Wiring for my 350 with cool fuel

rasbury

Someone from another forum provided the following info...I just don't have the electrical knowledge and I don't want to fry anything. Sure the low pressure pump seems to be running, I don't think it's the relay- I have two relays sitting side by side on the top of the motor and not sure which is which...but probing it seems to be the way to go. I have a regular meter and the probe won't fit into the pin area to probe...do you attach something to it to get in there? What do I do for a ground/negative probe? The other pin referenced, where is that at?  With where I'm at on this , can I put my volt probes on the plug itself disconnected from the pump, hit the key- if I have voltage then I know everything behind the plug is OK and it get my 600.00 replacement pump?

dang, it's not letting me copy from the other site...I will post.

rasbury

Attached is the diagram. Their comments next..

rasbury

 This is the info a fellow sent me..

Fuel pumps are energized by the ECM applying a ground to one side of the relay coil. The other side gets 12V from the Main Power Relay (MPR)

Which cool fuel do you have (no serial numbe

Fuel pumps are energized by the ECM applying a ground to one side of the relay coil. The other side gets 12V from the Main Power Relay (MPR)

Which cool fuel do you have (no serial number 

S/N shows a boost pump with 1st Gen cool fuel, 555 ECM and HSV distributor

Fuel pressure should be 43 psi at the rail

Relay setup, MPR 

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Key ON, MPR energizes and sends power thru out ECM and to FP relay

ECM powers up, hear beep and then applies ground to pin A-19 for couple seconds which powers on FP

If you put meter on pin A-19 or pi 86 of FP relay before key is turned ON you will see 0V. Key ON, 12V to relay coil and "may" see 12V then 0V when ECM energizes relay to power FP relay. When ground is removed will see 12V again

If you don't see 12V at any time then the fuse is blown, MPR is not energizing, bad connection, or relay coil is burned out

Boost pump is powered by the same FP relay. It's a add-on kit supplied by Merc to help stop vapor lock

The Boost pump can be removed and run without for testing with a bypass

Key ON, MPR energizes and sends power thru out ECM and to FP relay

ECM powers up, hear beep and then applies ground to pin A-19 for couple seconds which powers on FP

If you put meter on pin A-19 or pi 86 of FP relay before key is turned ON you will see 0V. Key ON, 12V to relay coil and "may" see 12V then 0V when ECM energizes relay to power FP relay. When ground is removed will see 12V again

If you don't see 12V at any time then the fuse is blown, MPR is not energizing, bad connection, or relay coil is burned out

Boost pump is powered by the same FP relay. It's a add-on kit supplied by Merc to help stop vapor lock

The Boost pump can be removed and run without for testing with out

Rich_

Go to the cool fuel connector and see if you have 12v there when key is initially turned on

rasbury

I think that pump is fine- it's the pickup or booster pump. Will have it home this weekend. The guy on the other forum seems to be now sending me helpful info..he has helped me a few times in the past...