Log in

View Full Version : Relay...Really?



Mike M
07-07-2012, 07:21 PM
About a month ago my car would not start intermittently. I would start it and drive 2 miles to work, try to start it again and it would crank but no start. Wait about 5 minutes and then it would start. Sometimes it would be fine for a few days sometimes it would happen several times in one day.

First thing I need to know was it fuel or spark...been here about a thousand times in the last 35 years (I have specialized in driveability problems almost exclusively). Unfortunately my experience didn't make it too much easier.

I started carrying a fuel pressure gauge and my OTC Genysis scanner around with me in the trunk. When the car would not start I would hook up the fuel gauge but by the time I would screw it on to the fuel rail the car would start. Same thing with scanner, by the time I would plug scanner in and power it up it was too late. I started leaving the gauge hooked up and the scanner hooked up as long as I could then after a few days of no problems I would disconnect them and wouldn't you know it went back to not starting.

I replaced the crank sensor with a new Ford unit as well as looking for chaffed wires everywhere. I even tried another key.

What I decided to do next was to swap out the PCM and fuel pump relays with the horn and A/C relays. So far it has been starting perfectly now for a week. I since replaced all 4 relays with new Ford units.
I took apart the 2 relays from the PCM and Fuel and I noticed this.....look closely and you will see a broken wire on the relay on the right towards the bottom left.

Mr. Man
07-07-2012, 08:13 PM
Great detective work. Hope it's the answer.:)

fastblackmerc
07-07-2012, 09:27 PM
Good catch!

Bruce Wayne
07-08-2012, 06:41 AM
Nice job, I have a '07 CVPI that left my son stranded on the freeway, and it turned out to be the fuel inj. relay, same one you have pictured. Thanks for sharing this with us. I wonder how many no-starts can be blamed on these relay's

GetMeMyStogie
07-08-2012, 07:43 AM
Where is this relay located in the car? Is it easy to swap out in the field, or is this something you have to do on a bench at home?

fastblackmerc
07-08-2012, 09:13 AM
Where is this relay located in the car? Is it easy to swap out in the field, or is this something you have to do on a bench at home?

I believe it's in the fuse / relay box under the hood, behind the battery.

Spectragod
07-08-2012, 09:18 AM
I believe it's in the fuse / relay box under the hood, behind the battery.

That would be correct.

Mike M
07-08-2012, 11:18 AM
Passenger frt under hood under plastic cover, there are 4 in a row and the middle two are for PCM and fuel pump. Easy to change but you will need pliers to them out(kinda like pulling teeth).

I keep 2 as spares in glovebox from now on.