Delayed Start with "Clicking Relays"?

[cricketxj]

Hey guys, I am officially coming out of my lurking closet to actually post a question that i havn't been able to search for and find an answer to as I have so many other times in the past. Hopefully this is an easy one....
I have a 92 sport, l6 auto 4x4, 115k, mostly stock, that I have been slowly resurrecting. When I first got it, it didn't run and have since replaced the computer, cps, fuel pump, ignition switch, etc. etc. Recently its developed this nasty habit of not starting (mostly) in the morning after its sat all night. When I put the key in and turn to the "on" position normally you hear the fuel pump prime, in the upper left corner of the dash you see the "maint required" and the "check engine" lights come on all in the same sequence. Lately however, When I turn the key on, I get nothing. after about 30 sec. to 3 min, I'll start to hear a very faint clicking sound coming from the relay box on the passenger side of the engine compartment, that will steadily get louder (takes about 15 sec.) until the you hear the fuel pump start to prime and the indicator lights (in the dash) come on synonymously. After it does this it usually starts on a few cranks but I have had to fuss with it more recently (Cranking it over until it finally sputters to life ). Once it starts, or has been driven for a while (25 min work commute) it seems to start up promptly, the fuel pump and all other functions seem to operate normally, and all symptoms are gone, even after it sits for a 10 hour day, it will only delay slightly if at all. As mentioned previously I did replace the fuel pump recently and have heard of symptoms where the internal parts inside the pump fail and allow the fuel to drain back into the tank making starting difficult. What I dont know is how to isolate the problem to the pump or how to at least test the pump itself. As far as the relays are concerned, I havn't replaced any of them, but I did leapfrog em around, took them apart and checked for corrosion, or carbon, sanded contact points and still no change. Checked wiring connections (at the gas tank under the vehicle) , added dielectric grease, no luck. diagnosing is a little difficult once you get it started as the symptoms go away......
If there is anyone out there that has had this problem before or has any suggestions on how to chase this down I would greatly appreciate any info. Mahalo

 

[joe_peters]

Sounds like a bad ASD relay possibly. The ASD relay provides 12 volts to the primary windings of the coil, as well as providing the "prime" power to the fuel pump for 3-seconds. This is controlled by the PCM through the ASD relay's ground. Try swapping another relay for the ASD and see if that helps.

 

[cricketxj]

So, I tried every relay in the box in the ASD spot, swapping them all out one by one till every one had a turn and no luck... Its strange to me how it wont work in the morning, but after the initial start up and go, it works fine.... When it does start to chime in, its the ASD and the fuel pump relay that both start to click until finally kicking in.. I'll purchase a few extra relays and swap one of those in and see if a brand new one helps. Any suggestions after that?
Thanks for the help.

 

[joe_peters]

Ok, lets do the grounds/harness.

Not sure on your 92 if the PCM still grounds at the dipstick tube.

Anyway, (FSM 95) pin/cavity 51 of the 60 pin PCM connector provides the ground for the ASD relay. I would start with cleaning that connector, hitting all grounds, see if that improves things.

Also, disconnecting the negative battery terminal and then unbolt the PDC, turn it upside down and check for corroded contacts.

Good luck.

 

[cricketxj]

So lately I've pulled the PDC, it was clean and dry underneath, I checked the ignition switch, actually pulled it apart, cleaned the contacts and re greased it, pulled the grounds by the dipstick cleaned scuffed and re attached, and nothing changed..... To check the 51 pin I just used a light tester from the battery to the harness or pin cavity and all that really did was activate the fuel pump. Im not sure if Iam testing it wrong or if there is a better way, or if that is perfectly normal for that to happen, but I am sure that it was the right cavity. The pcm is new and the harness isn't dirty or corroded but I put some electric grease on and reinstalled it with no change. The relays still click after some time in the morning and then it will usually run fine the rest of the day... I'm open to any other suggestions, thanks for the help so far....

 

[Pelican]

Are you absolutely sure the pcm is good as well as any temp sensor(s) that provide input for cold startup?

 

[cricketxj]

I dont know for sure if it is or isn't, thats actually why I'm here. Since it usually runs fine after its initial start up I was thinking it was just a loose ground or faulty connector not the PCM. However I'm not a mechanic (but I have replaced head gaskets, clutches etc) and electrical problems are my worst. If there is a way you could suggest to test the PCM for this function, or if there is another ground source that I may be overlooking I am open to suggestions. I will be getting a fuel pressure gauge to test if my hard rough starts are due to check valve failure or leaky injectors. (but thats kindof another story) Im wondering if the problem might lie in the fuel pump, but I'm not sure. Some times when i switch the key on and off for a couple tries I can see the "check engine and maint reqd" lights flicker for a moment, and when the relays finally do start to kick in the lights flicker in sequence with the clicking until finally they stay on for the duration of the priming and then turn off. Does the reaction I had with the 51 pin cavity seem normal or should the test light lit up being connected to the battery and pinned in the 51 cavity?

Thank you again for responding to my post, Aloha.

 

[joe_peters]

I'm leaning towards a poor connection somewhere.

Do this, unplug the crank sensor, then see if the relays click or not.

 

[cricketxj]

Thank you for the prompt reply, its running consistently now that its a warm Hawaiian afternoon, however in the morning I will try and turn it over with the CPS disconnected. Usually the morning routine involves turning the key on and leaving it on while i scramble around trying to find everything I'm forgetting until I eather hear the relays kick in or I'll have to sit there and flick the ignition on and off trying to get something to arc until finally you can hear it real faintly for about 5 to 15 sec then you can hear it progressively get louder until everything lights up and appears ready. From there you can turn the keys on and off with no problems however it does start like it has a faulty check valve. ( Meaning I have to crank it for 10 seconds or so until it coughs and sputters, occasionally backfiring a little, until starting roughly, feather the pedal slightly, let it die, start it again, feather the pedal, let it chug for a second, then give it a rev and its good. Doesn't matter how many times I let it prime I still have to do the routine....) Weather thats the check valve or has something to do with the pumps power source or some other sort of anomaly, I dont know.

Overall shes a great rig, strait body low miles, simple. There are those tell tell sighns of nightmarish electrical apostasy's, alarm hacking's, rusted windshield cavity, the stereos been hacked in and out several times, ect. But I got her for 500$ bucks with out any major kinks, I just hate doing electrical work. (Actually I don't mind it, I just dont understand most of it.)

So if I unplug the CPS and nothing changes, any recommendations from there? Chase down more grounds? Or should I clean it and reconnect it (theCPS) and then try? Anything under the dash I can try? ( the windshield did leak for who knows how long) Its a pretty annoying issue but it seems to only plague me in the morning or the first start of the day.

Anyway thank you for the reply's and I'll try some more in the morning.

 

[joe_peters]

Yeah, the only thing that would make the relays cycle is the ground from the PCM. In the later 97+ XJs when the crank sensor shorts to ground you will get a "NO BUS" signal in the instrument cluster and the gauges won't work, and a scanner can't communicate with the PCM.

Now, your 92 is acting funky, and the PCM is the source of the ground for the relays, from pin 51 (I got that out of the 95 FSM, so hoping its the right pin)--Soooo, I'm hoping that if you disconnect the crank sensor the relays WON'T click, and if so, you need to test the crank sensor and/or the harness looking for a short. That doesn't eliminate the PCM as a problem, but I would check the others first.

Good luck.

 

[Pelican]

Did you find your problem? I don't know that I have ever heard of a similar situation involving a slow increase of voltage after turning on the ignition until the various circuits finally begin to function.

Let us know.

 

[cricketxj]

No, I havn't found a fix for this yet. I'm real close to taking it into the stealorship to have them work on it but I'd do just as good to save my $$ and buy a FSM and do it my self... The PCM is only a few months old so I'm really hoping it's not the cause of all this. I'am pretty confident that it is a ground\connection issue, just not sure where. I did take a look at the fuse block from the engine compartment side and it was just a mess with all that black sh*t they put in there. I cleaned it out as best as I could, sanded the connections and added some dielectric grease but no dice... I was hoping that that was it. So in the mean time I've been car pooling so I havn't had too much time to try and think it back to normal but the symptoms still persist as mentioned, and once it starts initially in the morning it wont act up until its been sittin for the better part of the day, so testing it in general is a pain in the ass..
If you do have any other diagnosis's for this I would love to hear any thing any one has to offer. It almost seems to be between the ignition switch and the PCM seeing as how if I flick the ignition back and forth or on and off the "maint req'd" light to the left of the steering will flicker, but its not till after the relays really start clicking and are almost totally engaged that the "check engine" light comes on synonymously with the fuel pump priming and the "maint reqd" light. after that it runs perfectly normal for a 92 xj. So I'am trying to do as much research and dirty work as possible to try and figure this out on my own and when I do I will make sure and post my solution in case anyone else ever has this problem, thanx for checken in and let me know what you all think about this little anomaly... Suggestions are welcome.

 

[O-Gauge Steamer]

NSS? If it is slightly out ouf adjustment, the relay inside (passenger fuse box) will fire but ti heep may not always start. My 98 did it... Adjust the NSS and it fires averytime.

Just a thought...

 

[ehall]

If you feel up to it, use a multimeter to watch for signal on the input side of the relays. That will give you a better idea of what's going on. Could just be a low voltage condition that is preventing the relays from closing, or could be a broken wire somewhere, etc

 

[cricketxj]

Thank you for the reply's. As far as the NSS, I cleaned and lubed it really well a few months back when my back up lights weren't working, and its seems to be functioning properly. As far as the relays are concerned when I prod the pin 51 wire with a light tester to see if it was grounded, I hooked one end up to pos+ and poked the wire and the fuel pump relay kicks on and you can hear fuel priming. Interesting enough the other day when I was waiting for it to chime in I could actually hear the IAC clicking ever so faintly. After turning off the ignition and pulling of the connector and looking for corrosion (which it had none)I re connected it and turned it back on and all was well, until the next day it was right back where I started. I really don't know enough about electronics to give a complete diagnosis but it seems like little things here or there may spark a connection (plugging and un plugging, cleaning, lubing, etc) and running for a long enough time expands things enough to keep it connected but there hasn't been any thing thats held as a consistent fix. Again the only thing I get a reaction out of is cycling the keys back and forth ( I know it sounds lame) I even pulled the dash apart and found the wires to the gauge cluster with the "maint reqd" and "check eng" light and have been meaning to trace them to there source but that really does me no good without knowing what to look for once I trace it. All I can do really is check for corrosion or loose fittings. My multimeter doesn't make any noise to trace wires and my knowledge to do so is limited.... Interesting how no one else seems to ever have had this problem before.... I will probably end up doing both options as mentioned above, feed it to the dealership and hope for the best and then buy a FSM. I'm running out of ideas...

 

[cricketxj]

Did some digging and found these sites:


forum.doityourself.com/archive/index.php/t-208349.html
www.fixya.com/cars/t1373898-starting_problem_1994_jeep_grand
www.jeepforum.com/forum/f11/92-cherokee-electrical-starting-problems-fuel-pump-delayed-566355/

They all seem to have had the same problems with the same symptoms be resolved by the same fix= New PCM.


There are also a lot of posts about where to buy and what, for the PCM, to sum it up you get what you pay for wether it be a "factory reconditioned", or just repaired and replaced. Mine is only a couple of months old and has been having symptoms for half that time. but I would read up on a few different opinions before traipsing down to the fast food auto parts store.