1989 Ford Mustang GT Won't Start - Engine

Question: Installed 89 5.0 5 spd into 68 mustang, EFI, computer and all. Starts fine cold and runs without problems. When warm the starter can barely turn motor over. Battery volatage OK at starter relay.(battery relocated to trunk)Acts as if timeing to far advanced or vary high engine compression.

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Technican: Hello, How many cranking amps does your battery have? What is the length of the cables to the starter relay? Have you tested the starter for the amount of amps it draws during cranking? It should be around 175 amps. Is the engine grounded to the body by a ground cable of sufficient wire gauge? It takes amps to do the work. Not just volts. Example: A dome light will burn fairly bright on a battery that needs charged. But, when you try the starter...nothing, and the dome light dims. The reason is there are not enough amps to handle the demand. The size/diameter of your battery cables will factor here too. The longer the run, the more volts lost to heat/resistance due to limitations of the wire size to handle amps over distance/length of the cable. Timing is indeed important. Where do you have the timing set now? Will changing the timing allow the engine to crank faster?

Owner: Tried backing the timing off once to little effect at first. After several start attempts the motor suddenly started turning over normally but would still not start and had extremely excessive fuel in the exhaust. After the engine cooled it start but ran rough, probably due to the excess fuel in the exhaust fooling the O2 sensors. The battery is a stock replacement for 89 mustang 5.0 and in good condition. Cable from trunk is 2 AWG.

Technican: See if you can have the starter amp draw tested when the comdition is present. The amount of cranking amps called for by the starter is important information. A good groumd cable between the engine and the body is important. How accurate is your coolant temp sensor? If faulty, the computer may be calling for the wrong amount of fuel. Did you ensure the wiring harness for your engine connects every circuit of your computer's input and output parameter?

Owner: Used the original 89 harness and spliced in the run, run/start, and start only signals in several loactions. Spliced in the fuel pump, water temp and oil press gauges, put resistors in place of the EGR, thermactor, and vapor solonoids, eliminated EGR spacer and added reistors to simulate the EGR for computer. I'll check the coolant temp sensor but it is hooked up. Used 68 engine ground strap to engine, will try adding 89 too. Thanks

Technican: I'm most interested in the starter amp draw at this point (when the condition is present). I'll look for your next reply.

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