When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I am working on a 1990 F150 5.0 automatic 4X4 and I have a no start situation. I have 40Lbs of Fuel Pressure at the rail but it will not start. IF I spray Starting Fluid into the throttle Body it WILL start up and Die. So my Question is will the truck Start like that with a bad EEC relay or non powered EEC? I am new to Ford Fuel Injection so I have no clue.... I am hoping it could be the EEC relay and not the EEC itself.... This truck has been sitting a while (unknown how long) I have not tested for power at any of the injectors yet.... it was getting late and dark so hoping to go today again and test things.
Unfortunately you will need to do more diagnostic testing. Either the injectors are bad from sitting, the computer is not “firing” the injectors or both. A noid light will tell you if the computer is triggering the injectors to turn on.
Unfortunately you will need to do more diagnostic testing. Either the injectors are bad from sitting, the computer is not “firing” the injectors or both. A noid light will tell you if the computer is triggering the injectors to turn on.
Thank you for the reply. I am planning on going out there again today weather permitting to do more tests, But I was hoping for an answer to the starting fluid part.... Will the truck start without the EEC powered just by spraying starting fluid into the throttle body? It Seems the ignition (spark part) is seperate-ish from the EEC...... Looking at the 1 diagram I found. Not even sure it is remotely correct though. But it looks close.
Highly unlikely that all the injectors failed at the same time.
Basically, if the engine fires on starting fluid, then you know the ignition is good enough to start the engine. I would see if the injectors have power [you mentioned the fuel pressure is ok]. If it does, its not getting ground. The EEC not sending the ground pulse could be because of many reasons.
If you do not know anything about EFI, spend a few hours reading up on it vs looking under the hood. Don't shot gun parts. Save your money.
Highly unlikely that all the injectors failed at the same time.
Basically, if the engine fires on starting fluid, then you know the ignition is good enough to start the engine. I would see if the injectors have power [you mentioned the fuel pressure is ok]. If it does, its not getting ground. The EEC not sending the ground pulse could be because of many reasons.
If you do not know anything about EFI, spend a few hours reading up on it vs looking under the hood. Don't shot gun parts. Save your money.
Agreed. I am going to the various Mechanics shops local to me and using some of there test equipment. I already had to borrow a starter motor for the truck as the original was toast. (I assume last owner just let her spin trying to get it to start) I am planning on going out and testing for power at the injectors later today. I found this schematic that looks like it is correct for me. I noticed that the EEC relay Powers the Fuel Pump relay in that diagram and as I have fuel pressure at the rail and can hear the pump cycle, The EEC relay must be functioning. That will lead me down the rabbit hole of wiring issue from the EEC to the Injectors, Power to the Injectors or a Bad EEC. I am hoping it is not the latter.
Here's a screenshot from that link. Just remember that your truck's injectors are batch fired, not sequentially fired, like described in the link, and also, your firing order is different than described in the link.
Well I might have found the issue..... Looks like Mouse Urine and feces could have played a part in this failure. I am getting NO pulses on any of the Injector wires. I Do have solid 12 Volts on the red wires at the injectors. I am going to assume I have a bad EEC.
… But I was hoping for an answer to the starting fluid part.... Will the truck start without the EEC powered just by spraying starting fluid into the throttle body? It Seems the ignition (spark part) is seperate-ish from the EEC.....
You already answered your question when you said:
Originally Posted by DarrenA
I have 40Lbs of Fuel Pressure at the rail but it will not start. IF I spray Starting Fluid into the throttle Body it WILL start up and Die. .
The EEC and Fuel Pump relays have to be sending power to the computer for the PCM/ECM to be turning on the fuel pump. It dies because the starting fluid isn’t enough fuel. The computer controls ignition timing.
Originally Posted by 1Butcher
Highly unlikely that all the injectors failed at the same time.
That depends on your definition of failed. When I bought the Bronco II it would not run. Some of the injectors were dead electrically and others were clogged from the truck sitting for so long. I had to replace all six injectors.
Yup. Toast. You may be able to repair the components and revive the ECU, or just order a rebuilt unit and use yours as a core.
To answer your question: When the engine is cranking, the Ignition Control Module doesn't look at the computer and fires the sparkplugs purely off the PIP sensors raw signal coming from the distributer. After the engine starts, the ECU modifies the timing signal from the PIP to control the timing and spark. I've never tried to start an EEC-IV engine without a ECU connected, but I'm guessing it would run, very poorly, on just starter fluid.
That depends on your definition of failed. When I bought the Bronco II it would not run. Some of the injectors were dead electrically and others were clogged from the truck sitting for so long. I had to replace all six injectors.
You are correct, definition matters. In your case, if the injectors were clogged, the injector did not fail, it was the garbage that when through it, causing the injector to not allow fuel to pass. IF all the injectors failed [electrically] at the same time, I would ask myself what that would happen. Over voltage? Clowns, pretending to be mechanics, under the hood?
That is why for me, it is imperative to diagnose the problem. Know why the part is not working and why it has failed. 4, 6, or 8 individual injectors failing at the same time would be like winning the lottery that many times in the row.
