Problem: Motor Cutting Out

[Sarrus25]

1986 4Runner, 22RE 4-wd 5-speed, EFI

Hey guys,

I was driving to work one morning, accelerating a little harder than normal, and my engine cut out while I was giving it gas. It drove fine the rest of the way to work.

Later that day, the motor would cut out under a load, and gradually got worse til I couldn't drive any inclines. I had my poor truck towed home that night.

I am stumped as to why I am having this problem. Here is what I have checked so far:

• AFM: all ohm meter measurements within spec. I have two spares, they checked out fine as well
• Plugs: Changed them with new spark plugs
• Distributor: Changed the pickup coil with a spare; no luck
• Plug wires: Inspected and they look fine
• TPS: Adjusted by stealership ~4 weeks ago
• Timing Chain: Checked for chain slippage; no issues

The truck was throwing a code 6 before I cleared it, has not returned as of yet.

Here's a video:

https://goo.gl/photos/DAY4ub6gxndvAjbg9

 

[flyinhawaiian01]

You have a timing light? Hook it up and watch the light to see if its spark or fuel cutting out. When it cuts out, if the light is still flashing, its fuel, if its out, its spark.

We can go from there once you determine this.

 

[Sarrus25]

So I do have a timing light, and I actually ran it on all 4 plug wires (independently, one at a time) and made the motor cut out. It kept flashing on all four, during the motor cutting out.

 

[Bad_Vision]

Weak igniter or fuel system loosing pressure causing stall. Test both those and report results

 

[flyinhawaiian01]

Well, it shouldn't be spark then, so you should be able to rule the ignitor out. I'd look at fuel first.

See if its something simple next, I'd run a jumper at the check connector between "FP" and "B+" terminals. Try getting it to drop out again. If it does, then I'd start testing the wiring to the ecu, possibly the wires to the injectors, and maybe the resistor pack for the injectors. If it does not die out, you probably have a fault with either the fuel pump, AFM internal switch or relay.

This isn't an absolute list of what's wrong, there could still be something else, but these are the next, simplest, tests that don't cost anything.

Edit: When was the last time you replaced the fuel filter? If its clogged badly, you could get the same fuel starvation issues as you're describing.

 

[RAD4Runner]

Yes, wire between Injectors and ECU. There is a splice near the intake that could get corroded and brittle so easy to break. It happened to my truck after rebuilt engine was put in.

 

[Sarrus25]

Had a REALLY dumb moment just now...

I swapped my ICM (igniter, ignition control module) with my spare and someting shorted out, and now the truck will not crank over at all. When I put the key in, there is very low power to everything.

The spare ICM had a different model # and different wire connectors, but I took my time to adapt them to my harness. I have since put the stock ICM back into the truck...

• Battery reads 12.55v
• Starter was clicking, now will not do anything
• Safety override switch is not doing anything; light only comes on when buttin is held in
• Old ICM is re-installed and the issue persists
• Fuses under hood and in driver's side interior do not appear blown

Did I fry my ECU? What can I check from here?

 

[Sarrus25]

I have plugged in my battery charger to the battery, and it is charging. Hoping that I just had a weak battery.

I also noticed that when I plug in the battery terminals, that I can hear a humming for a few seconds. Fuel pump? Or something ele? Or, doesn't mattter?

I took out the ECU and it did not smell funny (circuit board), nor did I see any burned / scorched components on the top or bottom.

I have a spare ECU from a newer motor (from my spare parts collection), but I have not tried plugging it in as I have read that they are not all compatible (different model number).

 

[Sarrus25]

UPDATE

I jumped the truck off of another running vehicle, and it fired right up. Let it idle for about 5 minutes, turned it off. Battery was immediately flat, starter just clicked and battery power faded to nothing.

Possibly bad alternator? Bad battery?

I will get the battery tested tomorrow at Autozone and go from there.

Night!

 

[Sarrus25]

I had the battery tested at Autozone over lunch, and the battery tested out fine.

..... This means that by plugging in the newer (spare) ICM (ignition control module) / igniter I had, something must have shorted out. What's odd is I was able to get the truck to start fine last night by jump-starting it from another vehicle. Hmm...

Any thoughts on what I may have shorted out with the incorrect ICM module, but would still allow the truck to run when jump-started? Maybe a burned wire somewhere that is grounding out to the frame? I looked through my fuses last night and none of the small ones appeared to be burned out.

I have no idea where to start looking. Any help would be appreciated!

NOTE: The fuel filter is new as of last month. I should have followed the fuel delivery troubleshooting advice before swapping the igniter.

 

[grumpin]

I would make sure the battery connections are good. If you put the jumpers on the positive and negative as opposed to positive and a ground on the frame or engine. That might explain why it ran jumpered.

 

[Sarrus25]

Progress has been made!

STARTING PROBLEM: Solved

Thanks, Grumpin! You got me thinking last night about the battery terminals, and I was able to solve the starting issue that started after plugging in the later-gen, newer igniter.

I did the following work:

• Replaced 80amp fuse
• Replaced battery terminal connections
• Removed unnecessary accessory wires (hillbilly / hack wiring)
• Cleaned all ground / battery terminal hookup connections thoroughly with a wire brush
• Replaced fusible link wire with a standard terminal wire
• Charged battery externally to 100% (on a charger)

My theory is that the newer igniter was incompatible and shorted the fusible link. I will never truly know unless I test this further, but my problem is solved here and there is no reason to go back and mess with this more for now.


MOTOR CUTTING OUT PROBLEM: In Progress

The motor cutting-out issue is still persisting. I installed my LC Engineering 22RE fuel pressure gauge (cheaply made, not great quality for being ~$60) and here were the pressure results:

• Motor idling cold: 26 psi
• Motor idling warmed up: 24 psi
• Motor without fuel pressure regulator vacuum line: 35 psi
• Motor off: 0 psi (pressure decreases quickly from 24 psi; 20 seconds(ish) to 0 psi)

FSM / Manual SPEC

• Idle: 27 - 31 psi
• w/out Vacuum Hose (pressure regulator): 33 - 38 psi
• Motor Off: > 21 psi for 5 minutes (after power off)

Sooo... it looks like my fuel pressure is just a hair below spec, but definitely not maintaining pressure after power off. The FSM also states:

"Stop the engine. Check that the fuel pressure remains above 21 psi for 5 minutes after the engine is turned off

If not within specification, check the fuel pump, pressure regulator and/or injectors"
​

Looks like I need to inspect:

• Fuel pressure regulator
• Fuel injectors
• Fuel pump
• The fuel filter is new as of a month ago (mechanic installed it)

For what it's worth, I didn't check pressure during cutting out, but during revving (in neutral) the fuel pressure increased to about 30 psi.


What do you guys think?

 

[Sarrus25]

Fuel Pressure Spec (sorry mods, if you don't allow FSM data to be posted here-- then please remove)

 

[Sarrus25]

 

[grumpin]

It looks to me like the Fuel Pressure Regulator keeps the fuel from going back to the tank. I'm looking at my 1987 FSM, so I don't know if there are differences. That may explain the sudden drop after shutdown, but I don't know if that would cause the cut out. Unless your FPR is just shot. Glad you got the starting issue solved.

 

[Sarrus25]

UPDATE

The truck is now running like normal. I warmed it up and drove to the gas station down the street (very hilly street). I got it up to 70mph, floored it a couple times, put the most load on the motor possible, etc. and it did not cut out.

Here's what I did...

• While warming up, I clamped vice grips on the fuel pressure regulator return fuel line for about 30 seconds. I was going to do some testing... but I just ended up taking off the vice grips and not testing anything.
• Unplugged fuel injector #1 (front of motor), and just stared at it... plugged in a noid test light (bulb thing with two pins) and looked at it... then put it away and re-connected the fuel injector.
• I wiggled the #1 injector after idling & turning off motor-- didn't have any effect on the fuel pressure rate of dropping
• Fuel pressure after power down: 12 PSI (strangely, not 0 psi.....)

....I am wondering if me clamping the fuel return line has unclogged or otherwise caused the FPR to partially work? Or, if perhaps the fuel pump is behaving inconsistently?

I ordered a new fuel pressure regulator, and I will have it in tomorrow. Should I install it? Or drive until the issue comes back?

 

[The Count]

Watching the video immediately led me to believe you have a fuel delivery issue. If there isn't alot of dark smoke coming out of the exhaust or raw fuel smell WHEN THE MOTOR IS "CUTTING OUT" then I would say it is likely running lean at that point.

However, I do not think your fuel pressures readings are low enough for that to be the cause of the issue. I would look elsewhere, such as:

- fuel filter (already mentioned, and should have gradually gotten worse)
- ohm fuel injectors
- swap AFM with spare if you already haven't
- test coolant temp sensor
- test TPS

EDIT, just saw your new post.

I wouldn't install the FPR unless there is gas in the vacuum line of the one currently installed. I have NEVER seen a FPR fail that didn't leak gas into the vacuum side of it, that is the nature of the way they fail. It wouldn't "clog" up either, it constantly has fresh filtered gas running through it. I'd say you may have an intermittent problem on your hands.

 

[PRdubi]

where did you get your FPR and how much did it cost?

 

[grumpin]

I would, seems to me your valve in the FPR is "sticky". You could check you fuel pressure after power down and see how the new one does.

 

[Sarrus25]

UPDATE

The truck still does not run right, and I have replaced a number of other parts since the last post. This chase is driving me crazy, and I don't know what to do next..

• Replaced alternator, NO DIFFERENCE
• Brand new Denso fuel pump, NO DIFFERENCE
• New high pressure fuel line
• Charged battery
• Tried spare AFM, no difference
• Fuel filter is new as of December (gas tank is spotless inside)
• TPS ohmed out ok, spare TPS ohmed out ok as well
• Inspected ECU, no burning / funny smells on motherboard
• New FPR (fuel pressure regulator) from Oreilly, ran a hair better

Have not tested fuel injectors or coolant temp sensor.

What should I do now?