Real Time Help: Fuel delivery Issue (1 Viewer)

[Grench]

I'll post up the long story later. The short of it is I have a contaminated fuel system. The truck is 60 miles away at my brother in law's shop. My FSM is at home. I'm at work. My brother in law is working on the fix.

He's flushing both tanks and just changed the factory fuel filter. He and I agree that one is a major pain in the ass and I don't want to attempt it roadside.

So, while everything is pulled appart and being figured out, we want to add an additional, easier to get to, filter between the primary tank and the factory filter.

The questions...
What is the pressure on the fuel system at the following locations:
Directly after the in tank fuel pump
Directly before the factory placement fuel filter

Is there any additional hardware currently between the factory pump and the factory filter?

We need to know the pressure so that we can figure out what kind of filter we need to use and if this can even be done without having stuff hangning in bad places. The idea is to have a quick change 2nd filter so that the primary (factory) filter has much less to do.

Thank you!

 

[Grench]

After extensive searching I was able to find one reference to the fuel regulator going to bypass at 43psi. I'm not sure if this is a stock FZJ80 pressure or a Supra'd up fuel pressure as the conversation I found it in was regarding turbos & SC.

Is 43psi the right pressure on the forward fuel system on a 1996 FZJ80?

 

[Grench]

Bump.

We'll finish flushing the tanks (2 now) & lines today. Whether we install an easier to get to second filter between the pump and the factory filter is dependent on if I understand the pressure between the pump and the factory filter.

I'll have to hunt for a good spot to put it too, but that is secondary to making sure the solution meets pressure specs.

Thanks!

 

[Grench]

The long story.

Wow... Does everyone have me on the 'Ignore User' setting?

OK. The long story...
Yes, I asked for this as I senselessly bragged last week that my truck was running fine.

Background
Several months ago I purchased a 24 gallon aux tank from MAF. After encountering that the bracket that came with the tank wasn't going to fit in a way that made me happy, I decided to have a tank mount / hitch welded up.

Three weeks ago I worked with a guy who is a 20 year professional welder and we put in a receiver hitch and the tank mount cross member. Very similar to what the other IH8MUD member did with his 24 gallon install. That part went fine. Someday when the truck, my camera and I are in the same zip code I'll take some pictures of it for you all.

Wednesday last week we had the opportunity to install / plumb / wire the tank. I say we, because I try to avoid doing fuel system work in my garage (split level tuck under), so I took the truck 60 miles away to my brother in law's place. Real shop and he's a mechanic. So, it improves my odds of getting these projects done.

We installed the aux tank, plumbed it, wired it, put 5 gallons gas in it, used the transfer pump to move the gas to the main tank, fired the truck up to go fill the tanks and...

The state of my Grey truck now:
The truck stutters and stalls. It will hold idle for 2-5 minutes at a shot, then die. I tuned it up to 2200 RPM with my throttle lock. The RPMs start to bounce after 2-5 minutes, the truck struggles, and dies. Until the RPMs start to bounce, it runs -perfect-. It idles clean at 600 RPMs... for 2-5 minutes, then chokes.

We assumed that we had disturbed something and clogged the filter.

After a hunt I found one NAPA store in a 60 mile radius with 3 fuel filters. I bought them all. No local Toyota places had them, it was a Friday, and we wanted them then and now, so Dan will get the next one. Yes, I have been keeping his dogs well fed.

Factory fuel filter was replaced this morning. Both tanks have been drained, gas filtered, recycled into the tanks, drained, filtered, etc. until both tanks are clear-clean. The new tank had no sediment or junk in it. The primary had rusty bits and some mysterious black floaty snot things that disintegrated when we tried to pick them up.

We tested the elastomeric compatibility of the hoses that came in the kit and used only fuel rated hose that we tested by submersing it in gas for 5 minutes then rubbing it to see if we could get any deterioration or transfer. All hose tests clean.

The CEL has not come on -at all- during the entire install. I put the OBDII reader on it just to make sure. No dice, no code. The computer doesn't think the truck is sick.

The electrical for the ohm meter (tank level LEDs) and the transfer pump is wired as a hop from the cigarette lighter. The sputtering & stalling happens whether the transfer pump is running or not.

The truck sputters, stalls & dies completely at random. Restart, and it runs 2-5 minutes fine. Holding up the RPMs with the gas pedal does not prevent the behavior. No CEL code thrown. It is possible by dancing the right foot on the gas to keep it running through these spells. Kind of like

The process of elimination...
Oil looks fine.
Secondary gas tank disconnected. No change, problem persists.
Secondary gas tank electrical disconnected. No change, problem persists.
Fuel filter replaced. No change, problem persists.
Truck taken out an -run-. Struggle to keep it running as it wants to die at random every 2-5 minutes. No change, problem persists.
Both tanks filled (52 gallons total) with fresh gas. Did you know that BP stations pumps stop automagically at $100? No change, problem persists.

I'm 60 miles from the truck now. I've been searching IH8MUD for the last couple of hours. I have found a couple of ideas to try tomorrow, but not much. Maybe it is my exhaustion creeping in.

Things we will try tomorrow:
1. MAF sensor. I found a reference to unplugging and replugging this in?
2. Fuel pump electrical connections corroded or dirty. Spray with electrical contact cleaner.

I will be trying both of these, but its a pretty narrow list.

Some items I've considered
In theory, if it were injectors, I would get a CEL. Right? (Confirmation anyone?)
The fuel pump should either work or not, right? We did not disturb, move or dig to the fuel pump. Our wires are fully independent except for power, which is drawn via jumper from the + side of the cigarette lighter for now. We made our own ground to the frame rail.

Well, thats the long of it. I'm open to ideas.

Thank you,

Grench

 

[cam75w/ls1]

If you have an ignition failure or fuel problem the computer will most likely not set a code. If the fuel pump is failing the computer will not set a code. If the ignition fails there are some codes that can appear that are ignition related,most problems will not pull a code. I would start by connecting a fuel pressure guage to the truck and make sure it's fuel pressure related.

 

[Grench]

We pulled the regulator at the end of the fuel rail, tapped the key, got gas. Put it back in and did it again to ensure that the regulator was dumping to the return. Those check out.

Quantity of pressure... I just found it on EG-133 in the FSM. It should be 44 psi. We will be checking that tomorrow.

 

[cam75w/ls1]

Just keep the guage on it until it acts up and see if the fuel pressure drops at the same time the motor starts running bad. Good luck.

 

[landtank]

Just an FYI. On our trucks there is a vacuum line that cuts the fuel rail pressure during idle to something in the mid 30s.

So if there is more pressure than that you might have a rich condition because at 43.5psi the truck would be running about 20% richer than normal during idle.

Also make sure the system is bleeding off the fuel back to the tank.

 

[Grench]

A bump and another symptom / information bit.

Disconnecting the battery for 30 minutes, reconnecting and starting the truck results in good behavior for about an hour or 5 or so restarts. Then it behaves like crap.

So, if I wanted to pull over and disconnect the battery for 30 minutes every 60 miles, it would be fine.

Still digging through my list of 15 different possibilities. I'm still looking for additional things to try too.

 

[IdahoDoug]

I'm concerned about your fuel line compatibility test. Correct me if I'm wrong, but it sounds like you did not go out and purchase quality fuel line, but used unknown hose and a 5 minute "does it break down with gasoline" test. If so, that was a very highly suspect source of your problems. If you're wrong and the rubber breaks down it can create a chemical reaction that will go right through a filter designed to stop debris but not a rubber/fuel/chemical slurry. Might make it to the injectors and cause problems, might impact the fuel pump, etc. Dunno.

Bits of black stuff that breaks down sounds exactly like rubber. 5 minutes was not a reliable test. Did you pull the fuel pump and take a look at the strainer?

At the end of the day, I agree fuel pressure is going to be your most important input - what is it, and what happens to it when your symptom appears?

DougM

 

[Grench]

I'm concerned about your fuel line compatibility test. Correct me if I'm wrong, but it sounds like you did not go out and purchase quality fuel line, but used unknown hose and a 5 minute "does it break down with gasoline" test. If so, that was a very highly suspect source of your problems. If you're wrong and the rubber breaks down it can create a chemical reaction that will go right through a filter designed to stop debris but not a rubber/fuel/chemical slurry. Might make it to the injectors and cause problems, might impact the fuel pump, etc. Dunno.

Bits of black stuff that breaks down sounds exactly like rubber. 5 minutes was not a reliable test. Did you pull the fuel pump and take a look at the strainer?

At the end of the day, I agree fuel pressure is going to be your most important input - what is it, and what happens to it when your symptom appears?

DougM

No. I should clarify.
The fuel line we used for the fill tube splices was supplied with the kit. It says "Petrol Fuel" on it. For the tap into the breather tubes we used Goodyear fuel hose. The 'testing' was when we saw the black stuff and started to second guess if it had been misslabled.

The 5 minute test to see if the surface rubber breaks down enough to 'mark' a surface was adequate for this purpose. At this point we've taken the lines apart enough times that if there were going to be any softening, we would also feel it. All hoses check out and are clearly labeled as fuel

I had to take care of some family stuff this afternoon, but pulled the seats & hatch this morning in preparation of pulling the fuel pump. I'll be back on the project tonight.

 

[Grench]

Computer theory... Possible?

The more I think about it, at this point the most alarming bit is that the truck runs fine on computer reset (battery disconnect for a bit). It then runs progressively worse with each restart. On the first restart it will hold upwards of an hour. At the 5th restart it will not hold 5 seconds.

I have a theory. Is there anyone out there that can tell me if it holds any merit?

The computer & my theories. Please refute anything I have wrong.

When it is reset, the computer goes into a 'safe' mode with mappings stored in ROM. This is an inefficient and not overly pollution friendly mode.

Each time the vehicle is restarted the computer adds a bit of 'knowledge' about previous runs to create a new mapping that is stored in some sort of volatile RAM.

On each progressive restart the computer pulls more and more from the RAM mapping and less from the permanent ROM mapping. By the 5th restart it has more or less 'switched over' to the RAM map.

What if this theoretical RAM were to be fried? I.e. when the computer writes to it, it doesn't hold it. Then when it tries to read it, it gets scrambled eggs.

Is there a self test mode or test that I can perform to see if the computer is working right?

Yes, I'm continuing to check the other items on the list and will be pulling everything that can be pulled apart to see if I can eliminate them first.

Thank you!

 

[landtank]

to check your ECM theory jump TE1 and E1 on the service plug in the engine compartment.

This will put the ECM in service mode and it will not adjust itself.

But it's hard to ignore the fact that it ran fine, you modified the fuel system and now it doesn't.

 

[cam75w/ls1]

Grench, your theory w/ the computer is plausible but I don't think anything fried. Your computer is relearning as you drive it after the disconnect(battery)and something is causing the computer to relearn incorrectly, POSSIBLY...I still can't link the gas tank upgrade and the computer together though. Have you tried the fuel pressure guage yet??

 

[Photoman]

Check your sock. It’s possible the sock on the fuel pump in the tank is clogged or even fallen off. Some of that snot or rusty bits gets sucked up to the pickup tube and reduces the amount of fuel. After the cruiser sits without running, enough crap settles off from no suction, and it will go again. I know you said you flushed the tank but if the sock was gunked up and restricting flow, only removal would tell. Just a thought. Good luck!

Bill

 

[Grench]

I think we've got it... I hope we've got it...

In the process of figuring this one out we effectively did a monster check on just about everythying in the truck.

What the problem wasn't:
Sock is clean.
TE1 and E1 jumpered - runs and dies just like it did with them open.
MAF checks per FSM
Fuel pump pressure checks and holds pressure after shutdown with no loss after 30 minutes.
Fuel pressure regulator & bypass check
EFI relay - replaced
Distributor cap & rotor - replaced
Stator wire - cleaned tested and reinstalled
Coil resistances - checked per FSM
Intake tube - checked
Throttle valve - checked
TPS - checked
All fuel lines clean and tight
Coolant red and pretty
The list goes on and on.

I'm 60 miles away from the truck today. I started looking for other relays that IH8MUD members have found issues with and stumbled on a reference to the Fuel Pump relay that sits all by itself in a hole in the DS fender.

I called it into my brother in law - the truck is at his place. The truck was in one of it's well running spells. He touched the relay and it stumbled. Wiggled the wires, no change. He shut the truck down, opened up the relay and pushed the relay in. It gave by about 1/32 inch. After pulling the relay out and cleaning it up with electrical contact cleaner and reseating it, no failures in close to 25 starts and 90 minutes runtime.

So... Right now it looks like this issue was caused by a good relay that had vibrated just a touch loose over the course of 11 years and was making contact -most- of the time. It is an expensive unit as far as relays go. I have an order in with Dan for one and 3 EFI relays. One to replace the one we put in and two to put in my toolbox. The EFI relay we put in was an Autozone cross reference. The local Toyota dealers here don't stock much of anything.

The timing of failure to coincide with our installation of the second fuel tank? It appears to be pure coincidence. I'm going to drive the truck as much as possible over the next few days to see if I can make it fail. If it runs right, I'm taking it on a 1500 mile round trip with back woods camping in the middle.

Thank you to all of you who put in suggestions and ideas! This was an exercise in chasing a ghost. Spotty evidence and the only way to find the problem was by figuring out what it is not.

 

[Grench]

The ghost is back. It isn't the fuel pump relay in the fender. I swapped it out with the one from the other '96. No change to either vehicle.

It will run -perfect- for hours, then it will cough sputter and die 6 starts in a row, or will run fine for 30 minutes, stutter, then run fine again.

Totally at random. Highway, stoplights, left, right, idling in my driveway, high RPM, low RPM. I've run out of systems to check.

I'm going to still drive it on a 1500 mile round trip this weekend. Wish me luck.

 

[Grench]

I just got back from the 1500 mile trip.

So, my '96 was seeming to run pretty well on Thursday. It sputtered about once an hour, but was manageable. Then I got 6 hours into my 10 hour drive to Kentucky, which happened to be St. Louis. At rush hour. With stop and go traffic.

Every time traffic stopped, so did my engine. Restart, drive forward, hit brake, die. Working the brake and the gas at the same time I was able to cut down on, but not eliminate the restarts. By the time I got into Illinois I was starting to doubt my plans for back woods camping and moderate four wheeling.

About 50 miles into Illinois I had gotten down to the last quarter of the main tank and had exhausted the reserve. I hadn't filled up before I left, so it wasn't surprising. I made a quick stop at a CITGO station about 40 miles east of St. Louis where I just filled the primary tank. For the next 150 miles there were -no- hiccups. None. Then a few, but very minor and no more engine dying bits. I made it the rest of the way to Kentucky and the LBL area without problems. Once there I filled up with 93 octane premium in hopes that I could buy my way out of my troubles.

The girl behind the counter was shocked when I put $99.10 in the tanks. No, I wasn't all the way empty.

So, my thought was that I had gotten some real bad fuel when I did the initial fill.

Then we went out to go wheeling on Friday. The hiccups and lurching was back...then gone...then back... All...day...long. At random. It would run flawlessly for an hour or so, then I'd be stomping the gas to keep the engine running while center & rear locked and climbing out of a mud hole. Exciting, but not exactly great technique.

When I left Kentucky this morning, I topped off the main tank. The spare was still full. The truck decided to run great, at least until St. Louis. Sputter & lurch at 70 mph in Sunday noon traffic was still easier than Thursday 5:00.

It sputtered and lurched about 2-5 times per hour until the Iowa / Missouri border, then ran fine until the Nebraska border then sputtered and lurched to my driveway.

My mileage isn't suffering. I left the Land Between the Lakes (www.lbl.org) with full tanks, which from what I can tell is about 50 gallons. I made it to my driveway without filling up. The aux tank is empty and the main shows half full, which means I have about 6 gallons left. So... I went 650 miles (648.9 if you want to nit pick) on 44 gallons of gas = 14.77 mpg fully loaded with tools & camping gear & etc... netting to about 6,000 lbs. And I was bucking a head wind.

So, two full loads of fuel later and the problem persists. I keep coming back to maybe there is some water in the system, but I tried heet, no luck. Getting the truck back on the highway from a burger joint or rest stop can be tricky. It can die three times before getting it backed out of a stall, into drive and pointed the right way. That whole power steering thing is less fun when the engine dies.

At speeds over 10 mph, the momentary stall causes the truck to engine brake for a moment, then the momentum at the tires kicks the engine back into happy mode. This all happens in under 1/4 second.

It doesn't seem to matter what station the gas comes from. The problem seems to be fully at random. Although dramatic when it hits, I can go for an hour or more sometimes and wonder if it is finally gone. Then I end up lurching every 30 seconds to minute for 10 miles.

Sorry about the long winded story, but I'm still trying to find an answer for this one. So far I have a lot more things that it isn't than what it is.

I'm getting ready to start re-checking all the things that we already checked. Its coming down to that or taking it to the dealer, and the dealers here don't even know that these trucks exist. It could be an expensive diagnostic.

Any suggestions?

 

[NaterGator]

Does it only stall with little/no throttle application?

How about the IAC?

 

[Grench]

More details...

Does it only stall with little/no throttle application?

How about the IAC?

No, it gives a momentary stall at any RPM. At higher RPMs there is enough momentum to -push- the engine through it.

If I throttle lock it at 2200 RPM sitting in the driveway, it will sputter, keep running unless it sputters during the RPM drop from the first sputter, in which case it dies.

At 600RPM idle, the first sputter kills it.

At highway speeds 50-80 mph the whole truck pitches forward for a fraction of a second (like a sudden sub-second down shift) then carries on it's merry way as if nothing happened or does it again at a random moment 1 second to 90 minutes later.

No rhyme or reason to the timing. Curves, straights, bouncing on a trail, sitting in the driveway... Its run fine on all for an hour plus and its stalled 5 times in 5 minutes on all of the above scenarios.

The IAC... I'll have to look up the FSM instructions for testing it. The symptoms don't fit it well since the issue is at any throttle or RPMs, but at this point, that is one bit of the truck that hasn't been tested. I'll check it out.