No start 2004 8.1 MPI Port Side

Hello Team Crusader:

2004 8.1 MPI port motor 425 hours (new to me) cranks strong but wont start. On a couple of attempts there was some suggestion of the motor beginning to fire but not for long yesterday and not at all today. Fresh fuel, new 4D battery in parallel with Jumper Pack. Fuel rail pressure 58 PSI so now I'm thinking of moving on to ignition....

Some additional info. The engine hasn't run since 2019. It looks well maintained clear oil, new filter, and new impeller. Manifolds look fairly new and I'm guessing it was running fine when it was last laid up. The 3 year old fuel was pumped out and recycled--$2500 later I have 1/3 of a tank of fresh fuel. Both motors share a common tank. The starboard motor fired and ran fine after a few tries cranking with a jumper pack connected to the old battery.

What are some simple tests or checks I can do? Does the Oil Pressure switch come into play while cranking? I would think the OP switch would be bypassed during start up. I don't have a scan tool for MEFI-4 yet but the Rhinda device is probably next...

Best wishes,

Tom

I think I'd check the ignition and if the spark is present, then it suggests the injectors are not firing...

After cranking it a few times, you should be able to smell the fuel in the throttle body (with the throttle open)...if that's the case, you can use a little bit of starting fluid to verify the spark.

The factory MEFI manual should be in your inbox (email); not sure if I sent it previously. some of the sections/procedure will apply, not all.

I don't think the OP switch comes into play on the MEFI-4....that said, with 58 PSI in the rail, the fuel pump circuit is just fine (at least at low speeds).

Thanks Mako:

Agreed, ignition is next on the checklist and conservative use of starting fluid seems like the easiest away. However I cranked it quite a bit over the course of two days and I did not smell any fuel so the injectors might not be getting the pulse from the ECM. Reading through the MEFI-4 you sent (thanks) it looks like both the ignition and the injector signals are dependent on the the crank position sensor so that needs to be checked.

Best, Tom

Just a note figured this one out the key switch (very old) lost the 12 V "run" signal while it was cranking due to worn out contacts. New switch and it starts reliably now.