Engine 89 5.0 high output starting issues

RansomN · Mar 6, 2023

I'd appreciate any help with this problem. My '89 mustang Fox body 5.0 high output will only start after I clear the computer by unplugging the battery and turning on the headlights for a little bit. I plug it back in and I can get the thing to turn over and start on the first try. It'll start for about 20 seconds it's got some stumbles it's not perfect and then it dies. I can smell gas and it will not start up after that. Seems like it's flooded. The work that's been done is replaced the distributor it's on time I think I pointed the distributor dead center at the number one with it at 0°. And yes currently the spout connector is removed. Any thoughts

Blown88GT · Mar 6, 2023

Base timing is supposed to be 10degBTDC.

mikestang63 · Mar 6, 2023

If you hold the pedal to the floor, it will shut off the injectors, and. see if the car starts then. I would also dump the codes and see if you get 21, 51, or 61. Most likely cause is a bad IAC or EEC.

General karthief · Mar 6, 2023

Anything swapped or modified on this car?
Did you get the car not running?

RansomN · Mar 6, 2023

Blown88GT said:
Base timing is supposed to be 10degBTDC.

So at the 10° before top dead center mark I should set the distributor rotor pointed directly dead center at number one is that correct?

RansomN · Mar 6, 2023

So at the 10° before top dead Cinemark I should set the distributor rotor pointed directly that center at number one is that correct

RansomN · Mar 6, 2023

mikestang63 said:
If you hold the pedal to the floor, it will shut off the injectors, and. see if the car starts then. I would also dump the codes and see if you get 21, 51, or 61. Most likely cause is a bad IAC or EEC.

The codes I got was 21 because up here in Oregon it's cold lately I replaced the coolant temp unit anyway though before that I also got a throttle position sensor code I replaced the throttle position sensor right now it is reading at a closed throttle of a 1.19 which I guess is still in specs and lastly the air intake temperature was below threshold also but I'm guessing once again that's just because of our frigid temperatures out here lately so I will hold it open tomorrow and see what happens

RansomN · Mar 6, 2023

General karthief said:
Anything swapped or modified on this car?
Did you get the car not running?

Remind you I replaced the throttle position sensor without routing anything I was able to get it as far down as 1.19 it closed throttle I replaced the distributor and it's been sitting for a while I also replaced the coolant temp sensor the throttle position sensor in the coolant temp sensor in the intake air temp sensor were all codes at one point it gave me a mass air flow also but that hasn't come back no nothing's really swapped I don't think it's pretty well stock

RansomN · Mar 6, 2023

RansomN said:
Remind you I replaced the throttle position sensor without routing anything I was able to get it as far down as 1.19 it closed throttle I replaced the distributor and it's been sitting for a while I also replaced the coolant temp sensor the throttle position sensor in the coolant temp sensor in the intake air temp sensor were all codes at one point it gave me a mass air flow also but that hasn't come back no nothing's really swapped I don't think it's pretty well stock

And no I think the car was running is the story I got and then the distributor was moved during running and that's when the problem started so I figured it was just a simple timing issue but I put the distributor in correctly cleared all codes and I'm getting these issues after replacing all of the above mentioned

General karthief · Mar 7, 2023

Setting the balancer at 0* and the rotor at #1 on cap should get you started and then set the timing @ 10* with a timing light but since your engine will not start don't worry about that step yet.
First thing I would do is make sure I have the engine at TDC on the compression stroke, also pull the plugs to check for fouling, plugs are cheap.

Mustang5L5 · Mar 7, 2023

You always get code 21 on a cold engine. If you get code 21 on a warm engine (180-210 degrees), then you need to investigate the cause.

It sounds like you are flooding out and unable to restart. Can you try depressing the gas pedal to the floor and try to restart when it gets in the no start condition? This is flood clear mode for the ECU.

Can you confirm if this works or not?

Blown88GT · Mar 7, 2023

RansomN said:
So at the 10° before top dead center mark I should set the distributor rotor pointed directly dead center at number one is that correct?

No, that would retard the timing.

RansomN · Mar 7, 2023

Mustang5L5 said:
You always get code 21 on a cold engine. If you get code 21 on a warm engine (180-210 degrees), then you need to investigate the cause.

It sounds like you are flooding out and unable to restart. Can you try depressing the gas pedal to the floor and try to restart when it gets in the no start condition? This is flood clear mode for the ECU.

Can you confirm if this works or not?

I'm at the mustang now I'm going to install the IAT because that was one of the codes and then try to start it I also have a suspicion about the coil but I'm not going to install it until after I see what the IAT does I'll get back to you

RansomN · Mar 7, 2023

Blown88GT said:
No, that would retard the timing.

The new IAT didn't help and in fact now I can't even get it to start for even 20 seconds like I did the other day. Holding it wide open to shut off the ECUs fuel input and cranking it over multiple times didn't get any fires whatsoever I replaced the coil the distributor the rotor the cap I haven't done anything to the plugs and wires I replaced the throttle position sensor the coolant temp sensor I think what I'm going to do is check out the no spark checklist

RansomN · Mar 7, 2023

Mustang5L5 said:
You always get code 21 on a cold engine. If you get code 21 on a warm engine (180-210 degrees), then you need to investigate the cause.

It sounds like you are flooding out and unable to restart. Can you try depressing the gas pedal to the floor and try to restart when it gets in the no start condition? This is flood clear mode for the ECU.

Can you confirm if this works or not?

Holding it open to shut off the ECUs injector pulse doesn't help I installed the new IAT also called the ICT and it didn't help in total what I've done is installed a new throttle position sensor a new distributor rotor and cap I haven't done anything to the wires and plugs yet also new coolant temp sensor and as I mentioned the IAT

Mustang5L5 · Mar 8, 2023

Run through the crank, no start checklist. It's written in a logical order and does help if you go through it.

I think i have a suspicion, but would still go through the checklist. But, if you wanted to try and narrow things down, i would pull a spark plug and ground it on the engine with a wire attached and crank the motor over to see if you have spark.

I'm suspecting it might be PIP/TFI/Coil related.

RansomN · Mar 8, 2023

I'm wondering if I have spark at the correct time is what I'm thinking I know I have spark because I've already grounded out the spark. I replaced the distributor the cap the rotor and the coil so far I do need to pull all the plugs and check their condition though. What I'm going to do today is drain all the fuel out start from scratch I'm considering that that smell of gas that I'm getting is not gas that is ignitable but that still doesn't make any sense for why It would start up for 20 seconds and then die. What is the TFI

Mustang5L5 · Mar 8, 2023

TFI is the gray box that's on the distributor. But if you have spark, even when it not starting, that's a good sign that those components are working.

In addition to the no start checklist, you will want to open the ECU up and check the capacitors. The fact that it runs when power is drained, and stops after a short wire might also point to ECU issues.

But start working through this

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...

stangnet.com

General karthief · Mar 8, 2023

@RansomN .
You are discussing this issue on an another thread,

Engine - 1989 Mustang GT 5.0 HO Starting issues

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...

stangnet.com

Stick to this thread or you likely will be chasing your tail,

RansomN · Mar 11, 2023

Today I pulled all the plugs to do a compression check the only one that was dry was number seven because it's got a problem, It was down to 130 all the other ones were close to 150. every other one was fuel fouled badly. After I cleaned them and wire whisked the plugs and gapped them I was able to start the car and even give it gas one time before the throttle became useless and once again seems the vehicle flooded itself. timing seems to be pretty damn spot on but I can't keep the car on long enough to set the timing it seems like the injectors are stuck open.

Engine 89 5.0 high output starting issues

New Member

wonder how much it would cost to ship you a pair

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New Member

wonder how much it would cost to ship you a pair

That is…until I whipped out my Bissell

New Member

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New Member

That is…until I whipped out my Bissell

New Member

That is…until I whipped out my Bissell

wonder how much it would cost to ship you a pair

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