80 series fuel pump or fuel pressure regulator issues (1 Viewer)

LINUS

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Eddy - I hope you’re doing all your diagnostic work w/ that “extra” breaker off or fuse pulled out of it.....

Since I’m not there I can’t say but that line may be part of your CEL status being wrong, and I don’t see how that jumper addresses fuel flow under demand.

I’m unclear why you allowed that or paid the bill for that style work, as nobody can help without being right there - we can speculate but I’d want that unneeded jumper gone ASAP.

Did the mechanic check the injector flow / do anything of substance before jumpering the curcuit?

Under the EFI relay, is there any deformation of the plastic housing or melted insulation on the hot lead in?
I’ve never seen it 1st hand, but heard of it more than a few times here / 80’s tech.
People have uprated the hot tap line, as a “fix it right” method.
 
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I didn't notice any deformation to any plastic and no, the circuit breaker is still in there for now. I could jumper past it with a piece of fusible link easily enough if anyone thinks I should, but I believe it's passing voltage just as it was intended.

The CEL does not come on with the EFI relay out. I didn't say it did, I just said I didn't know. Now I checked and it, for sure, does not. It behaves as expected: no EFI relay, no CEL. I didn't check with the EFI fuse out, but I assume that works as expected as well.

I replaced the EFI relay and the fuel pump relay with new Toyota parts.

Update is: we have still had two hard-starting issues. One I was sure we were stranded and the 2nd one was no fun either. It really seemed like the fuel pump.

The mechanic went so far as to get the right fitting for his fuel pressure gauge so he could measure that and based on that decided that the fuel pump was good.

I'm starting to think this is a multiple-problem problem. Please comment on my hypothesis:
  • An intermittent pump problem drawing too much current sometimes zapped one leg of the fusible link, but only enough to make it intermittent, not fully zapped.
  • Probably the fuel pump relay needed to be replaced anyways? Not sure, but it's new now.
  • Pump needs to be replaced.
One issue with my theory is that it runs fine once it starts, other than the stuttering issue when we were climbing steep hills, but if the fuel pump ever draws over 30 amps, it's flipping that breaker.

It was really really dead at the pizza parlor. I tried cranking for 15 min, at least When I went back after 24 hours (overnight+had to work), it didn't start until after I mucked with both relays, then it fired right up.

Since I replaced the two relays it was hard to start twice out of about 20x, but hasn't left me stranded. I suppose I didn't look down into the connector when I replaced the fuel pump relay, so I'll do that when I get a chance...

Frustrating. :bang: I want to paint the hood, not f' with the fuel system. It's got me thinking bad thoughts about a couple hundred-series that I know about... :(
 

LINUS

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So the mechanic checked pressure, but did he check volumetric flow?

The fusible links & everything else are now 25-ish yrs old, so UV/ozone damage is real & possible too.

I’d pull the fuse / flip the breaker of whatever hodge-podge the mechanic did while you test all.

-Did the fuel sock get looked at like was suggested?
———————————
In order of operation I’d follow:



Get out the FSM & check your injectors flow & pattern.

Check the holy heck out of the underside of the underhood electrics - see if the hot tap to the EFI relay is discolored.

Buy new fusible links & install - keep the others as spares if they do nothing to your problem.

Swap your fuel filter on the firewall - I know, but your issue sounds exactly like a filter that lets enough fuel past under moderate throttle, but starves at WOT/draw.

If that all checks out & the injectors look awesome & the relay board isn’t showing an issue, and the fusible links aren’t to blame - then go ahead & evil eye / swap fuel pump.

Everything you touch wire-wise, shove dielectric grease at like it’s bedroom lube.

I went in order of cost, but if money is of no concern then go to a better mechanic (IDK who’s local & awesome to you inn Cali) - toss ‘em the keys & wait.

Demand real ‘Yota parts, I’m not rich but I generally never need repeat a job w/ real parts.

If you have any desire to do Joey’s turbo, look at what the current talk is about getting the Supra turbo pump / custom injectors.
IDK your goals.

Yes, an 80 is more complicated than your 40 - but IIRC you do wires for a living so I’ve no clue why you want a 100 - totally an apples / oranges situation unless you never see dirt.


Aside from that & getting past the fuel starvation/delivery issue - despite the miles your 80 needs a baseline anyhow - fluid flushes, heater valve changed & coolant system overhaul, alot of stuff.

You’re just seeing the visible 10% of the iceberg so far.

Then you get to do the pretty crap like hood painting.

Just know that going in, or flat sell & skip right to an early 200 if you aren’t into doing the fluids & all that.

100’s aren’t Spring chickens anymore either. :meh:
 
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There are several confusing statements in your post:

"but if the fuel pump ever draws over 30 amps, it's flipping that breaker"
The fuel pump gets its power from the 15 amp EFI fuse through the EFI main relay, through the circuit opening relay, through the fuel pump relay. Under no circumstances are you pulling 30 amps to the fuel pump, unless the 15 amp EFI fuse and EFI main relay have been modified somehow. If that's the case, then you are DOUBLING the supplied current without appropriate wire sizing and creating a possible fire hazard.

"The CEL does not come on with the EFI relay out. I didn't say it did, I just said I didn't know."
Your words: "I did turn it over with the main EFI relay pulled out, just to see. I was surprised that the CE light was lit no matter what I tried."

"An intermittent pump problem drawing too much current sometimes zapped one leg of the fusible link, but only enough to make it intermittent, not fully zapped."
That is not how fuses/fusible links work. Once max current is reached they open. They do not magically reset.

"it didn't start until after I mucked with both relays, then it fired right up."
Then this is the first thing to look into.

EDIT: You should also verify where that 30 amp breaker is in system. There are 3 fusible links that feed 3 different sub systems with 3 different amp ratings.
FL AM1: Black=80 Amps
FL AM2: Pink=30 Amps
FL MAIN: Blue=100 Amps

If this were my truck I would make certain that the wiring was brought back to stock.
 
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So the mechanic checked pressure, but did he check volumetric flow?
I doubt it.
The fusible links & everything else are now 25-ish yrs old, so UV/ozone damage is real & possible too.

I’d pull the fuse / flip the breaker of whatever hodge-podge the mechanic did while you test all.
Agreed. I wouldn't say it's hodge-podge, per se, he put a breaker in-line with one of the fusible link legs. I will repair it and I can jumper past it for testing.

-Did the fuel sock get looked at like was suggested?
He had it apart. I feel like he's competent and would have checked that.
———————————
In order of operation I’d follow:



Get out the FSM & check your injectors flow & pattern.
Probably not me. I suppose I could send them out somewhere though.
Check the holy heck out of the underside of the underhood electrics - see if the hot tap to the EFI relay is discolored.
Will do.
Buy new fusible links & install - keep the others as spares if they do nothing to your problem.
Yea, I f'd up on not adding them to my relay order.
Swap your fuel filter on the firewall - I know, but your issue sounds exactly like a filter that lets enough fuel past under moderate throttle, but starves at WOT/draw.
Are there two fuel filters? I thought it was on the frame by the driver's side tire? The mechanic replaced one for sure.
If that all checks out & the injectors look awesome & the relay board isn’t showing an issue, and the fusible links aren’t to blame - then go ahead & evil eye / swap fuel pump.
Ok.
Everything you touch wire-wise, shove dielectric grease at like it’s bedroom lube.
I think you mean conductive grease? Dielectric grease does not conduct electricity, so it shouldn't be applied directly to the mating surfaces (pins and sockets) of an electrical connection.

I went in order of cost, but if money is of no concern then go to a better mechanic (IDK who’s local & awesome to you inn Cali) - toss ‘em the keys & wait.
That's the problem with cruiser-specific mechanics. They will not commit to a time frame. I'd have to just bite the bullet and send it to the dealer who will commit.

Demand real ‘Yota parts, I’m not rich but I generally never need repeat a job w/ real parts.
100% agree. Some Denso versions can be had that are as good. The fuel pump is such a part.

If you have any desire to do Joey’s turbo, look at what the current talk is about getting the Supra turbo pump / custom injectors.
IDK your goals.
I'll have to look at the thread again, but it's a no-go until it passes the CA BAR.

Yes, an 80 is more complicated than your 40 - but IIRC you do wires for a living so I’ve no clue why you want a 100 - totally an apples / oranges situation unless you never see dirt.
Software != wires. I have built a few robots though. Just because I know how to do it does not mean I like doing it. I have a new mountain bike. :flipoff2: to wires. I also need to do the PS on my 40.

Aside from that & getting past the fuel starvation/delivery issue - despite the miles your 80 needs a baseline anyhow - fluid flushes, heater valve changed & coolant system overhaul, alot of stuff.
Coolant has been flushed in recent memory. I know it needs hoses/PHH.

You’re just seeing the visible 10% of the iceberg so far.

Then you get to do the pretty crap like hood painting.
Personal issues. :princess: loves the thing and the hood clear coat peeling is/was a constant annoyance.

Just know that going in, or flat sell & skip right to an early 200 if you aren’t into doing the fluids & all that.

100’s aren’t Spring chickens anymore either. :meh:

Fair point. I'm also baselining an '03 911 with 100k miles.

There are several confusing statements in your post:

"but if the fuel pump ever draws over 30 amps, it's flipping that breaker"
The fuel pump gets its power from the 15 amp EFI fuse through the EFI main relay, through the circuit opening relay, through the fuel pump relay. Under no circumstances are you pulling 30 amps to the fuel pump, unless the 15 amp EFI fuse and EFI main relay have been modified somehow. If that's the case, then you are DOUBLING the supplied current without appropriate wire sizing and creating a possible fire hazard.
Dunno. I'm grasping at straws trying to explain the uphill bucking behavior I experienced after the breaker was installed and at the same time trying to explain what happened to the fusible link. Perhaps trying to relate the two issues is a fool's game.
"The CEL does not come on with the EFI relay out. I didn't say it did, I just said I didn't know."
Your words: "I did turn it over with the main EFI relay pulled out, just to see. I was surprised that the CE light was lit no matter what I tried."
I turned it over with the relay out, but likely only looked at the CE light when it was not out. I wasn't specifically looking for CE light behavior when I was in the parking lot. I was trying to get it to start without much knowledge of that circuit.
"An intermittent pump problem drawing too much current sometimes zapped one leg of the fusible link, but only enough to make it intermittent, not fully zapped."
That is not how fuses/fusible links work. Once max current is reached they open. They do not magically reset.

"it didn't start until after I mucked with both relays, then it fired right up."
Then this is the first thing to look into.
Replaced both. The behavior is different, but the problem is not 100% solved. Maybe I solved one problem and I have yet another problem.
EDIT: You should also verify where that 30 amp breaker is in system. There are 3 fusible links that feed 3 different sub systems with 3 different amp ratings.
FL AM1: Black=80 Amps
FL AM2: Pink=30 Amps
FL MAIN: Blue=100 Amps

If this were my truck I would make certain that the wiring was brought back to stock.
I agree. Blue and Black are intact. The Pink is replaced with the 30a breaker. It's not right, and I will put it back to stock. I need the other end of that pink wire connector now.
 
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Update: The no-start problem happened today at a taqueria. (The rig seems very sympathetic to make sure I have food when it decides to not start.) I tried to start it twice. Once it cranked only, once it wanted to start, but didn't.

I pulled the EFI fuse to verify the CEL light did not light, put it back in and it started right up.
 
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If pulling and plugging in the efi fuse fixes the no start, than I sure know where I would be looking for issues.

Read out the codes. :idea:

What code reader? I see BlueDriver for $100, but I don't think I'll ever use anything other than the code scanner/CEL reset. There are a zillion on Amazon. Another search turned up Innova hand held or OBD MX+ as an alternative to BlueDriver. HF has a few and the 2nd in the range, $75 came up in a search in this forum.

Does the ECU remember the last code, after they have been reset, or do I need to have the code reader with me when it leaves me stranded with nothing but my take-out food? That would make a laptop version all but useless.

We really have to all proceed under the knowledge that I've been sitting behind a 2f, on top of a 4-speed for 15 years, fixing nothing more complicated than an e-locker actuator or a carb fan relay. :hillbilly:
 
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LINUS

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If the EFI fuse was not making contact, the CHECK ENGINE light would not illuminate.

I’m thinking he maybe knocked off some tarnish doing all that pull & replace, but if that mystery jumper is still in play - I wouldn’t even venture a guess on the CEL status / codes logged.

No clue if it’s just bypassing the fusible link, but functioning the same - or if key off means it clears out anything that constant power would have held.
 
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I’m thinking he maybe knocked off some tarnish doing all that pull & replace, but if that mystery jumper is still in play - I wouldn’t even venture a guess on the CEL status / codes logged.

No clue if it’s just bypassing the fusible link, but functioning the same - or if key off means it clears out anything that constant power would have held.
True. I'm making the assumption that the breaker was put in place of one of the fusible links, but without actually seeing what was done and checking with a meter, it's impossible to know what is going on here. The person who worked on this truck muddied the waters with this "repair".

I will say that all the manuals and schematics are available to download right under the "resources" tab. That should be the first step to bringing things back to stock. I would reach out to local LC club members and get some real help.
 
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Under the EFI relay, is there any deformation of the plastic housing or melted insulation on the hot lead in?
As Linus says above, that EFI relay gets HOT!! while running, don't believe him, try holding on to it after the motors been running for a few minutes. You should unscrew the under hood fuse box panel from the fender, and flip it over to inspect the wires underneath that feed the EFI relay. Below are a few threads that you may find helpful.
First time my 80 has let me down/towed - https://forum.ih8mud.com/threads/first-time-my-80-has-let-me-down-towed.998195/
 
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Thanks for all your help as I'm getting through this...

True. I'm making the assumption that the breaker was put in place of one of the fusible links, but without actually seeing what was done and checking with a meter, it's impossible to know what is going on here. The person who worked on this truck muddied the waters with this "repair".

I will say that all the manuals and schematics are available to download right under the "resources" tab. That should be the first step to bringing things back to stock. I would reach out to local LC club members and get some real help.

I have the EWD open on my desktop. I haven't found it to be hugely helpful so far. I do see that I could test voltage through the ignition at the coil or the ignitor, but I have the CEL on when this is occuring, so the ECM has power through that same circuit.

The breaker, 100%, is installed in place of the pink, 30a leg of the fusible link that goes to the w-r wire, page 54. I will bypass it with a new OEM fusible link when I get one.



As Linus says above, that EFI relay gets HOT!! while running, don't believe him, try holding on to it after the motors been running for a few minutes. You should unscrew the under hood fuse box panel from the fender, and flip it over to inspect the wires underneath that feed the EFI relay. Below are a few threads that you may find helpful.
First time my 80 has let me down/towed - https://forum.ih8mud.com/threads/first-time-my-80-has-let-me-down-towed.998195/

I will pull it off and look around. Just to verify, I checked and it looks like I have to remove the battery, shroud and the charcoal canister to get to the bottom of that fuse/relay block?

I’m thinking he maybe knocked off some tarnish doing all that pull & replace, but if that mystery jumper is still in play - I wouldn’t even venture a guess on the CEL status / codes logged.

No clue if it’s just bypassing the fusible link, but functioning the same - or if key off means it clears out anything that constant power would have held.

I have some pics that I don't have time to upload while I'm supposed to be working. The inside of that relay box looks new. I don't see any 'tarnish'. I cleaned it with alcohol just in case.

It's not a 'mystery jumper'. It's a breaker. It's hot all the time unless you trip it, in which case it takes a few seconds to reset.

View attachment 2601262
 
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I think you need to take a step back and reassess the issue.
When this engine refuses to run, you need to determine if you are missing fuel or spark. That will determine what road we travel.
From your previous posts, I would assume you are missing fuel. If that's the case, then let's leave the ignition system alone, let's leave the EFI system alone, and concentrate on the issue at hand.

You also mentioned that the breaker in place of the PINK FL AM2 pops once in a while. That tells me that you have a short downstream of that breaker. Have you inspected the wiring harness that runs close to the EGR pipe in the engine bay?
Page 40 of the EWD gives you a breakdown of what each FL feeds. You will notice that the 15 amp EFI fuse is fed from FL MAIN (100 amp), which in turn feeds the fuel pump. If the 30 amp breaker pops, it's a safe bet it's not from the fuel pump circuit.
 
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I think you need to take a step back and reassess the issue.
When this engine refuses to run, you need to determine if you are missing fuel or spark. That will determine what road we travel.
From your previous posts, I would assume you are missing fuel. If that's the case, then let's leave the ignition system alone, let's leave the EFI system alone, and concentrate on the issue at hand.
Good idea.
You also mentioned that the breaker in place of the PINK FL AM2 pops once in a while. That tells me that you have a short downstream of that breaker. Have you inspected the wiring harness that runs close to the EGR pipe in the engine bay?
I said I thought it might. After testing the breaker the reset time is much longer than what I was experiencing while climbing hills, so I no longer think it was popping.

I'll take a look at that harness.
Page 40 of the EWD gives you a breakdown of what each FL feeds. You will notice that the 15 amp EFI fuse is fed from FL MAIN (100 amp), which in turn feeds the fuel pump. If the 30 amp breaker pops, it's a safe bet it's not from the fuel pump circuit.

I really think the breaker is a red herring at this point. I will replace it.

The fact that pulling the fuse immediately solved the problem, twice, is a huge clue. Next time it happens, I'm going to be paying a lot closer attention to the CEL when it's not starting and I will have a multimeter. I didn't get the feeling anyone thought I'd have a code, so I'm holding off on the code reader.
 
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Good idea.

I said I thought it might. After testing the breaker the reset time is much longer than what I was experiencing while climbing hills, so I no longer think it was popping.

I'll take a look at that harness.


I really think the breaker is a red herring at this point. I will replace it.

The fact that pulling the fuse immediately solved the problem, twice, is a huge clue. Next time it happens, I'm going to be paying a lot closer attention to the CEL when it's not starting and I will have a multimeter. I didn't get the feeling anyone thought I'd have a code, so I'm holding off on the code reader.
I'm having a bit of a hard time following along here. In one of your earlier posts you said that playing with the fuel pump/circuit opening relay solved the problem.

I'm not questioning the breaker, as you seem to be sure of its purpose. But you did mention that it was popping. If it was a fusible link, chances are it would open, which is probably why it was replaced with a breaker in the first place.
 
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I'm having a bit of a hard time following along here. In one of your earlier posts you said that playing with the fuel pump/circuit opening relay solved the problem.
At the pizza place I removed and replaced both the efi relay and the efi fuse. I didn't try to start in-between.
I'm not questioning the breaker, as you seem to be sure of its purpose. But you did mention that it was popping. If it was a fusible link, chances are it would open, which is probably why it was replaced with a breaker in the first place.
There was stuttering when climbing a steep off-road hill that I thought might be the breaker popping and resetting. It's post #1. There was a "maybe" and a "perhaps" in that sentence. I was conjecturing and I apologize for muddying things up. Today I tested the breaker and it takes 1-2 seconds to reset and the cadence of the stuttering was more like 3-x/second, not one stall every 2 seconds.
 
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So, tonight's update, and again I thank anyone who's willing to listen and offer advice or support.

I went out earlier today, without really having time to f' with it and started to see what I had to do to unbolt the fuse/relay box there by the battery. I cleaned the EFI fuse clips and unbolted enough to see that you really have to remove some other things to get underneath to properly diagnose, so I quickly put it back together and went back to work.

At that time I verified, again, I did not have a CEL when the fuse was out.

Tonight I went to drive it to get some food. It wouldn't start. The CEL was lit as expected before and after cranking. Just for kicks I pulled the EFI fuse and the CEL remained lit. :(

I'm going to have to get very comfy with the EWD and a multi-meter and dig into it. I hope it's not two wires inside a harness somewhere in a melty glob. :(
 
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Real time:

I have the CEL illuminated with both the EFI fuse and relay removed. With the ignition on I have 2.5v (approx.) at pin 4 of the EFI relay.

Pin 2 of the relay goes to the output of the EFI fuse. I do have almost 12v at pin 3 of the relay with the ignition on. So it's supposed to close the relay with the ignition on and pass the 12v from pin 2 to pin 4, but there's already some voltage there. :(

What I don't get is why anyone thinks all the power for the ECM comes from the EFI fuse? In the EWD it clearly shows there is power from the IGN to the ECM, and the signal that closes the EFI relay comes from the ECM. The IGN powers up the ECM and the ECM, in turn, closes the EFI fuse. Why would the CEL not come on regardless of the EFI fuse/relay?

The wires under the relay are as new, no signs of wear or damage of any kind. Still searching...
 
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