engine dies when fuel pump is on
Thread Starter
On The Tree
Joined: Aug 2015
Posts: 102
Likes: 0
engine dies when fuel pump is on 70 nova, ls3, BTR stage 4 cam, fast 85 injectors, AEM 400 pump, aeromotive regulator set to 60psi (tried 43 also), stock ls3 rails, psi conversions harness, 2012 Camaro ecu with a "startup" tune (provided by my tuner).
I would ask my tuner but he's currently out of town and hoping to figure this out asap.
problem - engine will NOT start if I have the fuel pump running, it WILL start if I turn the pump off before trying to start it. once started, the engine will stay running until it runs out of fuel that's in the rails (15-20 seconds). if I turn the fuel pump on while the engine is running, it immediately kills the motor. so far I have tried lowering fuel pressure from 60psi to 43psi with no results. I have put a volt meter on the power in wire to the ecu and turned the pump on and did not get a voltage drop, but the engine dies so fast once the pump is turned on that I just might not have a chance to see a drop.
currently the MAF is just sitting in the intake tube as I have not welded the ls3 MAF bung on yet. (not sure what issues this would cause if any)
the fuel pump is not controlled by the ecu in my car. the ecu and fuel pump are powered by their own switches and have separate relays(ARC8000).
I would ask my tuner but he's currently out of town and hoping to figure this out asap.
problem - engine will NOT start if I have the fuel pump running, it WILL start if I turn the pump off before trying to start it. once started, the engine will stay running until it runs out of fuel that's in the rails (15-20 seconds). if I turn the fuel pump on while the engine is running, it immediately kills the motor. so far I have tried lowering fuel pressure from 60psi to 43psi with no results. I have put a volt meter on the power in wire to the ecu and turned the pump on and did not get a voltage drop, but the engine dies so fast once the pump is turned on that I just might not have a chance to see a drop.
currently the MAF is just sitting in the intake tube as I have not welded the ls3 MAF bung on yet. (not sure what issues this would cause if any)
the fuel pump is not controlled by the ecu in my car. the ecu and fuel pump are powered by their own switches and have separate relays(ARC8000).
Thread Starter
On The Tree
Joined: Aug 2015
Posts: 102
Likes: 0
wiring is the same wiring i had when i had my 572 in the car for the fuel pump. And its seperate from the ecu. So not sure how that would be a wiring issue .But maybe im overlooking something that youre talking about
I chased a similar weird issue in the LS10, and maybe this is relevant. Could not start car if radio was on or if HVAC was anything other than off or if wipers were on. Coils would not spark. Could hear pump running but no spark.
Problem turned out to be grounding.
The cab, frame, engine were not all grounded. Everything was undervolted as a result. Fuel pump, main ignition, ECU, everything undervolted. Lights were dim even. All those isolators in the truck body were electrically isolating everything.
Ran a #6 cable from cab to battery, and a separate one cab to engine to frame to battery. Underneath I ran one bed to frame. Made nice clean spots with grinder. For good current transfer. Completely fixed everything. Truck now starts even if all electrical accessories are on.
Problem turned out to be grounding.
The cab, frame, engine were not all grounded. Everything was undervolted as a result. Fuel pump, main ignition, ECU, everything undervolted. Lights were dim even. All those isolators in the truck body were electrically isolating everything.
Ran a #6 cable from cab to battery, and a separate one cab to engine to frame to battery. Underneath I ran one bed to frame. Made nice clean spots with grinder. For good current transfer. Completely fixed everything. Truck now starts even if all electrical accessories are on.
