80 Series Project!!! (1 Viewer)

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Dec 27, 2016
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Hi Mud Friends!

I have a new project; 1991 FJ80! This truck was advertised as a mechanics special due to its issue with starting. You have to spray ether into the intake for it to fire up, however when it gets running she purrs! The previous owner was not mechanically inclined at all. He took it to a few shops where they tuned it up but could never fix the starting issue. PO told me he thinks the issue is a bad alternator or fuel pump, I am thinking it is the latter. Any thoughts?

Thank you all!

Chris

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Does it restart once it's been running for a while? Could be cold start injector. Alternator is definitely not it. Fuel filter seems improbable too.

I'd get a copy of the 1991 Factory service manual. It has flowcharts for all sorts of conditions.

Congrats on the truck! Enjoy it.
 
Thee is a thread on here stating those EXACT issues with a 91 or 92.

Probably do a search with "ether" to see if you can find it and a solution.

Sounds to me like the fuel relay, wiring to the fuse panel, or vacuum leaks. But it's a 3FE, so that's not my expertise.

WELCOME! :flipoff2::flipoff2::flipoff2:
 
Does it restart once it's been running for a while? Could be cold start injector. Alternator is definitely not it. Fuel filter seems improbable too.

I'd get a copy of the 1991 Factory service manual. It has flowcharts for all sorts of conditions.

Congrats on the truck! Enjoy it.

Yes, it runs great once it has been started. Once warm, it seems to turn over much easier. I will check the cold start injector and see if that fixes the problem, THANK YOU!!!
 
Thee is a thread on here stating those EXACT issues with a 91 or 92.

Probably do a search with "ether" to see if you can find it and a solution.

Sounds to me like the fuel relay, wiring to the fuse panel, or vacuum leaks. But it's a 3FE, so that's not my expertise.

WELCOME! :flipoff2::flipoff2::flipoff2:

@BUILT4ME thank you for the advice. I am really hoping it is not an electrical issue. However, I will check! What was the final solution in the other thread? I will search for it.
 
UPDATE!!!

I was able to get under the hood this weekend and take apart the intake system and clean the MAF sensor, however I think this may be my main issue. I also cleaned the cold start fuel injector, however I don't think this is my issue. The truck will turn over on her own power, SOMETIMES. Most of the time, I have to spray ether into the intake (photo attached). When I do this, she fires right up. She does run a little rough after startup but no sputtering.

I really think it is an issue with the MAF sensor. Thoughts?

IMG_7839-1.jpeg
 
Cold start fuel injector was DIRTY! So was/is my intake manifold.

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I'm going to venture out on a guess here...

I think your problem is either to do with some electrical components, or your not getting fuel during startup, like fuel is bleeding back to the tank or something. Anyway you can verify fuel injection during a cold startup? Having success with ether seems to say your not getting enough fuel initially, perhaps it takes time for the fuel to get pulled through the system. A pinhole leak could allow fuel to fall back to the tank and draw air in. but you'd probably see and smell it somewhere as well. Your fuel pump could produce similar results, a pressure gauge in the fuel line near the engine would tell you a bit more, actually a clear fuel filter and gauge would be helpful there.

Have you pulled a plug to check they are firing well during startup, a cracked distributor component could hold you back too.

The nozzle on that sprayer looks clean enough, but the rest of your intake could handle some cleaning, or is that just some sort of gasket maker stuff on it?
 
I'm going to venture out on a guess here...

I think your problem is either to do with some electrical components, or your not getting fuel during startup, like fuel is bleeding back to the tank or something. Anyway you can verify fuel injection during a cold startup? Having success with ether seems to say your not getting enough fuel initially, perhaps it takes time for the fuel to get pulled through the system. A pinhole leak could allow fuel to fall back to the tank and draw air in. but you'd probably see and smell it somewhere as well. Your fuel pump could produce similar results, a pressure gauge in the fuel line near the engine would tell you a bit more, actually a clear fuel filter and gauge would be helpful there.

Have you pulled a plug to check they are firing well during startup, a cracked distributor component could hold you back too.

The nozzle on that sprayer looks clean enough, but the rest of your intake could handle some cleaning, or is that just some sort of gasket maker stuff on it?


Thank you for all the advice! No fuel seems to be leaking anywhere so I am leaning towards an electrical issue in the MAF or yes, something to do with the fuel pump. Any ideas how I can text fuel pressure? I would imagine someone has a thread on this.

Also, I think the distributor is newly replaced. A cleaning of the intake manifold is absolutely in order. Unfortunately, that gunk is also in there, too.

Thank you!
 
Since it runs well once started, we can assume your fuel delivery system is good.
If the issue is strictly when starting, then it is pointing to fuel pump logic.
1. Is your intake tube torn or loose? Check for cracks on the underside of the ribbed section of the tube between the AFM and intake.
2. On the diagnostic connector, use a small piece of wire and jump between pins 1 (FP) and 8 (B+). This will bypass the fuel pump logic that runs through the AFM. Your FP will now fire when the key is in the ON position. If your engine starts easily in this state, then we need to dig deeper into the logic.

Do not leave this jumper in place. It is for diagnosis only.

CheckConnector.jpg
 
Thank you, @jonheld!

I inspected my air hose his weekend and it seemed to be in good shape.

Sorry for my ignorance, however I have to ask. Is the Air fuel meter connected to the mass airflow sensor? Red arrow in the attached photo. Also, the fuse box that you are referring to is towards the front of the engine on the drivers side?

Thank you!!!!!!!!!!

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And whatever you do, do NOT remove the two screws on that wiring harness and tug on the wiring harness........


JonHeld has chimed in on your thread. He is the guru. Do and follow EXACTLY what he states. The rest of us will shut up while he walks you through this. If you don't understand something, ask.
 
And whatever you do, do NOT remove the two screws on that wiring harness and tug on the wiring harness........


JonHeld has chimed in on your thread. He is the guru. Do and follow EXACTLY what he states. The rest of us will shut up while he walks you through this. If you don't understand something, ask.

Ha! I will follow instructions to a T! I went and bought some electrical wire during my lunch break so I could follow his instruction. I plan to get after this tonight! Thank you all for the help! I really want to get this ol girl cleaned up and back on the trails!

Chris
 
Ok! We have a verdict... I did as @jonheld said and what do you know, it worked! I ran a wire between pins 1 (FP) and 8 (B+). She started right up 6/7 times that we tried. I think the one time was non-issue related.

So Jon, what is next?! Also, any Mud members who have another diagnostic connector or a cover for mine? It appears the one in my truck is corroded due to exposure.

THANK YOU!!!

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The 3FE has an AFM not a MAF. What you circled in the picture is the AFM. Conceptually the same, but air flow is measured differently.

You have an issue with the FP logic. There are 2 coils in the circuit opening relay (fuel pump relay) in the driver's side kick panel. The first one fires the FP during cranking and gets the signal from the starter circuit. That appears to be the one that is missing, or the COR is faulty.
1st thing to do is make sure that the COR is seated correctly and there is no corrosion on the contacts.
Do you know how to use a multimeter?

Relay block DS.jpg
 
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The 3FE has an AFM not a MAF. What you circled in the picture is the AFM. Conceptually the same, but air flow is measured differently.

You have an issue with the FP logic. There are 2 coils in the circuit opening relay (fuel pump relay) in the driver's side kick panel. The first one fires the FP during cranking and gets the signal from the starter circuit. That appears to be the one that is missing, or the COR is faulty.
1st thing to do is make sure that the COR is seated correctly and there is no corrosion on the contacts.
Do you know how to use a multimeter?

View attachment 1792235

Jon,

Thank you! I have never used a multimeter but I am sure I could learn quickly. What do I need to do to test the COR? Can I buy a new coil preemptively?

Also, does the multimeter pictured below work for this job?

Thank you!

Chris

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