1988 F-150 5.8 liter 4X4

Fuel- All three fuel pumps are working sending fuel through the filter, pressure regulator, and to the rail where I checked the valve that has strong pressure, relay is working.

Spark- Newer plugs, wires, rotor & cap, battery was tested as good.

My engine cranks over and over but won't fully start. I'm not sure if the problem is spark or fuel. I pulled out a plug which looked real good, tried cranking a few time, and noticed a white weak spark. I also noticed that there was no gasoline getting to the plug. Is it possible that I need new injectors as far as the fuel problem? Not sure why I have weak spark?

 

Start by pulling the codes... see here. Ford Fuel Injection.

The computer won't fire the injectors if it doesn't get the right input from the sensors and particularly the ignition module on the distributor. The codes will tell you if you have an ignition fault. If you get an all clear you may just have tired wires or a weak coil. The page above also has tests you can run on the various components, wires should measure about 5k ohms per foot.

 

Yeah Rothschild
I'm in the same boat here. 92 F150 M/T 4.9L 150K mi. Seemed like The fuel pump was going bad when it was stalling coming back from work. Got it home and barely in the driveway. Spark plugs are wet with fuel after a few cranks, weak spark and starting fluid doesnt work. Codes come up 111 and a weird one, 151 that doesnt appear in any manuals. I bought the Haynes manual and will start checking for a bad PIP in the distributer tomorrow. Coil is good and TFI module checks out at the autozone so hopefully someone chimes in with new info.
From what I read in Haynes, there are alot of IFFY things to test with the distributer and I dont have the money to start replacing parts without solid proof .

 

A white spark is a hot spark.

 

bad timing chain????? Seemed like my truck did when my chain pooped the sheets. Line up timing mark on balancer and see where rotor points. if u have fuel and spark and starting fluid wont fire it thats the next place id look

 

Since the last time I posted, I had the computer check out & seemed to be fine. I got a noid light to check the injectors, checked 4 of them and none would light up? What is that telling me? Also, sometimes I can hear the fuel pump buzzing, and other times its all quite. I check the fuel pressure and I am getting accurate pressure. I was also wondering in an '88 F150, does my truck have a timing belt or chain? We still can't get the thing to run.

 

Your truck has a chain.

A question for you. When you turn your key to the on position, does the check engine light come on?

If so, I really think you need to pull the codes like Conanski suggested. Just pull them like the website says, and post them here.

I don't have enough info to say much more right now. Your fuel pump shoud come on for one second or so when you turn the key from off to on. If it does this consistently, I wouldn't go in the fuel system direction just yet. The pumps pumping don't necessarily rule out a lot, but if the pumps are pumping and there's fuel in the rails, I think it's probobly something on the electrical side somewhere and we need to find out what it is. Do you have access to a fuel pressure tester? If you've got 45 psi or so in the rails, you can rule out a lot of fuel system issues (but not all).

Let us know about the check engine light and the codes and see where we go from there. Also, just for S&G's have you cleaned the low voltage terminals on your coil and cleaned the high voltage terminal on the coil? My coil was just rude when I bought my truck. Maybe measure the resistance on the coil wire too for the heck of it? I think someone said 5K ohms per foot?

If you're feeling motivated, you can do is the following. This will prove or eliminate the ignition module or TFI module. I assume you have the type that's mounted to the distributor.

Pull the TFI module and take a peek at it. You'll see three pins on the top, and you would have removed a six pin connector.

The names of the pins are as follows:

1. The top pin farthest away from the big six pin connector is the ground
2. The top pin in the middle is the PIP Power
3. The top pin closest to the big six pin connector is the PIP-IN
4. With the three pins pointing up, the bottom pin (#1) on the big six pin connector is Ignition ground
5. The second pin going up is the tach pin
6. The third pin going up is the TFI Power pin
7. The 4th pin going up is the Start pin
8. The 5th pin going up is the SPOUT pin
9. The top pin is the PIP pin (do not confuse tihs with the PIP power on the top or the PIP-IN on the top)

It might help you to draw a picture of the TFI module and label it.

Grab your DVOM, set it to ohms, and

1. Measure from Ground to PIP-IN (the first and third pins on the top of the TFI module). You need to see greater than 500 ohms
2. Measure from PIP-Power (the middle pin on the top) and the PIP-IN (the third pin, the one closest to the big six pin connector). You need to see less than 2000 (2K) ohms
3. Measure from the PIP-Power (the middle pin on the top) and the TFI Power (the third connecton from the bottom of the big six pin connector). You see to see less than 200 ohms resistance
4. Measure from ground (the first of the top pins on the TFI module farthest away from the big six pin connector) and Ignition Ground (the bottom pin on the big six pin connector with the top pins pn the TFI module facing up. Expect to see less than 2 ohms resistance.
5. Measure from PIP-IN (the third pin on the top, the one closest to the big six pin connector) to PIP (the top connection on the big six pin connector with the 3 pins facing up). Expect to see less than 200 ohms.

If any of the above tests fail, you need a new TFI module.

Let us know how you make out.

 

Thanks for the information, I will get to it soon! Like I said, I am getting accurate fuel pressure, yes, up to 45 pounds of pressure. QUESTION: Will I be able to pull the codes eventhough the truck doesn't start or hasn't been running?

 

Yes, definitely.

Check real quick though and see if you check engine light is coming on when you turn the key from off to on. If it's not you won't be able to pull the codes, and I'll have another long post to write..lol

 

No problem...glad to have some support!

 

I just checked my truck. After turning the key, I get a red light to the left that just says "ENGINE" with a battery diagram right next to it. Is that the check engine light? If not, I am not getting one.

 

Wow... That's not good. Do you have the fancy insturment cluster with the tach (it sounds like you do)? If so, the lights are in this order: Left turn signal light (green) , check engine light (amber or yellow) , engine warning light (red) battery warning (red).

So, you shut the truck off and you turn on the key but not to start. You hear the pumps going, the red engine light turns on, but no amber check engine light to the left of the red engine warning light?

Try this. Take the key out so that the ignition is locked. Turn the key to the on position, but not to start. Let me know if the check engine light comes on. If it doesn't, you have a computer power issue, a computer issue or the check engine light is burned out.

Try it again and post me, and I'll get ready to start typing.

 

Well after giving it another try, I only get an engine warning light (red) & battery warning light (red), no turn signal or check engine light at all. I changed out the computer once, but didn't have the check engine light then either. Over to the right I get an anti lock light (yellow).

 

Sorry I wasn't clear. You won't get the turn signal light on when you turn the key. I was just covering light positions.

Give this a shot

1. The first thing you need to do is eliminate the bulb. Test the check engine light bulb by measuring the resistance with a DVOM unless it's obvoiusly burnt out. If you want, swap the bulb with your engine warning light and see if that still works.
2. I suspect that there's nothing wrong with the bulb, but you have to eliminate it first, otherwise the rest of this work is meaningless!
3. If there's nothing wrong with the bulb, disconnect the negitive terminal from the battery. Undo the cable on the solenoind that has all the smaller wires going from it. Clean the ends... get rid of any corrosion. While your at it, clean all the wires going to the solenoid. Hook everything back up.
4. See if you have a check engine light. Key off, the on. If so, start the truck and you're done.
5. If not, trace all of the smaller wires back looking for butt connectors or splices or melting or any other damage. If you find butt connectors, pull them off, clean the wires and replace the butt connectors on a temporory basis. In order to make these permanent, you have to solder and heat shrink.
6. See if you have a check engine light again.
7. If not, you'll need to test the fuesable links. I think the easiest way is to take a 12 volt test light, turn your ignition key on, connect the end of the test light to the negitive post and test each fusible link lead close to the solonoid, and then as far away from the solenoid as you can. If you have power the fuse link is good. If you don't have power, then you've got a bad fuse link and this will need to be repaired.

Good luck. I suspect you'll find something here. If not, don't give up, there's lots of other stuff to check after this. The trick is, until you see the check engine light coming on when you first turn the key, nothing's going to work as the computer is not happy unless that light comes on.

I might be a bit scarce this afternoon as I gotta do spindle bearings on my own truck so I might not be able to get back to you right away today.

 

How's it going? Any luck?