Is this a Jeep thing?
- Thread starter Nathanael Rusciolelli
- Start date
94c2500
TJ Enthusiast
Yeah, I think that service bulletin focused attention on the #3 fuel injector being especially susceptible to Heat Soak.
You are correct, that TSB entails wrapping the #3 injector with insulation.
Quick update: Just started up the jeep a couple more times. The first time it cranked for about 4 seconds then it skipped a little (like it was about to start) then it cranked for another couple seconds before it finally did start. After maybe 30 minutes of it sitting, I go to start it again and it again took longer than usual (almost like the problem is getting worse). I'm starting to notice it seems worse in the hot weather (which it was today) so I guess it really must be a matter of cooling the injectors/fuel rail. I may just try and go crazy with the insulation all over just to see if that helps.
Well, I bought some spark plug boot insulators as well as some more of that insulating foil and I wrapped up the injectors with several layers of that stuff. I even insulated the fuel rail, none of it seemed to help. Still takes 5 seconds or so to start when hot. I am at a loss with this thing. The only other thing that I can think of is a sensor or something going bad, but I know nothing about those electrical components. Would this problem be throwing a code? I've had it tested for codes before but I know those OBD readers aren't incredibly accurate.
I'm now wondering if you didn't just get a defective fuel pump, perhaps even a "clone" (counterfeit) Bosch fuel pump. Replacing the fuel pump fixed the issue for a week, then the problem returned. That definitely could have simply been caused by a bad replacement pump. You're certain you installed a real Bosch?
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The important part - fuel pressure should not drop below 30psi after 5 minutes, otherwise it's just dripping into a hot manifold and turning to vapour. Clear this by holding the throttle wide open as you crank
94c2500
TJ Enthusiast
When the engine is completely cooled down, (let's assume after sitting overnight), do you EVER experience a normal start and idle without touching the accelerator pedal?
NovaTJ
Member
Ok, this sounds like a good plan. I do not have a fuel pressure test gauge so I will have to rent/buy one as well as those special adaptors. Are those hard to find or are they just a trip to the part store?
Many auto parts stores like Autozone loan them out for free, call around until you find one. You just put a deposit onto a credit card until you bring it back when the deposit is returned to you.
94c2500
TJ Enthusiast
I didn't see what year TJ you have and whether it still has the test port on the fuel rail?
In case it doesn't, I've linked to a video on how to source items needed to slave into your fuel line to test properly.
Mine is a 99 so it has a test port. I guess it's a lot easier to do it in that case?
94c2500
TJ Enthusiast
Yeah, you just screw your Gage onto the rail and do your test.
I have a 2003 model without the test port and had to cobble together fittings.
Finally got a fuel pressure gauge on the jeep. When I started the engine, fuel pressure was around the recommended 45psi. It ran like that with no problems. When I shut it off, after 20 minutes it was at 20psi. Seeing as I just replaced the entire fuel pump assembly, I'm kind of guessing I can rule out the check valve as a possible culprit. This means fuel injectors are leaking I suppose. Does anybody agree? Also, what replacements would you recommend?
94c2500
TJ Enthusiast
A couple of questions:
Does your TJ's check engine light ever come on during these hard starts and throw a fault code?
When started after sitting overnight, does it idle on its own at the correct rpm without touching the accelerator pedal?
Check engine light never stays on. After it sits over night it starts up pretty quick, then the rpms will bounce around just a little and smooth out after a couple of seconds.
Well, I went ahead a pulled the fuel rail off with the fuel line still connected and after cycling the key a few times, didn't notice any leakage from the injectors. Is there any other way that fuel pressure can bleed off besides a bad check valve?(once again, this is a brand new bosch fuel pump).
Did you ever get any resolution to this? My 03 is acting similar. New fuel pump, new cps, new plugs , and 2 new injectors and it still is hard to start when warm. Cold starts it fires right up idle bounces like it has a cam for a few seconds then smooths right out, but once it's warm I have to push the gas pedal to get it to fire. I even did the dei Jeep fuel rail heat shield kit still no luck
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