Engine 89 Won’t start when hot

[Aoneill5.0]

So
On an earlier post,
I thought I had it resolved by battery disconnect and reconnect
S
Thought I had it after cleaning a buncha engine grounds…

NOPE

so today I ran in town, she came up to operating tent..
Then wouldn’t start after…

So now I figure I got a
‘Won’t restart when hot ‘ issue

 

[90sickfox]

Is it a slow crank when hot ? If so it could be timing related.

 

[General karthief]

Slow crank/no crank issues most times are cable, starter or battery related. Describe what happens better or a video.

 

[Potomus Pete]

When my car had those symptoms it was the module on the distributor.

 

[Mustang5L5]

I'm leaning TFI/PIP

 

[AeroCoupe]

So my 93 had this problem a few months back. I went through all the cables on the car as they were about 10 years old and they are all 4ga custom built by me. Pulled everyone of them off and built new ones. This was ground and positive. Car cold started a lot better but still dragged on a hot start but not as bad. Battery tested good so that was out. Finally said F it and bought a lifetime warranty reman mini starter to replace the one on it and problem solved. The old starter was a salvage yard starter that was about 20 years old and had been rebuilt twice. Solenoid was good (less than 5 years old) but it was just mechanically wore out as the tolerances were crap and causing binding when it got hot. At least this is what the local starter rebuild shop was thinking. He’s a good dude and I trust the guy which is what led me to the new starter.

Anyhow, not saying this is the fix for your car but you need to check the cables themselves for internal corrosion. Two of my grounds were corroded the entire length under the insulation which was not helping.

 

[2000xp8]

You need to describe what happens when you try and start it.
These guys have given all the culprits.
If it cranks fine, it's probably the TFI.
If it cranks slow or is hard to turn over, it's probably cables or the starter itself.

 

[CAMTWO1070]

Im leaning towards the problem being either the coolant temp sensor or the Intake temp sensor being off..

 

[Aoneill5.0]

Ok guys,
All excellent replies,

I gotta describe better.

Basically, once car is running and driven for say 20 miles, errands or cruisin,

I’ll shut er down,
Then go to start it and
Cranks fine, won’t catch.
The fix at this point.. Disconnect both tmls, wait 5 mins,
She then cranks just fine and fires right up.. on we go,

My findings when it’s in the no start mode
Fuel pump energizes 2-5 sec at key turn
Lots of fuel press at Schrader on the rail
Good spark at Plugs while turning over
But…..dry plugs (no fuel past injectors obviously


Ordered CTS
TMI
as well as a new temp sender (fixin the guage)

I’ll repost if that takes care of things..

 

[AeroCoupe]

If you have access to another ECU swap them out.

 

[CAMTWO1070]

I agree its good to know your temps and theres a test you can do on the old CTS with a multimeter to see if its actually bad or not...

I also agree on swapping out ECU's...Thats why I always have a good working spare...Sometimes those internal voltage capacitors can be finicky.......

The EEC varies A/F ratios by varying the pulse width of the voltage applied to the injector solenoid. Pulse width is how much average voltage is applied to an injector coil over a given time span which is typically about 2.5 milliseconds for EFI cars.

12vdc is always applied to the injectors and triggered by the negative wires but when you average the applied voltage over a set time span, shorter pulses result in a lower leaner average voltage over that time period and if your injectors arent seeing a full 12v it will only get leaner..A noid light or a multimeter can verify voltage is strong enough with the problem being sometimes as simple as replacing the EEC relay or fixing / replacing or cleaning a ground wire... ..even a sensor ground...

Anything external to the EEC like the CTS BAP,MAP or IAT which tries to modify the desired air/fuel ratio with an Open Loop Fuel Table in closed loop operation, will cause the computer’s Adaptive Control feature to try to compensate for the change by writing correction multipliers to KAM that correspond to the load level at which the out-of-tolerance value occurred and sometimes an ECU reset will straighten things out temporarily by getting rid of the conflicting info it received and stop trying to overcome the problem its stuck on...


Checking grounds are fairly easy with a multimeter set to continuity test............


View: https://vimeo.com/761147609


Good Luck