New guy.

[76lcmike]

what does the fuel look like, water, e85, Deisel or just s*** gas.

 

[MissahPapaJ]

If you have a multimeter OHM check your temp sensor, one for the gauge and one for computer logic. Find the one for the ECU and OHM check it engine cool. Find the specs there will be a OHM spec for different temperatures find out the scale from the FSM. If the sensor always thinks it’s -10 degrees outside it’s gonna be pumping in extra fuel to try to warm up the vehicle faster and will cause a rich condition and if the sensor never rises to tell the computer the engine is warming up the engine will just keep running rich. At least it’s worth a shot. Could also be damaged or oxidized wiring to the sensor.

 

[jonheld]

I don’t have some of the tools to test electrical parts. I got a basic multimeter and that’s about it. Thanks for the EFI relay info.

1986 technology. All you need is a multimeter and the FSM.
EFI Fuse, not relay. Pulling the relay will not kill power to the ECU. It will just prevent the truck from starting.

 

[kvos40]

what does the fuel look like, water, e85, Deisel or just s*** gas.

Fuel looks and smells good. New fuel filter.

 

[kvos40]

If you have a multimeter OHM check your temp sensor, one for the gauge and one for computer logic. Find the one for the ECU and OHM check it engine cool. Find the specs there will be a OHM spec for different temperatures find out the scale from the FSM. If the sensor always thinks it’s -10 degrees outside it’s gonna be pumping in extra fuel to try to warm up the vehicle faster and will cause a rich condition and if the sensor never rises to tell the computer the engine is warming up the engine will just keep running rich. At least it’s worth a shot. Could also be damaged or oxidized wiring to the sensor.

I’ll dig in the FSM it seems like there is a few different coolant temp sensors. The FSM is kinda all over the place so I’m gonna have to figure out where it is in there.

 

[jonheld]

I’ll dig in the FSM it seems like there is a few different coolant temp sensors. The FSM is kinda all over the place so I’m gonna have to figure out where it is in there.

Having a .pdf copy of the FSM and EWD makes searching for terms pretty easy. Took all of 3 minutes.

Water temp switch is for fuel pressure control. FI-78 in the FSM.
Water temp sensor is for the ECU. FI-77 and A-8 (service specifications).
Water temp sender is for the dash gauge. Has no effect on anything other than the gauge.
Cold start injector time switch. FI-76 and A-8.
Cold start injector. FI-52.
BVSV valve. EC-7.

 

[kvos40]

Having a .pdf copy of the FSM and EWD makes searching for terms pretty easy. Took all of 3 minutes.

View attachment 4186823

Water temp switch is for fuel pressure control. FI-78 in the FSM.
Water temp sensor is for the ECU. FI-77 and A-8 (service specifications).
Water temp sender is for the dash gauge. Has no effect on anything other than the gauge.
Cold start injector time switch. FI-76 and A-8.
Cold start injector. FI-52.
BVSV valve. EC-7.

This is gold thanks dude! So I disconnect the water temp sender the water temp switch and she ran good no bouncy idle once it warmed up a bit. While I was sitting there in Drive messing with the center locker. It shut off and wouldn’t start again. I’m gonna test the water temp sw. looks like I can get a new one for 40 bucks. How does this fuel pressure seal work when it’s desmogged? Don’t you take all the VSVs out ?

 

[jonheld]

This is gold thanks dude! So I disconnect the water temp sender the water temp switch and she ran good no bouncy idle once it warmed up a bit. While I was sitting there in Drive messing with the center locker. It shut off and wouldn’t start again. I’m gonna test the water temp sw. looks like I can get a new one for 40 bucks. How does this fuel pressure seal work when it’s desmogged? Don’t you take all the VSVs out ?

Again, all info is in the FSM.
I've never desmogged my 3FE, but I wouldn't remove the fuel pressure VSV.
There are several threads on desmogging a 3FE on this forum. Do a bit of searching and I'm sure you'll find the answers.

 

[kvos40]

Alright guys we definitely have some grounding issues I cleaned the grounds on the right side of the engine bay while changing the dizzy. Grounds and ohm out at 2.5-3 ran the engine to adjust the dizzy got it running great idle was a little high but ok over all. The engine got to operating temp and it started running like s***. For s***s and gigs I checked the ground and they were at 25- 30 ohms. One other weird thing is we could get it to run good for a second by wiggling the harness that goes to the dizzy. Idk if that’s because of the ground issue or its own issue. Next plan of action is to change the ground cables.

 

[jonheld]

One other weird thing is we could get it to run good for a second by wiggling the harness that goes to the dizzy. Idk if that’s because of the ground issue or its own issue. Next plan of action is to change the ground cables.

The truck is talking to you but you're not listening.
If wiggling the distributor harness changes the way the truck runs, then there's an issue with the wiring to the distributor.
There's 3 wires with a shield.
ENGINE CONTROL section of the EWD gives a complete layout of the ECU and all connections/sensors.

Yes, resistive grounds are certainly an issue and should be addressed.
Crucial ground point is EC on the intake manifold. GROUND POINTS section of the EWD.

Idle speed is controlled by the ECU pushing the ISC valve, and should be a steady 650 rpm.
Did you adjust the distributor according to the FSM? IG-11 in the FSM.
Make sure the throttle cable has some slack at the idle position and the throttle valve is sitting on it's endstop.

 

[kvos40]

The truck is talking to you but you're not listening.
If wiggling the distributor harness changes the way the truck runs, then there's an issue with the wiring to the distributor.
There's 3 wires with a shield.
ENGINE CONTROL section of the EWD gives a complete layout of the ECU and all connections/sensors.

Yes, resistive grounds are certainly an issue and should be addressed.
Crucial ground point is EC on the intake manifold. GROUND POINTS section of the EWD.

Idle speed is controlled by the ECU pushing the ISC valve, and should be a steady 650 rpm.
Did you adjust the distributor according to the FSM? IG-11 in the FSM.
Make sure the throttle cable has some slack at the idle position and the throttle valve is sitting on it's endstop.

What is the shield connected to? The just gives the squiggle which I assume just means it continues on the next page. I tried to follow it but didn’t see the termination. Me and the truck don’t speak the same language. I’m trying to learn tho. I appreciate all your help.

 

[jonheld]

What is the shield connected to? The just gives the squiggle which I assume just means it continues on the next page. I tried to follow it but didn’t see the termination. Me and the truck don’t speak the same language. I’m trying to learn tho. I appreciate all your help.

Yes it continues on the next page. You'll see the matching "squiggle" along with the rest of the ECU layout. It's 3 or 4 pages.
I suggest you try to learn the language or you'll be in for a disappointing relationship.
Always refer to the Toyota manuals before attempting repairs.
Remember that it's a fuel injected tractor motor running 1986 technology.

 

[jonheld]

What is the shield connected to? The just gives the squiggle which I assume just means it continues on the next page.

One of the things I've done with the .pdf versions of EWDs, is combine multi page schematics into a single high resolution .pdf document using Photoshop.
I've done this with almost all multi page schemos for 1991, 1994, 1996, and LX450 EWDs.
I sometimes add notes, part numbers, and other pertinent information.
It makes following the specific circuits easier, and allows you to see the entire thing at once. You can zoom in to see it in agonizing detail.
Here's the 1991 ECU in full.

 

[kvos40]

One of the things I've done with the .pdf versions of EWDs, is combine multi page schematics into a single high resolution .pdf document using Photoshop.
I've done this with almost all multi page schemos for 1991, 1994, 1996, and LX450 EWDs.
I sometimes add notes, part numbers, and other pertinent information.
It makes following the specific circuits easier, and allows you to see the entire thing at once. You can zoom in to see it in agonizing detail.
Here's the 1991 ECU in full.

Trust me I wanna learn this truck lol. Dude thanks so much I’ll take a look at this and report back.

 

[kvos40]

One of the things I've done with the .pdf versions of EWDs, is combine multi page schematics into a single high resolution .pdf document using Photoshop.
I've done this with almost all multi page schemos for 1991, 1994, 1996, and LX450 EWDs.
I sometimes add notes, part numbers, and other pertinent information.
It makes following the specific circuits easier, and allows you to see the entire thing at once. You can zoom in to see it in agonizing detail.
Here's the 1991 ECU

One of the things I've done with the .pdf versions of EWDs, is combine multi page schematics into a single high resolution .pdf document using Photoshop.
I've done this with almost all multi page schemos for 1991, 1994, 1996, and LX450 EWDs.
I sometimes add notes, part numbers, and other pertinent information.
It makes following the specific circuits easier, and allows you to see the entire thing at once. You can zoom in to see it in agonizing detail.
Here's the 1991 ECU in full.

I plan on checking the sheilding by going from pin 26 on connector a to a ground. I’m wondering if the shielding is bad is this like all other shielded wires it’s a 3 conductor wire with a braid and then insulation on it ? What would be the best way to repair the shielding?

 

[jonheld]

That's not checking the shield.
Look at the schematic. Connectors E4-13, E4-26, E5-16, and E4-24 are all tied together to ground point EC. How are you isolating the shield?
The correct thing to do would be to check resistance between all the ECU ground points and the battery negative terminal.

However, you're still ignoring the obvious. If physical movement of a connector or wiring harness changes or causes an error condition, then there is an issue with that connector/harness.
You said, "we could get it to run good for a second by wiggling the harness that goes to the dizzy".
Why aren't you starting with that?????????

 

[kvos40]

I

That's not checking the shield.
Look at the schematic. Connectors E4-13, E4-26, E5-16, and E4-24 are all tied together to ground point EC. How are you isolating the shield?
The correct thing to do would be to check resistance between all the ECU ground points and the battery negative terminal.

However, you're still ignoring the obvious. If physical movement of a connector or wiring harness changes or causes an error condition, then there is an issue with that connector/harness.
You said, "we could get it to run good for a second by wiggling the harness that goes to the dizzy".
Why aren't you starting with that?????????

The plan is to physically inspect the harness obviously. But I’m trying to think
Ahead and electrically check it too. To isolate the shield I’d have to find the splice point I17 and figure out where its pinned or crimped.

 

[jonheld]

I

The plan is to physically inspect the harness obviously. But I’m trying to think
Ahead and electrically check it too. To isolate the shield I’d have to find the splice point I17 and figure out where its pinned or crimped.

IMO, you're getting ahead of yourself. Have you done the easy things first, like reseating and cleaning connectors? The 3 on the ecu would be high on the list, along with everything in the engine bay.
Low hanging fruit first.