Engine 1989 Mustang GT 5.0 HO Starting issues

tpearce89 · Aug 4, 2022

I've been having a hesitation issue with my 89 5.0. I replaced plugs, wires, cap, rotor and still had an issue. After driving it here and there, I pulled the plugs to see any fouling and found #5 was completely white. Replaced TFI and still misses. Went to replace the coil pickup and notices stress cracks in the bottom of the distributor shaft. Replaced the distributor and reinstalled as I pulled it out. It ran for about 30 seconds then died and wouldn't start here after. Decided to retime from TDC just incase I didn't install it perfectly, cranks and no start still. Pulled new distributor and reinstalled old distributor and same thing, cranks no start. Pulled plugs again and all seem wet with fuel. Cleaned and dried plugs and reinstalled all but 1 plug. Uninstalled plug installed on wire and grounded to test for spark, visual inspection shows there is spark. New distributor back installed and I've been doing various tests found on forums and I'm pulling hair out at this point. If anyone has some ideas, I'm willing to try them.

Thanks for any help!

Tyler

General karthief · Aug 4, 2022

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

Cranks OK, but No Start Checklist for Fuel Injected 5.0 Mustangs model years 1986-1995 A word about this checklist before you start: it is arranged in a specific order to put the most likely failure items first. That will save you time, energy and money. Start at the top of the list and work...

www.stangnet.com

Read and follow directions.

manicmechanic007 · Aug 4, 2022

Every distributor shaft you will look at for a small block ford will have those cracks
They are from the manufacturing process
Sounds like you have no spark and the Coil, stator or TFI module might be at fault
You might also have the timing out of whack
Good luck

tpearce89 · Aug 4, 2022

manicmechanic007 said:
Every distributor shaft you will look at for a small block ford will have those cracks
They are from the manufacturing process
Sounds like you have no spark and the Coil, stator or TFI module might be at fault
You might also have the timing out of whack
Good luck

Brand new coil, new stator that came in the new distributor, and tfi came new also. I did replace the tfi with a motorcraft a few months ago to try and fix the miss. It ran with the motorcraft. Timing is not out. Myself and another guy timed it.

tpearce89 · Aug 4, 2022

General karthief said:
Cranks OK, but No Start Checklist for Fuel Injected Mustangs

Cranks OK, but No Start Checklist for Fuel Injected 5.0 Mustangs model years 1986-1995 A word about this checklist before you start: it is arranged in a specific order to put the most likely failure items first. That will save you time, energy and money. Start at the top of the list and work...

www.stangnet.com

Read and follow directions.

Thanks, will have to work on these over the next couple days. Will post results after.

tpearce89 · Aug 6, 2022

tpearce89 said:
Thanks, will have to work on these over the next couple days. Will post results after.

Went through the check list and nothing was out of the ordinary. I decided to take a look at my timing in relation to valve position. I noticed when my intake valve was fully closed the piston was at the top of the stroke. Pulled the front of the engine apart this morning and found a sheared cam shaft pin and time to rebuild!

manicmechanic007 · Aug 6, 2022

I do not like the length of those pins
Short by at least .200" in my opinion
I ground the head off a grade 8 bolt and used the shank to make a longer pin
I made a pin just as long as would fit in there
I had a pretty radical bumpstick in mine back then with triple springs and .580 or so lift (was too much) (for my big valves)
That puts tremendous strain on that pin
Good luck

manicmechanic007 · Aug 6, 2022

The engine makes a funny sound when turning over with no or low compression
Remember that sound yours was making as it was turning faster

RansomN · Mar 6, 2023

tpearce89 said:
I've been having a hesitation issue with my 89 5.0. I replaced plugs, wires, cap, rotor and still had an issue. After driving it here and there, I pulled the plugs to see any fouling and found #5 was completely white. Replaced TFI and still misses. Went to replace the coil pickup and notices stress cracks in the bottom of the distributor shaft. Replaced the distributor and reinstalled as I pulled it out. It ran for about 30 seconds then died and wouldn't start here after. Decided to retime from TDC just incase I didn't install it perfectly, cranks and no start still. Pulled new distributor and reinstalled old distributor and same thing, cranks no start. Pulled plugs again and all seem wet with fuel. Cleaned and dried plugs and reinstalled all but 1 plug. Uninstalled plug installed on wire and grounded to test for spark, visual inspection shows there is spark. New distributor back installed and I've been doing various tests found on forums and I'm pulling hair out at this point. If anyone has some ideas, I'm willing to try them.

Thanks for any help!

Tyler

Hey I'm responding because it looks like you're having the exact same issue and you got the exact same car so what ended up being your solution?

manicmechanic007 · Mar 7, 2023

Replace the fuel injector on the cylinder with the white spark plug
Do a cylinder balance test first, and check the compression first
Get a few from a junkyard for testing, then replace with a new Ford one if you feel the need

manicmechanic007 · Mar 7, 2023

1989 was a very long time ago
Check your timing chain for wear
Watch the ignition rotor move when turning the crank back and forth
If it is more than about 14 degrees total, you got trouble

RansomN · Mar 7, 2023

Thank you for the advice I will get back to you if this IAT doesn't work

RansomN · Mar 7, 2023

manicmechanic007 said:
1989 was a very long time ago
Check your timing chain for wear
Watch the ignition rotor move when turning the crank back and forth
If it is more than about 14 degrees total, you got trouble

I'll check for more than 14° tomorrow if I have time What I've done in total is replaced the throttle position sensor the coolant temp sensor the intake air temp sensor the distributor rotor and cap and the best result I can get so far is about 20 seconds of runtime and then it will shut off and it won't respond at all to the throttle

manicmechanic007 · Mar 8, 2023

Put a vacuum gauge on it (see what it says during the 20 seconds)
Looking to see if the exhaust is plugged or the timing is incorrect
Does it backfire through the intake?

RansomN · Mar 8, 2023

What I'm going to do today is dump all the fuel out of it I'm starting to imagine that it's too old it. when I got it to run It wasn't backfiring. It'll usually only start like that when it's cold and then after that I can smell gas. I'm also going to check all the fusible links

Engine 1989 Mustang GT 5.0 HO Starting issues

tpearce89

Member

General karthief

wonder how much it would cost to ship you a pair

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

manicmechanic007

tpearce89

Member

tpearce89

Member

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

tpearce89

Member

manicmechanic007

manicmechanic007

RansomN

New Member

manicmechanic007

manicmechanic007

RansomN

New Member

RansomN

New Member

manicmechanic007

RansomN

New Member

Similar threads

Engine 1989 Mustang GT 5.0 HO Starting issues

Member

wonder how much it would cost to ship you a pair

Member

Member

Member

New Member

New Member

New Member

New Member

Similar threads

Privacy & Transparency

Privacy & Transparency