EFI installation dilemma

[HighwayThunder]

I've been trying to get my EFI to work for nearly a year now.

The main problem is that there is no signal coming from the HEI Distributor. The EFI injects fuel into the throttle body when it sees activity on the TACH-IN wire connected to the negative side of the coil. I have replaced the Hall Effect Module in the distributor 3 times with no success.

Then I thought perhaps there was something wrong with the magnets on the distributor shaft, so I said what the heck and ordered an entirely new HEI distributor (which required a new coil with a primary resistance of 0.5 ohms). Still no Module switching. I have looked at the coil negative with an Oscilloscope: it shows a flat zero volts when the starter is keyed. (It is not shorted to ground -- there is just no switching signal.)

I'm out of ideas on what to do to fix the problem. Anybody got any ideas?

Thank you.

Respectfully,
Richard

[simplyconnected]

On Pertronix, the reluctor must be in nearly perfect alignment with the hall-effect pickup. Too high or too low and output is erratic or zero. I don't have an HEI distributor to 'play with' but hall effect is the same with all of them.

For troubleshooting purposes, put your points back in. You will still get a tach signal.

Without seeing your setup and the inability to put my hands on, it's hard to troubleshoot from here in Michigan. You leave a lot out of your question.
You don't say what your 'starting voltage' is when you energize the starter motor. It may be too low for electronics to work. How good is your battery?
As with any distributor, you can take it out, connect it electrically (yes, with a good ground) and spin the shaft by hand. I would put a spark plug on a spare wire, lay the plug on engine metal, and connect the other end to the coil's center tower and spin it. If you get spark, look at your battery-to-starter motor connections. Electronics need FULL battery voltage. Points can run on full voltage without harm too, for a few minutes.

Remember, your electrical system doesn't run on 12-volts, it runs on 14.3 during normal operation. - Dave

[HighwayThunder]

Dave,
I was hoping you'd weigh in on this. Your suggestion gives me a new angle for figuring this out.

Thank you very much.

Respectfully,
Richard

[simplyconnected]

...Your suggestion gives me a new angle for figuring this out...

Richard, I'm here to help you. We tend to forget to step back 'a few squares' and start from the basics. Then, the 'forest for the trees' syndrome overwhelms us. An outsider or a fresh pair of eyes can be helpful, which is what I am because I realize you know this stuff.

Airing your issues in an open forum helps too. There may be other members who have your issues as well, even if it happens months from now. There are lots of people, more knowledgeable than me, that may impart their suggestions and experiences for all to read. There are no bad suggestions and we are not alone.

With regards to solid state components, they need at least ten volts to work. By contrast, points work when your battery is nearly dead, even when there isn't enough left to turn the starter motor. Many batteries have a dead cell, even when new, but the owner doesn't know it because he rarely ever measures battery voltage as long as the engine starts.

Who measures their battery when it's under starting load and with headlights on? My wife's Escape commonly starts with the automatic headlights on, even in Michigan winter temperatures after sitting all night. My point is, her electrical system demands a healthy battery which forces scheduled maintenance (or I will be wrenching in the cold). - Dave

[stubbie]

Richard is your EFI connected straight to battery or via a fuse block?

[OX1]

Which system is it again? The Fitech's seem to have "EMI" issues that many have not solved.

Some threads I found with a quick search

https://classicbroncos.com/forums/th...e-code.304396/
https://classicbroncos.com/forums/th...tion-q.297320/
https://classicbroncos.com/forums/th...sniper.288535/

https://www.youtube.com/watch?v=oseksQhKBCU

[HighwayThunder]

Here's the latest info on the EFI install: I gave up trying to get a usable tach signal from the "ready to run" HEI distributor, and installed a Capacitive Discharge Ignition module that outputs a good 12V tach signal. Now I've got spark and the ECU turns on the fuel pump, indicating 52psi pressure.

However, I don't seem to be getting much fuel (if any) from the throttle body. After trying to start the engine, I rubbed my finger on the inside of a throttle body cylinder and it's mostly dry. There is just a hint of fuel.

I'm wondering if there's an internal problem with the throttle body. Maybe the injectors are clogged, although I don't know how one would fix that. Or maybe the fuel pump pressure needs to be increased. According to the instructions the fuel pump is set to 58psi at the factory. There is a pressure adjustment nut on the pump.

[jopizz]

Are you getting power to the injectors so they open. If they aren't opening it doesn't matter if you have good fuel pressure or not.

John

[simplyconnected]

...I don't seem to be getting much fuel (if any) from the throttle body. After trying to start the engine, I rubbed my finger on the inside of a throttle body cylinder and it's mostly dry. There is just a hint of fuel...

EFI works opposite of a carburetor. Instead of controlling fuel, with EFI your accelerator pedal now controls AIR through the throttle body. The throttle body also includes a 'Throttle Position Sensor'.

I never heard of an accelerator pump in a throttle body or a fuel line going to it in a modern engine. Fuel is now totally controlled by electricity. More specifically, a pulse width signal that comes from a processor opens injectors. In order for this to work, there must be feedback inputs to the processor. The oxygen sensor in the exhaust and the throttle position sensor help the processor determine what is needed to produce 14.7 air-to-fuel ratio (stoichiometric ratio) as measured by the oxygen sensors after they get hot. A cold engine uses a 'canned program' before the oxygen sensors produce feedback. Every EFI system constantly hunts for this to attain the best efficiency and the most HP.

EFI systems want you to leave the gas pedal ALONE during startup, which is why modern cars rarely suffer from a 'flooded engine'. High pressure atomized fuel needs no accelerator pump. Carburetors that dribble fuel, do.

Having said all that, if you have a hot cam that produces very little vacuum, the throttle body AND injectors must be much larger than normal. These are factors that EFI systems cannot anticipate so these features must be understood when ordering. Otherwise as you can imagine, you won't get much fuel delivery or power output. - Dave