I've been experiencing starting problems on my '87 F150 302 AOD for some time now. When I come out to the truck in the morning to go to work, it starts immediately (the engine doesn't even turn over all the way). After I turn the engine off, it won't start. It acts like the starter is dragging or something because it hangs for a second before it starts to turn. I have replaced the starter however, and it still does this. I used to believe this was related to the timing at startup. The reason is that I could pull the SPOUT connector and get the truck to start, then I'd plug the connector back in. Well now that little trick doesn't even work. When I turn the key and it just turns and turns, there is a real bad smell of gas like it is flooding. While troubleshooting yesterday, I unplugged the high pressure fuel pump. Every time I tried to start it, it would start but die within a few seconds. This obviously because the high pressure pump wasn't running. So, I'm wondering if the fuel pressure relay might be the culprit? Does it make sense that the high pressure fuel pump not come on until after the the ignition key is back in the run position? Sorry this is so long. I can also post a list of parts I've replaced if necessary.

Thanks,
Joel

 

I had that kind of problem on my 73 olds cutlass...it start up just fine, but would not start after it was warm. I found that it was that starter. Never got the chance to buy a new one, mom sold the car.

 

I replaced the starter this weekend, and it still won't start when warm.

Thanks though.

 

The story on this truck is...... I bought it in a non-running condition. I have replaced the following parts through diagnosing with a multimeter, fuel pressure gauge, and compression tester.

right side head gasket
intake gaskets
right exhaust manifold
power steering pump
power steering gearbox
throttle postiion sensor
starter solenoid
starter
pip sensor
ignition control module
coil
spark plugs
spark plug wires
battery
fuel filter
egr valve

The only codes I'm getting are 33 and 29. I know 33 is egr related. I believe the sensor that sends vacuum to the egr is the problem. The 29 is a vehicle speed sensor. I'm not sure what this does to the performance of the truck. I will say that the truck seems to upshift too early and then the rpms are too low and it chugs until the rpms come up (and speed). I don't know if it's related, but thought I'd mention it.

I pulled out the fuel pressure gauge again last night. I turned the key on, engine off, and I got 40 psi. After starting the truck (unplugging the fuel pump to get started, then plug back in) the pressure was at 36psi. I unplugged the vacuum line on the regulator and pressure went to 41psi. I plugged it back in and pressure went back to 36psi.

I'm wondering if the high pressure fuel pump is supposed to run during the start sequence? I'm not sure if mine is when plugged in.

Thanks for your time.

 

Sounds like you are getting somewhere. I'm no expert mechanic so take my advice cautiously. I do make plenty mistakes but I try to make sure they don't cost much. I generally avoid the '87-89 trucks because of the 3 pump system but they can run just as well as later trucks. My problems were that high pressure pump would short out or the dual function reservoir did not work right.

Haynes #36058 p. 4-1 specs show that your truck is within the limits. Now why doesn't truck start with pump plugged up? And why the flooding gas smell? We could be leaking gas somewhere or not getting the proper fire to combust the fuel or some other reasons. Since your truck runs fine after cranking, I'll assume timing is correct. There was a thread here a few days ago about a truck with similar problems and they had luck changing TFI ignition module. I have absolutely no experience in this because my fuel systems mess up more often than the ignition. I did reference the same Haynes and p. 5-9, under Preliminary checks. The fuel pump should run for a few seconds. If pcm is not getting voltage, pump will not run. Check relays/fuses under hood. Consult owner's manual for location for fuel supply and EEC or VPWR. If you are getting power to the pcm, I'd check the ignition module. I know you already replaced it. Maybe there is an open short circuit somewhere preventing it from operating properly.

 

I read on this site that a few people had problems with the ignition modules. Someone said they put three different ones in before they got a good one. I tried to take mine back to Autozone a few weeks ago, but the guy said they had a tester. He tested it and said it was good. Maybe I'll try it again.

Is it possible that the injectors staying open during the start cycle? This would cause the flooding smell and no start. It might also explain why the truck will start with the high pressure fuel pump turned off. How would I check the injectors during start up? Put an analog ohmmeter across each injector?

 

Check the fuel pressure on the rail. After you turn the truck off, if the pressure leaks down very quickly, I would guess stuck injector, granted this is turning the truck off, not on as you described. Checking with an analog ohmmeter is also a good way.
When the guy at Autozone tested it, did he test it many, many, many times to get it to heat up enough to simulate a hot start condition? Having worked at AZ in the past, that was one of the common mistakes done when check the ICMs for our Fords. If it doesn't get very hot to the touch when testing, then it'll just show how it'll work cold and not where you're having your problem. You can check the ICM using a multimeter and a Haynes manual. That may be a better guarantee than having them test it.

Good luck,
Luke

 

I did check the leak down and it was within spec. It dropped very slowly and stopped when it got to 35 or 36 psi.

The guy at Autozone did run the test 5 or 6 times to get it hot. It passed every time.

Good ideas. Keep them coming.

 

I'm still looking at alternatives but will have to get back on that. Right now I am still concerned about wiring going from ign module to pcm. I am also wondering how the fire is when your truck does not crank. I understand when it does crank, it runs fine. Could be possible that why ever the pressure pump doesn't run, also prevents truck from firing. I know you said that it would crank with the pump unplugged for awhile so probably you are getting fire. All fuel tests so far indicate the problem is either electrical or ignition. I have a good fuel injection book, I'll look at later and get back to you.

Were the 33 and 29 codes with key on, engine off or running or in continuos memory? 33 is common on older trucks. Either EGR valve is sticking open or sticking closed. Cleaning with carb or brake cleaner sometimes helps. 29 means that pcm is receiving signal with too low voltage from VSS. I don't have any experience with VSS problems but will also look for more info. Bad sensor or partial broken wiring? Or possibly gears were changed or tire size without recalibrating speedometer? Good luck.

 

I'm starting to wonder if the computer is sending a bad signal to open one or more of my fuel injectors during the start cycle. I have two computers though and get the same results with either one. I'll look at the wiring diagram for the fuel injectors tonight.

Both codes were continuous. I got no codes during koeo. The code 33 shouldn't have anything to do with my starting problem. I'm not sure about the 29.

 

This sounds a lot like a bad module but , since you've had that tested several times, let's look in another direction. I was leaning towards the PCM but, now you say you tried another one? Are you sure IT was a good one? How about parts inside the distributer that are used to send the signal to the module? Can you check to see if it has a good spark? Do you or can you get a "noid" light? You can plug that into your injector harness and see if they are firing.

The 29 won't affect your trying to start it.

 

I don't know if either pcm are good. I bought the second one at a salvage yard out of a wrecked 87 bronco. It might be junk as well....... I also replaced the pip sensor (also called a pickup coil) inside the distributer when I replaced the ICM. I think that's what you're talking about. I'm not sure what a noid light is. I do have a test light that I could stick in the back side of the injector harness. Would it light up as the injector is energized. I must also note that I can only get to the four injectors on the drivers side, and possibly the front injectors on the passenger side. The upper intake blocks the other three.

 

If you're getting fuel to the cylinders. Which it sounds like you are at least to a few...I'd think the truck would at least fire.
How hot does the ignition control module feel when its not starting - will it start if its even hot?

You have twelve volts at all the relays? (key in run postion engine off) .

I might of missed it but do you have a healthy spark when hot?

I'd check voltages at key components when cold and hot and see if you have a connection thats intermittent. Relay area, tfi area could be heat is causing enough expansion on a poor connection that you're getting this no start condition.

A bad thing to do but would work to verify if you are getting spark is "mist" fuel into the throttle body while trying to start hot. If it fires up or tries you got spark -- don't use ether --or ignore my comment totally --bad things happen when not done right or starting fluid is used.

 

I'm still leaning towards the PCM. You should go to the parts store and get a "noid" light and a spark tester. A test light won't work.

If you have 40psi at the rail, that should be plenty and I wouldn't think you have a pump problem. It is the PCM's job to "fire" the plugs and the injectors. It relies on the signal from the module though to know that the motor is turning. If you have spark, than It would seem that the PCM is seeing the signal....If you use a "noid" light and it don't flash, then it would seem that the PCM isn't sending its signal.

Another thought...how many volts do you have at the battery when this happens? You must have a min of 10.6 in order to operate the computer.

 

It soounds like your timing is out and yes the speed sensor is very important as I believe it tells the computer how fast you are going and the computer uses this imfortmation to control fuel and ignition. maybe it's time for professional help.

kn.