No start this morning

My 96 (4.0 auto with 100,000 miles) has been Swiss reliable for the 2 years I've owned it. This morning it turned over fine but wouldn't start up. If I really pumped the throttle it would try and a few times it actually started but I had to have the accelerator down and RPM's up near 2500. As soon as I let off the throttle, it died. Was running late for work so I rode my motorcycle (brrrrrrrrrrr).

Search brought back similar situations that possibly point to CPS or Ignition Control Module. I know I need to do some investigation after work. I'll start by checking for spark. Can someone guide me through the easiest/most reliable way to do this? Also when checking for fuel, it's not enough to just listen for the pump is it? Can I just check in the throttle body for evidence of fuel?
Once I get that narrowed down, I should have a better understanding of what I need to closer at. Thanks all.

-Chris

Not sure if this will help or not, but I have been in the same situation with my 1990...even down to the 2500 rpms before dieing!

I have replaced the fuel pump, fuel filter, plugs and wires, battery and cables, CPS, and fuel pressure regulator, and bypassed my ballast resistor all to no avail.

I haven't tested my fuel pressure, but other people on told me you need to hook a pressure gauge to the Shrader valve on the fuel rail to test it. Just becuase the pump is running doesn't mean the pressure is correct. I understand it needs to be 31 psi.

During my last search under the hood for symptoms, I noticed the smell of fuel in the oil and I was told, again by members, that possibly my fuel injectors are stuck open and therefore making the engine not operate properly.

I ordered 4 port fuel injectors last night, and will change them this weekend.

Again, I don't know if any of this will help you, but it at least will give you an idea on what I have tried...unsucessfully...to do to remedy the same situation on my 1990.

start and stall, have the battery load tested, could be bad battery or corroded terminals.

Where is the fuel pressure regulator on this? I believe the battery is fine. I don't see any vaccum leaks, all lines look good. Brakes feel good (thought maybe the booster might have gone south and created a vaccum problem there). I went to test the TPS but my voltmeterdoesn't go that low (200 millivolts at closed throttle). Considered Ignition Control Module but I have spark. Also, I can get it to run if I'm all the way in the throttle. After that, it runs good through the RPM's but will not idle. If I hold it at 1000, it doesn't act like timing is off but as soon as I let off, it dies. Can't I rule out ICM b/c of the fact that it does run albeit sh!tty? I am also looking at CPS. Just don't know. I have not put a guage on te fuel rail. Only parts store in town wants 60 bucks for a guage and they have to order it. Can anyone help? Thanks.

I would bet it is your MAP sensor. I replaced my (good) MAP with a new one that was bad out of the box and had exactly the problem you are having. Unfortunately, on the 96 it's an $80 part, so you may want to try cleaning the connections on it before you swap it out (unless you have access to salvage or a friend with XJ with same style sensor)

Definitely not CPS if you have spark.

You can press the schrader valve on the front right side of the fuel rail to test if fuel is being delivered, but you can't measure fuel pressure without a gauge. You already know fuel is being delivered, however, or you wouldn't get it to run at any speed.

Someone in one of these forums posted that they had success fitting a tire pressure gauge (stick style, not dial) to a makeshift adapter. It may take a bit of sourcing/rigging, but it's sure to be cheaper than $60

The regulator on 96 is built into pump and is in tank from what I have read, so you really don't want it to be that

lilredwagn said:

The regulator on 96 is built into pump and is in tank from what I have read, so you really don't want it to be that

Click to expand...

I believe the regulator and filter come as a single unit on OBDII vehicles. It's not in the tank.

Have you checked your IAC motor? Just a thought.

K

Corbina...you might be right. I did see something above the filter. I have not checked the IAC. I guess my thoughts were TPS or CPS, maybe MAP. I'll look for a test on that IAC. Thanks guys. What are symptoms of bad CPS?

If you can get the engine to run by pressing on the throttle but it doesn't idle, I would seriously consider the idle air control motor.

It is very common for the passage in the housing where the idle air control motor is installed to get gummed up with carbon deposits.

I have a 99 with 120,000 miles and have had to clean that thing twice since I've had it.

On my 99 there are 4 torx bolts that attach the idle air control motor housing to the throttle body. The motor is held by 2 screws to the idle air control motor housing.

Remove the IAC from the IAC housing, then remove the IAC housing from the throttle body.

With some carb cleaner and a toothbrush clean up the inside of the housing and the conical end of the IAC motor. You might even need to lightly sand the cone shaped end of the IAC motor to remove the carbon deposits. You want this area to be smooth so that it can seat properly.

The first time I did this procedure I just removed the IAC and left the IAC housing intalled on the throttle body.

The 2nd time I did the whole procedure as I explained and I noticed a much improved idle and the engine wouldn't rev high on start up.

Be careful with the screws holding the IAC housing to the throttle body. Go slow with those. Once you loosen them slightly you might want to tighten and loosen them as you back them out. Try some WD-40. I ended up snapping one of the screws.

Good luck.

MAP

I'm a bit confused. On the throttle body, I see 2 sensors connected. The TPS is closest to the linkage. Is the IAC on the head side of the TB? I thought that was the MAP.

The IAC is on the head side. If you like and can wait a couple minutes I can go try to take a picture.

Here's a diagram of the various components.

I'll have to dig out the 97FSM and go thru it for possibles, but I'd start by going over all the grounds. One of the first things about troubleshooting any automotive electrical, I've found, is to go through any and all related grounds and look for corrosion. I know it sounds odd sometimes, but it often works.

When you check each one, take it apart, remove any paint, and apply Ox-Gard on reassembly. Replace any screws and ring lugs showing evidence of corrosion. Also, replace lugs if the wire crimped into it is corroded - and a little Ox-Gard and heat shrink on reassembly there won't go amiss, either.

5-90

Disco the battery and do not turn on the key with the IAC removed but still hooked up or you will end up buying an IAC. Also during cleaning, be careful not to rotate the plunger, aka pintle. Get carb cleaner and hose the housing where the pintle forms the air valve against the TB.

Do not get any cleaner on the TPS, the other possible problem.

I think it's one of those 4 crappy sensors...just dont know which one. Doesn't help either that I was conducting a TPS test on the MAP sensor. What a knucklehead. OK...maybe I'll clean the IAC tomorrow then try it. After that, I guess I'll look at the sensors. It sucks that my new RE SYE and driveshaft will be here probably monday and now I can't even start the crappin' thinng. Thanks guys. You rule. Stay tuned please.

look out for the o ring on the iac . mine was all cracked and not sealing . i had to replace mine after the yearly cleaning .

First off, don't worry about the 02 sensor. It doesn't play into things until the engine starts to warm up. A horrible vaccum leak can cause the symptoms you are describing as well. About the only way you can get a vacuum leak that bad is if the intake is loose, the throttle body is loose, or the brake vacuum booster is leaking. The other vacuum lines just don't have the volumetric capacity to cause this symptom.

Clean the IAC and if that doesn't do it, then the TPS is most likely the problem.

If it runs at higher rpms, that pretty much means it isn't the fuel pressure, since you need less at an idle than at higher rpms. Somehow the computer is telling the engine to run too lean or way too rich. If you don't smell tons of gas out the tail pipe, then it is most likely too lean.

Three sensors/actuators control all of this. The IAC simply bleeds air to set the idle speed instead of the old fashion way of opening the butterfly, the TPS tells the computer how far open the throttle is, and the MAP tells the computer about the load the engine is under along with the "altitude".

Find a buddy with a running XJ and have him stop over and play switch the sensor.

Lots of Luck.

Ii would have expected a map sensor bad enough to prevent you from running at all would give you a check engine code, but if it's able to start and run, it might be bad enough to mess you up without a code. When My MAP sensor went south it affected mostly high-speed running and ran badly under low vacuum conditions (for example climbing hills). Have you tried retrieving codes yet, or doing an OBD2 check?

Sorry I can't come up with much more on the spur of the moment. If it starts at all, it means you're getting some spark and fuel. It would be a good idea to check vacuum if you can, and see if there is a major leak, or if a gauge reading reveals anything else.

By the way, if you're looking to hook up a homemade pressure gauge, or want to do that in the future, keep your eyes open for an a/c recharging hose for the older r-12 systems. The fitting on these is correct for the fuel rail.

Can you retrieve the codes on your 96 with the key method? My 96 is an export and I think is a change over model, mine is an OBD 1.
I was having to start mine with about 1/4 to 1/2 throttle and kind of coaxing it into starting. If I released the throttle it would die. But once it got hot, it seemed to do OK. On a hunch, I removed the top air box, coaxed it to life and sprayed a light oil into the IAC opening, a couple of good squirts. Seemed to cure the problem. I had to repeat a couple of weeks later and that was 4 or 5 months ago.
The O2 sensor and the MAP are most of the fuel control and a faulty sensor will most likely throw a code.
I use an old style refrigeration gauge (freon 12) to test fuel pressure, the low pressure gauge. It has the correct end, with the tit to depress the valve. I've been using the same gauge for 15 years, the gas never seemed to hurt it any.
A couple of years back, there was a rash of internal fuel tank fuel line disintegration and pieces of rubber plugging the filter. In a few cases it actually affected pump pressures because of the holes in the lines. Didn't seem to happen to all 95-96, but many.

I have the same year as you, to clarify some things, the fuel pressure regulator is part of the fuel pump assembly. This could be simply clogged fuel filter. Was this the first freezing morning in Colorado? Could there have been alot of water in the tank and now your fuel has bits of gel in it? Good information what they others saying about the sensors still I think its rare for electricals to be fine and 8 hours later crap out completely.

Incidentally, my sisters jetta had this problem. On mornings with a lot of dew, the plug wires would get wet and short out on the block because they were old. I'm thinking this is something like this, don't assume sparking wire on the block= spark in the cylinder or that gas squirting from the fuel rail valve = adequate fuel pressure and flow. Also my XJ had this problem, the ignition coil was completely corroded (salt water got on it don't ask).

So, I'm thinking fuel flow problem, ignition system or vaccuum leak.