No voltage to fuel pump

JasPruden

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I have a Volvo Penta 5.0 GXi-A. 4012050969 3869116

We had to remove the engine from the boat to do some water jacket repair. (Yep, I welded up a cracked water jacket.) When I re-installed the engine, It turns over, have ignition, compression, and timing. IF i pour a bit of fuel down the throttle body it fires right up. Unfortunately, it is getting no fuel from the fuel pump to the throttle body.

I have taken the fuel pumps off and applied 12volt to both the high pressure and low pressure pumps. Both pump diesel just fine. Fuel filter and pumps were purged with gasoline and re-installed. Both relays have been tested good but replaced anyway.

I have NOT been able to locate a fuse blown. The schematic shows 4 fuses. One is for the fuel pump. I have only located 3 fuses. All three were in he box on the side of the engine that has the diagnostic port. All appear to be good and were tested with a VOM. Is there any other place to look?

I use a paper clip and test light to see if there were any codes set. None showed up.

What is my next step in finding out why I have no voltage to my fuel pumps?

Thanks for any assistance and advise!
 

alldodge

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Howdy
The GXI-A should have only 3 fuses and one main breaker

The ECM turns the fuel pump ON. When key is turned to ON before starting do you hear any beeps?
 

JasPruden

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It does make a short chirp that is then reverberated. A sound file is attached.

I would expect a low oil pressure warning that my inboard gives. (It is a Mercriuiser setup with a carbureted engine.)
 

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alldodge

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Sure not much of a noise.
I see the purple wire from the key to the motor should be hot.
Have you checked to see if you get 12V when key is ON?
 

JasPruden

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Yes. I have 12.5 volts when the switch is turned on. No voltage when key switched off.
 

alldodge

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I would suspect a bad connection on the relay or fuse, and bad connection between relay and ECM, defective relay
 

JasPruden

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I have the relay partially unplugged so I can get my VOM probe to the connection. The purple wire goes to pin 85 on the relay and when energized, It triggers the relay allowing voltage to be passed from the red purple wire on pin 30 to be connected to pin 87 on the relay which is a pink white wire. I have my 12 volts exiting the relay on pin 87 when the key is on.

Started tracing out the pink/white wire. By my wiring diagram, it is supposed to go to the MAP sensor, to the fuel injectors and coil and control module. Well it does make it to everywhere it is supposed to EXCEPT for the MAP sensor. Dont know if the schmetaic shows actual pin numbers on the control module plug but mine goes into the first pin or last pin. Schematic shows it somwhere in the middle. Did this with a VOM from the relay to all the points mentioned. The diagram shows 4 wires to the MAP sensor. Mine only has 3. None are pink and white. VOM show 2000 ohms on one pin K on the center pin and 400 ohms on 3rd pin.

Relay has been tested OK but I replaced it with a new one with the same results.

Ill trace out the wires on the other relay tomorrow. I am leaning toward that a sensor is bad and the controller is keeping the fuel pump shut down.
 

alldodge

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The relay which is energized by the purple wire is the Main Power Relay (MPR). Since it does energize then were good for that one. I am puzzled about wire colors. I see purple as 85, and Black 86 (ground). When energized power is transfered from Red/Purple 30 to Pink/White 87

Unless there is another wiring error on the drawing (fix one so far) then the MPR does not transfer power to the FPR as it does on future designs. That said the MPR does keep power up the ECM

The FPR is turned ON by the ECM applying a ground on pin 86 Black/Yellow

Slide2.JPG
 

JasPruden

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I hooked up my test light to ground and touched the wire from the 86 pin. That did turn on the fuel pump.

Of course that goes directly to the other side of the controller. I did not ohm out the wire but will do that tomorrow.

I am looking that the schematic on my computer right now, not my iPhone. I think they have the MAP sensor and the Coolant temperature labels reversed. That would more match my wiring diagram. Ill have to locate the coolant temperature sensor tomorrow and check the wiring to it out. Just observing that sensors go in on one side of the controller and the output is mostly on the other side of the controller.

Looks like the the controller is not turning on the pump for some reason.
 
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JasPruden

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Still working on this thing. I have not located on the engine where the item 15 on the schematic is. I actually believe it to be the coolant temperate sensor not the MAP sensor
 

alldodge

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Item 15 is the MAP and should be mounted on top the manifold. Plastic rectangular object
 

JasPruden

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After doing a substantial amount of reading today, I have come to the conclusion the ecm is bad for multiple reasons.

1. not much of a chirp when you turn it on.
2. Should always get a 12 blink code 2 times when first turned on and checking codes.
3. Even with the fuel pumps running by jumper cable, no fuel coming out injectors.

From what I have read, either the ecm is bad or the engine is shut down due to over heating.

I have located a place in California that will diagnose the ecm for under $100, if it is bad, the repair is typically under $500 including the diagnostics.
 

alldodge

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Would it happen to be OBD Diagnostics, of so its a good place and Bob will do you right
 

QBhoy

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Hi. With the engine being out of its normal set up...is the ignition sensor purple wire and kill safety switch acting and connected as they would be normally ?
 

muc

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From what I have read, either the ecm is bad or the engine is shut down due to over heating.

Not sure where you read that. As far as the ECM is concerned.
This engine will NOT shut down due to overheat.
 
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