Jeep Enthusiast Forums banner
1 - 20 of 29 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter · #1 · (Edited)
Long time listener, first time caller. I'll try to make this short.
I have a 1995 2.5L 5 speed manual. Rebuilt the entire engine due to a blown piston skirt. Had about 215,000 on it. I also added a 2.5inch lift running 31x10.50.
Started up and ran fine the other day after a 4 year sit while I finished another car. Then I started having issues starting, felt like it was flooding. But eventually it would start and run ok. City driving seemed normal but then getting into 4th and 5th gear it was a struggle bus. Could barely hit 50mph. Did some diagnosing and tweaked my distributor to a more correct tooth and it ran better. I read on here things about TPS sensor so I tried that but the one I bought was not right. In doing so I saw some fuel pooling inside my intake manifold/throttle body. Tested my injectors with the 9 volt trick and everything seems normal. I am 90 percent sure #1 and #2 aren't leaking after shutoff. Went for another drive and could now hit 60mph but it still struggles to hold that. Then when I got home I looked up under and my exhaust manifold is glowing. Diagnosed this and landed on running lean/Vacuum leak/timing issues. You know, cause that's all connected.

Here is what I have tested/looked into,

New:
Crank position sensor
Dist. Cap, rotor, cam position sensor
Upgraded power wires and spark plug wires
Coolant Sensor (back of head and at T.stat)
Air temp sensor
02 Sensor
Fuel pressure regulator at rail (updated* new one was set to 41psi, replaced with old one and psi was back to 31.)
Fuel Filter
Fuel return line flow is normal.

Tested:
Injectors (upgraded 4 hole) = Good
Vacuum leaks via propane. = None detected around intake manifold, MAP sensor, valve cover, the one near the battery tray.
Voltimeter test on MAP sensor = good
Double checked timing via TDC and Rotor at #1 dist cap wire.
Oil pressure and temp are normal according to my gauges inside.
No noises or slips or vibrations etc from transmission
I have no CAT and exhaust out seems normal (ruling out clogged exhaust.)
Fuel rail psi = good

So here are the questions:
-If I am running lean, how would I adjust if my timing is good, and I have no vacuum leak when timing is controlled by the ECU? Should I just replace the MAP since its 30 years old anyways?
-I know its just "4 angry squirrels" but I was hitting 70mph easily before just without a lift. Would this lift really make this much difference? My rear driveshaft angle is a bit steeper than expected and I did not do an SYE (yet). Would this have any effect on my power?

Am I missing something? I feel I may need to re gear in general but that will not take care of my glowing exhaust.

Thanks in advance everyone!
 

·
Registered
Joined
·
12,506 Posts
some thoughts
you need a cat.
did you try to check codes? post ALL codes.
How do plugs look - 'read' them - WET, dry, BLACK, tan, damaged?
Do a fuel pressure test use a gauge post PSI.
Don't move dist trying to set timing.
 
  • Like
Reactions: fishadventure

·
Registered
Joined
·
12 Posts
Discussion Starter · #3 ·
some thoughts
you need a cat.
did you try to check codes? post ALL codes.
How do plugs look - 'read' them - WET, dry, BLACK, tan, damaged?
Do a fuel pressure test use a gauge post PSI.
Don't move dist trying to set timing.
Thanks jtec.

Interesting about the CAT. I have not heard of people having issues with out them. Is this because of back pressure?

I currently have no engine light on. Would there be codes with out it illuminated? I have never checked if the light was off.

I did check the plugs last night. Since I am assuming I am running lean, there was a small amount of white on the node. And they were dry.

I have done a fuel pressure test on my fuel rail. It is within the normal range at idle (about 30) and when I pull the vacuum on the pressure regulator it jumps to 40psi. My only other concern with fuel is that I lose pressure in the rail overnight. I think this is normal and is primed when you turn the key.

I wouldn't say I "moved" the distributor for timing. I think when I initially installed it, I was not in the right spot. I do understand that moving it to adjust timing is not a thing with this Jeep because the computer will adjust it automatically.
 

·
Registered
Joined
·
862 Posts
A plugged cat will cause loss of power and glowing manifolds.

An exhaust shop can check the back pressure through the O2 bung to see if it's plugged, or you can remove the O2 and drive it and see if the power improves.
 

·
Premium Member
Joined
·
2,411 Posts
I had something similar years ago with my 2.5... Granted these were aftermarket headers but this was idling in the garage for about 5 minutes. I was trying to diagnose the problem on the side of the road and of course I was out of town. The fuel rail had loads of pressure but the only thing I could find was the fuel pump was tired and performance would drop off the longer I drove. Replacing the pump fixed the problem for me but it's very possible we have a different issue. Driving a short distance was no problem but anything more than about 30 minutes and everything would run like crap. Maybe drive it for a little bit and immediately test the fuel pressure and see if it's still good. I'd also rev the engine a little and see how the pressure reacts. A dip in pressure is normal under a quick blip of the throttle but if you rev to say 2000-3000rpms, it should still be able to hold 31psi or so. It's rare but the fuel pump can provide adequate pressure but lack enough flow although this is more often a problem with the fuel filter and not the pump itself. The pressure will normally bleed down over night. If it falls off in a matter of seconds, the check valve is faulty but that shouldn't affect running...would just make it harder to start.

Motor vehicle Automotive fuel system Vehicle Automotive exterior Auto part
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #7 ·
I had something similar years ago with my 2.5... Granted these were aftermarket headers but this was idling in the garage for about 5 minutes. I was trying to diagnose the problem on the side of the road and of course I was out of town. The fuel rail had loads of pressure but the only thing I could find was the fuel pump was tired and performance would drop off the longer I drove. Replacing the pump fixed the problem for me but it's very possible we have a different issue. Driving a short distance was no problem but anything more than about 30 minutes and everything would run like crap. Maybe drive it for a little bit and immediately test the fuel pressure and see if it's still good. I'd also rev the engine a little and see how the pressure reacts. A dip in pressure is normal under a quick blip of the throttle but if you rev to say 2000-3000rpms, it should still be able to hold 31psi or so. It's rare but the fuel pump can provide adequate pressure but lack enough flow although this is more often a problem with the fuel filter and not the pump itself. The pressure will normally bleed down over night. If it falls off in a matter of seconds, the check valve is faulty but that shouldn't affect running...would just make it harder to start.

View attachment 4149276
Thanks Waternut.

In my mind I have thought about my fuel pump. I just don't want to believe it right now. I have heard of this difference of Flow vs. Pressure. I'm not 100 percent versed in it but it makes sense. I will see if I can rig up my gauge to read while driving maybe, or check it like you say after driving. If your fuel pump was tired and that fixed this issue, why would it make the exhaust ultra hot though?
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #9 ·
A plugged cat will cause loss of power and glowing manifolds.

An exhaust shop can check the back pressure through the O2 bung to see if it's plugged, or you can remove the O2 and drive it and see if the power improves.
No cat in this one. but I have heard that. I do like the unplugged 02 idea though. Not sure if I should be worried about that hot gas shooting back into the engine bay on the other hand.
 

·
Premium Member
Joined
·
2,411 Posts
If your fuel pump was tired and that fixed this issue, why would it make the exhaust ultra hot though?
Roughly 10% leaner than stoichiometric yields the highest exhaust temperature. If the pump can't supply the needed fuel flow or pressure, you'll end up running a little lean which in turn makes the exhaust gases hotter.
 

·
Registered
Joined
·
862 Posts
Missed the part above where you stated no cat. Exh shouldn't be plugged then.

With your fuel pressure gauge installed run the RPM up and see if the pressure drops. My 92 4.0 was cutting out under load/high RPM due to weak fuel pump, however, the pressure was fine when tested at idle. When I blipped the throttle the pressure would drop out below spec.
 

·
Registered
Joined
·
12,506 Posts
have you changed the fuel filter?
Agree with 93YJ 4fun - does the CEL come on fro @2seconds every start then go out?
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #13 ·
have you changed the fuel filter?
Agree with 93YJ 4fun - does the CEL come on fro @2seconds every start then go out?
Yes to the new fuel filter. sorry missed that one! The CEL comes on then goes out. In the past few weeks while trying to diagnose, I do remember it not coming on occasionally. But that is after I turn the key on and off a bunch trying to check stuff. Might have been due to not turning it all the way.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #15 ·
So did another fuel pressure test because I still had the rental. Jeepa been sitting for about 24 hours 0 psi when I hook up the gauge. With key on I had 21psi. I did that again and it jump to 41. Then I started the Jeep and it stayed at 41. When I do a quick throttle pull it jumps but drops back to 41. When I hold at 2500 rpm it stays at 41. When I disconnect the regulator vacuum it jumps to 50psi.
Turn it off and watch the bleed down went from 41 to 36 in about 20 minutes.
Sounds high on all tests.
 

·
Premium Member
Joined
·
2,411 Posts
I agree... Sounds like the wrong regulator since it appears to be working right but it's too high for the 2.5L engine. After 95, the Jeep engines started running higher pressures around 41psi at idle but all the multi port fuel injected engines prior to 96 ran 31psi. I took a quick look at Rockauto and it looks like the specs on most of those regulators is too high so there may be a bad cross reference at other parts stores too.
 

·
Premium Member
Joined
·
4,116 Posts
You may want to check the fuel lines near the tank where they go over the crossmember and make sure that they are not pinched. Bad body mounts can cause this. It is somewhat of a common problem. If the return line is restricted then the pressure will rise.

EDIT: Another thought is about your exhaust glowing. If it is at the manifold/header like @Waternut posting then it is a lean condition for sure. If it happens further downstream like at the cat (which you do not have) the muffler, the tailpipe, the pipe where the cat should be, etc. it can be from raw and unburned fuel entering the exhaust and combusting in the exhaust system.

Faulty ignition system operation can create issues also but your high fuel pressure should probably be addressed first.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #18 ·
I agree... Sounds like the wrong regulator since it appears to be working right but it's too high for the 2.5L engine. After 95, the Jeep engines started running higher pressures around 41psi at idle but all the multi port fuel injected engines prior to 96 ran 31psi. I took a quick look at Rockauto and it looks like the specs on most of those regulators is too high so there may be a bad cross reference at other parts stores too.
Thanks again, gotta love making an easy thing harder. Well I'll pick up another and test that out. Hopefully that extra psi is my hot exhaust issue.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #19 ·
You may want to check the fuel lines near the tank where they go over the crossmember and make sure that they are not pinched. Bad body mounts can cause this. It is somewhat of a common problem. If the return line is restricted then the pressure will rise.

EDIT: Another thought is about your exhaust glowing. If it is at the manifold/header like @Waternut posting then it is a lean condition for sure. If it happens further downstream like at the cat (which you do not have) the muffler, the tailpipe, the pipe where the cat should be, etc. it can be from raw and unburned fuel entering the exhaust and combusting in the exhaust system.

Faulty ignition system operation can create issues also but your high fuel pressure should probably be addressed first.
Thanks Boojo35,

I'll take a look at my lines. My lean condition makes sense to me at this point. I think everyone is right about that.
 

·
Premium Member
Joined
·
4,116 Posts
Where exactly does your exhaust glow at?
 
1 - 20 of 29 Posts
Top