no start when hot.

[Charles Musick]

1999 5.4 EB. Truck runs great.
Problem when the truck gets hot it will not restart is if sits for 5 minutes. It will, if i restart immediately. After the 5 minutes, it will start, idle very rough, starve for gas. Press the gas and it takes in to much air killing the engine. Finally it acts like it runs out of fuel and will not restart untill it cools. I have now noticed the smell of gas. My thoughts were fuel pump, untill the gas smell. I've changed the filter, plugs, fixed vacum leaks. I need to do a pressure test on fuel. Think it may be fuel regulator? I didn't think it would be the hot starter issue because it will start - run for a minute, after that it will crank but nothing on fire.

 

[Charles Musick]

Forgot to mention this has been going on for a while. I checked the o2 sensor on driver side upflow. Couldn't get other side out. Autozone test showed pvc and o2 however after changing the plugs the o2 reread good. I also homed the top plug coil and they tested good, however i only have the problem when motor is hot, so is that a true test.

 

[stamp11127]

Get the facts instead of guessing at the problem. Fuel pressure is one thing I would check. I think the min running is 35psi. They usually run like crap in the high 20's and lower.

 

[docraymund]

It may be a leaking fuel injector/s or a loose vacuum connector on the fuel pressure regulator. You should do an injector balance test.

 

[Charles Musick]

Get the facts instead of guessing at the problem. Fuel pressure is one thing I would check. I think the min running is 35psi. They usually run like crap in the high 20's and lower.

Thanks, minus the "get the facts" comment. Searously what's up with that. Take it to a garage for test? Test the fuel pressure? I plan on testing the pressure, I thought others may have had the same problem and.....
I have not done anything to the truck that didn't need to be fixed, so I'm not simply guessing.

 

[Charles Musick]

It may be a leaking fuel injector/s or a loose vacuum connector on the fuel pressure regulator. You should do an injector balance test.

This is a bit crazy, but if I pump the brakes while starting it will start (while hot). Thinking it has something to do with vacum.

 

[Bedrck47]

What is meant by get the facts is when I see your original post it appears you are guessing

"My thoughts were fuel pump"
"Think it may be fuel regulator"

By get the facts means test and be sure Check for fuel pressure and report the reading Check for voltage etc.


The more information (facts) you provide will result in better answers and not members also guessing.

Thinking others may have had the same problem doesn't mean what was the fix for them will be the same fix for you.

 

[Charles Musick]

Agreed on the fuel pressure test. I'm going to do that this weekend.
If i understand correct
Facts: that commonly cause this problem.
Bad Coil on plug . Bench test ohm. Done.
Bad o2 sensor. Ohm heat test. Done
Bad Vacum line. Done but need rechecked.
Hot starter pulling to much power. Simi ruled out because it will start just won't run. Once the cranking stops the starter shouldn't pull power. correct?
Fuel filter, changed.
Fuel pump needs pressure test.
So other items that may cause this issue that I should check this weekend. In case it's not the full pump. Also if there a good bench test I can preform. I don't really have money to spend at the garage.

 

[Charles Musick]

What is meant by get the facts is when I see your original post it appears you are guessing

"My thoughts were fuel pump"
"Think it may be fuel regulator"

By get the facts means test and be sure Check for fuel pressure and report the reading Check for voltage etc.


The more information (facts) you provide will result in better answers and not members also guessing.

Thinking others may have had the same problem doesn't mean what was the fix for them will be the same fix for you.

I understand what your saying, however not completely true. They are know issues that can cause this problem. There are also many ford owners with the same problems, same fix. Maybe not in this case, but how do I know unless I ask. How may owners have had rear control arms rust out. Same problem same fix.

 

[Bedrck47]

You may want to test fuel pressure when you have the no start condition Its possible that you have good fuel pressure when cold but something could be causing low fuel pressure when hot. This may not be happening but needs to be ruled out

How many miles are on the expy??

 

[Bedrck47]

I understand what your saying, however not completely true. They are know issues that can cause this problem. There are also many ford owners with the same problems, same fix. Maybe not in this case, but how do I know unless I ask. How may owners have had rear control arms rust out. Same problem same fix.

You are somewhat correct Rear control arms What else could you use in their place No options.

And yes there are known issues but at this point your guessing and until you do some troubleshooting and rule things out. And throwing parts into it can be expensive.


Your problem is no start when HOT. So is it an electrical problem or a mechanical problem or a combination of both?

 

[stamp11127]

You get the facts to help narrow the search for the cause.
Are you getting enough fuel?
Are you getting spark?
Is the crank sensor failing?
Is the ignition switch or harness the cause?
Etc
Right now you have a bunch of "could be's" that need to be eliminated.

 

[Charles Musick]

You get the facts to help narrow the search for the cause.
Are you getting enough fuel?
Are you getting spark?
Is the crank sensor failing?
Is the ignition switch or harness the cause?
Etc
Right now you have a bunch of "could be's" that need to be eliminated.

Yes I know that. That is what I'm asking. I have not checked the crank sensor. I'm not sure how. Do I need to check when hot, sense that when the problem occurs? Ive considered the ignition switch also. I'm not sure how to test it. Would it allow the car to start at all if failing? I've tried different keys as well. The anti theft light seems to be working properly.
It would seem that I'm getting a spark because the truck will start when hot runs lean for a minute and finaly stalls- afterward it will not start. I checked the coils (not saying that they are getting power). If they are failing when hot will a cold ohm test work. I know it could be a lot of different things causing this. I thought the occasional smell of gas might help point to the problem. I'm not just throwing darts, replacing parts.

 

[Charles Musick]

You are somewhat correct Rear control arms What else could you use in their place No options.

And yes there are known issues but at this point your guessing and until you do some troubleshooting and rule things out. And throwing parts into it can be expensive.


Your problem is no start when HOT. So is it an electrical problem or a mechanical problem or a combination of both?

Thanks. Maybe I stated the original post incorrect. It should be.
How do I trouble shoot hot start problems. I have checked these.
I have not ruled these out however it does start for a minute. When I smelled gas humm the pump must be working, so what else could this be. I working on it this weekend so IF it's not the fuel pressure , I wanted to know the next step.

 

[Flexpedition]

My focus would be on what the Intake Air Temperature Sensor is reporting when this occurs. When they fail or begin to fail, its not uncommon for them to "report" to the PCM that its -40° F outside. When that kind of reading is given, a rich mixture is ordered and your truck won't start. Might be worth removing and cleaning this sensor from the intake tube if you haven't already. Wouldn't merely replace without knowing its output.

 

[Bedrck47]

The bad thing about doing bench testing is you are doing it under different conditions. cold vs. hot load vs. no load.

Try getting a can of starting fluid and the next time you get a no start spray a little into the throttle body and see if you get it to fire up. It will only run for a short time but if it does fire and then you try again and it doesn't start it could be something if the fuel lines

Maybe you have a fuel line collapsing. I know that sounds like a guess but it could prove to be a good guess.

How many miles are on the expy??

 

[Charles Musick]

The bad thing about doing bench testing is you are doing it under different conditions. cold vs. hot load vs. no load.

Try getting a can od starting fluid and the next time you get a no start spray a little into the throttle body and see if you get it to fire up. It will only run for a short time but if it does fire and then you try again and it doesn't start it could be something if the fuel lines

Maybe you have a fuel line collapsing. I know that sounds like a guess but it could prove to be a good guess.

How many miles are on the expy??

I was wondering about the hot vs cold bench test. Thats all I'm looking for is a few suggestions, and yours sounds good. I had thought about the vacum lines collapsing but didn't think about the fuel lines. Do you happen to know, If it were a coil pack would it only show bad when hot. I've heard they can crack and cause this. Is the crack visible. I'll try the starting fluid.
Millage 180,000. Been a good truck.

 

[Charles Musick]

I got a scan tool
ST FTRM1 % 5.4
LT FRRM1 % 25
ST FTRM2 % 3.1
LT FTRM2 % 25

From the reading does it seem that my O2 sensors are bad? Or not enough info?
Rps 749
Maf flow 6.28
I'm working today so still unable to pressure test fuel.
I did check the intake air sensor, and I think it's ok. If I'm reading correct.

 

[docraymund]

Based on your data, you may have a bad fuel pump check valve and a weak fuel pump. Though you didn't mention how it starts in the morning when it's sitting overnight. You need to get a fuel pressure gauge and monitor the reading when the engine is both cold and hot.

 

[jaytron]

sounds like a lose of vacuum...these motors are notorious for having pcv lines go bad from rot and wear....with motor on a idling rough spray some brake cleaner in the areas along the pcv line...if idle picks up to normal then you have a hole in the line somewhere