RedHeep
NAXJA #1499
- Location
- Landenberg, PA
Do you have pressure at the rail?
Have you changed the fuel filter?
Have you changed the fuel filter?
-
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Head Swap Issues - Need Help Troubleshooting
- Thread starter jls095
- Start date
Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
After priming did you put the cam sensor back in correctly? It needs to be indexed.
Ordered a gauge (will be in tomorrow) to check pressure at rail. Will report back when I have a number. I have not changed the fuel filter.
Talyn - I misstated above. I did not prime the oil pump, I bled the fuel rail by turning the ignition on and off a few times.
I'm thinking that maybe the injectors got dried out or gummed up while sitting exposed for 2 months. Curious to see what the fuel rail pressure is. If the rail is fine and the injectors are gummed up, I would still see normal rail pressure, right?
RedHeep
NAXJA #1499
- Location
- Landenberg, PA
Fuel filters commonly cause no start issues. That's $10 variable reduction.
RedHeep
NAXJA #1499
- Location
- Landenberg, PA
Troubleshooting symptoms based on what the engine did before you took it apart is an expensive way to learn. You should troubleshoot what it does now. Good luck.
- Location
- Torrance, CA
I've never seen a fuel filter cause a no start on a 97+ plus it's built into the FPR and isn't a $10 part nor easy to change. I'd get a fuel pressure gauge and confirm you're loosing fuel pressure and it's not something else.
Last edited:
Ok update...
I confirmed that the fuel rail has good pressure (49psi). This led me to believe that perhaps the injectors had dried out and gummed up in the 2 months they've been out and exposed. I ordered new injectors and just got around to installing them. They had no effect.
To recap:
Jeep turns on and runs for about 5-10 seconds, idles a bit rough (not terrible) and then dies. When I try to start it again, it dies almost immediately. If I try to start it again, it barely starts up. It dies even if I try to rev it slightly.
This pattern of events led me to believe that it was fuel starved (and is why I changed the injectors). Does anyone have additional suggestions? It always has the pattern I describe above.
Could this be a sensor issue? I had removed the IAC, TPS and MAP sensor on the throttle body.
Could the symptoms be related to the new head / valves? I don't see how this could be given the odd starting pattern.
I'm going to check the plugs tomorrow and make sure that the engine ground that connects the firewall to the rear-right head bolt is clean (does it matter if I used a stainless nut?).
At least it looks good...
I confirmed that the fuel rail has good pressure (49psi). This led me to believe that perhaps the injectors had dried out and gummed up in the 2 months they've been out and exposed. I ordered new injectors and just got around to installing them. They had no effect.
To recap:
Jeep turns on and runs for about 5-10 seconds, idles a bit rough (not terrible) and then dies. When I try to start it again, it dies almost immediately. If I try to start it again, it barely starts up. It dies even if I try to rev it slightly.
This pattern of events led me to believe that it was fuel starved (and is why I changed the injectors). Does anyone have additional suggestions? It always has the pattern I describe above.
Could this be a sensor issue? I had removed the IAC, TPS and MAP sensor on the throttle body.
Could the symptoms be related to the new head / valves? I don't see how this could be given the odd starting pattern.
I'm going to check the plugs tomorrow and make sure that the engine ground that connects the firewall to the rear-right head bolt is clean (does it matter if I used a stainless nut?).
At least it looks good...
Last edited:
Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
Did you check fuel pressure when the problem was happening?Ok update...
I confirmed that the fuel rail has good pressure (49psi). This led me to believe that perhaps the injectors had dried out and gummed up in the 2 months they've been out and exposed. I ordered new injectors and just got around to installing them. They had no effect.
To recap:
Jeep turns on and runs for about 5-10 seconds, idles a bit rough (not terrible) and then dies. When I try to start it again, it dies almost immediately. If I try to start it again, it barely starts up. It dies even if I try to rev it slightly.
This pattern of events led me to believe that it was fuel starved (and is why I changed the injectors). Does anyone have additional suggestions? It always has the pattern I describe above.
Could this be a sensor issue? I had removed the IAC, TPS and MAP sensor on the throttle body.
Could the symptoms be related to the new head / valves? I don't see how this could be given the odd starting pattern.
I'm going to check the plugs tomorrow and make sure that the engine ground that connects the firewall to the rear-right head bolt is clean (does it matter if I used a stainless nut?).
At least it looks good...
Yes, stays pegged to 49psi. Will confirm again tomorrow. Doesn't appear to be a leak down issue either.
Another idea...could be a gas issue? The gas is 2-3 months old at this point, which I think it approaching the life span for 10% ethanol gas.
RedHeep
NAXJA #1499
- Location
- Landenberg, PA
Sometimes my jeep doesn't get started for 3 months and runs just fine.
Another update:
When I replaced the head I put new copper NGK plugs in. I pulled them today and found this:
Plugs 1-4 show signs of combustion, while plugs 5 and 6 are totally clean. I confirmed yesterday that the fuel rail has good pressure and there is no leakdown issue. All fuel injectors are new as of yesterday.
To recap: Jeep turns on and runs for about 5-10 seconds, idles a bit rough (not terrible) and then dies. When I try to start it again, it dies almost immediately. If I try to start it again, it barely starts up. Today, before I pulled the plugs, I was able to keep it running if I revved it up slightly. As soon as I took my foot off, it died.
So, any ideas? Fuel doesn't appear to be an issue. I can't imagine the plugs were faulty. What could cause this? I will pull the valve cover (again) tomorrow and confirm that the pushrods are properly seated on the lifters for 5 and 6.
When I replaced the head I put new copper NGK plugs in. I pulled them today and found this:
Plugs 1-4 show signs of combustion, while plugs 5 and 6 are totally clean. I confirmed yesterday that the fuel rail has good pressure and there is no leakdown issue. All fuel injectors are new as of yesterday.
To recap: Jeep turns on and runs for about 5-10 seconds, idles a bit rough (not terrible) and then dies. When I try to start it again, it dies almost immediately. If I try to start it again, it barely starts up. Today, before I pulled the plugs, I was able to keep it running if I revved it up slightly. As soon as I took my foot off, it died.
So, any ideas? Fuel doesn't appear to be an issue. I can't imagine the plugs were faulty. What could cause this? I will pull the valve cover (again) tomorrow and confirm that the pushrods are properly seated on the lifters for 5 and 6.
westvirginia24976
NAXJA Forum User
- Location
- west virginia
I would make sure your wires to the coil rail are ok. They fire in pairs. You have a pair that appears to not be firing.
Shot in the dark... does your XJ have any type of theft devise or a coded key that might need to be reset after the head swap? I may be way wrong on this, but your description sounds like what happens to other vehicles that try and use a non-coded key in a vehicle equipped w/the coded key theft devise. I don't know the exact term, but just a thought.
I think if your gas was bad your rig either wouldn't start or would start and just run poorly until you ran some good gas.
I think if your gas was bad your rig either wouldn't start or would start and just run poorly until you ran some good gas.
I will check the coil rail / spark. While the rail does fire in pairs, 5 and 6 are not matched together. 1 and 6 are matched and 2 and 5 are matched.
What's the best way to check for a spark? I could do something like this video...
https://www.youtube.com/watch?v=Sk_8TKMwyPo
Redsnake - I agree with you on the gas point. Either it would start or it wouldn't. Regarding the theft devise, I don't think that's it. This XJ has been in the family since it was new and doesn't have any of that "hi-tech" stuff.
cr2000xj
NAXJA Forum User
- Location
- Huntsville, Alabama
Just a random thought, my XJ has behaved similarly to this when it had the battery disconnected for a long period of time. I had to give it throttle to get it to start as well as stay in the throttle to maintain idle. The jeep would not idle at all, if I let off the gas it would die. I had to keep it running for around a minute feathering the throttle before it would idle on its own. After that, no more issues.
