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Can heat soak cause intermittent injector problems with starting?

MattS

NAXJA Forum User
Location
Danville, VA
Like the title says. Can heat soak cause intermittent injector problems with starting? I have a problem with starting only when it's hot outside and the engine is warm. It takes a little more cranking than usuall to turn over. I did have the "vapor lock" problem, but now it's turned into this.
 
What exactly is heat soak?
 
That makes sense. All of this happened after I replaced the entire "in tank unit" for my 99 XJ. Could increased/proper fuel flow, from a clean fuel pump and filter, cause an injector that was failing to start acting up?
 
more often than not, a decrease in pressure would be the cause of heat soak problems, but if the injector has varnish build up on it, I guess extra pressure could allow it to bleed down under some conditions.

--Shorty
 
In a nut shell, heat soak is when the ambient temperature is higher than normal inside the engine bay and causes odd problems like vapor lock and such.
 
could be some very early signs of cps trouble. does the jeep ever "hiccup" while driving?
 
Sounds like yours is doing the same thing as mine see my post http://www.naxja.org/forum/showthread.php?t=925621
I also installed a new iac yesterday and no change,I also confirmed that the rail is holding pressure when tuned off. I am going to try some heat tape on the fuel rails and wherever else I can put it.
 
It does surge every now and then while going down the highway. I let off the pedal and it's lke it resets itself. Does fine after that, for a while anyway.
 
MattS said:
It does surge every now and then while going down the highway. I let off the pedal and it's lke it resets itself. Does fine after that, for a while anyway.

I'm leaning towards CPS then.
 
You may also want to check the output of the PCM/ECU temp sensor (the one in the t-stat housing)With a scan tool. Ive seen these read -40* F when the engin is at operating temp +200* F This will trick the PCM into all kinds of wierd stuff.
 
I did find out yesterday that I am running 70+ lbs of fuel pressure. It's supposed to be about 52 in a 99, so I'm guessing that my starting trouble is from that. Also, I didn't have the starting problem until I put in a pump from ebay. I'm kicking myself over that one and am hoping that a new pump will solve all of my problems. I've thought about the CPS though. Mostly when it surges, I am give it steady gas as I'm going down the road. A CPS is next if the new pump doesn't help the surging.
 
Put me on the interested list. I'm having similar issue no surging but won't start when hot. Open hood for 5-10min and fires up.
 
I bit the bullet and replaced the fuel pump assembly with one from the dealer, instead of ebay. So far so good! It has had plenty of opportunities to repeat the symptoms this weekend and I start up perfectly every time. I'm going to give it a week before I count it as "fixed" It better be after what I paid for the assembly from the dealer!
 
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