1986 740 turbo crank no start issue

1986 740, B230FT LH 2.2 Crank no start issue.

Car cranks over with no sputtering or attempts to start up at all. Car will start and run if fluid is sprayed in TB until you stop spraying.

Fuel is present in rail, spark is also present. Cam is turning, along with belt. Tach moves as you crank. New main and secondary fuel pumps, along with new fuel filter. Both pumps are working, fuel pump relay confirmed working. New plugs, wire, cap, rotor.

Also to confirm, being that this car is a 1986 it is not equipped with an RSR as far as I can tell,
eliminating that from the equation.

What's next, FPR? No unit on hand to check fuel pressure. Diaphragm on current FPR is not ruptured. All Injectors not firing? Fuel computer shorted possibly? Is there a way to test this without buying a new ECU?

Since it runs on fluid it's likely a fuel issue. Test light to injector negative and check for blinking.

Test for power to main fuel pump.

You could also pull the relay and do electrical tests with the cover popped off.

dfk said:

1986 740, B230FT LH 2.2 Crank no start issue.

...

What's next, FPR?

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I presume the car has been running and not sitting?

You definitely need a fuel pressure gauge. There are a number of items that could prevent you from having enough fuel to run.

The fuel pump relay would be highly suspect. But also note that you have a year model that likely has the biodegradable wiring... Is your wiring harness oil soaked in the engine compartment?

ZVOLV said:

Since it runs on fluid it's likely a fuel issue. Test light to injector negative and check for blinking.

Test for power to main fuel pump.

You could also pull the relay and do electrical tests with the cover popped off.

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+1

Checking the fuel pressure on these is a pain, I've never been able to find a suitable adapter, should probably make one some day. I agree with the advice of checking for injector power, any kind of 12V test light will work. Just find some wires you can poke into one of the injector plugs without damaging it.

James10952001 said:

Checking the fuel pressure on these is a pain, I've never been able to find a suitable adapter, should probably make one some day. I agree with the advice of checking for injector power, any kind of 12V test light will work. Just find some wires you can poke into one of the injector plugs without damaging it.

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Get a fuel rail with a schrader.

Don't all of the fuel rails that have schraders also have the 5th injector for LH 2.4?

It's a moot issue for me anyway since the 2.2 car I had got rear ended and totaled and my current car is LH 2.4.

I always test whatever is fastest and easiest to access. In this case, isn't there a fuse for the main pump? Instead of pulling the relay or going under the car I would first start with checking for power for the pump at the fuse.

The efi/fuel pump relay commonly craps on these. That's why I suggest you start with checking for fuel pump power since it runs on fluid.

Pumps are both running. Currently in the middle of repairing harness. Anyone have a good diagram that doesn't make me want to end my life? Have some weird looking stuff in the harness.

Weird as in the insulation has disintegrated? That's not weird on an '86, it's par for the course.

Go to Dave Barton's website and order an updated one, and save yourself a thousand headaches.

88 is when the wiring got better.

The older ones fail by the firewall plugs and mainly under the inlet manifold.

One test that is risky but tells you a lot: pull the rail, reground the wires, aim injectors at sky, and see if they spray. Disable the ignition coil. I started a fire once doing this, but the only tool needed is a 10mm socket.

Shifted said:

Weird as in the insulation has disintegrated? That's not weird on an '86, it's par for the course.

Go to Dave Barton's website and order an updated one, and save yourself a thousand headaches.

Click to expand...

Weird as in I have a collection of black wires that are ended with a metal bracket and heatshrinked over, can provide a picture if that makes no sense

ZVOLV said:

88 is when the wiring got better.

The older ones fail by the firewall plugs and mainly under the inlet manifold.

One test that is risky but tells you a lot: pull the rail, reground the wires, aim injectors at sky, and see if they spray. Disable the ignition coil. I started a fire once doing this, but the only tool needed is a 10mm socket.

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Did this, but with a less dangerous and hardcore method, pulled the rail, unplugged all but one injector plug at a time and aimed it into a plastic container, nothing. No clicks, no fuel. Any tests to make sure the resistor pack is working as intended?

dfk said:

Weird as in I have a collection of black wires that are ended with a metal bracket and heatshrinked over, can provide a picture if that makes no sense

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That sounds like your ground.

dfk said:

Did this, but with a less dangerous and hardcore method, pulled the rail, unplugged all but one injector plug at a time and aimed it into a plastic container, nothing. No clicks, no fuel. Any tests to make sure the resistor pack is working as intended?

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Did you reground the fuel rail grounds?


Did you check for power at the positive wire for the injectors?
Do this before worrying about rez pack, but it's worth a visual of it.

Do you have power to the fuel pump?

dfk said:

Anyone have a good diagram that doesn't make me want to end my life? Have some weird looking stuff in the harness.

Click to expand...

I got good, legible diagrams for my 240 and 740 by going to my local library and photocopying the diagrams contained in their volumes of the Mitchell auto repair manuals.

ZVOLV said:

Did you reground the fuel rail grounds?


Did you check for power at the positive wire for the injectors?
Do this before worrying about rez pack, but it's worth a visual of it.

Do you have power to the fuel pump?

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Yes, Yes, Yes.

Wiring harness is repaired, throwing it in and then checking rez pack

Ok so power to the injectors is good. That means your rez pack is ok if you have 12v on all 4 injector positives. I guess current could be low, but that's unlikely.

Next I would be checking for injector pulse. A test light on the negative should blink while cranking. A noid light would be nice. Or a screwdriver tip to the injector and the handle touching your ear and a friend or remote starter crank. Or a stethoscope, or a spare injector in your hand to feel for operation, or a needle probe backprobing the injector negative and a labscope. It's a universal tool when a test light is tough to shove into a connector. Never front probe!

You asked how to diag the ecu. Well first you would check for injector pulse. Then if none, see if the Ecu has proper power and ground. Then you would check for input signal, which in this case comes from the EZK box, which gets it's input directly from the crank sensor. You know the crank sensor work a because it runs on ether.

Fuel pressure should also be verified. Or at a minimum, verify voltage to the pump. You could have a bad fuel pump relay, fuse, or wiring, but you need to test for this. On a 740, there should be a main pump fuse. Spare yourself from crawling under the car and verify voltage here during cranking. If no voltage, suspect the relay. Apply 12v to the pump or fuse directly and see if the car starts.

You wrote fuel is on the rail, but how do you know if you have no gauge (if you have pressure or not?)
Just dribbling out doesn't count

You can do the shade tree thing (since you don't have a gauge) and depress the valve core at the test fitting while a helper TAPS the starter (just be smart and don't start a fire) to get an idea - if it sprays out hard that's a pretty good indication you've got some pressure

If you have fuel pressure, spark and 12V+ at the injectors then your injector pulse is missing
You have an open circuit on the control side or an ECU problem

ECU is the LEAST likely unless there's more to this story than has been told

Control reg's not going to affect that (the injector pulse)

Done any recent work on the car? Maybe left something unplugged or not fully seated? Loose or disconnected ECU ground? (there's more than one)

You can use a piece of fuel hose and a funnel or a long thin screw driver with a hard handle (if you don't have a mechanics's stethoscope) and listen to hear if the injectors are clicking while a helper cranks the engine

From what you've said though I don't think you will - you have an open ground circuit somewhere - that's what that bundle of black wires is for one - grounds