Stumpfarming's 73' CJ5 Build - Page 89 - JeepForum.com
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post #1321 of 1365 Old 03-29-2021, 09:32 PM Thread Starter
Stumpfarming
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I am curious too. Keep us posted...
If it works out, maybe you’ll be with me the next time. It seems to only want to do it when I am in 4-Lo and on a trail. Got the gauge installed tonight too.

And on another note I decided to trim the fender flares a bit, which must have been the right decision because I didn’t hear them rub at all while in Moab.

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post #1322 of 1365 Old 03-30-2021, 09:35 PM Thread Starter
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I drove the Jeep into town tonight to get fuel. I experienced what typically happens before it goes into a stalling episode. On several occasions I’ve noticed the engine idling high with the air/fuel ratio creeping into the mid 14’s. If I keep driving it slow on the trail, and the temp climbs into the upper 190’s, the Air/Fuel ratio will spike to 35, and the engine stalls. I call this video the “premonition.” Hoping to capture the actual stall on video at some point. https://youtu.be/oXukKNqNPvc

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post #1323 of 1365 Old 03-31-2021, 10:00 AM
PNWGERMAN
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Is the entire carb body heating up maybe? Do they make phenolic spacers for carbs so the heat from the engine doesn’t equalize with the carb?

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post #1324 of 1365 Old 03-31-2021, 03:08 PM Thread Starter
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Is the entire carb body heating up maybe? Do they make phenolic spacers for carbs so the heat from the engine doesn’t equalize with the carb?
I ordered a combination spacer and heat shield kit. It should be here tomorrow. However, I’m still very puzzled by this. 195* is not that hot. I don’t think it’s unreasonable to think that the Sniper unit would function correctly at an “average” engine temperature. I won’t argue that the engine bay of a CJ is smaller than a square body Chevy (from which my engine came), but I’m operating in very mild conditions (50*F weather) and the engine is not even close to overheating.

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post #1325 of 1365 Old 03-31-2021, 09:05 PM
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We are all just as puzzled as you are!
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post #1326 of 1365 Old 04-02-2021, 11:13 AM Thread Starter
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I had a scheduled call with the Holley tech again this morning which lasted about an hour. We did a thorough walk-through of my set-up just to make sure we were not missing something. One idea he wanted to explore is that perhaps it's actually not a heat related issue, but rather some kind of electrical interference or other issue that is revealed under certain conditions. With him on the phone I traced wires to look for any potential cross-over. I did find one spot where my #8 plug wire crossed over the wires running from the firewall to the Sniper unit, so I did re-route that wire, though we are somewhat doubtful that is the issue.

One anomaly we did discover is that my fuel pressure is running at 65 psi at idle, rather than the 58 lbs. that is considered "normal." I did mention that my fuel pump is VERY loud, and I recall the sound changing to a higher pitch when my other symptoms appear (this was noticeable on Thursday when we went to Rose Garden Hill). Could it be a faulty fuel pressure regulator or fuel pump? He is sending me a new pump and regulator to install and see if that changes anything. Unfortunately both are on back-ordered and won't be here for 2 weeks. In the meantime, I will check voltage running to the fuel pump and verify there is not an inconsistency there.

I drove the Jeep into work today and will try to drive it as much as I can over the weekend. I hope to replicate the stalling scenario again and capture a data log of it. The video was helpful in providing a bit more info about my issue, and hopefully the data log will fill in some blanks.
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post #1327 of 1365 Old 04-21-2021, 10:41 PM Thread Starter
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I finally found time to make a trip up the mountain to see if I can catch a data log of my EFI stalling issue. Just when I thought it wasn’t going to happen....... it happened. It ended up stalling twice in about 10 minutes. I captured some of it on video, and more importantly, got data logs of both. I sent the data logs and video link to the Holley Tech who is helping me.
https://youtu.be/0xzRcNZgivM
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post #1328 of 1365 Old 04-28-2021, 05:30 PM
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Any word from Holley on what they were able to make of your data logs?

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post #1329 of 1365 Old 04-28-2021, 11:19 PM Thread Starter
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Any word from Holley on what they were able to make of your data logs?
Here’s the reply I got on Monday:

“The data logs show that everything that the ecu is reading appears to be normal. I think this is taking us back to a fuel delivery problem. After watching the video and hearing that the fuel pressure was dropping down into the 20’s points to that as well. It sounds like the pump may be heating up and losing pressure. It is either that or there is something within the tank that is causing cavitation. I’m leaning more towards pump overheating though.”

I’m still waiting on a replacement fuel
Pump, which is on back order.

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post #1330 of 1365 Old 04-29-2021, 11:07 AM
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Hmm. I'm skeptical. The pump is back by the tank, right? Why would slightly higher engine temperature affect it to that degree back there?
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post #1331 of 1365 Old 05-01-2021, 08:16 PM
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Hmm. I'm skeptical. The pump is back by the tank, right? Why would slightly higher engine temperature affect it to that degree back there?
I can tell you when my LS overheated once my Holley system overcorrected and went pig rich. Hot engine - more demand on a pump that is barely working. That is just a theory, but fuel pressure in the 20's is way too low and that's a fact. Something is wrong with fuel delivery. Have you ruled out fuel pressure regulator? Probably not that, they tend to produce high pressure when they fail, not low pressure. It's more likely pump-related somehow, or sucking air somewhere between pickup tube in tank to pump inlet.
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post #1332 of 1365 Old 05-04-2021, 09:58 AM Thread Starter
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I can tell you when my LS overheated once my Holley system overcorrected and went pig rich. Hot engine - more demand on a pump that is barely working. That is just a theory, but fuel pressure in the 20's is way too low and that's a fact. Something is wrong with fuel delivery. Have you ruled out fuel pressure regulator? Probably not that, they tend to produce high pressure when they fail, not low pressure. It's more likely pump-related somehow, or sucking air somewhere between pickup tube in tank to pump inlet.
I drove the Jeep into town over the weekend. While it didn't have a stalling episode, it did idle high (1400-1500 rpm) the whole trip from start to stopping in a parking lot. See video. I shut the engine off and restarted, and it ran fine. I did a few errands in town, and on the trip home it did the same thing, ran at 1400-1500 rpm at all of the stops and turns I made. Upon my return home I sat in my garage and let it idle for over a minute, and it would not drop down below 1400 RPM. I stopped and restarted it, and it idled perfectly at 800 rpm and for the subsequent 20 minute drive following that it would return to 800 rpm.

I have been back in touch with Holley. The tech I am working with wants to rule out the fuel pump and regulator first. I got notice today that my replacement fuel pump has been shipped. The pressure regulator kit is still on backorder. We'll give the pump a try and see what that does. My current pump does scream horribly, and I have noticed that it takes longer to prime than it used to when I initially turn the key, so perhaps it is defective. Correct me if I'm wrong, but under less pressure fuel can vaporize more easily, soooo....... if my pump is not putting out pressure (or the regulator is defective), then as the engine heats up the lower pressure fuel that makes it to the intake could vaporize more easily? Or more simply put, it's just not getting enough fuel and effectively running out of gas..... Just trying to understand how the fuel pump and warmer engine temp could be causing an AFR spike. Perhaps what I am experiencing is comparable to a chainsaw (or other small engine) having an rpm spike as it leans out when running out of gas.


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post #1333 of 1365 Old 05-13-2021, 11:06 AM Thread Starter
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I took the Jeep out on Tuesday and the same high idle thing happened again. Idled at 1400-1500 RPM all the way to town. Stopped it and restarted again, and it idled at 800.

Last night I got the replacement fuel pump and pressure regulator installed. I found it interesting that I received a different model of pump than I had before which came with a “new and improved” sticker on the box. (Perhaps there is a known issue with some pumps?)

The old pump had an obnoxious high pitched whine that sounded horrible, but I had no basis for comparison. The new pump sounds completely different, or rather “normal” for what one might expect. I cannot hear the new pump while the engine is running; whereas, the old pump never let you forget it was there. Regardless as to whether the pump was the source of the stalling issue, it needed to be replaced. I fabricated an aluminum mounting bracket that places the pump level with the bottom of the tank (per Holley’s instructions). At some point I need to built a skid plate/shield for it, but for now I just want to ensure my stalling issue is resolved. Would be a waste to fabricate something only to learn I need an in-tank pump.

With the new pump and regulator installed, the engine started from cold at 1500 rpm, and slowly idled down to 800 rpm after warming up for a few minutes. You could watch the computer do it’s work, bringing it to 800 gradually and consistently. I took it for a short drive and it idled like a boat when I needed it to. Fingers crossed that the pump was the issue. Now for a wheeling trip to test it again. The pressure gauge still reads a bit high at idle (64 lbs instead of the target 58 lbs), so not convinced I’m done yet, but I’m pretty sure things have improved.
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post #1334 of 1365 Old 05-13-2021, 12:58 PM
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Hopefully this solves it. Expensive fuel injection systems are supposed to simplify driving. Yours has not.

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post #1335 of 1365 Old 05-13-2021, 01:13 PM
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Sounds like first impressions are good, Stump. Hope it continues.

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