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Discussion Starter #1 (Edited)
I purchased a 1995 4-Runner with 224 000 KM back in January 2008 and with it came 3 problems which I didn’t know about:

1)Difficult to start when engine is cold (also worse when outside temperature is cold like winters), cranks fine
2)Bucking/missing under load specially in cold weather on highways and more noticeable when engine warming up but still present with warm engine
3)Idles fine at 750 rpm but once warmed up if you shut engine off and re-start idles low (not O2 sensor because I changed it), also idles low if coming from highway speeds and rpms are kept low while slowing down and not using brakes as fast and hard, meaning gradually coming to a stop. If using brakes quickly and hard usually she idles fine at 750 rpm

I replaced the following parts (90% OEM Toyota) because most needed replacing and hoping that it would solve my above 3 problems as well but they didn’t:

Complete tune up parts (spark plugs, wires, rotor, dist cap, PCV valve & grommet, air filter, fuel filter, O2 sensor, cleaned AFM housing and throttle body) & ran Sea Foam several times in the fuel, oil and vacuum system. The plastic washable/re-usable fuel pump filter (inside the gas tank) is in excellent condition.

Main fuel line, fuel pump bracket, fuel filler pipe (my mechanic replaced these parts)

Complete exhaust system, front to back, again all OEM except for stainless Magnaflow cat

Head gasket (head was corroded from prior head gasket failure where prior owner’s mechanic didn’t have head examined), head was welded and shaved, timing chain kit was replaced (an engine rebuilder shop replaced these parts)

I found 2 ground corroded/rusted wires, one connected on firewall and engine hoist hook (4th spark plug wire) and the other was broken because the battery was loose so the wire broke between the negative battery terminal and passenger fender wall. I replaced both wires.

I pulled the ECU (EFI computer codes) and nothing came up, I also measured the voltages and resistance at each ECU wire and compared with FSM (factory service manual) still nothing, I also did a spark test and compression test. I used a timing light to check for engine base timing and it’s at 5 degrees BTDC with T-E1 shorted in diagnosis box. My mechanic took these fuel pressure readings after replacing main fuel line but before the fuel pump bracket and am not sure where he placed his fuel pressure tester:

Dead head=55 PSI (the factory service manual=38-44 PSI)
Idle=36 PSI ( the factory service manual=38-44 PSI)
Idle without vacuum=40 PSI (the factory service manual=33 PSI avg or 23-37 PSI)

I measured the resistance on the cold start injector, cold start injector time switch, intake air temp sensor, water temp sensor for ECU, AFM and TPS. I measured the wire harness for each of the above parts and nothing. I unbolted the cold start injector and moved it back about 1" and had a friend crank cold engine and fuel spray came out and was uniform. I also removed cold start injector from vehicle and dipped in Sea Foam for 10 minutes even though nozzle tip and it's fuel line entrance was clean.

When I say it's difficult to start with cold engine I mean the engine turns over but doesn't start until about 3 seconds (more in colder weather) and once engine is warm (after driving) she will start sooner but not instantly like Toyotas are known for. I found that when engine is REALLY COLD (in cold winters) I crank it for 2 seconds then stop then crank then she will start if I attempt another technique she will start then shut off right away.

I know for an engine to run you need the 3 basics: fuel, spark and air. When I jumper Fp (fuel pump) terminal and B+ (battery) terminals in the diagnosis box thereby bypassing the AFM power switch and circuit opening relay (fuel pump relay) found behind the glove compartment, the engine starts faster almost instantly. The AFM and circuit opening relay are fine as I measured their resistance and voltages and compared the readings with the service manual as I stated earlier.

I was told it may be a vacuum leak or EGR valve but I don’t have an unlit propane torch to use and visually inspecting the vacuum lines I didn’t see any obvious cracks. I do have the factory service manual but am at a lost hence why my post, if it may be an air problem how do I find it?

Can anyone help me?

Sidney
E-mail:sidneybek(at)yahoo.com
Dartmouth,Nova Scotia
Canada
1995 Toyota 4-Runner, 22R-E, G52 with 235 000 KM
 

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The fuel pressure tests (if done correctly) indicate the pressure regulator is faulty. It's out of range both low and high with vac attached, and out of range high with no vac. It also sounds like your system is not holding fuel pressure, and is allowing some fuel to drain back into the tank, which means the check valve in the fuel pump may also be tired.

It's possible your pulsation damper is also faulty - it's attached near the front end of the fuel rail, on the underside. If it's the original, there's a tiny little bolt in the center of it that's attached to the diaphragm. When there is pressure in the fuel rail, the head of the bolt should be about flush with the top surface of the damper, and when the system has de-pressurized the bolt should be pulled inward as the diaphragm relaxes.

If $$ is tight, rockauto sells a Beck/Arnley regulator for $76 that is very likely made in Japan. Most of their parts for our trucks are. I've had very good luck with the B/A parts I've used. Otherwise, the OEM is $101 at 1sttoyotaparts.com.

If the fuel pump's check valve is leaking, you will always have a delay to start the engine after it sits for a while. If you wanted to replace that, autohausaz.com sells denso pump kits with the sock and assorted parts for very good prices. You'll still want to get a fuel pump bracket gasket and new screws from the dealer, and probably also a tank drain plug gasket. Be sure to have the tank thoroughly cleaned before installing the new pump.

Glad to see you posting again - I've found many of your posts helpful as I've searched the forum. Good luck with the runner - let us know how you make out.
 

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Discussion Starter #3 (Edited)
I forgot to mention that if I jumper the Fp & B+ terminals for about 1 minute then remove the paperclip and try starting it, she still takes along time. Again this problem is more noticeable in winters.

I cannot drop the gas tank (the 1st generation 4-Runners:84-89 you access the fuel pump through back passenger seat) and already paid my mechanic twice to drop the gas tank, 1st time to replace main fuel line and 2nd when the fuel pump bracket began to leak shortly after the 1st repair. In my opinion when he had the tank down he should of known the fuel pump bracket looked RUSTED OUT.

I hate car mechanics hence why I visit 4-Runner/pickup dedicated discussions sites and have learned so much about car repairs and "try" to do my own repairs and try to help fellow owners on here and other websites. I don't have any more money as I spend ALOT on all the parts I already replaced which most were bad. My mechanics fuel volume tester tool is leaking hence why he didn't use it.

From all of the reading I had done in the past Toyota fuel pumps usually only fail when the vehicle has been sitting for many months or years and the pump seizes or the vehicle is driven low on gas so the pump overheats and pumps air instead of fuel am I correct? or is there a possibility my pump is bad with my symptoms? thanks.

Sidney
Repairs TV's,VCR's,home/car audio out of my apartment
Dartmouth,Nova Scotia
Canada
1995 Toyota 4-Runner, 22R-E, G52 with 235 000 KM
 

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Did you have the ignition on when you jumped B+ & FP? If not, it didn't run the pump. You don't have to remove the jumper before starting - you can do it after.

With all that rust in the tank, the condition of your sock is critical - if the old sock had holes, that would explain a messed up check valve. You may need a new tank.

Yes, sitting too long and running dry are the two big killers of the pump, which otherwise should last well over 300,000 miles. If it sucked up rust particles, though, that could also damage it.

Before I worried much about the pump, I would worry about the fuel pressure, which is controlled by the pressure regulator, not the pump.
 

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Discussion Starter #5 (Edited)
Did you have the ignition on when you jumped B+ & FP? If not, it didn't run the pump. You don't have to remove the jumper before starting - you can do it after.

With all that rust in the tank, the condition of your sock is critical - if the old sock had holes, that would explain a messed up check valve. You may need a new tank.

Yes, sitting too long and running dry are the two big killers of the pump, which otherwise should last well over 300,000 miles. If it sucked up rust particles, though, that could also damage it.

Before I worried much about the pump, I would worry about the fuel pressure, which is controlled by the pressure regulator, not the pump.
Yes I had the ignition as well I heard the buzzing noise from the fuel pressure regulator, I know I don't have to remove the jumper but I was trying different technique in order to isolate problem. My vehicle was not sitting for months nor was it ran dry on gas and again my mechanic stated my plastic fuel pump filter is in excellent shape. Thanks again.

Sidney
E-mail:sidneybek(at)yahoo.com
Dartmouth,Nova Scotia
Canada
1995 Toyota 4-Runner, 22R-E, G52 with 235 000 KM
 

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"3)Idles fine at 750 rpm but once warmed up if you shut engine off and re-start idles low."
If your truck drops in rpm every time it sounds like an electrical problem.
Now all you have to do is find out what changes when you restart the truck?

Have you changed the Temp sending unit yet?


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Discussion Starter #7 (Edited)
By installing an electrical switch (On-OFF SPST) electrically in parallel with the AFM's safety switch for the fuel pump as Toyota fuel pumps do not come on when ignition switch is open only when cranking as their is a vacuum effect and the air filter's housing built in safety switch closes.

So when I open the ignition switch and press that manually installed switch several times (each time about 10 seconds) I am manually building up fuel pressure and then my truck will start very quickly almost like a brand new truck. so now 5 years later I narrowed the problem to a fuel pressure problem (not electrical, not spark and not air).

So anyone know which part is defective? as I spent alot of money on repairs and disnhonest mechanics so I cannot throw a part in based on "trial and error" or "shotgun troubleshooting technique". Thank you.

Sidney
E-mail:sidneybek(at)yahoo.com
Dartmouth,Nova Scotia
Canada
1995 Toyota 4-Runner, 22R-E, G52 with 275 000 KM
 
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