Hi guys,
Over the last year I have been rebuilding the engine in my 86.5. I bought this car out of Texas after the TB broke and bent the valves. I got a 55k miles engine from Mark Benton and, while changing the rod bearings, found a small piece of metal in the middle of one of the bearings. So, that lead to disableing the entire engine. So, the engine is back together and in the car. At first all it would do was click. So, got a new starter from Roger and then she turned over just fine but would not fire, even with starting fluid. So, after reading everything I could find on RL, I changed the CPS next. Now it will fire and even start for a split sec until the fluid is gone. I jumpered the fp relay and had 40lbs of pressure. I tried to start the car with it jumpered and no go. The car has the 24lb Ford injectors. I have all of Porken's stuff so I know that the timing is perfect. I checked the grounds on all the injectors that I could reach without dissassembly and had continuity on all. This was at the 4 corners. I have no idea where to go next.

Car is an 86.5 with an adjustable FPR, and Ford 24lb injectors. This is in preperation for the Porken Chips. The car did run before removing the engine, it just sounded like a garbage disposal with a spoon dropped in and had no power.

Any help will be greatly appreciated. I can't wait to hear her run...

 

If you have fuel pressure and fire, but the engine will not run, the usual suspect is the fuel injection relay.

The ignition relay, fuel pump relay and fuel injection relay must all work before the engine will run...

While the engine is spinning on the starter, you shoul be able to hear a regular "click" from each injector - one click per engine revolution. A mechanic's stethoscope is the tool of choice - cheap-cheap at Harbor Freight.

 

Thanks Wally, I have changed them all, but maybe I changed the bad one with another bad one. Now, I did rebuild the FI harness and added all new connectors. I have them both grounded at the rear under a 10mm bolt that holds the CPS connector. I checked the ground continuity everywhere I could think of and it was pretty darn good. I found a bunch of your old threads where you told how to test a bunch of stuff and they all checked out. Since I am by myself, I can't spin it over and listen for the injectors. Can you tell me the procedure for testing the relays at the board? Also, I did have some trouble getting the W connector back on the bottom of the fuse panel. Mabe I should remove the fuse panel again and check it out well. I had to take it loose to get the wireing harness out.

Do you or anyone out there know anyone in this area who would know how to troubleshoot this that I could hire for a few hours?

Thanks,
Frank

 

UPDATE:

After speaking with Miles at 928 Motorsports yesterday and reading Wally's post above, and not being able to sleep, I decided to pull the end caps from the intake and test the full FI harness. What I found I am not sure is correct or my issue.

Ok, I checked the ground continuity on each FI connection and they were great. Then I checked the continuity on the positive side of the connection with the positive side of the next injector and they were all great. Then just for kicks, I checked ground continuity on the positive side and got just as much reading as the ground side. I then tested them all and got the same thing. So, did I discover that the harness is shorting itself out? I believe this to be the case but am not familiar enough with the system to know for sure. If this is the case, and these connections are in series, then any short b3etween the wires on any terminal would short the entire thing. Is this correct?

If you know the answer to this, please respond ASAP, I would love to get this thing running today. My wife is having some very serious surgery early next month and so I am running out of days.

Thanks again for all your help,

 

Yes, a single shorted injector brings the whole thing down. Most commonly the shorts are inside the injector plug boot. You can't really inspect the inside without destroying the boot since they by now are quite brittle and are filled with some material that gets rock hard. It's common to find twisted frayed wires in there and the solution is to replace the entire plug, readily available for a few dollars on up. The boot is usually extra unless Roger or someone else has put together a kit. If you examined and replaced those, then check them and look elsewhere.

Since a short in the harness prevents the injectors from firing, it would not start at all. So, I'm not sure why your car starts briefly and then fails. That points to something else.

If the car "runs" on a brief spray of starter fluid into the MAF throat, something that has been criticized due to some fire/explosion hazard, then that establishes you have spark and points to fuel delivery as the likely issue. Of course, you can verify spark directly by pulling a spark plug and shorting it against the block while turning the starter. And you can verify lack of fuel by looking at the plugs - they will be dry.

A noid light would verify whether the injectors are getting the proper signal from the LH, but without that tool, with the ignition switch in the on position you should find 12V on both sides of the injector plug, not ground. The LH takes one side to ground to fire the injectors. So, the green/red [Correction: red/yellow] wires on each plug all go to pin 87 on the fuel pump relay, as does the O2 sensor and idle stabilizer - check fuse 42. Of course, if that is blown, the fuel pump would not run as well. The brown/red wires from each injector all go to pin 13 on the LH. Neither side should be ground.

You might have a bad LH. If you still find ground on the injector leads, you might pull the harness connector off the LH and see if the ground goes away. Turn the ignition off before you disconnect it.

 

It's a good idea to check injectors before installing. New, used, or rebuilt, they all stick if they've been sitting.

They should make a good clack when you hit them with 9-14 volts. If not, a few hits of power should get them working.

 

Thanks Bill and Ken, I just went through the harness. I had replaced all the connectors and to my embarassment had the wires on the wrong side on 7 of them. I fixed them all but still have the same issue. Bill it will only start with a shot of either, so I am pretty sure that the issue is in the FI harness. My wires seem to be red/yellow on the left side with the cutout facing up and the red/brown on the right side. On the #1 injector the colors are so obscured, im not positive but I think it was the only one turned the right way. Ken, if one of them was stuck, wouldn't it at least attempt to start?

 

Yes, they are red/yellow instead of green/red.

So, you have established you have spark, and it looks pretty certain there is no fuel being delivered. If the fuel pump runs when the relay socket is jumpered and you have verified that fuel is being delivered to the rail, then the FI harness or POSSIBLY the LH is the issue. Other than the individual FI plugs, I'm not sure where the next likely site for a short would be. Recheck whether each side of the FI plugs have 12V or not with the ignition switched on. If you find ground there on any of the plugs, you know you have a short to ground in the harness - no need to check them all.

 

Bill, I just went through the entire harness. I pulled the MAF and checked them all. I am not getting 12v with the switch on, on either side of the plug. Am I supposed to be putting my red lead on the socket and grounding the black lead to check for voltage? This is my weakest point of my skill set. I am not even sure I am checking continuity correctly. If i touch the leads to each other I get a good reading, I get the same reading touching the connectors to ground on each side. Get the same when touching each side of a plug with each other. I am getting these results with the LH disconnected and both ground straps for the harness disconnected....

Any other ideas? I have studided every connection on the harness and can see no possible place where a short could be. I just cut and re-soldered each connector this morning, ensuring that they were on the correct side of the connector. All but one that is. It looked correct. Should I go switch it just for kicks?

 

"Since a short in the harness prevents the injectors from firing, it would not start at all."

And there's a good possibility that the LH ECM was damaged as the injector driver lacks any
current limiting.

"I am getting these results with the LH disconnected and both ground straps for the harness disconnected...."

The LH ECM must be connected and the key 'on' to check for voltage at the injectors.

 

When a car wont start, I jump 87-30 on LH, EZF and FP relays sockets first. You may have done that, but that's sort of where I start. If the LH or FP relay are bad, you won't see 12V at the injectors. So, jumping eliminates that variable. If the LH itself is bad, you should see 12V at least on the red/yellow side with the ignition on or with the FP relay socket jumped but the injectors won't get a ground signal to fire from the LH.

Like Loren said, the tests should be with the LH connected. If you see ground on the brown/red side, I would then disconnect the LH (ignition off). You won't see 12V, but if the ground goes away. the problem is either the LH or the wiring to it from the injectors.

 

Thanks Bill. Loren, what I ment by that was I was getting ground continuity at the FI connectors even with all the ohter stuff disconnected. Bill, I will try your idea of jumpering the three relays. Take a little while to put it back together. I just traced the entire harness from the 1st injector back through the firewall to the computers to look for a possible short. Nothing stood out. Will put it back together and try again.

 

Ok, I decided to unplug everything on the wiring harness one plug at a time until the short went away. Unfortunately it went away after unplugging the LH. I guess that could mean it is bad???

 

"I guess that could mean it is bad???"

Not necessarily. Remember, the LH ECM enables the injector power. So if you unplug it,
there's no more power. The easiest test is to unplug all the injectors first. Then measure
any injector and you should read 12 volts on either connector pin. If only one side has
12 volts, then there's a short in the ECM or the harness. You can then disconnect the
ECM and use the ohmmeter to check pin 18 of ECM for ground. If it's open, then the
ECM injector driver is shorted internally, i.e. With all the injectors disconnected. Pin 17
of the ECM connector should be ground.

 

Thank you Loren. Man, what a crock. I have been working on this engine for over 6 months and run into something like this at the end just sucks. I have removed the intake tanks again and have access to all the injectors. I am going to pull the entire harness out where the whole thing can be reached. Then I will start where you suggested.