i replaced the temp sensor in the front of the intake and apparantly on the 454 this ones for the gauge cause now it reads 160-165 all the time, it always read right about 180 with the 180 thermostst before so im thinkin this new ac-delco unit is not reading correctly. and yes it has the same problem still. ill have to replace the one in the head now and see if that changes anything. might put the old one back in the intake just to see if the gauge reads normal again also.
7.4L vortec hard start
- Thread starter dkh_524
- Start date
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bigsteve10580
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i have a '99 topkick 7.4L w/ propane injection. it fired up this morning and ran for a little while, then i turned it off and tried cranking it again, and it wouldn't crank. any ideas?
JollyGreen
Metalworking Madman
My guess would be the injectors or fuel pump. It should be 56-62 psi give or take. You need to put a gauge on it and see what pressure you're getting when you turn the key on, at start-up and what it bleeds down to once the key is off, say after an hour. It will bleed down, but it should stay above 30psi after that time. If it bleeds down to that amount in 15-20 minutes I'd say the injectors are leaking. As stated previously, these 454's are notorious for a few things, and the injectors are one of them.
Edit: It seems that the Bosch injectors I was thinking of are no longer available in new condition. Here's a link for some reconditioned ones:
http://www.ebay.com/itm/Bosch-Fuel-...221-GMC-2500-3500-Suburban-7-4L-/300682731857
Edit: It seems that the Bosch injectors I was thinking of are no longer available in new condition. Here's a link for some reconditioned ones:
http://www.ebay.com/itm/Bosch-Fuel-...221-GMC-2500-3500-Suburban-7-4L-/300682731857
Last edited:
dkh_524
I'm Awesome
I actually got some new ones in the other day from there. Just got my gasket and cap and rotor to replace while in there.
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bigsteve10580
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whatever it is it's heat decided. let it cool down and it cranks again
dkh_524
I'm Awesome
Got them replaced there was four injectors that were leaking. So far it runs good but broke a coolant hose so have to get a new one.
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JollyGreen
Metalworking Madman
Good to hear that maybe the injectors fixed it.
Ive got to replace the injectors on my 97 3500, It will always crank up instantly....but if I run it a while, and turn it off...come back 5 mins later..i have ot give it some pedal to clear it out enough to crank up, and I get smoke out the back.
Im going to use some from FIC
2 year warranty, and come with a flow sheet showing what each of them flowed on the flowbench prior to packaging.
http://fuelinjectorconnection.com/shop/viewitem.php?productid=484
Im going to use some from FIC
2 year warranty, and come with a flow sheet showing what each of them flowed on the flowbench prior to packaging.
http://fuelinjectorconnection.com/shop/viewitem.php?productid=484
KennyT
Newbie
Stephen
OBS Enthusiast
I replaced the temp sensor 1st. Then when I had the rear brakes done by my mechanic I had them replace the FPR when we both agreed that as the most likely culprit. Still hard to start. When the weather cools here in Atlanta I am going to replace the fuel rail and all 8 injectors. I looked on Youtube and it did not look a hard as I thought. 1996 Chevy Silverado CC SRW long bed 7.4L w 226,000 miles. Will post when finished if that solves the hard hot start issue.
