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No fuel pressure

K

Kwall

New member
Have a 2012 115 EFi , trying to figure out what tells the high pressure pump to turn on, I’ve hooked 12v to it and it works but when I turn the key on no pressure at the fuel rail , pick up pump works fine
 
Serial numbers are always best to have

The FP is turned on by the ECM applying a ground to one side of the FP relay.

Depending on your model it may have 2 relays, one main power and other FP. Check fuses and connections at the relay(s) and see if 12V is present
 
AllDodge said:
Serial numbers are always best to have

The FP is turned on by the ECM applying a ground to one side of the FP relay.

Depending on your model it may have 2 relays, one main power and other FP. Check fuses and connections at the relay(s) and see if 12V is present
Click to expand...
 
1B956321, ck all that , relay are good, I’ve kinda narrowed it down to the ECM, just trying to see if I’m on the right track before I sent the ECM in to get repair, it’s about 1/4 cost of a new one, it ran fine and shut it off and troll with a kicker and went to start it and no start, replaced the pump and the float switch, still the same problem , I’m going to double ck that I have 12v at the fuse , fuse is good
 
Your motor shows 4 fuses and 3 relays
This is Merc wiring but should be similar. Power comes in on Red/Pur, then thru fuses to FP relay

Also check that one side of the FP is actually ground good. If you loose ground pump won't run

555 relays.jpg
 
Here is a good test
Place probe of voltmeter on pin 86 of FP relay. With it in place, turn key ON. You should see 12V, it go to zero then back to 12V. If it goes to zero and back up, then ECM is working. If it stays at 12V always then ECM is not applying a ground

With key ON and motor off there should be 12V on pins 85 and 30
 
I don’t have a separate relay for the fuel pump, it’s part of the main relay, I have a repair manual, that I trying to take a picture from but it’s keeps saying file to big
 
no not sure how to do that , as far as the ground, the high pressure pump goes directly to the ecm then the pickup pump goes to different sensor and then to the ecm
 
I don't know what software you have. Something like MS paint can resize.
Take the picture and import it to another document then save as, maybe ever PDF
I bring it into MS power point and then save it a JPG

If you have google drive save it there then set a link up so any other can access it.
 
Kwall said:
I don’t have a separate relay for the fuel pump, it’s part of the main relay, I have a repair manual, that I trying to take a picture from but it’s keeps saying file to big
Click to expand...
Save the photo to an image hosting sight. You can then post the image to here.

Postimages — free image hosting / image upload

Provides free image upload and hosting integration for forums. Free picture hosting and photo sharing for websites and blogs.
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boscoe said:
How are you able to give advice when you don't have the manual?
Click to expand...
This doesn't even deserve an answer, but I'll try to explane for your limited understanding.

I have many Merc manuals for both I/O (39 different ones) and OB, even one for the New V8 Verado but I don't have his exact motor. So based on information found any many of the Merc manuals I am trying to help with basic advise
 
AllDodge said:
This doesn't even deserve an answer, but I'll try to explane for your limited understanding.

I have many Merc manuals for both I/O (39 different ones) and OB, even one for the New V8 Verado but I don't have his exact motor. So based on information found any many of the Merc manuals I am trying to help with basic advise
Click to expand...
I appreciate all the advice I can get , as far as doing this other stuff lol 😂 I’m in my 60 and not smart with computers, my daughter coming over later I’ll see if she can help
 
The pic with wiring helps a little but doesn't show if ECM or a relay energizes the fuel pump, and isn't very easy to read

35 is fuses and 38 is FSM

I still believe the ECM applies a ground to a relay because it's chancy for high current to be push/pulled directly thru the ECM.

Slide1.JPG
Slide2.JPG
 
There’s only 3 relays, 2 are for trim up and one for down, the other is the main , the fuel pump hot wire goes to fuse then to the main relay, the black-tan wire goes to the ECM which is the ground wire for the high pressure pump
 
Yes , that why I believe my problem is in the ECM , the pickup pump ground goes to the ECM in a different location which is why there no problem with that ground, thanks for your help
 
Just received a update on my ECM , found a overheated driver in in the ecm , hopefully that’s my problem, I guess find out when I get it back , I’ll update to hopefully save someone 800.00 thinking bad fuel pumps when it’s the ecm
 
Finally found out my fuel problem, turn out to be a corroded connection at the ECM , was giving up and put everything back together to take it to the dealer, hit the key and she fired up , we probably had that connection on and off 10 times.
 
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