jammer48

this is my son's car and he as all but given up on it. 1993 hatchback just quit running one day. It has spark at plugs. I sprayed either in air intake and the car would run as long as I kept spraying into the intake. i checked the fuel relay based on a repair manual and it was not good and was replaced the new relay was checked prior to install and it functioned as a new one. there is no power to the fuel pump but when the pump was pulled and power is applied it pumps fine. when you turn on the ingition key you do not hear the fuel pump cycleing to build pressure. I am stuck any suggestion on what to do now...there is a power line coming from the relay (i think it is yellow with a green line) to the pump. that has no power anywhere along its path to the pump. I tried jumping the pins of the relay as described in the manual and still no power to the pump...Help

ezone

Use a wiring diagram and see if the ECM is turning on the relay for the fuel pump.

The ECM turns on the pump relay by grounding the green/yellow wire (terminals A7-A8 at the ECM)

jammer48

I was leaning towards the ECM next but have to read up a little more on it. Not even sure where in his car its located. I will check and let you know what i find.

ezone

Behind the passengers kick panel

jammer48

Ok so I had a couple of minutes when I got home from work to look for the ecm I found just lying under the carpet. I can see where it is supposed to be bolted to the passenger foot well but it wasn't. I checked to see if the ecm box was grounded and of course it wasn't so I temp connected a wire to ground and the ecm is now grounded to the body. Not sure how to check the ground for the fuel pump relay as you suggested. Could you give me a more detailed explanation on what you think I should check now. Also how do I check the main relay? I did a two step check for continuity and based on what was in the manual that I have the relay failed. My son went up and got a new relay from the parts store but that looks different. I tried it anyway but it still didn't fire the fuel pump.

ezone

Not good, may be a clue someone else was having issues with it.
Grounding the case wasn't really necessary as the ECM is internally grounded, not externally.

A wiring diagram, a volt-ohm meter and/or test light, and some understanding of how the system is supposed to work.... would be my tools of choice.
What exactly was this check?

Yeah, manuals and step-by-step testing (or flowcharts) can leave a lot to be desired.
That's why it helps greatly to have a good diagram, be able to read the diagrams and understand how things work based on JUST the diagram, and then dynamic testing to see if the items are actually doing their jobs while the system is operating (live tests), is very beneficial.

In 90% of electrical issues I encounter, my troubleshooting begins with a wiring diagram, not a flowchart or trouble tree.

jammer48

ok where do I get a good wiring diagram?

ezone

Search the forum, search google images, check service manuals maybe from Autozone and others, your local library may have access to Alldata or Mitchell..... and there's paying for factory info at Honda Service Express.

I cannot post or link my info due to copyright.

jammer48

Thank you for your efforts.

jammer48

Just an update: I went to another forum and they walked me through the entire process and we were able to fix the problem. The folks at the other forum were fantastic. Thank you to everyone who made an effort on this forum I really appreciate it.

rodan

What was the fix?