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No start after rebuild on 1990 Mustang 5.0 ho

2K views 11 replies 5 participants last post by  89coupe 
#1 ·
New here and I got a question for yall. My buddie and I just rebuilt his motor 1990 5.0ho. Its all timed right theres good spark and its not firing. We checked for gas on the plugs and they are dry as a bone except for the anti seise on the threads. Everythings hooked up right and gas flows great up to the fuel rails and not sure after that I don't know how to check it. There is no farting or anything just turning over with no attempt to even try fireing.

So I'm at a loss I have no idea on where to start help would be great thanks
 
#4 ·
Ok if they are NOT what should I be looking at I just dont want to plan a day to do it and find out they not working then sit and wait for replies.

Also we put this cam in.

COMP Cams 35-308-8 - COMP Cams Magnum Hydraulic Roller Camshafts

That wouldn't cause valve issues would it. We asked around and people said no but I thought i would throw it out there for ya.

I suck at diagnosing stuff but have a good mechanical know how i guess.
 
#6 ·
Ok if they are NOT what should I be looking at I just dont want to plan a day to do it and find out they not working then sit and wait for replies.

http://store.summitracing.com/partdetail.asp?part=CCA-35-308-8&autoview=sku
If not then you would need to find out if its not getting power from the ECM relay, You would also check the blue 20g fuse link at the starter solenoid. IF the fuse link is good. And all the ECM grounds, one by the ECM itself in the kick panel, another behind the factory Battery location on the inner fender well. Then its most likely the ECM relay and/or its wiring or in the Salt & Pepper connection.

The ECM relay should have 1 wire that hot at all times, and with Key on 3 should be hot.
 
#5 ·
If the injectors have no power first step is to check the fuses. After that i would follow the stickie not they have for 5.0 Fuel injected crank no fire. There is a whole section for fuel injectors in there. Its also pretty in depth for everything else if the injectors have power.
 
#8 ·
How did u get the timing right if it wouldnt fire up??? Possible you have your timing 180 off? If you used tdc for cylinder #1, maybe ur on the exhaust stroke.....just a thought.
 
#9 ·
You time it by pulling the #1 plug and feel for air being pushed out. Then your on the compression stroke. On your balancer there is timing marks and a pointer a stock 5.0 is 10 deg BTDC.

Well we got ours running great today. We found out we were really low on gas. We dumped 5 gal in her and that fuel was flowin perfectly. After about a hour dinkin with the timing she fired right up and ran strong. Stock says 10 deg BTDC and she would just sputter and not catch and run so we just kept advancing the timing little by little till we were about 19 deg BTDC. she ran rough but we advanced it to about 21 BTDC then ran great. I think over the weekend we are going to advance it a little more maybe to 25. We are going to try to get the most horses as we can out of her. Can't wait till we are done breakin her in so we can really get on it .
 
#10 ·
You time it by pulling the #1 plug and feel for air being pushed out. Then your on the compression stroke. On your balancer there is timing marks and a pointer a stock 5.0 is 10 deg BTDC.

Well we got ours running great today. We found out we were really low on gas. We dumped 5 gal in her and that fuel was flowin perfectly. After about a hour dinkin with the timing she fired right up and ran strong. Stock says 10 deg BTDC and she would just sputter and not catch and run so we just kept advancing the timing little by little till we were about 19 deg BTDC. she ran rough but we advanced it to about 21 BTDC then ran great. I think over the weekend we are going to advance it a little more maybe to 25. We are going to try to get the most horses as we can out of her. Can't wait till we are done breakin her in so we can really get on it .

Did you pull the SPOUT out when you set the timing? Theres no way that thing is gonna act right at 21 base timing.
 
#11 ·
It runs great at 21 BTDC. And WTF is a spout? It could get advanced even more maybe 25 to 28. I'm not understanding why you think it won't act right at 21. Ive seen people push theirs to 34 BDC. The only thing I can think of what a spout is is some sort of word for a distributor. And why wouldn't you pull the distributor to set the timing.
 
#12 ·
The Spout is in the TFI wiring harness. Its grey and looks like a fuse of some sorts. To properly set timing, Remove the SPOUT( this keeps the ECM from making any advancement of timing), then set base timing( 12-14°) or what ever. Then put SPOUT in. and the ECM will advance the timing accordingly.
 
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