Novak Conversions Jeep Wrangler TJ radiator

Heat soak or something else? (03 TJ Sport 4.0)

k0m0d067

TJ Enthusiast
Original poster
Joined
Jun 9, 2019
Messages
139
Location
Victoria Australia
I searched, and have found the solutions to heat soak...but the descriptions of the symptoms aren't lining up with my TJ's behavior.

9 times out of 10, it starts up like a champ, idles perfectly (maybe a little on the low side), and drives just fine...but the 10th time...well anyway...a bit of backstory below (sorry if it's a little long-winded):

My last major issue with it was the fuel pump (early 2023)...my original one went out, so I replaced it, but used a cheapish one from eBay (Chinese made, I'm sure)...during the process of dropping the tank, I broke all 3 of the fuel line retaining clips (only exception was the one at the fuel pump connection), and I couldn't find the correct ones to replace them with...when I asked in here, I was told, by several people, that I could just use zip ties...so I did, and it seemed to work ok, and I drove it for a couple months...

Then, I assumed the fuel pressure regulator that came with the Chinese pump assembly had gone bad, because after sitting, it would take several cycles of the key on and off before the fuel pressure would be good enough to start. I contacted the seller, and they sent me a replacement...but because it was still running, and I was being lazy, not wanting to drop the tank again, I just drove it that way, and left the new pump in the garage...again, 9 times out of 10, no problems at all...then occasionally, I would park somewhere, and when I went to leave, it wouldn't want to fire...starting fluid would eventually work...but it was getting to be a pain in the ass...

So I eventually dropped the tank, and replaced the unit again...

It seemed to sort the problem, but one day I drove to pick my daughter up, when I went to restart, it wouldn't start...I still had the starting fluid in the car, so used that, and it would fire, and the second time, it fired and ran...drove it home and parked it, not wanting to go through all that again, and forgot about it for a while...

I had to move it a few times, and it started like a champ every time (except the last time, when it sat for 5 months, and needed the battery charged, after which, it fired right up)

I started thinking maybe the 1 time picking up my daughter had been a random occurrence, and decided to try driving it again...

Drove to the local shopping center (maybe 10 minutes away) and it refused to start...got out to try the starting fluid, and could smell a LOT of gas...walked around the other side, and saw a puddle of gas, and quickly realized the fuel line had come apart at the connection (zip tie was still intact) and fuel was pumping gas onto the ground every time I cycled the key

Had it towed home...jacked it up, and put the connection back together (zip tie)...pulled on it real good after reconnecting, and it seemed to be holding again...drove it again a few days later, made some stops, and it would start no problem, then stopped for gas on the way home...fuel line came loose...towed it home again...

Searched and searched, and found a kit that came with 2 different size fuel retainer clips on Amazon...a bunch of each size for $10 and took a chance that one of them would fit, and got lucky (one of them was the correct size)

Jacked it up, replaced the uncooperative zip tie with the proper retainer clip, and have been driving it every day for a couple weeks, with no issues...until today, when I drove it to the shopping center, and it decided it didn't want to start again, without the assistance of starting fluid...but the fuel line stayed connected

Bear in mind, the 2 other fuel line connections (returns or breather/vent lines or whatever they are) are still zip ties (I only replaced the one that kept coming apart)

I intend to jack it up and replace the other 2 zip ties with the proper clips, but wanted to ask the experts in here if there was anything else I could check, that might cause my issues?

Thanks in advance folks!
 
Fuel pressure?

Got a link to those Amazon clips? I might want to order some for my spares bag.

-Mac

Haven't checked the pressure yet...my fuel rail is the newer style, without the schraeder valve, so it's a pain in the ass to check...

This is the Amazon link, but they may not fit yours...when I first replaced the pump, I bought the ones that were "supposed to be the correct ones" from RockAuto but they were way too big (I'm in Australia, so maybe the export models use a different size? 🤷‍♂️)...as I said, for $10 I took a chance on these, and they worked


https://www.amazon.com.au/dp/B0DC9YBLNQ?tag=wranglerorg-20
 
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Is it always hot when it won't fire? Could be a crank position sensor going bad? My thought doesn't make sense if it fires with starting fluid, but a heated cps that is starting to go bad will give you problems with restart when warm.
 
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Have you installed a DEI heat shield on your rail?

-Mac

It has the manifold shield, but has never had the rail shield, or the individual injector wraps...but never had this issue prior to messing with the cheap fuel pump


Is it always hot when it won't fire? Could be a crank position sensor going bad? My thought doesn't make sense if it fires with starting fluid, but a heated cps that is starting to go bad will give you problems with restart when warm.

It seems to start just fine at the moment, from a cold start...it only seems to do it after I've driven it enough for the engine to come up to running temps, and turned the car off...

Although this last time it acted up, after I got it started with the starting fluid, and drove it home, I turned it off, and restarted it, and it started just fine...so maybe it's only after it's been turned off for a few minutes?


I suppose my next step should be to check the fuel pressure, as annoying as it is without the schraeder valve...could just be that the cheap chinese pump is barely keeping up?
 
I checked my fuel pressure, and it read WAAAAY high...I made a loop with a shrader valve, and checked it while running, and then just with the key on.

both read REALLY high (like 85-90 psi)...I read another thread on here where a guy was having the same problem, and he was told pressure that high shouldn't be possible from these pumps, but he checked his gage against something else, and it read fine...I don't have anything to check it against, other than car tires...guess I might try that, and see if it's anywhere close to correct...however, I have to mention, it read perfectly a year and a half prior, when I replaced the faulty pump initially, and has just been sitting in its box ever since...

Also, when I shut it off, it had fairly rapid pressure loss...like would hit zero within a few minutes...

So now I'm thinking bad regulator? Bad pump? this Jeep is supposed to be my daily driver, but the unreliability it's currently experiencing is putting a damper on that...

I'm looking on RockAuto (aka Australian Jeep owners best friend) and the regulators listed range anywhere from $38 (AUD) to $133 (I don't like presuming more expensive means better, but going the cheap route is what got me to this point in the first place) But it also shows complete pump and housing assemblies ranging from $94 (AUD) to $182...I know people say to use Bosch when you can, but beggars can't be choosers (the brand of the "expensive" pump and housing assembly is Delphi)

I don't want to throw parts at it, but it ran unfailingly, prior to the old stock pump giving up the ghost...would anyone advise against replacing the cheap Chinese pump/housing assembly with the Delphi from Rock Auto? I really don't want to keep having to drop the tank...

Really appreciate the help guys
 
Mine had an issue with heat soak for a while. It would stumble when trying to start hot. I also replaced my fuel pump and serviced the whole system. I ended up removing the injectors to have a look at all of them. Every one had cracks in the bodies of the injectors from age and heat exposure. Once i replaced all of them I have never had an issue. It could be 118-120 outside and it starts perfect. Have you looked at the condition of your injectors? Sounds like you have everything else in good condition.
 
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Does Rock Auto Australia have a Brute Power fuel pump assembly?

That's what I put in my 97 and it's made it most of the year... Oregon to the Rubicon Trail and back and I just drove three hours south to Ashland for some snow wheeling and back...

It was like $80 US.

-Mac
 
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Mine had an issue with heat soak for a while. It would stumble when trying to start hot. I also replaced my fuel pump and serviced the whole system. I ended up removing the injectors to have a look at all of them. Every one had cracks in the bodies of the injectors from age and heat exposure. Once i replaced all of them I have never had an issue. It could be 118-120 outside and it starts perfect. Have you looked at the condition of your injectors? Sounds like you have everything else in good condition.

Anything is possible, but the super high pressure reading I got yesterday, plus the fact that all the troubles seemed to start when I replaced the original fuel pump with a cheap one, are making me suspect that that is the culprit...

I suppose I might take a look at them though...

Does Rock Auto Australia have a Brute Power fuel pump assembly?

That's what I put in my 97 and it's made it most of the year... Oregon to the Rubicon Trail and back and I just drove three hours south to Ashland for some snow wheeling and back...

It was like $80 US.

-Mac

There isn't a Rock Auto Australia (I wish)...it's the same one you use back in the states...they're just the best source I've found for quality parts with reasonably priced, quick shipping...recommended by the TJ guys here...

Brute Power sounds familiar...I'll have a look...did you replace the whole assembly? Or just the pump?
 
Novak Conversions Jeep Wrangler TJ radiator