Fuel issue
Open the gas cap and listen for air being suck in. If you hear air then your drawing a vacuum in the vent because the vent is clogged
If not hearing air, check to see if you get a squirt of gas when throttle moves. Might also be fuel pump is weak, antisiphon valve on the tank is...
It is safety Bondo said ". It should be replaced 1st"
If it wallow's out it could even crack and then steering is gone. Imagine running and the steering breaks
Would need to check for codes. Can check by using a digital multimeter with a tone built in, or a 12V resistor LED
Put meter or LED across pins E and F of the DLC connector (on top motor near ECM with a cap on it). Put paper clip or other wire across A and B. Turn key ON (do not start) and...
If your ECM is a MEFI-4 then there is a power reduction mode that does not let rpm's go above 2500. MEFI-3 does not
I'm seeing part numbers but I'm unable to determine if it's a MEFI 3 or 4
3858863
3801310
Replaced by
3860614
7749063
21242085
21242092
21242089
3832370
948211
If these where good then the motor would start, something is not present.
Most likely it's an electrical issue, loosing spark or injector firing.
You have a Flat distributor cap, has it been replaced?
When cranking do the fuel pumps run?
Is there 12V on the pink wire of the coil?
Putting good gas in bad gas just makes more bad gas. Doing 1/2 tank replacement a couple times will make the gas not so bad and enough should be fine
Pressure going from 4 psi to zero after replacing gas filter is weird, maybe the gauge. Spec list 4.9 to 8.5 psi at idle. Have you checked the...
The motor is a 5.0 what (Gsi, Gi, other)?
Did the motor ever run ok?
How is the compression?
What is timing set at, and does it advance as rpm increases?
What is the fuel pressure?
There different because someone messed up, don't know if it's the manual or the parts list. I would probably go with the manual unless the manual has been revised (newer date).
My opinion VP want's to make sure its not installed top/bottom and can be placed in either position (inside or outside)
Not to be a negative Nelly, but
Chevy, same as any other competitor, GM and Chevy has nothing to do with it. Cars, motors, drive train is nothing like anything in the real world. Would like it again if they went back to stock car
Thanks
This is your motor
https://www.mercruiserparts.com/350-mag-mpi-alpha-bravo-1a611928-thru
Having Alpha drive then your fuel pump is under the port side motor mount
This is the fuel rail, and item 18 where to measure
https://www.mercruiserparts.com/bam/subassembly/31753/15044/90
Could use a serial number of motor to verify what your configuration is?
Measure the fuel pressure at the rail, should be 43 psi at 1800 rpm. Should be close or slightly higher up to WOT
The Purple wire going to the ALT should have 12V when key is turned ON and 0V when OFF
Your ALT needs 3 connections to work correctly
Orange wire - Output wire to Battery via the Starter post
Black wire - Ground
Purple wire - Excite wire that turns the ALT ON when key is turned ON
If you have...
