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NOTE: This issue has been resolved. Please see post 51 for the details and photos.
So my XJ8 left me sitting. No issues prior. I felt a little hesitation as I was moving places to get gas but it restarted just fine I drive about 2 blocks to a light and then when I went to pull away no power backfiring and stumbling with a top speed of about 3 mph.
I got it off the road and it would idle but as soon as it went into gear almost nothing and it barely ran.
I unplugged the MAF and it seemed better. I left the MAF unplugged and managed to get it about the 3 miles back to work.
With the MAF unplugged I looked at the connection and 2 of the terminals on the MAF and harness were heavily corroded. So I thought I had my problem. I was going to the junk yard the following day anyway so while I was there I grabbed a MAF and harness.
I only had a few min today so I cleaned the harness end with a terminal file added some stabilant and tried both the old and new MAF but with no result. It won’t run on either.
I May have a bad New maf, the connection may still be crap, or both. But I haven’t found a good description of what my readings should be. Anyone have that info? MAF specs for KOEO?
It’s possible the fuel pump died as well or I’ve heard the crank sensor is a probable issue so I have a little work ahead of me to figure this out
If any one has the specs on the MAF or the crank sensor handy that would be awesome.
Jeh, one test for the crank sensor is to crank the engine over and look at the rev counter ...if it's dead, (no movement) that can indicate a faulty CPS.
I keep an eye on the connector at the MAF on my 94, it has caused me some grief in the past but nothing like as serious as your issue - the only time my old bus let me down with symptoms like you describe (touch wood) was when the fuel pump quit.
Luckily a tow-truck driver friend showed me a highly technical get-you-home trick with a faulty pump - whacking the tank with a baseball bat.
I’ve never paid attention to the tach while it was cranking but I’ll go look. I’ll get a master fuel set from a coworker and I’ll try to get a pressure reading. It may take a few days to figure it out but at least it’s parked at work.
. . . highly technical get-you-home trick with a faulty pump - whacking the tank with a baseball bat . . . Sorry not much help, but good luck. Larry
I disagree Larry. I think your advice, amusing as it is, could well be spot-on. Question of Jeh . . . why did you aim straight to the MAF? Your symptoms and well known history here would point to fuel delivery problem and in particular, pump & filter. Seems this may be confirmed by replacement MAF (not "new" as you say, but I know what you intended) having no impact on your problem.
Suggest you check fuel rail pressure, then work back towards pump, filters etc according to what you find. Please keep us posted.
I checked the maf initially as the car idled fine and as I’ve seen a failed maf do this on other vehicles. I was in the middle of the road and unplugging made the car run ok. Not well but well enough to get back to work. 45+ mph. So I didn’t suspect fuel right away.
When I was able to look a little closer not being in traffic I saw the corrosion on the 2 terminals of the maf and the connector. It really seemed to be the answer and I was at the yard anyway so I grabbed it.
That being said at lunch I went out to look and check for fuel just for the hell of it as I wouldn’t be able to get a pressure gauge on until tomorrow. As it turns out ther is zero fuel pressure or volume. I have a pump, screen and filter and like you said and I’ve seen it’s a known problem.
The whack on the tank has diagnosed many fuel pumps over the years, I just didn’t try it Friday as the trunk was full of stuff for the following day.
Jeh, if you have to get a pump (I know I've said this before but ...) don't be fooled by any "fancy" [read spendy] brands ...all the pumps, even OEM are the same and made by Walbro ..regardless of brand on box "Bosch", "Denso" etc. they are all Walbros.
Buy the cheapest, I think the Airtex is pretty reasonable on Amazon? I fitted one and touch wood, no issues in a few years.
If you have to do the pump, here's an indispensable tool for rotating the fuel line clips at the tank
odd think was I bought a pump years ago a Hella. And it’s been sitting in my box so it should be a good one.
Thanks for for the tip about the pliers. I need to do this after work hours so it’s grab whatever I think I need and if I’m wrong wait for the next day. I did all the up top stuff so tomorrow I’ll grab my jack and stands and do the undercar stuff and hopefully have the tank out enough to get the pump out.
The bad bad is I just put gas in it before it died so it’s going to be heavy. Not full but heavy.
Drain it into some jerrycans Jeh, you'll be glad you did - you have to fish around for the canister that holds the pump and you don't want to be doing the disassembly and re-install with any significant amount of gas in there ....and apart from the damn thing being unwieldy empty, with gas it's going to be a real pain.
Good news is once you rotate those clips on the fuel line (DON'T take them off, easy to lose and hard to reinstall) you can pull out the lines and the tank won't leak and gas out. Because there's so little room up there under the tank, I found (was this Don's tip? can't remember!) the best way to remove the lines if they are a bit "sticky" was to loop a wire or cord over the line, close to the fitting, and give it a good yank.
If you do siphon out the gas (I really would do that) you won't get it all, a gallon or so will stay in there.
There's a few threads on pump swaps, one of mine is this one, some pics so some of what to expect etc ...some of the thread is about the manifold but you can skip that
A. Swap in a known good relay for the fuel pump relay and see if the pump works properly.
B. Check the electrical connector in the fuel pump harness behind the battery. On our '93 that connector vibrated loose and had been arcing for awhile before it burned and caused a no-start. There are photos in my albums at the link in my signature. Also, check the electrical connector on the evaporative flange at the top of the tank for any signs of arcing, and check the "RFI Protection Module," which is just a diode and capacitor covered with heat shrink tubing near the top of the tank. On our '93, either the diode or capacitor shorted internally and kept blowing the fuse. I replaced both.
C. If those things all check out, follow the diagnostic procedure by Bryan N at the Jag-Lovers forum. It has worked for me every time I've needed it:
XJ40 - ‘93 / ‘94 Fuel Pump Circuit Test Procedure - Issue 2
[Assuming that you have dash lights with the ignition 'ON']
3) Do you get 12 volts at pin 30 (Brown/yellow) of the fuel
pump relay base from fuse C6 in right fuse box?
4) If yes, jump pin 30 (Brown/yellow) and pin 87 (Blue/red)
in fuel pump relay base - does the pump run continuously?
5) If pump does not run, fault is in the wiring / connector
between fuel pump relay and pump
6) If pump runs, suspect fuel pump relay is defective.
7) Replace / re-fit fuel pump relay
8) Remove oxy sensor heater relay (yellow base on firewall)
9) Do you get 12 volts at pin 30 (Brown/pink) of the oxy
sensor heater relay base from fuse C4 in right fuse box?
10) If yes, jump pin 30 (Brown/pink) and pin 87
(Blue/purple) in oxy sensor heater relay base - does the
pump run continuously?
11) If pump runs, suspect oxy sensor heater relay is defective
12) Replace / refit oxy sensor heater relay
13) Remove EMS main relay (black base on firewall)
14) Do you get 12 volts at pin 30 (Brown/yellow) of the EMS
main relay base from fuse C1 in the left fuse box?
15) If yes, jump pin 30 (Brown/yellow) and pin 87
(White/brown) in EMS main relay base
16) Try this both with the ignition ON and the ignition OFF
17) Do you hear the fuel pump give its half-second priming
burst? [You can repeat this many times and you (or an
assistant listening at the open filler neck) should hear the
half-second 'whirr' of the pump every time you jump pins
30 and 87 of the EMS Main relay base]
18) If yes, suspect the EMS main relay OR the EMS ECU is
defective (the latter, very unlikely but possible)
19) Turn ignition OFF
20) Replace / re-fit EMS main relay
21) Remove Ignition 'ON' relay (on a '94 it should be in a
white base on the firewall but on a '93 it may be buried
under the dash behind the radio)
22) Do you have battery voltage at pin 30 (Brown) of the
Ignition 'ON' relay base?
23) If yes, temporarily jump pin 30 (Brown) and pin 87
(White/pink) in the Ignition 'ON' relay base
24) Do you hear the half-second priming burst from the pump
each time you jump those pins in the Ignition 'ON' relay base?
25) If yes, suspect the Ignition 'ON' relay is defective or
fuse A5 (fuse A3 on ‘94 models) in the left side fuse box -
but if either is defective, you will get NO dash lights when
you turn on the ignition.
26) If when you jump pins 30 and 87 of the Ignition ‘ON’
relay base you do get dash lights but you do not hear the
half-second priming burst from the fuel pump suspect the EMS
Main relay.
If you conclude that the pump has failed, be sure to depressurize the system before you disconnect the lines on the underside of the tank. Even though not much fuel will escape from the tank when you disconnect the lines, unless the pump rollers stop in just the right position, a lot of fuel may drain out of the lines themselves, moreso if there's any pressure in the system.
To depressurize the system, remove the fuel pump relay and crank the engine for several seconds. If the engine starts, just let it run till it dies. The fuel lines and rail are now depressurized, but it's also a good idea to remove and reinstall the gas cap to relieve any residual pressure in the tank.
Well this has been a bit of a pita so far. My jack broke, and my stands are mismatched. After all these years of having acces to a lift my working on the ground stuff is lacking. So over the weekend I bought New 3 ton stands and a new 3 ton floor jack. So tomorrow after work I try again to get the car setup high enough to drain the tank and get those 2 fuel lines off. When I looked on Friday I couldn’t even see them and assumed maybe my later vin vehicle had changed from the book. (Not the first time this has happened soooo)
Your car is the same age as mine Jeh, no worries, they ARE up there, pretty much directly above the handbrake cable union but way up there.
Clamp a light and shine it up there then use the long needle nose to rotate the clips 90 degrees ... loop a length wire over the line and pull each line out.
Don't forget to keep your mouth closed or you'll end up with a drop or two of gas in your gob.
Not much room to move down there - but - if I could manage it at my age I'm sure you can.
BTW I jacked up the rear of the car with a block of wood under the rear end, my jack goes almost to 18" and even then it was tight under the car.
Good luck, nice to have new jack and stands though, eh?
Not trying to beat a dead horse, but have you confirmed the fuel pump has died? I just hate for you to go to the trouble of replacing the pump if the problem is the relay or something else. You've suspected the MAF, CPS and fuel pump so far - I just hate for you to do the pump replacement on a guess.
Re-reading your first post, I'm sorry I missed your request for specs on the MAF and CPS. As far as I know, the only reference that may provide data for those is in the Engine Management manual, which you can download here:
I did check the pump. I’ve have the normal momentary power cycle with the key on and and I even applied 12v to run the pump and nothing up from fuel pressure wise. So at this point I would be shocked if it was something else.
the reason I was looking for the specs on the MAF and crank sensor was they are both problematic in the normal scheme of things and they are both easily accessible and easy to check. I also had a a very corroded connection at the MAF on the connector and the unit itself. Also the vehicle ran better if only marginally with the maf unplugged.
hey all, Sorry for this slight hijacking, but I don't think it merits its own thread. I Will Be changing my fuel tank in the 92 out Soon. (grrrrrrrr) I have a replacement which I removed from the same car again at the same yard again as Ive got so many other parts. (I swear Ive bought half that car- their prices are unbeatable...) It was raining on me and between being tired and wet and crabby (and ignorant and in a hurry), I didn't take the time to go under the car and twist or remove the clips from the lines under. Just kept pulling and finally out they came. Dumb. I know. As I say, I was tired and wet. Anyway, I got that tank out and left because the place was trying to close up around me, so I didn't take time to look at those connections. Are those clips made so that a twist to the right position will release the line or does the clip need to be pulled out? I guess I'm wondering if maybe there's a flat spot on the line for the clip to slide past when the clip is set right. I read Larrys thread which he linked to, but it seems to read both ways and I would simply like a path of least resistance. Thanks guys.
Rotating clip 90 degrees raises the clip from the flat and releases the fitting ...when you turn the clip you can feel it raise up out of the slot plus it's pretty easy to see what's happening if you've got good light.
Well that was terrible. Being a dumbass I had moved the tank forward a little and struggled to see the clips that needed to come off. After I pushed the tank back in place it was a little more obvious how they came out. Getting a hand up there and seeing was a different story and I managed to fling the clips into oblivion.
I found one and hopefully I'll find the other once the tank is all the way out. Ill grab a co-worker tomorrow to haul it out of the trunk since its still 1/2 full. Hopefully Ill find the missing clip.
...struggled to see the clips that needed to come off. After I pushed the tank back in place it was a little more obvious how they came out. Getting a hand up there and seeing was a different story and I managed to fling the clips into oblivion.
I should have mentioned earlier that I figured out that if I threaded some strong fishing line or upholstery thread through the loops on the clips and knotted it once, I could pull the clips off without losing them. I then used the same strong line to tie around each fuel hose to give me extra pulling power with one hand while with the other hand I twisted and wiggled the fitting to work it loose from the tank fitting.
Originally Posted by Jeh
Ill grab a co-worker tomorrow to haul it out of the trunk since its still 1/2 full.
You don't have to remove the tank from the trunk - just pull it far enough back that you can easily access the evaporative flange and fuel pump. If it's still too heavy to maneuver, you can siphon some more fuel via the sender port (if the fuel level in the tank is below 1/2 full) or via the evaporative flange opening if you can get the tank far enough back to remove the flange.
Sorry the large images at Jag-Lovers are still down, and the photos are not my best work, but you can see some thumbnails here:
Here's the tank moved back enough to access the flange ..I took mine out completely (it was empty though) rather than work in the trunk, but it can be done in the trunk too.
Tank released and supported by toolbox on floor of trunk
Thanks but I had to pull it out to hunt for the missing clip. That I fortunately found.
Now that it’s out on a solid surface. I can drain it And
replace the pump.
So the alarm on my truck just decided to start hocking the horn and not responding to the remote and now the XJ gets put on the back burner for another day.
Tip - fit the clips to the tank before you put it back in position then all you have to do is push the lines on to the tank fittings from under the car, they'll snap into place.
10-16-2017, 10:33 AM
94 XJ6 Extreme loss of power while driving
