I have been away from 5.0s for a while, but recently purchased a 92 Limited edition Convert with 5.0/ AOD and 60,000 original miles for my daughter. Other than the battery and tires it was 100% stock. I had a Mustang Shop in Dallas install a New Old Stock GT40 upper and lower intake, injectors, 1.7 roller rockers, 73 mm MAF and 70 mm throttle body so the car would be ready for her birthday. At first they installed 30# injectors (thinking ahead for the Vortech!), but it ran so rich at idle they suggested changing them out to 24#. Now that I have the car back, it starts and runs ok when cold, (although I think there is a vacuum leak since the car whistles when it shuts off), but once you shut off the car with the key it will not restart until it cools off 20-30 mins. It never dies while running, just won't restart. I took it back and they replaced the distributor module, ( which they said usually fails when it gets hot and causes the car to die), which made no difference. There is 38 psi fuel at the rails when it fails to restart. The spark looks a little yellow when you ground a plug and turn over the engine. There are not check engine codes stored or pending in the computer. The car has left her stranded now so much she doesn't want to drive it, and I am going broke towing it back to Dallas. Any ideas of things I could check? I am about ready to replace all the parts back to stock, or put it up for sale. Thanks
Hot starting issue
- Thread starter David B
- Start date
-
Sponsors (?)
It sounds like it will crank but not restart. Correct?
Your spark should be blue, not orange or yellow. What do you have for injectors right now? I would have left the car stock till the blower actually went on. 24's or 30's can lead to hot start issues (too much cranking fuel).
In a controlled environment (your driveway, etc), let it idle up to temp. Shut if off and get it so it won't restart. Pull a plug and see if it's really fouled.
For a quick fix that might get it running if the car is not home, flooring the gas pedal while (and only while) cranking will shut off the injectors. This helps clear a flood condition.
Be sure to see Jrichker's Cranks but No-Start checklist when you can do some diagnostics.
Good luck.
Your spark should be blue, not orange or yellow. What do you have for injectors right now? I would have left the car stock till the blower actually went on. 24's or 30's can lead to hot start issues (too much cranking fuel).
In a controlled environment (your driveway, etc), let it idle up to temp. Shut if off and get it so it won't restart. Pull a plug and see if it's really fouled.
For a quick fix that might get it running if the car is not home, flooring the gas pedal while (and only while) cranking will shut off the injectors. This helps clear a flood condition.
Be sure to see Jrichker's Cranks but No-Start checklist when you can do some diagnostics.
Good luck.
+1, hard starting when hot has alway been a rich condition for me. car starts when cold since it'll take more fuel then, but flood it out when its hot.
seeing how the car has bigger injectors with no tune i am guessing thats what it is.
in all honesty, if its just for your daughter and not for hot rodding around. i'd just throw the stock injectors and MAF back on, i bet this will cure your problem entirely.
seeing how the car has bigger injectors with no tune i am guessing thats what it is.
in all honesty, if its just for your daughter and not for hot rodding around. i'd just throw the stock injectors and MAF back on, i bet this will cure your problem entirely.
The source of the problem(s)
Sorry in advance for the length of this, but I think this information might be helpful to others. Thanks for the checklist, it was a great tool. Also, the links there gave me the testing values for the TFI module when it is off the car, something I did not have before. I was able to go through several old TFI modules and find which ones were good.
After posting last time, the car again died and was taken back. This time they installed a new fuel pump (which the car did not need) and as soon as my daughter left, the car died again. This time I had it towed home. Here’s what I found when I started looking:
The computer ground wire is pinched between the intake and the block. They obviously knew it occurred, because there is about 1/3 a tube of silicone sealer smeared around it trying to stop the oil leak. Sloppy work from a company with Mustang in its name and that published a National Mustang parts catalog. So the intake will have to come back off to fix this.
I let the car warm up, shut it off, and it would not start. I borrowed some FORD service manuals and I installed an OTC breakout box and started checking things. I had 56 psi at the regulator (the 38 psi or so the tech stated was with engine vacuum). Too much so I turned it down.
I had good spark at the plugs testing the voltage, but noticed no signal at the injectors. I tested the ACT sensor voltage, and saw the voltage drop to confirm the computer had gone from warm up mode to hot-run. Then I checked the TPS return signal and saw 1.1volts at closed throttle with KOEO status. I looked under the hood at the switch and saw where the mounting holes were slotted out with a hacksaw to allow it to rotate to this setting. The FORD service book shows 0-.2 volts at closed throttle, .995-.997 volts at max rotation. I set the voltage to .2 and the car started right up. After some more reading in the service manual, I believe the car was going into what Ford calls de-chock mode. When the car is hot and tries to flood, depressing the throttle turns off the return signal from the injectors to shut off fuel and clear the flood condition. To verify this, I installed Noid lights at the injectors, reset the TPS to 1.1, and saw no signal. I placed with the TPS, and somewhere around .6 volts is where the injectors signal was blocked. So I believe the computer thought the throttle was depressed, entered de-choke and shut off fuel. After the car would cool down enough for the voltage to rise on the ACT sensor, it would allow the injectors to fire.
The car still had the small vacuum leak, and looking at the intake, I saw the gasket between the EGR plate and the intake was left out. I think as the intake heated up and moved around, the leak would get better or worse. Just more sloppy work.
As an update, I pulled the intake back off to fix the oil leak and free the pinched wire, reinstalled the 30 # injectors and correct sample tube, installed the EGR spacer gasket, and reset the TPS to .2 volts. Now the car will idle at 675 RPMS in drive with the A/C on, and the vacuum gauge shows 19.2 inches. Throttle response is very good. I have driven the car very hard over the last two days, shutting it down often to check restart, and it has not failed to start at the turn of the key. Now if I can just get my daughter back out of her EVO……
Sorry in advance for the length of this, but I think this information might be helpful to others. Thanks for the checklist, it was a great tool. Also, the links there gave me the testing values for the TFI module when it is off the car, something I did not have before. I was able to go through several old TFI modules and find which ones were good.
After posting last time, the car again died and was taken back. This time they installed a new fuel pump (which the car did not need) and as soon as my daughter left, the car died again. This time I had it towed home. Here’s what I found when I started looking:
The computer ground wire is pinched between the intake and the block. They obviously knew it occurred, because there is about 1/3 a tube of silicone sealer smeared around it trying to stop the oil leak. Sloppy work from a company with Mustang in its name and that published a National Mustang parts catalog. So the intake will have to come back off to fix this.
I let the car warm up, shut it off, and it would not start. I borrowed some FORD service manuals and I installed an OTC breakout box and started checking things. I had 56 psi at the regulator (the 38 psi or so the tech stated was with engine vacuum). Too much so I turned it down.
I had good spark at the plugs testing the voltage, but noticed no signal at the injectors. I tested the ACT sensor voltage, and saw the voltage drop to confirm the computer had gone from warm up mode to hot-run. Then I checked the TPS return signal and saw 1.1volts at closed throttle with KOEO status. I looked under the hood at the switch and saw where the mounting holes were slotted out with a hacksaw to allow it to rotate to this setting. The FORD service book shows 0-.2 volts at closed throttle, .995-.997 volts at max rotation. I set the voltage to .2 and the car started right up. After some more reading in the service manual, I believe the car was going into what Ford calls de-chock mode. When the car is hot and tries to flood, depressing the throttle turns off the return signal from the injectors to shut off fuel and clear the flood condition. To verify this, I installed Noid lights at the injectors, reset the TPS to 1.1, and saw no signal. I placed with the TPS, and somewhere around .6 volts is where the injectors signal was blocked. So I believe the computer thought the throttle was depressed, entered de-choke and shut off fuel. After the car would cool down enough for the voltage to rise on the ACT sensor, it would allow the injectors to fire.
The car still had the small vacuum leak, and looking at the intake, I saw the gasket between the EGR plate and the intake was left out. I think as the intake heated up and moved around, the leak would get better or worse. Just more sloppy work.
As an update, I pulled the intake back off to fix the oil leak and free the pinched wire, reinstalled the 30 # injectors and correct sample tube, installed the EGR spacer gasket, and reset the TPS to .2 volts. Now the car will idle at 675 RPMS in drive with the A/C on, and the vacuum gauge shows 19.2 inches. Throttle response is very good. I have driven the car very hard over the last two days, shutting it down often to check restart, and it has not failed to start at the turn of the key. Now if I can just get my daughter back out of her EVO……
Similar threads
