Yes, once again my stupid F350 is not starting.
1988 F350 - 7.5L Fuel Injected

And just so you know, I have flushed out the gas, so bad gas should not be an issue.

There are no engine codes to effect this. Any codes it has are from emissions things that have been missing for ages now, and were missing when the engine still ran normally.

So for.. ages now.. I have had a lot of no-start issues randomly. It has been re-occurring for quite awhile and I can't seem to get it to start now. The engine turns over and fires intermittently. It's not constantly firing, and it's just enough to make you think "It'll start!" but it never does. The engine makes plenty of power when it will actually start, but it just has fits.

I have 40 pounds of pressure at the fuel rail with the key on. (Just primed.) I also have spark at the plugs. Seems like a fairly strong spark. I have tried switching out the coil either way just to be sure, I have two other coils I have tried on it and they both have the same results.

I have checked and rechecked the timing again and again. I have done what I can to check the timing chain without actually pulling the cover. From what I can tell, it's fine and the engine is timed correctly. I've checked valve position with the engine at TDC, and I have done the test my manual says, which is somewhere along the lines of "put the engine at TDC and turn the crank, if it takes more then 5 degrees to see the rotor turning, the chain is worn." Well, it doesn't take 5 degrees for the rotor to turn so I assume i'm fine in that area.

So what's left here, compression? It's a fairly low mile engine, but it does a lot of sitting. (It's a wheeling truck, it doesn't get driven much.) I was going to put a little bit of oil in each cylinder to see if I could start it with that. I do not have a compression gauge on hand, so my best guess was just a little squirt of oil in each cylinder to help out compression if it were a problem. So I have spark, fuel and timing down. Compression does not seem really probable to me, but I will try some oil to see if it works.

If you ask me, this truck should frickin start right now. A problem I have had a lot of issues with is the ground wire that is by the battery, I have heard it is the ECU ground? Anyways I had soldered the wire and grounded it, but recently figured I would be safe and redo that. I opened the harness and cut the three grounds. I have them grounded to the battery and to the body, no help there.

Another problem I had a a couple years back is that my ignition switch was all effed up. The key stopped making it start, my remedy? Push button start. I have been running it for awhile and it has not made any difference to the starting. The key still needs to be in the on position. (Fuel pump and everything need the key.) The button just made it turn over. I assume my signal wire was screwed up somewhere along the line, so I just put the button in. The neutral safety switch was giving me issues ever since my new transmission went in. The wires had to be switches around because of a plug issue. I believe some of the stupid "crimp" connections were not getting a good connection, but it is now hot wired so I can be sure it's not an issue. (Not that it matters with my start being engaged by a push button.)

The MAP sensor is new-ish and was working last time I checked.

The TFI module is new. Or, newish I should say. I replaced the distributor with a known working one a few months back, and it was running good for awhile. I grabbed the multimeter, which I might add I can't work worth a damn, and started testing things.

I did the "PIP stator sensor checks" for the distributor mounted ICM, it says it should be between 3 and 8.5 AC volts. The spout sensor a/c voltage should also be 3 to 8.5. Both are going up to 9.0, if I tested it right. That seeems like an issue to me, but I have no effin clue how to remedy it. My manual says to "locate the SPOUT single wire connection near the ignition module and disconnect it." If voltage is in range, the ICM is shorting something something blah blah blah. And could the .5 that is out of range even be my no-start issue?

If someone wants to "Dumb that down." for someone not at all oriented with this kind of thing, that would be great.

Well I really don't know what else to put. If you have a suggestion, please do your best to at least give me some kind of idea how to test these parts before suggesting to replace them. I am by no means made of money, and this truck is getting on my last nerve, so i'm not going to just go buy any random part that is suggested to be bad.


Thanks for reading.

 

Don't know if it is the same on my '94 460, or yours but.....I spent weeks last summer tracking down a no start, no spark/intermittent spark problem on my '95 F150 with a 351W. I replaced everything: Two new fuel pumps (rear one was shot anyway), new ignition control module, new coil, new plugs, wires, cap, rotor, etc. etc. Finally, I tore apart the distributor and installed a new magnetic pick-up inside it. It fired right up, and I have had no problems since. Well, ignition problems that is.

 

A magnetic pick up? I'm really not sure what that is. But like I mentioned I swapped out the distributor a few months ago. So, whats the difference between the TFI Module and the ICM? Or is the TFI on the ICM??! If I knew more about all this electronic stuff, I'd probably have my issue tracked down already. I forgot to mention it has new plugs, cap, rotor. Wires are... fairly new, and still in good condition. Have not been run long enough to have issues. I don't think I should replace the fuel pumps, as my fuel pressure is at 40psi. (Its supposed to be between 35-45. So I think that's just about perfect.

Thanks for the reply.

 

If you have good spark and good fuel pressure that only leaves the injectors not firing off. Other than major internal engine problems of course.

 

I do recall testing the injectors to see if they were firing, but a couple clogged injectors is a possibility..

 

A couple of clogged injectors would not keep it from starting.

 

The magnetic pickup is a little part inside the distributor that has a slot in it. It reads the breaks in the side of the round part that fits inside it. At least in my '95 351w. I am not sure if my 460 even has one. Just throwing out some suggestions. It's always the little things that seem to be the hardest to track down.

 

Indeed. As for the injectors, who knows if it's a couple, or all of them, or any of them?

Any other idea's? The injectors are indeed pulsing, so it's just a matter of fuel flowing through them.. which i'm sure there is. (As sure as I can be without removing them.)

 

How long ago was it when the truck last ran?

 

Not sure exactly. Why do you ask?

 

Well, if the engine has ran in the last couple weeks it would be highly unlikely the injectors could all be plugged. If it hasn't ran for 6 months, the injectors could all be plugged, but I would still doubt it.

 

Give it some starting fluid........just a small amount, and see if it does anything. If it does rules out a spark issue. I would guess the icm or tfi.........same thing is a first possabality. Second is the pip or pickup coil, which is under the rotor in the dist. Dist gear has to come off and the dist. shaft removed to change it. have the module tested at a autoparts place and have them test it enough to get warm. I have had a bad module, or tfi give me spark but not start the truck.

 

Starting fluid makes no difference. It still does the intermittent firing.

The tfi module is newish. I replaced it a few months back while trying to diagnose the no-start then. It wasn't bad, I was just throwing parts at it. Something i'm trying to avoid this round.

I put a little oil in each cylinder, and will go out and reinstall the plugs and try to start it.. hoping it raises compression and starts? If that doesn't work I will pull the fuel rail and see how the injectors work.

 

When the T.F.I. module goes out, it is completely out. No partial working. The pickup inside the Dist. can cause an intermittent spark.

 

Yep. That's what mine was doing. Would only start when it wanted to, but not very often.