Jump to content

400 Cid/vortec/efi Issues

tonkawilly

Recommended Posts

tonkawilly New Member

tonkawilly

Posted
Posted

Hi,

I have a 1990 Chevy K-3500 that had a 350 EFI thrttle body engine that got too tired so I put together a +.020" 400 SBC motor with 350 rods/stroker pistons, Votec heads with a special 4bbl manifold to fit the heads. In the place of the carburetor I mounted an adapter plate and the stock EFI that was on the original 1990 GM truck with the 350 engine. It has never run right since the day it was started-it always seems to run lean, and won't idle. We have run about every diagnostic test, and replaced almost every electronic component at least once. Has anyone put this combination together and made it work? I'm really thinking that I may need larger injectors like a 454 EFI would use. Can anyone shed some light on this before I resort to going back to a carburetor?

Thanks!!!!

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Latest Articles

  • Posts

    • haoleboyZ71
      Radio Update

      By haoleboyZ71 · Posted

      Hi, New here.  2026 Denali HD.  Just purchased 7/2/26. I am having the same issue.  I just traded in my 2024 AT4, and the truck connected to bluetooth and Android Auto Immediately!  Now, with the new HD, it connects when it wants to, which is usually not at all.  I have to use the usb-c cable to get it to connect.  Bluetooth won't even connect without the AA. Now after saying all that, I'll take a 20 min drive with the phone plugged in.  Stop at a store, restaurant, etc....  Get back in my truck and DO NOT plug the phone in.  The truck then decides at this point, lets connect BT & AA and work perfectly, ie how it should.   I have deleted (forget phone) the phone multiple times.  I guess I'll just get used to plugging it in every time. even though I don't think its good for the phone battery to have it on charge after it hits 100%. I have searched all over.  No one else seemed to be having this issue, until I read this thread today.   thanks for reading.
    • Heath
      2004 GMC Sierra Crew Cab Ignition issues

      By Heath · Posted

      I have an issue with my ignition hanging and I have to tilt the steering wheel to get in the off position. I have used a great key lock spray and it doesn't help resolve the issue. Is this an ignition assembly issue or something else. If anyone has a past experience with this please advise.   Thanks  Heath
    • jl6690506
      Bent valve in 2025 GMC Canyon Denali - Requires engine swap at 14K miles

      By jl6690506 · Posted

      This is a terrible GM warranty experience, two months waiting for a covered engine swap with no loaner or timeline is not allowed under GM’s courtesy transport policy.Escalate straight past regular support to a GM executive case manager, document every closed service ticket and dealer repair paperwork. File a complaint with NHTSA to force faster action, and ask for daily rental reimbursement while your truck is down. If it’s been out of service over 30 days, your state lemon law may let you pursue a full vehicle buyback.
    • jl6690506
      2019 GMC Sierra 1500 - 8l90

      By jl6690506 · Posted

      198°F isn't unusually hot for an 8L90, so I don't think temperature alone caused the issue. Since everything returned to normal after the truck sat for several days, I'd be looking at an intermittent electronic or hydraulic control problem before assuming the transmission itself has failed. The first thing I'd do is scan the Transmission Control Module (TCM), not just the ECM. GM transmissions can store manufacturer-specific or history codes that won't trigger a check engine light. I'd check: TCM history and pending DTCs Commanded vs. actual gear Line pressure Shift solenoid status Torque converter clutch (TCC) slip Transmission fluid temperature If it happens again, try to capture the data before cycling the ignition, since some intermittent faults disappear after a restart. A professional scan tool that supports full GM transmission diagnostics makes this much easier. For example, the Foxwell NT809BT can access the TCM, read manufacturer-specific transmission codes, and display live transmission data that's not available on a basic OBD-II reader: https://www.foxwelldiag.com/products/foxwell-nt809bt Hopefully it's just an intermittent control issue, but I'd definitely pull the TCM data before replacing any parts.
    • jl6690506
      2019 GMC Sierra 1500 - 8l90

      By jl6690506 · Posted

      Sorry, I accidentally posted in the wrong language. I'll repost it in English.

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...