel to flow back to the tank when vacuum is high (lowering fuel rail pressure. Try clamping off the return hose and see what the 'squirting force' does. You can check the fuel pressure where the line attaches to the fuel filter--that will test the pump.

[Q451990]

Didn't notice that it would run on starting fluid... I believe there are some connectors that can be connected backwards that can cause this? Near the knock sensor harness? I would confirm that these are correct per the FSM...

Heath

[aoktech]

But nothing was disconnected to.cause this im starting to think it th ecm

[Q451990]

Very rare to see them fail, but anything is possible - especially on a 23 year old car...

Heath

[SanCarlosQ45]

I think your going to see more failures of the early ecus because the hot ignition source(pin 45) which goes to a diode and capacitor(filter and surge protection) is a very thin copper trace. They seem to have beefed it up in the 94+ ecu as shown in the pic. I will try and find another ecu to look at because the trace had corrosion and most likely a surge broke it. Its just something to keep in mind, these things are robust but time will tell.

[aoktech]

It suck I loved this car I had to go out and buy another vehicle cause of this if I cant get it started off to the scrap yard it goes