5.3 swap cold start problem
Thread Starter
Teching In
Joined: Jan 2013
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5.3 swap cold start problem Swapping 2006 DBW 5.3L in my cj-7 and runs great with no error codes but takes a few seconds of cranking to start. When I first fired up I had not noticed there was no coolant sensor (salvage yard removed it for some reason). I then fired up and ran with a bolt plugging the hole but did not run great. I then figured out that the missing plug was actually a missing sensor (duh), fixed that which eliminated all error codes. Chasing this start problem for 2 weeks since has had me clean injectors and replaced fuel pump only to still have hard cold start. I now have 57 fuel psi. Wondering though if my problem was related to running for awhile with no coolant sensor (running rich)? I had new plugs and new spark plug wires before first startup so not sure if fouled my plugs with no sensor but it runs awesome once started.
thanks for any help.
thanks for any help.
Thread Starter
Teching In
Joined: Jan 2013
Posts: 23
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Still fighting this. Seems to be running worse. starts hard and idles rough now. I bought a walbro 255 fuel pump thinking I was still having fuel pump issues but now I get 60 psi and still starts hard cold and now runs rough. I cleaned the throttle body and no change. Plugs look a little dark like it is running rich. Any thoughts on what I missed on this swap?
This could be any number of things, but generally when you have an extended cranking time, it's due to the fact that your fuel pressure is bleeding off and it takes a while to build the pressure back up. Does your fuel pump prime when the key is first turned on? Does it hold pressure when you turn it off, or does it drop off fast? Anything in the tune been changed other than removing VATS to get it to run? You say it has no error codes, is that because there's no check engine light on, or do you have a scanner and a way to look at the data? I could go on, but this should be a start.
Thread Starter
Teching In
Joined: Jan 2013
Posts: 23
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Thanks for the reply, I get pressure right away and does not drop off. Running I have 65 psi according to harbor freight pressure guage. Could that be my problem that my pressure is too high? I think spec is 55-62psi but not sure how accurate the guage is. I have a scanner (code scan not analyzer) and am not getting a code. The tune was basic VATS delete. I am running the S10 fuel filter with built in regulator.
Last edited by rkcbvw; Mar 16, 2013 at 10:06 PM.
