I get these gen v 454 suck but atleast it moved before last weekend. I parked it and monday morning when I went to head to school and had an extremely low idle around 6-700 rpm. left it home and took dads car came back home started looking for what was wrong and found a snapped vacuum line for the map. fixed it and now when I floor the truck all it does it scream and barely moved. before it screamed and had the back tires spinning all the way down my dirt road. Now the only thing it does is scream and suck down gas. I think its my map sensor but I don't know. my fuel pump has been whining lately after I shut the truck off but its been doing that since I got it. any ideas? I really want my 10-11mpg and my monster back.
My 1995 GMC 7.4L lost all of its power
- Thread starter camarokid
- Start date
OldCracker29
I've been knocked down drug out and left for dead
to 
There are a couple of guys, well at least one that I know of that run the 454. Maybe he'll chime in with some pointers later.
Draenor
KILL ALL HUMANS!!!!
how do I check that?
and thanks for the welcome glad to join
You will have to put a "Tee" in the fuel line. IIRC you should have 25-30lbs.
What get me that this started with just a cracked vacuum line. Have you checked other lines? How is the trans fluid? Does the engine run the same in park/ neutral and when in gear?
Sent from my overly sofisticated electronic device.
dirtyoldman
I'm now on Medicare,officially old.
First off welcome to TMC 
Could you explain this '' when I floor the truck all it does it scream and barely moved'' a little better? Does the vacuum line from the map sensor go to a ''t'' where it connects to two intake runners?
When cold and when it's first started does the idle go up to about 1300 rpm then after a minute or so start going down?It should.Once warm mine idles about 800-850,when in gear it idles 750-800.
John's right on the fuel pressure and I believe the ''t'' is installed in place of the fuel filter,but only long enough to check the pressure.
How many miles on the trans,maybe just coincidence that it decided to give up now.
Could you explain this '' when I floor the truck all it does it scream and barely moved'' a little better? Does the vacuum line from the map sensor go to a ''t'' where it connects to two intake runners?
When cold and when it's first started does the idle go up to about 1300 rpm then after a minute or so start going down?It should.Once warm mine idles about 800-850,when in gear it idles 750-800.
John's right on the fuel pressure and I believe the ''t'' is installed in place of the fuel filter,but only long enough to check the pressure.
How many miles on the trans,maybe just coincidence that it decided to give up now.
in park and neutral the truck runs and sounds like normal but in gear it acts like its hauling a huge load above about 65+% throttle. I've checked all other lines and the one for the map sensor was the only cracked one. it was cracked right before the "t" goes to the two intake runners. The monster has 193,300 miles on the odometer. and the trans still shifts like normal so I doubt its that. before this happened the truck started at 1500rpm at start up then when warmed up was at about 950-1000 rpm.
dirtyoldman
I'm now on Medicare,officially old.
What does the injector spray pattern look like? Is it a nice upside down cone?When snapping the throttle does it shoot a lot more fuel while still maintaining the cone? What I'm trying to do is get an idea of how good your fuel pressure is,how good the injectors are and how good the fuel pressure regulator is.
We really need to find out how much fuel pressure there is.You need that ''t'' for the fuel supply line and a gauge to read it.
You don't by chance live in SoCal do you?
We really need to find out how much fuel pressure there is.You need that ''t'' for the fuel supply line and a gauge to read it.
You don't by chance live in SoCal do you?
dirtyoldman
I'm now on Medicare,officially old.
Sitting here thinking,a shot in the dark.....unplug and remove the EGR valve.Clean as much of the built up carbon off of the valve and the opening on the intake manifold where it bolts to.Have a vacuum handy to suck all the loose carbon from the intake.You may have to buy a new gasket.Brake cleaner works good to clean the carbon off.
This is what the bottom of the EGR valve should look like after cleaning and the little circle with the torx bit looking hole in the center should move in and out freely.
This is what the bottom of the EGR valve should look like after cleaning and the little circle with the torx bit looking hole in the center should move in and out freely.
Last edited:
one injector was spraying a pretty good cone the other one was spraying just a little less fuel then the other one. I didn't see what happened when I opened the throttle. I didn't want to piss off my neighbors. what should I see if my fuel pump isn't supplying enough fuel or pressure? and no I'm not in so-cal. I'm in CO.
I also cleaned out my EGR and IAC about 300 miles ago.
I also cleaned out my EGR and IAC about 300 miles ago.
