BradHSo
Newbie
Do they use a similar spider injector?
iNope I believe they are a traditional MPFI. But I could be wrong
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Do they use a similar spider injector?
Welcome from Asheboro NC! Theres quite a few Of us from NC on here. My truck (5.7 vortec) has the leak down problem I believe, after i drive it and cut it off to get gas or something and go to crank it rolls and rolls and act’s like it’s not gonna start then it starts and it runs fine lol. I really dread doing the injectors on itI don’t believe so, but they are stricken with the common leak down problem, if it sits for a awhile it’ll just crank and crank and crank, then blow black smoke. Plus the MPGs took a turn for the worse around 6-8. It’s a pretty well know issue for the vortec 7400’s
Do they use a similar spider injector?
Cool, I wasn’t familiar with that term, but thought it was a normal MPFI with two rails. I’ve sprayed ether around the vacuum lines after I replaced them and didn’t get a raise in RPM so I think I’m good. Now the 454 needs a lot of work, but that’s different thread lolNo spider injectors on the 7.4. It has individual injectors on an external fuel rail like any modern engine. I've never owned with one and was aware that they had issues, but recall seeing someone here that the aftermarket injectors solves this problem. Bosch injectors, I think?
At least you can replace them without pulling the intake manifold plenum like the 4.3/5.0/5.7.
I'll just add to the OP to check vacuum hoses, as some tend to dry out and crack and go unnoticed. Maybe someone already brought it up.
Fuel pressure was 8-9 at idle cold and after it warmed up it dropped to a steady 7, my fuel filter was slapped fuel of black and red gunk. I unplugged the tan and black wire then checked the timing and holy crap was it retarded, it was so far to the right that it was off the timing marker.I re timed and changed the filter, I think I’m making progress as the truck feels a lot better and doesn’t hesitate off idle. Will be ordering a fuel pump next and changing the ICM and coil as I listened to PlayingwithTbi’s advice and misted it with water and it immediately ran like crap.
Thanks for everyone’s help!
Great progress. The black gunk might be pump guts, so a new pump may be on your list soon. What's the pressure now you've replaced the filter? Spec is 9~12 psi but anything less than 10 and I'm giving it the side-eye.Fuel pressure was 8-9 at idle cold and after it warmed up it dropped to a steady 7, my fuel filter was slapped fuel of black and red gunk. I unplugged the tan and black wire then checked the timing and holy crap was it retarded, it was so far to the right that it was off the timing marker. I re timed and changed the filter, I think I’m making progress as the truck feels a lot better and doesn’t hesitate off idle. Will be ordering a fuel pump next and changing the ICM and coil as I listened to PlayingwithTbi’s advice and misted it with water and it immediately ran like crap.
Thanks for everyone’s help!
Yep, super typical behavior of leaking injectors and bad fuel pressure regulator on the Vortec 7.4. Replace 'em with the Bosch pieces and a new FPR, be sure to replace the vacuum line to the FPR while you're at it and be sure the line is fuel/vapor rated so it will live.I don’t believe so, but they are stricken with the common leak down problem, if it sits for a awhile it’ll just crank and crank and crank, then blow black smoke. Plus the MPGs took a turn for the worse around 6-8. It’s a pretty well know issue for the vortec 7400’s