Malibu fuel pump stays on

[justgary]

Pull all of the injector wires off and test the fuel pressure.  Then put one injector wire on at a time and test the fuel pressure each time.  Note that they bank fire, so all of the blue ones fire at the same time and all of the green ones fire at the same time.  I would test them that way.  

Before you do this, remove the connectors from the ECM and carefully inspect each pin/socket.  Clean any crud and repair any pushed or bent pins.  Carefully reassemble the connectors and try it.

[Dan04]

3 hours ago, tvano said:

imho if you are filling the chambers and running fuel out of the throttle body you have one or more stuck (open) injectors.

I had all the injectors tested and cleaned and all are working as they should, the fuel pump just doesn’t shut off, leading me to think it’s the ecm not telling the injectors to close

[justgary]

5 minutes ago, Dan04 said:

I had all the injectors tested and cleaned and all are working as they should, the fuel pump just doesn’t shut off, leading me to think it’s the ecm not telling the injectors to close

Perform the test mentioned above.  The ECM tells the injectors to fire by grounding the Blue or Green wire (via an open collector circuit).  The Red wire carries constant voltage.  While you have the connectors apart, you can check for constant voltage on Red and for open/ground on Green and Blue.  If either of the Green or Blue wires is shorted to ground in your harness, you will easily achieve your symptoms.

https://cdn.bakesonline.com/media/resourcelibrary/Indmar_MEFI4manual.pdf

Sections 3 and 5 both seem appropriate here.

[Dan04]

Key on and cranking I get about 5 psi of pressure

[electricjohn]

22 hours ago, Dan04 said:

I never got it running yet due to the fuel filling the entire engine and cylinders til it dumps out the throttle body

You may have a ground fault on the blue  and/or green wires coming off the fuel injections. The red wires are constantly hot when the key is on and the ecm grounds (pulses) the blue and green wires to batch fire (4 at a time) the injectors. Unless the 380 is sequential injection.

[Dan04]

With the injector harness unplugged the fuel pump won’t go on, with it plugged in the injectors won’t go unless I plug the first one on each side then it’s a continuous stream from all injectors 

[Dan04]

Has anyone had any experience with the aem ecm?

[Dan04]

Waiting for new ecu to come in I found the original mefi 4b after calling about 20 different places that deal with them and ordered new alternator and a bunch of other parts... will swap everything over then the ecu last and see what happens

[Dan04]

Thanks everyone for help and thoughts I’ll be posting my progress up here for anyone interested to know what happens!

[Dan04]

Update. I got the ecm in and replaced all spark plugs and in line fuel filter. Put everything else back together, Took it out on the water starts good but stalls out at idle, I can give it throttle to about 2500 rpms and then it begins to bog down misfire and stall out. Any suggestions? I will drain all fuel and pour new 93 in first. Cap and rotor? 

Edited June 16, 2021 by Dan04

[footndale]

Correct wires on correct cylinders?

 

[Steve B.]

ECM was programmed for your engine? Confirmed? Verify fuel pressure at idle? Have you cleaned the plenum/intake manifold? Replace Idle Air Controller and throttle position sensor? Verified timing?

After that I would look for intake air leaks, but usually those will give you a high idle. Keep us posted.

Steve B.

[formulaben]

On 5/18/2021 at 9:58 PM, Dan04 said:

...it had a small bilge pump fire...

Could you elaborate on this?

1 hour ago, footndale said:

Correct wires on correct cylinders?

Agree with @footndale that you should verify the wires are attached correctly.

5 hours ago, Dan04 said:

Any suggestions? I will drain all fuel and pour new 93 in first. Cap and rotor? 

For sure if it hasn't been done in recent years I would replace the cap, rotor, wires and even the coil.  While they may not be your actual problem, they will for sure fail in time, so chalk it up to preventive maintenance and eliminate them from the troubleshooting tree.

[Dan04]

Yes all wires in correct places I never removed them off the distributor, ecm was tuned to my engine, I haven’t had time to work on it but will this weekend. I’ll change out the fuel then test fuel pressures at key on, idle and wot, recheck spark plug gaps, check for any leaks anywhere. I cleaned everything replaced all sensors with new ones might try old ones to see if there’s a difference as well. I’m just happy I got it running at this point the fine tuning can always be done

[formulaben]

7 hours ago, Dan04 said:

Yes all wires in correct places I never removed them off the distributor

But you did remove them from the old plugs to install the new ones.  Unless you are certain you only did them one at a time, you need to confirm they are positively in the correct order.  It's a very easy mistake, and the plug wires are long enough to transpose them.

[Dan04]

I will double check it all still haven’t had a chance to get in there, if someone can send me a firing order corresponding with the cap that would be helpful too or I’ll look it up 

[formulaben]

This is what I have, probably copied from here at some point...take it with a grain of salt, I can't verify it at the moment.