help, car wont start after head swap

does it even have any fuel in the cylinders?

rculjak said:

Hey guys I have a big problem. I just finished putting on afr 165 heads, trickflow intake and the 70mm TB. Now the problem, I went to start the car up (keep in mind I have done this job a few times in the past ) and the car wouldnt start, it just seems to slowly crank but not catch in any cylinder. Here are the things that I have tried already:

Battery swap, jumpered the starter solenoid, checked for spark from coil and also at spark plug wire, swapped distributer shafts with tfi module, verified timing, scanned for trouble codes, verified stud mount rockers pushrods and primed the lifters, verified engine ground and main harness ground, verified fuel pressure and injector resistance and verified the plugs were threaded in enough.

If anyone has any suggestions it would be greatly appreciated like I said before, the car doesnt seem to even try to start just turns over with out any igniting, thanks.

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You only need three ingrediants for a car to start. Spark, fuel and compression. If you have spark and fuel, the next step is to check compression.

have you "jumpered" the battery (add another battery, like a jump start)? with the other battery you used, did it crank any faster? make sure you have a really good battery ground, as well as motor to frame grounds. a screwdriver can even be used to help out with diagnosing (adding a ground). sometimes the cables rot from the inside out, and moving them while workin on it, creates a problem.
i wonder if you have everything you need, but arent spinning the motor fast enough.


all of your other tests are things i would have tried. if you have a noid light, i might toss it on an injector you can access for fun (though i know you have done other tests to verify that you have fuel delivery....

good luck.

What kind of starter is it? stock? It might be that the compression is too high and if its a stock starter it just cant do it if the compression is too high. A buddy of mine has a 91 Z28 camaro and we swaped the heads out. Did the same thing yours is doing, turning over slowly. we had spark, we had fuel and pressure but just wouldnt crank. His dad had an old mini starter off there drag boat, put that in and it cranked over the 1st time and its been 3 years now and it still cranks over on the first flick of the key.

i hate to recommed it, but spraying starter fluid or a mist of gas (being super dooper careful and all that) might help tell if you have fuel.

you did testing on the injector harness didnt you? i thought you mentioned that. a noid light is the easiest way, that i know of....

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

1.) Remove push on connector from starter solenoid and turn ignition switch on. Place car in neutral or Park. Remove coil wire from distributor & and hold 3/8” away from engine block. Jumper the screw to the big bolt on the starter solenoid that has the battery wire connected to it. You should get a nice fat blue spark.
Most of the items are electrical in nature, so a test light, or even better, a voltmeter, is helpful to be sure they have power to them.
No spark, possible failed items in order of their probability:
A.) Coil
B.) TFI module
C.) PIP sensor in distributor
D.) ECC relay next to computer - look for 12 volts at the fuel injector red wires
E.) Fuse links in wiring harness - look for 12 volts at the fuel injector red wires
F.) Ignition switch - look for 12 volts at the fuel injector red wires
G.) Computer

2.) Spark at coil wire, pull #1 plug wire off at the spark plug and check to see spark. No spark, possible failed items in order of their probability:
A.) Moisture inside distributor – remove cap, dry off & spray with WD40
B.) Distributor cap
C.) Rotor
D.) Spark Plug wires
E.) Coil weak or intermittent - you should see 3/8" fat blue spark with a good coil

3.) Spark at spark plug, but no start.
Next, get a can of starting fluid (ether) from your local auto parts store: costs a $1.30 or so. Then pull the air duct off at the throttle body elbow, open the throttle, and spray the ether in it. Reconnect the air duct and try to start the car. Do not try to start the car without reconnecting the air duct.
Two reasons:
1.) If it backfires, the chance for a serious fire is increased.
2.) On Mass Air cars, the computer needs to measure the MAF flow once the engine starts.
If it starts then, you have a fuel management issue. Continue the checklist with emphasis of fuel related items that follow. If it doesn’t ,then it is a computer or timing issue: see Step 4.

Clue – listen for the fuel pump to prime when you first turn the ignition switch on. It should run for 5-20 seconds and shut off. To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground. See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html for a description of the test connector. If the relay & inertia switch are OK, you will have power to the pump. Check fuel pressure – remove the cap from the schrader valve behind the alternator and depress the core. Fuel should squirt out, catch it in a rag. Beware of fire hazard when you do this. In pinch you can use a tire pressure gauge to measure the fuel pressure. It may not be completely accurate, but you will have some clue as to how much pressure you have.

No fuel pressure, possible failed items in order of their probability:
A.) Tripped inertia switch – Coupe & hatch cars hide it under the plastic trim covering the driver's side taillight. Use the voltmeter or test light to make sure you have power to both sides of the switch
B.) Fuel pump power relay – located under the driver’s seat in most stangs built before 92. On 92 and later model cars it is located below the Mass Air Flow meter. Look for 12 volts at the Pink/Black wire on the fuel pump relay.
C.) Clogged fuel filter
D.) Failed fuel pump
E.) Blown fuse link in wiring harness. Look for 12 volts at the Orange/Lt Blue wire on the fuel pump relay
F.) Fuel pressure regulator failed. Remove vacuum line from regulator and inspect for fuel escaping while pump is running.

Fuel pressure OK, the injectors are not firing. A Noid light available from Autozone, is one way to test the injector wiring. I like to use an old injector with compressed air applied to the injector where the fuel rail would normally connect. I hook the whole thing up, apply compressed air to the injector and stick it in a paper cup of soapy water. When the engine cranks with the ignition switch on, if the injector fires, it makes bubbles. Cheap if you have the stuff laying around, and works good too.

A.) Pull an injector wire connector off and look for 12 volts on the red wire when the ignition switch is on.
B.) No power, then look for problems with the 10 pin connecter (salt & pepper shakers at the rear of the upper manifold).
C.) No power and the 10 pin connections are good: look for broken wiring between the orange/black wire on the ECC relay and the red wire for the 10 pin connectors.


4.) Spark & fuel pressure OK.
A.) Failed IAB (no airflow to start engine). Press the throttle ¼ way down and try to start the car.
B.) Failed computer (not very likely)
C.) Engine ignition or cam timing off only likely if the engine has been worked on recently).
D.) Firing order off: HO & 351 use a different firing order from the non HO engines.

noid light

my car ran funny when i put a 65mm tb on, cobra upper/lower, and a 73mm MAF. it idled all funny then i heard a weird noise so i shut it off. i went ot start it again and it wouldnt start. i kept trying to turn it over but it wouldnt go. i finally got pissed and just started turning and turning the key then i pressed the gas pedal a few times while trying to start it. the car started back up adn i let it sit for a few and then it was normal. and yes i disconnected the battery during the whole install.

I know you stated you verified timing but it sure sounds like a timing issue to me.
Check again to make sure you are not 180 out.
Good luck

HISSIN50 said:

noid light

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A noid light or tester plugs in the wiring harness in place of any one of the injectors. When you crank the engine with the ignition switch on, the light flashes when the injector fires.

rculjak said:

I might as well tell you the whole story sorry for the length though. The car ran perfect and a few weeks ago I decided to install afr 165's with a trickflow intake and 1.7 stud mount rockers. I have done head gaskets in the past so I was familiar with the job. After everything was put back together the car fired up right away ran very rich and rough for about a minute then died and would not start up anymore. The car turns over but does not seem to try and fire up, The starter is turning over the engine fine, I found top dead center on cylinder 5 with my finger in the head and when it blew it out the rotor points to wire 5 on the cap, I verified fuel pressure at the shrader valve, I verified spark at the plug, I have 12 volts at the red wire on the injector harness and what I did was plug another injector in a harness and put my finger on the tip of the injector and I could feel the pulses and the engine cranked, I pulled out a plug and could smell gas on the threads of the plug and the threads felt moist, I verified the 10pin connectors outputs with another stang and it was fine which leads me to believe that the computer is fine, I even swapped entire distributer shafts with tfi module from a functional stang and didnt change a thing the the cranking. I have run out of electrical things to check I think, I also think its getting fuel and the timing is correct, maybe I didnt do the stud mount rockers correctly, could this cause the problem? Thanks for listening.

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Have you checked the compression yet???
Does it sound abnormal when you crank it. Did you check the valve to piston clearence before hand? Maybe those 1.7 rockers pushed the valves open to far and you bent the valves. You've tested all kinds of things but I have seen no mention of a compression test.

rculjak said:

I have never done a compression test before, how do you properly do one, I dont have a compressor, do you need one? I didnt check p/v cleareance, I used the stock cam and stock length push rods hardened with the 1.7's, so you think I might have ruined my brand new heads?

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I wouldn't rule it out until you can verify by doing the compression test. It's a gauge btw, not a compressor. Do you have a local parts store that rents out tools? If so, rent one it is very easy to use. It's just a gauge and a hose. The hose treads into your spark plug hole, then you attach the gauge. Crank the engine over 7-8 revolutions and see what the gauge reads. Do this on all cylinders and make a note of each one. Disconnect the fuel and the spark during the test. Compression on each cylinder should be at least 125. You may even see as high as 150. The main thing to look for also is that all the cylinders are close in compression. 10% or so. Good luck!