Have Spark, Have Gas, Cranks, No Start

Hey guys,

I researched yesterday, and all this morning, and I think I've nearly nailed the problem.

Yesterday, I went to start the jeep (1991, 4.0, manual, 5" lift) and, it started for 2 or 3 seconds, then died. I sprayed some carb cleaner in the TB, and nothing. So I researched, and was fairly sure it was the CPS. Last night a buddy came over and I was able to check the spark by pulling a plug, and I have good blue spark.

So, I went to check the schrader valve on the fuel rail, and I push it, and nothing comes out, leading me to believe it's not getting any fuel. To be sure, I swapped relays and jumped the ballast resistor. Still, no pressure/fuel at the schrader. I DO hear the pump prime when the key is switched to on.

I do not have a volt meter, and I'm stuck at home at the moment. However, my testing and researching leads me to believe that my fuel pump is dead. I figure if I can hear it priming, that the electrical is good. I also figure that if I've got good spark, it's likely not the CPS. I replaced my distributor, cap, rotor, plugs, leads, battery and starter for high end stuff last summer too.

(It is 20F here in Utah too, but this thing has never had an issue starting in the cold, even in the brutal Alberta -35C cold)

I'm going to pull the pump this afternoon, and pick up a new one from the dealership tomorrow. Any other ideas/confirmations before I do this? Thanks for everything guys, without , I don't think I could keep the XJ running!

Re: Have spark, no fuel, cranks, but won't start

Had a similar problem, cold start trouble. Also changed the temperature sensor- didn't help. Took it to the dealer in frustration, he changed a diff sensor- fixed it. Can't remember which one- had done the CPS before, that was a different issue.

Re: Have spark, Have fuel, cranks, but won't start

Here's an update: I pulled the hose from the fuel pump, and put it in a container. I then cranked it and it started!?! It quickly ran out of fuel as the pump was pumping into the container (it filled the container). So, the fuel pump is working. I reconnected the line, and no start. I also tested the fuel filter in the same way. Not clogged.

I saw a test for the fuel regulator. I clamped the return hose that comes off the fuel rail. It gave me a nice stream of fuel from the schrader valve on the fuel rail. I removed the clamp, cranked again, and I've still got good pressure from the schrader. (but no start)

I tested spark again, and I'm getting spark. So now, I've got spark and fuel pressure, and I'm confused, I could really use some help! Could it be the MAP sensor? I'm going to purchase a voltmeter tomorrow, and test all the sensors.

Any insight/ideas would be awesome! Thanks in advance guys!

Re: Have spark, no fuel, cranks, but won't start

Ok, I've got lots of fuel pressure now, the fuel rail schrader spurts fuel as soon as the pump engages. The spark is not all that strong. It's orange, and will not ark unless the plug is nearly touching the ground. Any ideas?

Re: Have spark, no fuel, cranks, but won't start

I would replace the CPS just to rule it out, since it's relatively cheap. And clean it's connector (two-pin, near the intake)

As it is right now, with fuel pressure, and weak spark, does it fire at all?

Re: Have spark, no fuel, cranks, but won't start

As of right now, it will not fire up. I'm under the impression that a CPS will not allow any spark. I'll try to pull the at the connector and see what happens.

If your jeep has a sensor inside the distributor, REPLACE THIS FIRST. It is about $20 at NAPA, and will cause all kinds of problems. What happens is the engine will spark until it senses discrepency between the crank position and the cam position. Engine will have fuel, have spark and will not start. Replacement is 5 mins or less.

I know my 96 has one I am not sure if the 1991 would.

Hmmm, what sensor is inside the distributor? What name does it go by? Thanks!

Called the cam position sensor..... again I am not sure the earlier models have it, but my 96 does.

cps also.
Camshaft position sensor

yeah what Wildmatt said

I ordered an ignition coil and CPS this morning. I should also have access to a voltmeter this evening to test the camshaft sensor..... Thanks for any and all ideas guys, much appreciated!

Man, on the up side, by the time you get done you're going to have replaced every piece Jeep ever used to keep us owners confused. The down side is that you still might not know which piece it was that started the whole issue, just because they never act up when you put a volt meter to em.....

Gotta love Murphy... it's the only law that routinely gets broken due to it's own existence.

x2 on the coil. I once had a coil go weak on me. I was getting spark from it, but not the nice good spark. I replaced the CKS and CPS( crank and cam) to no avail.

As Gyro said, you'll have all new stuff, and you can keep the old good ones for spares. give it a tune up and she will take care of you for the winter.

CAS, Cam ANGLE sensor..... i finally remembered what they called it

Wildmatt said:

CAS, Cam ANGLE sensor..... i finally remembered what they called it

Click to expand...

sometimes called a "pick up sensor"

RyanM said:

sometimes called a "pick up sensor"

Click to expand...

sometimes its also called a stator

Hey guys, this evening I replaced the ignition coil and the Crankshaft position Sensor. Unfortunately I'm still in the same boat, cranking but not starting...

I noticed tonight that after cranking, I have very little fuel pressure. It seems fuel pressure is intermittent. This leads me to believe that it could still be the fuel pump. I'll order one tomorrow from the stealership as it sounds like the OEM Bosch model is the way to go.

The cam angle sensor in the distributor is a great idea too, I'll pursue that as well. Thanks for everyone's help! Any insight or ideas are much appreciated.

if it's the fuel pump, pour some sea foam or like wise down the TB while someone cranks.

If it cranks, it's a bad pump, still no start, its not the pump.

I have the same problem and so far have replaced the Distributor, CKP, Coil, Wiring Harness under the hood, and the Ecm, just to find out the Ecm is the wrong one for my 91. We still don't know what the problem is. Waiting one the correct one to come from the dealer, hopefully this will solve the problem. Victor