'86 MJ 2.5L ECM....good?

[SoCalManche]

I also soldered an addition ground to the fuel pump harness and chassis, per Cruiser tip 20-something, and added an addition ground to the driver's side rear taillight grounding point.

[eaglescout526]

1 minute ago, SoCalManche said:

I don't have a ground going to alt bracket, but rather from neg post to radiator bracket.

 

Yes confirmed spark. I can dump some fuel into throttle body and it will fire until all fuel added was burned off.

Huh interesting. So the MAP circuit and the fuel pump are affected. Hmmm let me see what the diag chart says.

[SoCalManche]

1 minute ago, eaglescout526 said:

Huh interesting. So the MAP circuit and the fuel pump are affected. Hmmm let me see what the diag chart says.

Maybe the wiring at the dipstick stud is toast?

 

[eaglescout526]

Could be. You have verified that the pump does indeed work correct?  Theres a few possible causes for engine not starting but most aren't the issue. But it seems fuel related as you said the engine fires when given fuel. But still that MAP circuit is concerning. 

[SoCalManche]

Just now, eaglescout526 said:

Could be. You have verified that the pump does indeed work correct?  Theres a few possible causes for engine not starting but most aren't the issue. But it seems fuel related as you said the engine fires when given fuel. But still that MAP circuit is concerning. 

Yes, I can throw a fused jumper wire in pins 87 and 30 and it will immediately start pumping. I did notice after doing my tests a while ago that the relay was cycling quite a bit while key was ON.

 

Is there a way to test for voltage to the injector? I honestly don't think it is getting a proper power supply either.

[eaglescout526]

here's a couple tests from the book

 

Injector resistance is too high, Ohmmeter should indicate less than 10 Ohms.

 

ECU is not switching the injector. Remove injector harness connector. Connect a test lamp to the connector. Engage starter the starter motor. The lamp should pulse dimly.

 

These are the only tests I found for the injector.

[SoCalManche]

3 minutes ago, eaglescout526 said:

here's a couple tests from the book

 

Injector resistance is too high, Ohmmeter should indicate less than 10 Ohms.

 

ECU is not switching the injector. Remove injector harness connector. Connect a test lamp to the connector. Engage starter the starter motor. The lamp should pulse dimly.

 

These are the only tests I found for the injector.

Ah, okay. I'll have to get a test lamp then. 

 

Would it be dumb to solder the wires together that end up at the dipstick tube?

[eaglescout526]

I have no idea what the soldering would do. Probably would make it more challenging to replace the rings if they disintegrate.

[SoCalManche]

Just now, eaglescout526 said:

I have no idea what the soldering would do. Probably would make it more challenging to replace the rings if they disintegrate.

Well the torx bolt is already too stripped to pull out of the block. I had to cut the wires once and re-crimp them with new eyelets after refreshening the ground. I'm contemplating re-cutting and re-crimping the wires again, and the thought of soldering entered my mind. 

 

Do you any better ideas than re-crimping?

 

[eaglescout526]

Oh ok I see what you’re saying now. Soldering them at the crimps will help. Nope none enter my mind unless changing where the sensors ground at but I’m sure somebody else would speak before telling you to change the ground for the sensors. 

 

Odd that you have a torx bolt for the dipstick. 

[SoCalManche]

1 minute ago, eaglescout526 said:

Oh ok I see what you’re saying now. Soldering them at the crimps will help. Nope none enter my mind unless changing where the sensors ground at but I’m sure somebody else would speak before telling you to change the ground for the sensors. 

 

Odd that you have a torx bolt for the dipstick. 

It's the same for my TJ too. Was torx incorrect to say? Star-headed bolt that typically fits a 7/32" ratchet/wrench size. Has a nut on it to torque down the eyelets.

 

[SoCalManche]

Welp, looks like I'm back to square one when I first attempted to figure out this issue a year ago. 

[eaglescout526]

My block has a standard hex head. That’s why I find it odd. 

 

We will get this figured out. Know of any rodents that could’ve gotten in?

[SoCalManche]

Just now, eaglescout526 said:

My block has a standard hex head. That’s why I find it odd. 

 

We will get this figured out. Know of any rodents that could’ve gotten in?

Not that I'm aware of. I'll give you the big picture on how this issue happened.

 

I was driving to the machine shop to drop off the block of my TJ and I was racing against the clock to get to a gas station to fill up. Well, the truck died about a block away from the gas station, figured from running out of fuel. I found a gas can, threw 5 gal in the tank, and it hasn't fired since (minus throwing a bit of fuel down the TBI). That's where I am today. 

 

Grounds have been refreshed since then, and the baseline is still that she will only fire with a bit a fuel thrown down the TBI, with additional grounds added where Cruiser has recommended.

[Ωhm]

You mentioned the fuel pump motor runs when you jumper the fuel pump relay. With relay removed and jumper in place, does vehicle START and RUN?

[SoCalManche]

1 minute ago, Ωhm said:

You mentioned the fuel pump motor runs when you jumper the fuel pump relay. With relay removed and jumper in place, does vehicle START and RUN?

In the past, when I tried to start her up with jumper wire in place of relay, it did not work. I will go try right now.

[SoCalManche]

9 minutes ago, Ωhm said:

You mentioned the fuel pump motor runs when you jumper the fuel pump relay. With relay removed and jumper in place, does vehicle START and RUN?

So same thing is occurring;

 

With relay in relay socket, the truck will START with fuel added in TBI.

 

With jumper wire in relay socket, the truck will not START with fuel added in TBI.

[Ωhm]

That confusing since jumper wire is acting like a relay would. So with relay in, truck will START and RUN when fuel is added to TB, but will START and not RUN when fuel is added to TB using the jumper wire.

[eaglescout526]

Hmmm. 

 

Something is funky with the wiring and I'm not sure what. Would an 86 have two of those five pin connectors by the relay center?

[SoCalManche]

I am aware it seems confusing, but that is correct. Jumper wire will keep the truck from starting somehow, but will engage fuel pump. Relay will not engage fuel pump, but will let truck START. I will go out again to verify for sure that truck will not START with jumper wire.

 

Edit: I just re-read you, Ohm. Truck will not START with jumper wire. It will just continue to crank. But again, let me go see if I can make it START with jumper.

[SoCalManche]

7 minutes ago, Ωhm said:

That confusing since jumper wire is acting like a relay would. So with relay in, truck will START and RUN when fuel is added to TB, but will START and not RUN when fuel is added to TB using the jumper wire.

So I concur with my initial assessment;

 

With the relay in the socket, the RPMs flutter when I flip the key to START, to where the engine will FIRE, but it is an extremely rough FIRE (to be expected considering the minimal fuel added to TBI). With the jumper wire in the socket, the RPMs do NOT flutter at all, and it makes no attempt to FIRE. It will crank like a madwoman, but no FIRING occurs. 

[Ωhm]

Under both conditions (relay/jumper wire) you added fuel to the TB?

[SoCalManche]

1 minute ago, Ωhm said:

Under both conditions (relay/jumper wire) you added fuel to the TB?

Correct.

[eaglescout526]

RPMs fluttering would be a possible MAP sensor issue or something with the EGR and its solenoid.

[Ωhm]

Yes there seems to be a difference, but I just don't understand what it could be.