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No fuel pump power. Need advice


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ChevyTrucks
Novice

Apr 26, 2013, 6:56 AM

Post #1 of 13 (1563 views)
No fuel pump power. Need advice Sign In

Hi, I am a new user and just started building older trucks with my son. Recently got an 86 S10, was running fine and just quit. Thought it ran out of gas but after putting gas in no start. Here's what I've done: Have 12V on orange wire to FP relay,can jump that 12V to tan pump wire and pump runs. No pulse at grn/wht wire from ECM. Have 12V at injectors and most everything else seems to work. Removed ECM plug and don't get a 2 second voltage one pin A1. I am by no means an expert mechanic but have basic knowledge of auto repair and have electrical experience. Not sure if I am checking correctly or missing something. Any help or advice would be appreciated.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 26, 2013, 7:39 AM

Post #2 of 13 (1528 views)
Re: No fuel pump power. Need advice Sign In

You seem to be checking correctly.
Now you have to check all the power and ground inputs to the ECM before condemning the ECM.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



ChevyTrucks
Novice

Apr 26, 2013, 7:43 AM

Post #3 of 13 (1519 views)
Re: No fuel pump power. Need advice Sign In

I did check the orange B1 (I think) wire at ECM and do have 12V. Will look at diagram and check others and ground later. Thanks


ChevyTrucks
Novice

Apr 26, 2013, 6:43 PM

Post #4 of 13 (1480 views)
Re: No fuel pump power. Need advice Sign In

Should there be zero ohms from one side of ECM b fuse to Pin A1


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 26, 2013, 7:45 PM

Post #5 of 13 (1476 views)
Re: No fuel pump power. Need advice Sign In

I don't know what that test is supposed to prove. You're supposed to be testing power supplies and grounds coming into the ECM



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



ChevyTrucks
Novice

Apr 26, 2013, 7:54 PM

Post #6 of 13 (1471 views)
Re: No fuel pump power. Need advice Sign In

Couldn't do any testing tonight had ball game. I was just thinking about it and was wandering if that wire goes straight from fuse to ecm. Just thought it may be good info to have while doing those checks you mentioned tomorrow. I know I am getting power to both sides of the fuse and if I get no power to the ecm then thought maybe broken wire in between


ChevyTrucks
Novice

Apr 29, 2013, 9:53 AM

Post #7 of 13 (1425 views)
Re: No fuel pump power. Need advice Sign In

Found it was ECM. I have spent a couple of days tracing this issue so now I'm very fimilar with the process to run the fuel pump. Maybe I can be of some help if needed. Thanks for responding.


ChevyTrucks
Novice

May 3, 2013, 11:07 AM

Post #8 of 13 (1392 views)
Re: No fuel pump power. Need advice Sign In

Need to ask silly question. The gas tank was removed when I got truck. I installed new tank and pump and now have pump running. I know where the hose from filler neck goes but there are 3 other lines on pump, 2 in front and 1 behind them. I turn key on and gas comes out of one in front on left so that is feed. There are 3 lines at the frame, do they line up with the pump lines. Left to left, center to back, right to right or do I have to trace them down.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

May 3, 2013, 12:16 PM

Post #9 of 13 (1391 views)
Re: No fuel pump power. Need advice Sign In

Hmmm? Hope it's somewhat obviuos by length or position the hoses are in now. One should be plain out, one return and one evap to allow vapors thru the evaporative emissions which is up front.

Old stuff now. Maybe someone here has some diagrams but I wonder on something like that?

T



ChevyTrucks
Novice

May 3, 2013, 12:36 PM

Post #10 of 13 (1387 views)
Re: No fuel pump power. Need advice Sign In

No hoses just hard lines and new pump. I will try to trace them if I don't get a pic from someone.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

May 3, 2013, 1:42 PM

Post #11 of 13 (1378 views)
Re: No fuel pump power. Need advice Sign In

There will be a feed line (3/8) and a return line (5/16) going directly to the pump and then there will be a vapor line going to the charcoal canister. At the filler there will be another vent hose alongside the filler.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



ChevyTrucks
Novice

May 4, 2013, 6:06 AM

Post #12 of 13 (1357 views)
Re: No fuel pump power. Need advice Sign In

Ok thank you got it and finally getting fuel through injectors. Was so happy but short lived. Won't start, can see fuel check spark on couple of wires, have that still no start. I think I saw on here where a coil was weak and also timing issue. Could either of those be problem now. Thanks again


HT
User

May 4, 2013, 7:06 AM

Post #13 of 13 (1353 views)
Re: No fuel pump power. Need advice Sign In

If you're testing the spark correctly with an adjustable spark tester, you will already know if the coil is delivering sufficient spark.










 
 
 






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