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87 2.5L XJ No start

G

greensbuickfarm

NAXJA Forum User
Location
Oklahoma
Hello all. New XJ owner here, sounds like I have common problem Googled all over the place, found lots of helpful info but Jeep still won't start.

Symptoms: Drove the Jeep three or four times, seller advised that truck would occasionally die after running for 15 minutes or so. Let it cool and would restart. Never expereinced that until last weekend. Was running fine, died and NO restart. When the key is turned on, the anti-diesel(?) solenoid clicks, and the relays on the fender click. Pump wil engage for about 2 seconds that stop. Checked the pump. Even with 12Vapplied to the pump (pump works), still no start. Truck will run off of starting fluid, though. Have fuel to TB. Where should I start next? TB? Wiring harness connectors?

Thank you in advance for your responses...

Jason
 
The 2.5L has a crankshaft position sensor just like the 4.0L. Do a search on here for CPS and you will find a ton. It is located on the bellhousing on the drivers side. Unplug it and plug it in again and see if that helps. The contacts sometimes get corroded. The cable can also get melted on the exhause manifold.

good luck
 
OK, check the CPS. Has had connectors removed and soldered together...maybe CPS has been replaced at some point? Anyway, not sure what voltage to be looking for, but there was none with key on. disconnected CPS. 1.5ohm resistance across CPS. With unit disconnected, xj wouldn't start, even on starting fluid. cleaned, reconnected, will start when primed, but then dies. Sounds like CPS is toast--but before I go and buy one, is there anything else I should check?

Thanks,

jason
 
No, it doesn't sound like the CPS is toast. If the CPS was toast, it probably wouldn't start at all.

Have you checked the injector to see if it is receiving a signal? There is a noid light that fits that injector. I don't remember what make it is listed for, I just remember that it wasn't listed for a Jeep, but there is one that fits.

Starting fluid is more volatile than gasoline, so might start on a weaker spark. If it starts reliably on the ether, try dribbling some gasoline directly into the throttle body and see if it will start on that. You might even be able to keep it running if you can manage to dribble at the correct rate of flow. If that works, then you know you need to check the injector, both for signal and for flow.

Pray that you don't need an injector. That one injector lists for about 200 clams.
 
Injector was first thing I checked. Have fuel there, but not from. So injector isn't opening? Tested injector with current, can hear it click. I can get it to start on gas, poured into engine. After doing more research, I am concerned that it is the CPS, since my resistance measured was very low. I'll grab someone and see if we can do the voltage check while cranking.

Is ther a cam postion sensor on that model?

Again, the strange thing is that I can get it to start with fuel/ether...TPS maybe? (Not getting proper voltage so it is not sending fuel?

Appreciate the help, and any other suggestions are welcome!
 
greensbuickfarm said:
Injector was first thing I checked. Have fuel there, but not from. So injector isn't opening? Tested injector with current, can hear it click. I can get it to start on gas, poured into engine. After doing more research, I am concerned that it is the CPS, since my resistance measured was very low. I'll grab someone and see if we can do the voltage check while cranking.

Is ther a cam postion sensor on that model?

Again, the strange thing is that I can get it to start with fuel/ether...TPS maybe? (Not getting proper voltage so it is not sending fuel?

Appreciate the help, and any other suggestions are welcome!
Click to expand...
Why are you fixated on the CPS? If it will fire on ether and fire on gas poured into the throttle body, the CPS is doing its thing, and the cam sensor in the distributor is doing its thing.

Your problem is getting the injector to inject. Buy or borrow a noid light and check to see that the injector is getting a signal.
 
Sorry, just wanted to make sure I that the CPS wasn't the problem, given the 1000s of posts that that is what is usually the problem...

If it is the injector not getting a signal, what should should I check from there? TPS? Connection somewhere? Thanks.

I'll check the injector and get back with you guys if that's not the problem...
 
The TPS can cause the problem, but only if it fails so that it looks like it is at WOT wide open throttle. The computer senses that condition as you trying to clear a flooded engine and shuts off the fuel. More likely it is a bad connection. I think the 2.5L has the C101 connector above the vacuum booster just like on the 4.0L's. It is notorious for getting crappy. Plug and unplug it a couple of times. You said you had gas at the injector. How did you tell? it needs somewhere around 40 psi. Also do the plug/unplug routine on the connector on the computer as well. The drive for the injector comes directly from the computer.

If you need a computer, I think I may still have one for an 87 2.5L & manual tranny. I would have to check.
 
Pulled the fuel line at the intake--gas shot out. I haven't put a pressure gauge on it yet...was goign to do that this weekend. I'll check those connections and see if it works! If not, I may be in need of that computer...
 
OK- checked out the connectors-- I didn't find the one above the vacuum booster--could it be below the booster to the left? There is a connector there with quite a few wires...could you give me a better description of what I am looking for (number of wires, shape) for some guidance?

Thanks!
 
gotta pop in here. If this is a 2.5 and manual transmission it could ctill be the cps.

I had the same symptoms, the cps was coated with hydrolic fluid from the slave cylinder inside the bellhousing.

took it out and cleaned it no more problems. with the non starting that is.
 
OK wait start over!! before getting to in depth here at the time when it died (engine still hot) did you ever check for spark? I just had this problem with my 87' 4.0 . It ended up that the coil was bad. Sometimes it would run great and then once in a while it would run for 15 minutes or so then die , let it cool down it would fire right back up. Before going around and checking sensors and fuel pressure and getting all confused try this. Drive the Jeep or let it run in your driveway until it dies like it did before and at that moment check for spark if it doesnt have spark then the coil would be a good place to start.If thats not it start with the simplest things first! Good Luck.
 
I have checked--I have spark--engine will run on ether or fuel poured into TB. So, I thinking it is fuel related--somehow.

Still have the question about the c101 connection--is it beside the vacuum booster on the firewall?

Thanks!
 
Jason a long shot here. have you replaced the fuel filter yet? It sounds life it is starving for fuel after a few minutes. might be partially clogged
 
greensbuickfarm said:
Still have the question about the c101 connection--is it beside the vacuum booster on the firewall?
Click to expand...
Yes -- directly in front of the driver, high on the firewall with a FAT wire loom going in from each side.

However, before you rip into it, check the schematics, because I don't think the fuel pump wiring goes through it. Although the wiring from the ECU to the injector does, so that's a possibility.

Have you put a noid light on the injector?
 
Checked the injector--I'm getting voltage there. I'm getting 5 volts to the TPS, but when I did the TPS test, I got 3.5 volts, and it never changed...so maybe a bad TPS? I ahve another one and I'll try that.

I'll also check the fuel filter, even if its not the problem, it proablaby needs it anyways...

Thanks!
 
No, I haven;t put the gauge on it yet. But, given the other strange readings on the TPS and injector, I'm wondering if the problem isn't electrical/ECU related--maybe the computer isn't firing the injector for some odd reason?

Thanks,

jason
 
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