Thanks for the motivation! I’ll figure it out eventually. I emailed Mark from wranglerFix about the PCM. He was quick to respond which was great. I’m going to give him a call Monday and send them my PCM and see if anything is wrong with it.
Fuel injector magic? Bad PCM?
- Thread starter Terrrs01
- Start date
My fuel system is a tad complicated because I’m currently running a FMU with my turbo set up with a fuel cell.
HOWEVER. To rule out any of that nonsense i by passed all of that and ran a fuel line with a in line gauge just for diagnostic reasons and there was no change at all. My regulator seem to be working properly as far as I can tell.
It’s VERY annoying, because these symptoms all point towards a fuel pressure/blockage problem. I’m at the point where I’ve triple checked pressure problems/blockages/vapor lock. No luck.
I’ll give you a call tomorrow if that’s ok, but I do appreciate the quick response to the email! My actually ends in 305ac.
Update: I checked the resistance on the 2 ground wires going into the PCM. Both read right around 1.5. That’s a tad high, not sure if that is really the problem, but it needs to be addressed non the less.
I'm interested to find out if the PCM is the issue... Seems like we don't hear about a lot of PCM issues on older TJs, & your situation is a weird one.
I 100% agree to this. And from the hours and hours I’ve been reading forums I haven’t came across anything that has good injector pulse, fuel pressure, and injectors AND then systematically shuts down/stops spray fuel starting with cylinder 1, then 2, AND NOW I noticed it shuts down cylinder 3 right before it gives up on life and dies.
now noticing the systematic injector shut down 1,2, then 3 before it dies, it just gives me this more mechanic problem than electrical/PCM. With my motor mount lift for my tuck, my fuel rail is at a decent angle with cylinder 1 is the highest then aimed down towards cylinder 4.. Could air be causing this??
I put I my homemade in line pressure gauge straight from my regulator to my rail (I don’t have a Schradder valve) ) and fuel pressure is great.
-I did run all new fuel line and a new pump this winter. With good pressure between the rail and regulator can rule out any problem between the tank and regulator correct?
I put I my homemade in line pressure gauge straight from my regulator to my rail (I don’t have a Schradder valve) ) and fuel pressure is great.
-I did run all new fuel line and a new pump this winter. With good pressure between the rail and regulator can rule out any problem between the tank and regulator correct?
Do you have an inline pressure gauge connected so you can monitor fuel pressure as it misbehaves?
I once spent a YEAR troubleshooting a dying 460 in my old Mercury (granted it sits in the garage & I didn't get to it that often). It would die after it started to get warm, then I'd have a hard time restarting it. I dicked with it forever, changed the pump, rebuilt the carb, then I decided I was going to pull the tank & see if there was some shit in pickup sock. As I'm pulling the rubber fuel line off the tank I notice that the line was wrapped up & over the spring perch... The year before I got some new exhaust welded up & the guy moved the fuel line out of the way so he could fit new pipes & never put it back. It was bent perfectly so that when it was cold the ID of the tube stayed open, but as soon as the exhaust got hot it would warm up & kink completely.
I once spent a YEAR troubleshooting a dying 460 in my old Mercury (granted it sits in the garage & I didn't get to it that often). It would die after it started to get warm, then I'd have a hard time restarting it. I dicked with it forever, changed the pump, rebuilt the carb, then I decided I was going to pull the tank & see if there was some shit in pickup sock. As I'm pulling the rubber fuel line off the tank I notice that the line was wrapped up & over the spring perch... The year before I got some new exhaust welded up & the guy moved the fuel line out of the way so he could fit new pipes & never put it back. It was bent perfectly so that when it was cold the ID of the tube stayed open, but as soon as the exhaust got hot it would warm up & kink completely.
UPDATE With some results!!!!!!!!!!
-after spending hours on end checking more resistance in wires. It got me thinking how odd it is that’s the front 2 cylinders systematically stop spraying towards cylinder 4. Between motor mount lift/ and sagging rear springs my fuel rail is angle..
-I jacked up the rear end and deflated front tire and guess what??? Cylinder 4 started acting up now (now the highest part of the fuel)... I HAVE AIR (unless anyone has another option) in my fuel rail???
-initial though was air got trapped after cleaning (like a master cylinder) and once I cleared the air out back jacking the jeep up and down we are good. It ran great for 15min. Shut it down let it cool off... right back to normal....
-a few options.......
1: somehow air is getting in, but that doesn’t really make sense, because I don’t see fuel spray out anywhere? Assuming 55PSI would spray and not sucks air lol.
2: Maybe it’s air but in the form of bubbles??? I moved my fuel regulator up to my engine bay (it use to be next to my fuel cell) my regulator is 18” before my fuel rail? Would that cause bubbles or be too soon to not let the fuel settle??
3: Bubbles round 2: I’ve also only been keeping 3 or so gallons on gas in while testing. My return Line trickles in from the top on my fuel cell. NEVER had a problem before, but I’ve heard gas falling far and splashing can cause bubbles in gas? Maybe this has always been the case but with my regulator in the rear I never noticed??
Any ideas what you guys think it could be? Do regulators cause bubbles???
-maybe whatever that thing is on the front of the fuel rail that dampens the fuel is letting air on but not fuel out???
-after spending hours on end checking more resistance in wires. It got me thinking how odd it is that’s the front 2 cylinders systematically stop spraying towards cylinder 4. Between motor mount lift/ and sagging rear springs my fuel rail is angle..
-I jacked up the rear end and deflated front tire and guess what??? Cylinder 4 started acting up now (now the highest part of the fuel)... I HAVE AIR (unless anyone has another option) in my fuel rail???
-initial though was air got trapped after cleaning (like a master cylinder) and once I cleared the air out back jacking the jeep up and down we are good. It ran great for 15min. Shut it down let it cool off... right back to normal....
-a few options.......
1: somehow air is getting in, but that doesn’t really make sense, because I don’t see fuel spray out anywhere? Assuming 55PSI would spray and not sucks air lol.
2: Maybe it’s air but in the form of bubbles??? I moved my fuel regulator up to my engine bay (it use to be next to my fuel cell) my regulator is 18” before my fuel rail? Would that cause bubbles or be too soon to not let the fuel settle??
3: Bubbles round 2: I’ve also only been keeping 3 or so gallons on gas in while testing. My return Line trickles in from the top on my fuel cell. NEVER had a problem before, but I’ve heard gas falling far and splashing can cause bubbles in gas? Maybe this has always been the case but with my regulator in the rear I never noticed??
Any ideas what you guys think it could be? Do regulators cause bubbles???
-maybe whatever that thing is on the front of the fuel rail that dampens the fuel is letting air on but not fuel out???
Okay maybe I missed this before, but you have a completely aftermarket fuel system? The fuel system in our TJs is returnless in that there isn't a separate line going back to the tank, the regulator built into the pump module returns it directly.
Yes. I have I have a fuel cell in the back with a a inline fuel pump and external regulator with a return back to the cell. I did this as a pre requisite for a stretch. This was done last winter and had no problems all last summer.
IN the process of building a turbo for my 2.5 (I kinda left that part out to avoid confusion, as it’s not complete and the engine has never seen boost yet) I had to bring the fuel regulator up to the engine bay so my FMU can attached into the return line. I also did put a higher output fuel pump in the process. I’ve always ruled out fuel problems cuz at the rail it reads perfect... My goal was to see if I liked the turbo with a cheap FMU, and if I did I would ditch it and swap over to HP tunners.
Oddly enough as soon as you posted that I was going to say I was going to check for a small leak right before the fuel pump where pressure is minimal.
-BTW you guys rock. The Information is supper helpful, but even more so simply writing it down and a simple convo gets my brain moving and helps with diagnosing and problem solving.
-Gonna spend a little more time looking into. I’ll for sure let you know what I find.
-BTW you guys rock. The Information is supper helpful, but even more so simply writing it down and a simple convo gets my brain moving and helps with diagnosing and problem solving.
-Gonna spend a little more time looking into. I’ll for sure let you know what I find.
Yeah when you finally let us know on post #31 that you have a goofy ass fuel system it gets our brains working too
.Just giving you a hard time, I hope you find a pinhole, sure sounds like what's happening.
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