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Ron
Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 35490
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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Ron I have trouble with my 93 5.0 mustang. it has spark,

Customer Question

Hi Ron I have trouble with my 93 5.0 mustang. it has spark, injector pulses and fuel squirts out when i push on the schraeder valve. it cranks but wont start. New fuel pump which i can hear prime. I sprayed starting fluid into the intake and it wont start with that either. I tried 2 new ECU's. New coil, new distributor (with new pip and TCI). no dice.
Submitted: 2 years ago.
Category: Ford
Expert:  Ron replied 2 years ago.
Hello and thank you for your question, My name is ***** ***** I will assist you today.
Have you checked to see if you have a nice blue spark out of the coil while cranking and out to the spark plugs?
Customer: replied 2 years ago.
the spark looks more orange to me. i checked multiple plugs, they spark. noid like on multiple injectors.
Customer: replied 2 years ago.
the car doesn't even threaten to start, just cranks and cranks. I'm not leaning on looking for a bad ground. I've found that the HEGO ground is bad - or at least cant find it. COuld that cause a no start/
Expert:  Ron replied 2 years ago.
Okay even with orange spark and injector pulse it should attempt, if it where me, the next step would be to remove all the spark plugs and run a compression test on all cylinders. Do this and post back with the results and we can work from there.
Customer: replied 2 years ago.
Previously I was having a problem where it would start and run for about 5 minutes then die. When troubleshooting that I burned out the ECU I think, which has made me thing I have electrical problems. For some reason I can't pull codes either. I hear the fuel pump kick on when i attach the scanner, but no codes ever come up. ill try and test the compression.
Expert:  Ron replied 2 years ago.
Well if you have proper fuel pressure (32 to 45 PSi) as well as injector pulse and spark it should start if you have good compression, let check the compression to at least rule it out.
Customer: replied 2 years ago.
I'm waiting on the compression gauge to arrive.
Expert:  Ron replied 2 years ago.
No a problem, Im here when you ready.
Customer: replied 2 years ago.
Hi Ron - I checked compression today on cylinders 1,2 5 and 6. They were all 55-60 PSI. I didnt pull all the plugs, just the one(s) as I was testing them. I did it with the pedal down as well as up. Lastly I disconnected the ECU to turn off fuel and spark. Does it sound like I did it right? What does 60psi to both sides mean?
Expert:  Ron replied 2 years ago.
The problem is with the compression, if low compression on this many cylinder then it's most likely you have a valve timing concern likely due to a timing chain concern. The engine is not going to start with anything less then 100 to 125 PSI on each cylinder.
Customer: replied 2 years ago.
ok - pulled all the plugs and tested each cylinder with the gas pedal to the floor. much different results - seems almost like the pressure drops along with the firing order...Cylinder/PSI
1/115
2/90
3/105
4/705/90
6/65
7/82
8/60
Expert:  Ron replied 2 years ago.
Unfortunately your problem is still with the compression, the engine is not going to start and run with this many low cylinders. Your still looking at either a bad timing chain and or bad piston rings, I would suspect the timing chain. There really is nothing else that will affect compression.