No Start Help

Ptstew · Oct 1, 2017

I went out recently for a joy ride in my FFR Cobra, which is built using a 1991 Mustang LX 5.0L donor car. The engine started normally and idled normally for ~ 20 seconds and then stopped dead as if the ignition had been turned off. The fuel pump, which had primed normally before stating, continued to run. Without recycling the ignition I tried to restart. It cranked fine but no start. The fuel pump turned off when I turned off the ignition but would not come on again when the ignition turned back on. All electrical components, to include the ECM, and wiring are stock from donor car and have been running without incident for 15 years. Car is garaged and has never seen rain.

Following diagnostics completed:
- Inertia switch OK
- ECM relay OK with 12v power to fuel pump relay control side and fuel injectors.
- Fuel pump relay fuse link OK with 12v power. Relay does not click with ignition and no fuel pump.
- When fuel pump relay grounded at test link pump runs normally, good fuel pressure, no start.
- Test light from battery to fuel injector ground does not flash when cranking.
- When fuel pump relay removed and computer plugged in the relay ground wire has partial grounding (has some resistance); when computer unplugged wire shows no grounding.
- With ignition on 12v at coil but no spark at distributor when cranked.

I have at least 3 ground control issues going on, fuel pump relay, fuel injectors, and coil. Is it the ECM and, if so, what is best way to get it repaired.

Thanks for help.

General karthief · Oct 1, 2017

Try this diagnostic checklist
http://forums.stangnet.com/787471-cranks-ok-but-no-start-checklist-fuel-injected-mustangs.html

Ptstew · Oct 1, 2017

karthief said:
Try this diagnostic checklist
http://forums.stangnet.com/787471-cranks-ok-but-no-start-checklist-fuel-injected-mustangs.html

Thanks. I did use this as a guide in my diagnostics.

General karthief · Oct 1, 2017

Any codes?

Ptstew · Oct 1, 2017

karthief said:
Any codes?

There is no check engine light wired into car and I don’t know how to check for codes. I will try to figure that out. Thanks.

General karthief · Oct 1, 2017

Do you have the diagnostic port? The checklist has a pic of it and instuctions on using a test light

Ptstew · Oct 1, 2017

karthief said:
Any codes?

There is no check engine light wired into car and I don’t know how to check for codes. I will try to figure that out. Thanks.

karthief said:
Do you have the diagnostic port? The checklist has a pic of it and instuctions on using a test light

i have the port and will check that out. Thanks.

Ptstew · Oct 2, 2017

Hi, Karthief. I see the diag port picture which shows a tan line to the CEL, but see no instructions for how to use it with a test light. Can you please tell me where those instructions are? Thanks.

General karthief · Oct 2, 2017

the test light is used in the place of the cel so test leed goes into that slot and the other to + battery
study the picture it shows you how, sometimes you have to read it a couple times, I did.

jrichker · Oct 2, 2017

Dump codes sticky

Look at the top of the 5.0 Tech forum where the sticky threads are posted. One of them is how to dump the computer codes. Codes may be present even if the CEL (Check Engine Light) isn’t on. You don’t need a code reader or scanner – all you need is a paper clip, or if your lady friend has a hair pin, that will do the job.
I highly suggest that you read it and follow the instructions to dump the codes. http://www.stangnet.com/mustang-forums/threads/how-to-pull-codes-from-eec4.889006/

Ptstew · Oct 2, 2017

karthief said:
the test light is used in the place of the cel so test leed goes into that slot and the other to + battery
study the picture it shows you how, sometimes you have to read it a couple times, I did.

I tried getting codes two different ways. I jumped pin 46 to the fuel pump test port and a test light glows steadily with 12v when connected to the CEL tan line port from battery +. It does this with and without ignition on. There are no flashes with ignition on even after waiting a full minute. The same thing happens when I jump pin 46 to the separate single wire port that also plugs into the diag cover. When I built the car I had a guy remove all unnecessary wires from the stock harness which is why there is no CEL. It could be that I lost diag capability when he did that.

Ptstew · Oct 3, 2017

Karthief, any other suggestions? I’ve gone back through the checklist and keep winding up at a point where it says computer. Thanks.

General karthief · Oct 3, 2017

Possible ecu problem
Pull it out, what computer do you have in it?

Ptstew · Oct 3, 2017

Thanks, Karthief. Here is a picture of the computer from the car. I took it apart and noted no burned smell nor obious, to me, shorted areas. I did notice that one of the three blue capacitors was drippy wet. The others were sticky but not wet to the touch. With the top cover removed and the pins at the top, the wet capacitor was the one on the left side. Do you think this could be causing my problems? I am sure it needs to be fixed, regardless. Anyone to recommend?
Thanks for all your help.

General karthief · Oct 3, 2017

Have you checked into a rebuilt from a parts store? You can replace the little gizmos if really good at very small spot soldering

@jrichker

Ptstew · Oct 3, 2017

No, I checked on line and there are a few folks there but not sure how good they are. I have no experience spot welding myself. I take it from your response that the only way to check to see if the computer is the problem is to replace it.
Thanks

General karthief · Oct 3, 2017

That stuff is above my pay grade, I sent a flag up to the automotive surgeon on staff, he knows more about this stuff than I,

Ptstew · Oct 3, 2017

karthief said:
That stuff is above my pay grade, I sent a flag up to the automotive surgeon on staff, he knows more about this stuff than I,

Thanks

jrichker · Oct 3, 2017

Ptstew said:
Thanks, Karthief. Here is a picture of the computer from the car. I took it apart and noted no burned smell nor obious, to me, shorted areas. I did notice that one of the three blue capacitors was drippy wet. The others were sticky but not wet to the touch. With the top cover removed and the pins at the top, the wet capacitor was the one on the left side. Do you think this could be causing my problems? I am sure it needs to be fixed, regardless. Anyone to recommend?
Thanks for all your help.

Liquid leakage or bulging tops on electrolytic capacitors is a sign that they have failed.

There are vendors on ebay that repair your computer for a flat fee. Unless you have steady hands, sharp eyes and some solid electronic experience doing component level repair, I would suggest that you find one of these vendors that has a good rating and use their services.

Ptstew · Oct 3, 2017

Thanks, jrichker

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