Close to giving up...can't find the misfire! (1 Viewer)

[landtank]

Years ago I bought an 80 that a local dealership couldn’t get running. Recently I’ve been working with a member with a similar problem that you are describing.

I finally linked the two together and solved his problem.

The power for the fuel pump is supplied through various connections one that is particularly hidden and not obvious.

The power comes down the DS door sill and then branches off to go under the drivers seat and through the floor to the underside of the cabin. It’s here where Toyota decided a connector was needed. In both cases that connector was corroded and the problem.

Good luck

 

[ajax1]

Make sure all injector plugs are fully seated and in the correct order, colors alternate and if I remember correctly you can put number 5 in the 6 position and vice versa

 

[SpeedAgent]

Years ago I bought an 80 that a local dealership couldn’t get running. Recently I’ve been working with a member with a similar problem that you are describing.

I finally linked the two together and solved his problem.

The power for the fuel pump is supplied through various connections one that is particularly hidden and not obvious.

The power comes down the DS door sill and then branches off to go under the drivers seat and through the floor to the underside of the cabin. It’s here where Toyota decided a connector was needed. In both cases that connector was corroded and the problem.

Good luck

Is there any chance you have photos?

 

[SpeedAgent]

Make sure all injector plugs are fully seated and in the correct order, colors alternate and if I remember correctly you can put number 5 in the 6 position and vice versa

I'll check.

 

[SpeedAgent]

Years ago I bought an 80 that a local dealership couldn’t get running. Recently I’ve been working with a member with a similar problem that you are describing.

I finally linked the two together and solved his problem.

The power for the fuel pump is supplied through various connections one that is particularly hidden and not obvious.

The power comes down the DS door sill and then branches off to go under the drivers seat and through the floor to the underside of the cabin. It’s here where Toyota decided a connector was needed. In both cases that connector was corroded and the problem.

Good luck

I will say, when I replaced the fuel pump I drove around for a couple days with the carpet pulled back and the top of the tank exposed to the interior so I could listen to the pump. The pump sounded like it was operating perfectly. In fact, after I replaced the fuel filter the pump got quieter.

 

[BILT4ME]

The temp sender affects the file pump for open)closed loop.

Maybe Throw more parts cannon at it?

 

[bigredmachine]

I meant to list that in the original post; those are new.

id pull back the loom to check for any wire damage, mine had been worn through on the front drive shaft and the old wire repairs were turning green. any corrosion in the connectors?

 

[SpeedAgent]

id pull back the loom to check for any wire damage, mine had been worn through on the front drive shaft and the old wire repairs were turning green. any corrosion in the connectors?

There wasn't any when I installed the new. Would there not be a code thrown if the 02s were an issue? When I replaced them I was chasing down codes 24 and 25, and new sensors fixed the problem. No codes have come back.

 

[shocktower]

What about igniter ??

 

[landtank]

Is there any chance you have photos?

Pretty easy to find. Just lift up the carpet under the drives seat and follow the wire where it passes through the floor and then follow it under the truck to the connector. I would do this first thing

 

[SpeedAgent]

What about igniter ??

Have not looked into this yet.

 

[bajaphile]

Symptoms could also point to a vacuum leak. No one has mentioned that yet. It is worth inspecting your intake tube along the bellows sections. Also check the vacuum lines you're able to see.

 

[bigredmachine]

There wasn't any when I installed the new. Would there not be a code thrown if the 02s were an issue? When I replaced them I was chasing down codes 24 and 25, and new sensors fixed the problem. No codes have come back.

not necessarily, I had codes 24 25 and replaced the o2 sensors and still had the misfire. there was corrosion in the connector that was an additional issue. replaced the connectors and problem solved, for now

 

[SpeedAgent]

Symptoms could also point to a vacuum leak. No one has mentioned that yet. It is worth inspecting your intake tube along the bellows sections. Also check the vacuum lines you're able to see.

I did replace the intake tube and have sprayed starter fluid to ID leaks, no luck.

 

[SpeedAgent]

Make sure all injector plugs are fully seated and in the correct order, colors alternate and if I remember correctly you can put number 5 in the 6 position and vice versa

I checked and the order 1-6 is Grey, Orange, Grey, Orange, Grey, Grey. Is that correct?

 

[SpeedAgent]

Pretty easy to find. Just lift up the carpet under the drives seat and follow the wire where it passes through the floor and then follow it under the truck to the connector. I would do this first thing

I didn't lift the carpet, but looking underneath I did not see any wiring coming from the front seat area to the tank. However, I did find a connector on the outside of the frame rail in front of the DS rear tire and it looked to go to the tank. I pulled it apart and there was surprisingly zero dirt inside and no corrosion.

 

[SpeedAgent]

Well, I checked and greased the temp sensor connection, checked and greased the possible fuel pump power connection, and double checked the injector connection order. I can't reach all of the connections to each injector, but the ones I could reach were not corroded and were snapped on. Fired it up and within minutes it was stumbling again.

Should I;

A- get a timing light and check timing

B- buy a new temp sensor because this could easily be the problem

C- I can't think of anything more

 

[Mudder]

I've not messed with the valves, but I do know the guy who installed it said he had to dial back the timing from 9 degrees to 3 because he said it wasn't running well.

This stands out to me. Why was the engine orignally at 9 degrees and had to be bumped back to 3, I'd double check timing following the FSM and make sure it is within spec. And if it's not adjust it so it is, and if it runs worse than something is going on there.

 

[landtank]

I didn't lift the carpet, but looking underneath I did not see any wiring coming from the front seat area to the tank. However, I did find a connector on the outside of the frame rail in front of the DS rear tire and it looked to go to the tank. I pulled it apart and there was surprisingly zero dirt inside and no corrosion.

So you didn’t follow my directions and didn’t find the connector I was talking about.

 

[Zjohnsonua]

This stands out to me. Why was the engine orignally at 9 degrees and had to be bumped back to 3, I'd double check timing following the FSM and make sure it is within spec. And if it's not adjust it so it is, and if it runs worse than something is going on there.

This. A brand new ignition system is useless if it isnt set up properly. Set the base timing and reassess your probs.

Also, the IAC circuit plays a significant role in these engines and can directly cause your idle issues. It's also reasonably easy to service. Pull the throttle body to get to those IAC screws. They strip easy, so be careful or go for a little impact right away. The IAC has a phenolic poppet that fits into a polished port to give you the smooth idle your chasing. Yours may have a carbon build up. Clean them both then change out that likely flattened o-ring. There are heaps of IAC threads on here as well that go into far more detail.

Don't throw in the towel. You've covered some good ground thus far.