XJ40 ( XJ81 ) 1986 - 1994

Fuels problem?

 
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Old 07-10-2019, 08:31 PM
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Default Fuels problem?

So I was driving home from school the other day, which is about a 30 minute drive, when I started to lose engine function. If I tried to get on the throttle, the engine would sort of bog down, seeming to not be getting enough fuel. If I put the car in neutral or park I could rev to about 1500-2000 RPM before I'd lose power. I parked the car on the street as this happened within a couple minutes of my home.

We went back for the car something like 5 hours later, and it started right up and drove the last couple blocks home without any problem. I drove the car the next day without any problems, although only in town.

Today I drove the car to school again, and on my way home I encountered the same problem. The car's currently waiting a few blocks away. This time I had to limp a bit of distance to get to a safe spot, and the car would shift up into second if I rode the throttle ever so lightly, but if I got on the throttle more than maybe half an inch or an inch, it would bog again. Also the engine idles kinda rough when this starts to happen.

This feels like a fuel delivery problem to me, like the pump is overheating or something, but I couldn't really say. I think I can hear the fuel pump through the trunk, but I don't know if that's normal. On my VW it's normal to be able to hear both fuel pumps whirring away, but this is unfamiliar territory for me.

I've bought a new fuel filter, and am looking at picking up a new fuel pump, but I'd like to know if there are any other approaches to diagnosing this before I sink the money into a part I may not need.


Edit: I forgot to mention the VCM is flashing fuse 2 and fuse 3. related?
 

Last edited by Ijgabloo; 07-11-2019 at 05:03 AM. Reason: forgot a detail
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Old 07-12-2019, 11:13 AM
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Both my XJ40 and X305 had pumps that made enough of a buzz at idle to know they were running, so I think that's quite normal.

You'd definitely want to get those fuses replaced. Do you have a Check Engine light illuminated?

IIRC, Fuse 2 is the Left Hand fuse box, Fuse 3 is the Center Console fuse box. Do pull the fuses out and check for bad ones. Are there any functions that aren't working correctly? Please let us know which fuses were bad.

While you're taking the fuses out, I've had very good success with giving the contacts a light cleaning with a small wire brush. You'll most likely see lots of oxidation on the fuse contacts which will lead to voltage drop. I noticed a noticeable difference with the speed of my power windows, brightness of lamps, etc. just from cleaning the fuses contacts.

Nick
 

Last edited by NTL1991; 07-12-2019 at 11:19 AM.
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Old 07-12-2019, 03:07 PM
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Thanks, I will definitely post an update later today. I'm checking the fuses after I change out of work clothes. One of my teachers has owned a few XJ's and he suggested that it may be the ignition coil overheating and fouling. That is waay easier to get to and test than the injection system, so that's where I'm starting. And yes my check engine light is lit. Nothing electrical is misbehaving that I can tell, but I haven't gone through the fuses piece wise to check. Luckily the labels on my fuse boxes are still affixed and clean.
 
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Old 07-12-2019, 05:29 PM
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With a check engine light on, it means there is a fault code available to display.

Turn the ign on, then, without starting the engine, press the vehicle condition monitor (VCM) button on the panel at the right of the steering wheel. Usually a fault code (either FF and a number or Fuel Fail and a number) will appear in place of the mileage readout on the dash.

When you have that FF code, re-post it here on the forum and someone will eventually chime in to help.

Hopefully your fuel pump is not crapping out as replacement is a fairly big, (but not difficult) job.

Larry
 
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Old 07-12-2019, 07:16 PM
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Okay, first, I may be remembering incorrectly because the codes went away, but I got Fuel Fail 44 or FF23 or vice versa. I checked my fuses and 3 were out; ABS (which promptly blew again), cruise control (which rectified that mystery), and the driver's passive restraint (which I left empty because the motor doesn't work and I didn't want to waste a fuse).

I checked the resistance value on my ignition coil, as per the Hayne's. It was reading 1.3 when the manual said it should read .5 tops.


*Edit: My Anti-Lock light came right back, but the engine light has vanished for now.
 

Last edited by Ijgabloo; 07-12-2019 at 07:46 PM. Reason: foretfulness
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Old 07-12-2019, 10:33 PM
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Hi - Fuel Fail 44 or FF23 are both codes for a too rich condition - code flagged by oxygen sensor when ECU compensation is out of range.

Often temporary and caused by some other issue (vacuum leak, bad connection at MAF, coolant sensor, etc)

this manual is a pretty handy thing to have around if you're going to be diagnosing these kind of issues

http://www.mediafire.com/file/szzac3...stic+Guide.pdf

Larry
 

Last edited by Lawrence; 07-12-2019 at 10:43 PM.
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