someotherguy
Truly Awesome
OK y'all, this is just a cut/paste of my post over on LS1truck but I figured this forum might get more traffic. Need to get this one figured out:
LS newb here so please be gentle
This is (likely) a '98 LS1 swapped into a '97 Suburban. I bought it already swapped, needs lots of wiring work, but ran and drove until now. I've put probably a hundred miles on it. Previously it ran OK; had a surge in the idle once it warmed up, but otherwise no obvious issues. Plenty of power including crazy passing speeds on highway.
Drove it a few days ago and all was normal as I described. Came home, it sat a few days, went out today to start it and it immediately backfired through the throttle body and stalled. Tried to start again and it's like it wasn't getting fuel. Threw gauge on it and key on/engine off is 60 PSI, watched while cranking and I can get it to run a moment while pressure is steady 60 PSI, stalls and drops off to 50 and verrrrry slowly starts dropping off afterwards.
Edited to add more info: trying to start (with everything connected as normal) gets an intial very high RPM then settles down to an extremely low erratically stumbling idle, with random popping in the intake, and may stall. If I feather the pedal I can get it to come up some but runs rough and it's got random popping in the intake. Engine not making any vacuum - brake pedal hard as a rock. I checked all vacuum lines I could find, no leaks, also disconnected brake booster and plugged its source - no change in how it runs.
If I unplug the MAF it will start but has an extreme but steady lope to the idle, down to almost a stall, then raises up high and down to almost stall again, over and over. If I feather the pedal it will come up and run reasonably smooth, no popping. Undriveable like this - it briefly lurches hard as if I was very quickly nailing the pedal. Doesn't even run well enough to reposition it in the driveway.
Ideas? Nothing done to the truck between running fine and today, it just sat in the driveway.
Thanks!
Richard
LS newb here so please be gentle
This is (likely) a '98 LS1 swapped into a '97 Suburban. I bought it already swapped, needs lots of wiring work, but ran and drove until now. I've put probably a hundred miles on it. Previously it ran OK; had a surge in the idle once it warmed up, but otherwise no obvious issues. Plenty of power including crazy passing speeds on highway.
Drove it a few days ago and all was normal as I described. Came home, it sat a few days, went out today to start it and it immediately backfired through the throttle body and stalled. Tried to start again and it's like it wasn't getting fuel. Threw gauge on it and key on/engine off is 60 PSI, watched while cranking and I can get it to run a moment while pressure is steady 60 PSI, stalls and drops off to 50 and verrrrry slowly starts dropping off afterwards.
Edited to add more info: trying to start (with everything connected as normal) gets an intial very high RPM then settles down to an extremely low erratically stumbling idle, with random popping in the intake, and may stall. If I feather the pedal I can get it to come up some but runs rough and it's got random popping in the intake. Engine not making any vacuum - brake pedal hard as a rock. I checked all vacuum lines I could find, no leaks, also disconnected brake booster and plugged its source - no change in how it runs.
If I unplug the MAF it will start but has an extreme but steady lope to the idle, down to almost a stall, then raises up high and down to almost stall again, over and over. If I feather the pedal it will come up and run reasonably smooth, no popping. Undriveable like this - it briefly lurches hard as if I was very quickly nailing the pedal. Doesn't even run well enough to reposition it in the driveway.
Ideas? Nothing done to the truck between running fine and today, it just sat in the driveway.
Thanks!
Richard