Q45 won't start (cranks easily) how to diagnose?

Can you help me diagnose this Sunday my 1990 Q45 not starting?
Two days ago, the car would not start. It cranks wonderfully - but the car won't start.
I've been staring at the engine for two days.
I have lots of questions:
Q1: How do I check that fuel is getting to the cylinders? Do I remove a fuel injector and crank to see if gas spurts out? Do I listen to the fuel pump at the gas cap? What for? Do I the 'fuel controller' (whatever that is); how? If it is the fuel pump -- do I get it out from the bottom of the car? Or do I go thru the rear seat? How?
Q2: I'm just going to assume air is getting to the car as this happened all of a sudden. The filter is clean though.
Q3: How do I check for spark? I can't even FIND the spark plugs? They must be under the cover on each side (I guess). How do I get to them?
Q3: Likewise for compression. I pored oil in the oil-opening to see if cylinder wash was the culprit. I will look to see if I can see things moving about from the oil-entry hole ... Is there any other way to tell if the timing belt snapped? I guess I could put a compression gage to the cylinders ... but I can't even find the spark plug. How do I get a compression gage into the cylinders?
Q4: I seriously doube timing went out of whack so I wont' try to test this.
Mostly I suspect GAS and SPARK. How can I diagnose the problem? Is there a computer code somewhere. Oh, I wish I could find that manual!
Please help, Alora D.
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snipped-for-privacy@yahoo.com (Alora Duncan) wrote:

I removed the fuel filter & cranked the engine with a result that no gasoline whatsoever eminated from the open hose going INTO the fuel filter. Proof positive, I guess of one of four broken parts:
These two I've found the location of: - fuel pump fuse, 15 amp (located to the left of steering wheel) - fuel pump (is apparently in the gas tank behind the rear seat)
Would Q45 experts help me find these two items? - fuel pump relay (dunno where to find this fuel-pump relay) - fuel pump control unit (dunno where to find this control unit)
QUESTIONS for Q45 experts: a. Where is the fuel pump relay (is it in the engine compartment)? b. Where is the fuel pump control unit (is it near the fuel tank)? c. Do I access the fuel pump from the trunk, back seat, or underside?
Thanks for your kind assistance, Alora
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I've read EVERYTHING on this topic and I have only a few remaining questions.
Q: What is the Infiniti Q45 "package tray" & "storage compartment"? Q: What is the Infiniti Q45 "trunk room"?
I read the shop manual (from http://www.nissan-techinfo.com/infiniti ). I searched the USENET groups (from http://groups.google.com ). I searched NICO (Nissan/Infiniti owners) http://nissaninfiniticlub.net ). I searched Yahoo (http://groups.yahoo.com/group/infinitiownersclub ).
Since there is no fuel eminating at the fuel filter inlet, I suspect: - The fuel pump, or, - The fuel pump relay, or, - The fuel pump control unit.
To further diagnose, I need to get a Fluke meter onto each of the above.
Apparently, the fuel pump relay & fuel pump control unit are in the so-called "trunk room". My first question is how to access that trunk room. I know I remove the rear seats (done already). But, then I'm supposed to remove the "package tray" & "storage compartment". I can see what the storage compartment is (not the one on the middle arm rest but on the shelf at the rear of the car); but what is the package tray?
Q: Is the package tray the horizontal shelf that is in the back of the car between the top of the rear seats and the rear window?
Alora
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I see you're crossposting to 3 different groups.
Was not going to reply because of this, but--
Try the easiest things first.
Get a hammer or crowbar, and bang on the bottom of the fuel tank a couple of times. Then try to start the car. If the engine starts, its probably the fuel pump.
Jim
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snipped-for-privacy@yahoo.com (Alora Duncan) wrote:

I've got everything out of the car now and am testing. Understanding the fuel system is the key component of this test.
Electrically, the battery feeds juice to the FUEL PUMP 15 amp FUSE on to the FUEL PUMP RELAY which is activated by the ON position of the IGNITION SWITCH to cause 13.8 volts to go to the FUEL PUMP which is grounded through the FUEL PUMP CONTROL UNIT which basically provides three (5.6v, 7.8v, 11-14v) pathways back to the negative terminal of the battery (like a large-wattage three-position potentiometer). (Fuel gage is separate.)
Hydraulically, the FUEL PUMP sucks fuel through a white FILTER SOCK and pushes the benzene onward to the FUEL FILTER and then to each FUEL INJECTOR and into the engine for the 14:1 pow part of the combustion chamber pull/push/pow/puey sequence. Any left-over fuel is apparently sent back past the FUEL REGULATOR into the FUEL TANK.
If a jumper wire grounding the fuel pump starts the fuel pump, then the FPCU is suspect. It's also a very good emergency procedure to limp along the five miles or so to the nearest help sans towing.
I took photos of the step-by-step removal sequence (the rear bench and seat back, storage tray and storage compartment, rear brake light, etc. all need to be removed as access is thru the rear seat).
I'll document the entire sequence (so the next person doesn't have to) and post it to the Nissan Infiniti Owners Club web site (apparently rec.autos.tech folks don't know much about this so this is probably the last posting to rec.autos.tech on this topic).
Alora
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After studying ALL fuel-pump-related posts & searching the Q45 FSM), I emphatically state NONE mention the LOCATION of the 1990 Infiniti Q45 fuel pump relay hide-and-seek is simply: > The fuel pump relay is behind the right trunk panel ... > The green one is the one you want to test ... ----------------------------------------------------------------- Also, none seem to mention exactly HOW TO REMOVE the 1990 Infiniti Q45 fuel pump control unit, which is simply: > Remove the rear seat bench, rear seat headrests, rear seat back, > rear shelf tail lamp, rear shelf, rear shelf storage basin, > trunk divider (between the trunk & the rear seat back) ... And then: > Remove the thick black sound-deadening material on the rear > shelf to access the four bolt heads holding the fuel pump > control unit to the underside of the rear shelf via brackets. ----------------------------------------------------------------- The next question appears to be about seemingly magic connections. Oh, where is a good Infiniti Q45 owner when I really need them?
The factory shop manual (FSM) says (on page EF & EC-185) to DISCONNECT the fuel pump control unit (FPCU) harness connector; and then inexplicably, the FSM says to re-connect it magically: - Connect proper terminal wires between the fuel pump control unit harness terminals. Then it says to "Start engine" and check the voltage between terminal 7 and terminal 4.
Well, the engine won't start unless the connector is connected. Yet, testing connections can't be done with the connector connected.
How can I even GET to the metal terminals 7 & 4 when the connector is connected? +------++---------+ 4-------| || |-----D 5-------| || |-----E 6-------| Male || Female |-----F 7-------| || |-----G +------++---------+
Am I to (somehow) connect (magic) wire jumpers BETWEEN the connector? +------+ +---------+ 4-------| |<----->| |-----D 5-------| |<----->| |-----E 6-------| Male |<----->| Female |-----F 7-------| |<----->| |-----G +------+ +---------+
And then (somehow) attach a VOM to terminals #7 & #4? +-------------------------+ | | +------+ | +---------+ | 4-------| |<--+-->| |-----D +--+--+ 5------| |<----->| |-----E | | 6-------| Male |<----->| Female |-----F | VOM | ==> 13.8 V 7-------| |<--+-->| |-----G | | +------+ | +---------+ +--+--+ | | +-------------------------+
The FSM diagrams (SEF882J, SEF883J, & SEF884J) show (somehow, magically) a VOM inserted IN THE MIDDLE of the CONNECTED terminals #7 & #4! How can that be? What is this magic?
And, how do I (one by one) connect ADDITIONAL wires? The very next diagram shows a fifth wire (#2) connected: +-------------------------+ | | +------+ | +---------+ | 4-------| |<--+-->| |-----D | 2-------| |<----->| |-----B +--+--+ 5-------| |<----->| |-----E | | 6-------| Male |<----->| Female |-----F | VOM | ==> 7.5 V 7-------| |<--+-->| |-----G | | to +------+ | +---------+ +--+--+ 8.1 V | | +-------------------------+
And the last diagram shows (yet another) sixth wire (#1) connected: +-------------------------+ | | +------+ | +---------+ | 4-------| |<--+-->| |-----D | 1-------| |<----->| |-----A | 2-------| |<----->| |-----B +--+--+ 5-------| |<----->| |-----E | | 6-------| Male |<----->| Female |-----F | VOM | ==> 5.5 V 7-------| |<--+-->| |-----G | | to +------+ | +---------+ +--+--+ 5.7 V | | +-------------------------+
QUESTION for q45 owners: How (the heck) can I (possibly) insert the VOM into the MIDDLE of the CONNECTED terminal?
Q: Is there a magic 6-wire bare-metal jumper somehow?
Likewise, given the seemingly explicit statement: > When a car gets towed in the first thing we do is use a > jumper [wire with two alligator clips] to directly ground > the fuel pump ground terminal [the junction of pump and > controller] ... supplying 12-14 volts to pump.
QUESTION: How do I get the METAL connection to ground for the fuel pump when the fuel pump harness has to be CONNECTED in order to supply power to the fuel pump - and when the harness is connected, there is NO BARE METAL wires to connect to?
Said another way, when the connectors are connected, there is NO METAL SHOWING. And when the connectors are unconnected, there is NO POWER TO THE FUEL PUMP. So, what is the MAGIC that gets a metal alligator clip into the middle of the connected connector?
Is there a magical 4-wire jumper that has bare metal in the middle so both power to the fuel pump and ground to the car body can be accomplished at the same time?
Please advise a poor soul who doesn't have the money to pay for full service yet who would like to diagnose this problem.
This seems to be the last of my LOCATION & DIAGNOSIS dilemmas. ---------------------------------------------------------------- Alora
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A fuel pump relay are easily located by a click, then followed by another click when ignition is first switch to run, if it or what ever is powering it is still working.

Remove the four bolts holding it, he's suggesting the unit with four bolts.

Normally, you don't test a fuel pump with a car running, unless pressure testing. You don't need to start it, just turn it to run position.

Easy, use a sewing needle and drive it into the wire. Connect an aligator clip to the needle. Don't listen to manual about test harness, you won't find one but you can always make one, but you won't need it.

I heat my probes with MAP torch first and my probes sinks right into any wires, connectors, etc. It's like magic. I do this all the time.

I'm struggling with English, here goes. Splice the intended wire, wrap another pre-spliced wire (same type) onto this and solder it or crimp it with a pair of pliers. You now have a split wire capable of handling the currents demanded by the fuel pump. Tape this wire securely with only electrical tape to prevent fires. Note that without proper currents, your fuel pump won't spin if it's slighty seized from formations to the prepellars.
The other cleaner but difficult method is to remove the lead(s) you want from the male or female connector. Attach a copper wire to this carefully, and securly. Solder it. Inserted the lead(s) back into the male or female connector.

There's no such thing, I can solve a fuel pump problems with no tools on hand, I just rip a wire and a bulb from anywhere in the car and diagnose fuel problems in seconds. The SM are suggesting a test harness that jumps from the male to female. I've made several of these myself. They work fine in controlled enviroment but in reality, cars don't die inside a well lit garage. They always die in a dark, windy, rainy bad neighborhood.

I'm aiming for financial security myself by working hard to gain knowledge, which is what you're doing. Knowledge is what you need. Rick

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A fuel pump relay are easily located by a click, then followed by another click when ignition is first switch to run, if it or what ever is powering it is still working.

Remove the four bolts holding it, he's suggesting the unit with four bolts.

Normally, you don't test a fuel pump with a car running, unless pressure testing. You don't need to start it, just turn it to run position.

Easy, use a sewing needle and drive it into the wire. Connect an aligator clip to the needle. Don't listen to manual about test harness, you won't find one but you can always make one, but you won't need it.

I heat my probes with MAP torch first and my probes sinks right into any wires, connectors, etc. It's like magic. I do this all the time.

I'm struggling with English, here goes. Splice the intended wire, wrap another pre-spliced wire (same type) onto this and solder it or crimp it with a pair of pliers. You now have a split wire capable of handling the currents demanded by the fuel pump. Tape this wire securely with only electrical tape to prevent fires. Note that without proper currents, your fuel pump won't spin if it's slighty seized from formations to the prepellars.
The other cleaner but difficult method is to remove the lead(s) you want from the male or female connector. Attach a copper wire to this carefully, and securly. Solder it. Inserted the lead(s) back into the male or female connector.

There's no such thing, I can solve a fuel pump problems with no tools on hand, I just rip a wire and a bulb from anywhere in the car and diagnose fuel problems in seconds. The SM are suggesting a test harness that jumps from the male to female. I've made several of these myself. They work fine in controlled enviroment but in reality, cars don't die inside a well lit garage. They always die in a dark, windy, rainy bad neighborhood.

I'm aiming for financial security myself by working hard to gain knowledge, which is what you're doing. Knowledge is what you need. Rick

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I've been driving on the new fuel pump & resoldered fuel pump control module for a few weeks now. I wrote up the entire sequence (with pictures) and will post to the yahoo & NICO newsgroups for the next Q45 do-it-yourself mechanic. (This writeup will be especially useful because the procedure to follow is NOT the procedure in the factory shop manual. The yahoo & Nico newsgroups were especially helpful so I feel I should give something back to them.)
The new Infiniti Q45 fuel pump barely makes a sound. Even hot-wired to ground (with full battery voltage), the new fuel pump was still MUCH quieter than the original Q45 fuel pump. Next time, when I hear a Q45 fuel pump hummin', I'm going to replace it BEFORE it eventually destroys the fuel pump control unit.
If I had simply replaced the fuel pump control unit (which exhibited the classic Q45 #4 ground-wire solder melted-open problem), the old fuel pump would have still drawn enough current to burn the new fuel pump control unit out in a short while.
If I had simply replaced the noisy fuel pump, the Q45 still would not run because the destroyed fuel pump control unit left open the circuit to ground.
The non-intuitive repair consisted of replacing the working fuel pump (which drew too much current) with a new $312 dollar fuel pump; and resoldering (after reinforcing) the non-working #4 ground-wire circuit to ground in the Q45 fuel pump control unit (saving a $500 dollar replacement cost).
I left the trunk bulkhead loose so I could check for overheating, but, the resoldered Infiniti Q45 fuel pump control unit appears only slightly warm to the touch, even after 50 miles of highway driving.
Total time for repair: About 3 weeks elapsed time; maybe 5 hours actual, of which 4 were debugging which could have been replaced with 10 minutes of debugging time had I known what I know now about Q45 fuel pump diagnostics).
Total cost for repair: $312 for the Q45 fuel pump; $12 for the 0 ring.
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===========================================================================Diary of a classic 1990 Infiniti Q45 fuel pump & pump control unit failure By Alora Duncan http://profiles.yahoo.com/tangalora ===========================================================================Note: Photos were taken of every step below; but I do not know how to post these revealing photos to this forum. ---------------------------------------------------------------------------- 0. One morning, my 1990 Infiniti Q45 (125K miles) wouldn't start:
The 4.5 liter 8-cylinder engine cranked wonderfully, but would not catch. It wasn't the starter motor nor the battery (as it rotated perfectly). As always, it had to be either gas, air, spark, compression, or timing.
Following is an idealized path others can follow to debug & repair.
Note: My actual debug & repair path took three weeks and much trial & error; which is exactly why I wrote this howto for others to follow.
Note: Re-assembly, in all cases, is the reverse of the dis-assembly procedures described below.
Note: This dozen-step diagnostic, removal, & replacement procedure is accompanied every step of the way with digital photos illustrating every described action. ---------------------------------------------------------------------------- 1. I ran a quick visual/audible gas, air, spark, compression & timing check:
GAS: The gas tank was completely full (filled the night before). The 15 amp fuel pump fuse was intact (replaced it anyway). I could NOT hear the fuel pump humming (at any time). AIR: The air intake & air filter were not clogged (left it open). SPARK: I did not know how to run a quick test for spark. COMPRESSION: The engine did sound like cylinder wash (no compression?). TIMING: The camshaft rotated (looking in the oil-filler hole). ---------------------------------------------------------------------------- 2. I soon realized no gasoline was being pumped INTO the fuel filter:
- I removed the 15 amp fuel pump fuse (by the driver-side right kneecap); - I cranked the engine in order to release any residual fuel pressure; - I removed the two 10mm bolts holding the fuel filter clamp to the body; - I removed the two #2 phillips screws holding the fuel filter hoses on; - I replaced the 15 amp fuel pump fuse and cranked the engine again. - No gasoline spurted out of the open fuel line hose.
Note: One clue was that, after an overnight sitting, with the fuel filter and activated carbon fuel cannister still on the car, the engine started for a split second. This happened for two mornings. I suspect this momentary ignition was due to the burning of fuel fumes collecting in the fuel system over long periods of time.
Note: I blew through my fuel filter and there was almost no resistance; so, despite the fact almost everyone says that a clogged fuel filter can cause the fuel pump to overwork and therefore heat up and therefore melt the solder connections on the fuel pump control unit, I suspect a clogged fuel filter was not my problem. ---------------------------------------------------------------------------- 3. I studied the 1990 Q45 fuel system electrical & hydraulic circuits:
ELECTRICAL: - Battery voltage goes to the fuel pump relay ... - to the fuel pump (in the gas tank) ... - to the fuel pump control unit (under the rear sundeck platform) ... - which provides three resistive paths (fuel pump speeds) to ground ... - based on input from the engine control unit (passenger side dash).
HYDRAULIC: - Fuel is pumped out of the fuel tank ... - to the inlet of the fuel filter ... - to the fuel line & fuel plenum ... - to each of the 8 fuel injectors (which open at the same time) ... - with pressure regulated by the 43 psi fuel pressure regulator ...
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Thank you very much for the detailed information. My wife and I have a 93 Q with 101K on it and at some point it is going to need a fuel pump. The dealer is great but very expensive as I'm sure you know. I have printed out your information and will keep it handy.
Thanks again!
Dave

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I'm glad to be of service. Every Infiniti Q45 owner (up to 1996 I think) should learn about this Q45 engineering fault.
Just remember two things: - Do NOT follow the factory shop manual! - Keep a 1-foot 14 AWG aligator clip wire in your trunk.
When your Q45 dies in the middle of nowhere, you merely remove the rear trunk fiberboard bulkhead; unclip the white fuel pump control unit harness connector; jump the correct wire to ground; and voila! You're on your feet again!
Back at the farm, if you follow the factory shop manual, you'll correctly diagnose the burned-out fuel pump control unit (aka the fuel pump modulator); but you'll likely conclude the old fuel pump was good (it still works). Second opinion is that the old fuel pump is what burned out the Q45 fuel pump control unit in the first place; so, you're in for a repeat episode of chronic fuel-pump 'modulitis' if you follow the FSM prescription.
The recommended prophylaxis is to resolder & reinforce the fuel pump control unit ground cnnections and to perform a fuel-pump'ectomy.
Alora
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replying to Alora Duncan, Allen wrote: Its in the window area.when taking it out the trunk it has to come through the hole
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replying to Alora Duncan, Allen wrote: Fuel pump in trunk.have to take out back seat an cover to take fuel rail an pump out trunk.I have a q45 1991 an it has the same problems.
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replying to Alora Duncan, grod wrote: Cranks over teally hood n t wont start
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grod wrote:

It ran out of gas 14 years ago and has been sitting in his driveway ever since.
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replying to Alora Duncan, Paypaul wrote: 97 Q45 won’t start and I don’t hear the fuel pump I need to know where the fuel relay and control module is located
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