just put new pistons/ rings, bearings and seals due to oil pump drive failure. now it starts & runs for 5 seconds and dies. spark good, grounds and wiring are good. have 34 psi fuel but a little low in voltage at injectors.?????ECU?
What does "a little low in voltage at injectors" mean? The injectors sit at 12VDC and are opened up by dropping one side close to ground. You want that side going as close as possible to 0VDC. Where is this "low voltage" of which you speak? How are you measuring it? You'll need an oscilloscope to really see what the pulses look like.
Furthermore, a low injector voltage swing wouldn't cause the engine to run fine and then just die after five seconds. The engine would stutter, cough, run roughly, or some other symptom.
Please describe in detail exactly what happens. From what you've typed, it sounds like you start the engine, it runs perfectly for five seconds, then it dies suddenly as if the safety switch had been pulled or the key turned off. Is that correct? Can it be restarted IMMEDIATELY and repeat the same five seconds of operation?
I'll jump the gun a bit while we wait for more info and take a shot in the dark: This sounds like a fuel problem to me. You say you have 34 PSI in the high pressure fuel system. Pressure is not the same as volume, though.
When you first start the engine, the electric fuel pump runs for a while to prime the fuel system. That would fill up the VST and give you fuel on which to start and run. But then the electric pump stops and the pulse pump is supposed to take over. If there were something wrong with your pulse pump, the engine would likely do what you're describing - run for a short time and then starve for fuel and die. Restarting would work because the electric fuel pump would have another opportunity to recharge the VST.
The engine manual contains a series of fuel system tests, one of which is the pressure test you performed. Have you done the fuel flow tests? Have you confirmed that you get fuel flow from (specifically) the fuel/water separating filter? That's the last component before the VST, and downstream of both low pressure fuel pumps. You doubtless have flow while starting, but the question is whether you have flow while the engine is actually running.
I'd connect up an external outboard tank (no need for premix, as the oil is mixed within the VST) to where the fuel/water separating filter connects to the VST. Keep the tank above the engine so gravity is working in your favor; prime the system using the hose bulb and start a syphon that hopefully will persist long enough to run this test. Dangle the hose from the fuel/water separating filter into a gas-safe container, and have someone start the engine. See if you get continuous fuel flow from the loose hose. Ideally you should let the engine run at least 60 seconds to guarantee the electric pump times out normally.
Waiting to hear from you....
