Runs perfect!!.....heat soak.....won’t stay running
11-05-2018, 05:05 AM
#22
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OKAY GUYS!!! This might show fault here! So with the truck cold, ign to ON and testing leads going into relay. Leads are reading 11vdc off of b+ to ground and 11vdc off of Fp to ground. With truck running it’s reading 13vdc b+ To ground and 13vdc Fp to ground.
Now!!! I duplicated the issue. Started it while bogging and getting ready to die. The read was b+ 12vdc to ground and 12vdc Fc to ground!...
Now!!! I duplicated the issue. Started it while bogging and getting ready to die. The read was b+ 12vdc to ground and 12vdc Fc to ground!...
Just so you know, 11v is pretty low. You should be getting very close to battery voltage, which should be close to 12.6v key-on, 13.1v running (both temperature dependent). As a sanity check, put your meter leads directly on the battery with key-off. If you're getting close to 11v, either the battery is VERY discharged (but probably not, as you're able to start it), or your meter is off.
Just to repeat: it looks like you have an open in the Fc CIRCUIT. This could be a loose connector, a broken wire, or the switch in the VAF. Don't start replacing expensive components (VAF?) that have already passed a diagnostic test.
11-05-2018, 03:05 PM
#23
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Just so you know, 11v is pretty low. You should be getting very close to battery voltage, which should be close to 12.6v key-on, 13.1v running (both temperature dependent). As a sanity check, put your meter leads directly on the battery with key-off. If you're getting close to 11v, either the battery is VERY discharged (but probably not, as you're able to start it), or your meter is off.
Just to repeat: it looks like you have an open in the Fc CIRCUIT. This could be a loose connector, a broken wire, or the switch in the VAF. Don't start replacing expensive components (VAF?) that have already passed a diagnostic test.
Just to repeat: it looks like you have an open in the Fc CIRCUIT. This could be a loose connector, a broken wire, or the switch in the VAF. Don't start replacing expensive components (VAF?) that have already passed a diagnostic test.
Maybe take the plate off the AFM and see if their is any loose connections?
11-08-2018, 06:37 PM
#24
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Is their a way for me to test the VAF switch independently?
11-08-2018, 07:22 PM
#25
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It seems that Scope103 and Co_94_PU have things pretty well covered, but I did not see what vehicle you are working on. I can probably safely assume that it is a Toyota Truck from 1985-1995 with fuel injection, but what engine?
The Air Flow Meter fuel pump switch testing should be in the same test procedure as testing the rest of the Air Flow Meter. I will double check that the test procedure is not elsewhere in the manual.
The Air Flow Meter fuel pump switch testing should be in the same test procedure as testing the rest of the Air Flow Meter. I will double check that the test procedure is not elsewhere in the manual.
11-09-2018, 05:37 AM
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As CO_94_PU says. But here's the manual if drawings help: http://web.archive.org/web/201003261...92volumeai.pdf
01-14-2019, 12:41 PM
#28
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Update. I went to clean afm a while ago and did the stupid act of pulling the 2 screws off the side and pulling the connector off. In return breakin the solder joints. Well that’s fixed as of TODAY. BUT this whole time Iv been cruising around with a jumper between Fp and b+ in the diagnostic port. Well for the first time the OTHER night it wouldn’t start even with that in. Today after working on it and soldering connections it started up and ran fine. I let it idle for about 20 min to see if it would stall. It didn’t so I shut it off. Went back 5 min later and it started but idled low. Shut it off and waited about 15-20 min and it won’t start. Won’t even start with the jumper in again. Pulled coil pack wire and it’s getting spark and pulled banjo at fuel rail and gas spitting out. I’m thinking vapor lock? How can I test this and what is a way around it? Unfortunately this problem is still haunting me. All the resistance checks are good
Last edited by bensyota; 01-14-2019 at 12:42 PM.
01-15-2019, 11:42 AM
#29
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Okay im confused!! Im currently trying to test fuel
pressure. Hook gauge up at driver side fuel rail. It’s reading zero. Got a rent a kit from Autozone. Seen nipple was bent in my adapter. Replaced it with another. Still reading zero. Truck is starting because it’s cold and im not letting it run. Bring gauge over to air compressor and blow air through it. The gauge does work! With the ignition to on I took the gauge off but left the adapter on with the nipple. I pushed in the nipple and no gas is coming out. Isn’t the line supposed to be pressurized with ignition key on? I jumped b+ and Fp in diagnostic port and then push nipple in and gas comes out. Doesn’t seem that strong but it does. When I start the truck and jump the fuel pump with the gauge connected it still reads zero!! WTH is going on here.
pressure. Hook gauge up at driver side fuel rail. It’s reading zero. Got a rent a kit from Autozone. Seen nipple was bent in my adapter. Replaced it with another. Still reading zero. Truck is starting because it’s cold and im not letting it run. Bring gauge over to air compressor and blow air through it. The gauge does work! With the ignition to on I took the gauge off but left the adapter on with the nipple. I pushed in the nipple and no gas is coming out. Isn’t the line supposed to be pressurized with ignition key on? I jumped b+ and Fp in diagnostic port and then push nipple in and gas comes out. Doesn’t seem that strong but it does. When I start the truck and jump the fuel pump with the gauge connected it still reads zero!! WTH is going on here.
01-15-2019, 03:12 PM
#31
Bottom line you don't have vapor lock, you might have an air fuel mixture issue which is a sensor issue or pumping problem.
Okay im confused!! Im currently trying to test fuel
pressure. Hook gauge up at driver side fuel rail. It’s reading zero. Got a rent a kit from Autozone. Seen nipple was bent in my adapter. Replaced it with another. Still reading zero. Truck is starting because it’s cold and im not letting it run. Bring gauge over to air compressor and blow air through it. The gauge does work! With the ignition to on I took the gauge off but left the adapter on with the nipple. I pushed in the nipple and no gas is coming out. Isn’t the line supposed to be pressurized with ignition key on? I jumped b+ and Fp in diagnostic port and then push nipple in and gas comes out. Doesn’t seem that strong but it does. When I start the truck and jump the fuel pump with the gauge connected it still reads zero!! WTH is going on here.
pressure. Hook gauge up at driver side fuel rail. It’s reading zero. Got a rent a kit from Autozone. Seen nipple was bent in my adapter. Replaced it with another. Still reading zero. Truck is starting because it’s cold and im not letting it run. Bring gauge over to air compressor and blow air through it. The gauge does work! With the ignition to on I took the gauge off but left the adapter on with the nipple. I pushed in the nipple and no gas is coming out. Isn’t the line supposed to be pressurized with ignition key on? I jumped b+ and Fp in diagnostic port and then push nipple in and gas comes out. Doesn’t seem that strong but it does. When I start the truck and jump the fuel pump with the gauge connected it still reads zero!! WTH is going on here.
The system does not preform a pre run pressurization like some other makes and models. The pump only runs if there is airflow and for a short duration after the key is placed into the start position.
You have a gauge that works but isn't reading the system pressure, maybe a device issue.. What scale does this guage read?
Low fuel pressure could be various things such as, low battery voltage, low voltage at the pump due to voltage drop or bad ground path, crushed supply lines, clogged prefilter (pump sock), closed fuel filter, a bad pressure regulator, and finally just a worn out pump.
01-15-2019, 03:13 PM
#32
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why would you say that?
update! I Got the gauge to work. Even though it was rigged and dripping gas at connection. It read fine during idle and psi went up to service spec when I pulled FPR vacuum hose. But im getting 0 pressure when the ignition is turned to ON and truck not running?
update! I Got the gauge to work. Even though it was rigged and dripping gas at connection. It read fine during idle and psi went up to service spec when I pulled FPR vacuum hose. But im getting 0 pressure when the ignition is turned to ON and truck not running?
01-15-2019, 03:20 PM
#33
why would you say that?
update! I Got the gauge to work. Even though it was rigged and dripping gas at connection. It read fine during idle and psi went up to service spec when I pulled FPR vacuum hose. But im getting 0 pressure when the ignition is turned to ON and truck not running?
01-15-2019, 03:29 PM
#34
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Thread Starter
This means it's not really susceptible to vapor lock, any bubbles of "air/gas" get pushed back into the tank. Secondly, what model year is this does it have the fuel pulse damper, there is a screw on this which protrudes when the system is pressurized it's a quick touch test to know if there is pressure and the pump is/was running. Every time you open that connection and don't replace the crush washers you are risking a fuel leak in the engine bay. The "right thing" to do is pull the CSI out of the intake and leave it attached to the fuel line, you can also check the flow in the return line.
Bottom line you don't have vapor lock, you might have an air fuel mixture issue which is a sensor issue or pumping problem.
Show us what you got from Autozone and how it was attached.
The system does not preform a pre run pressurization like some other makes and models. The pump only runs if there is airflow and for a short duration after the key is placed into the start position.
You have a gauge that works but isn't reading the system pressure, maybe a device issue.. What scale does this guage read?
Low fuel pressure could be various things such as, low battery voltage, low voltage at the pump due to voltage drop or bad ground path, crushed supply lines, clogged prefilter (pump sock), closed fuel filter, a bad pressure regulator, and finally just a worn out pump.
Bottom line you don't have vapor lock, you might have an air fuel mixture issue which is a sensor issue or pumping problem.
Show us what you got from Autozone and how it was attached.
The system does not preform a pre run pressurization like some other makes and models. The pump only runs if there is airflow and for a short duration after the key is placed into the start position.
You have a gauge that works but isn't reading the system pressure, maybe a device issue.. What scale does this guage read?
Low fuel pressure could be various things such as, low battery voltage, low voltage at the pump due to voltage drop or bad ground path, crushed supply lines, clogged prefilter (pump sock), closed fuel filter, a bad pressure regulator, and finally just a worn out pump.
01-15-2019, 03:34 PM
#35
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Thread Starter
See above its not supposed to have pressure. Unless the pump is running or was recently ran, o don't recall the spec off hand but it's something like 30psi for atleast five minutes after the system.was pressurized.. If you have appropriate pressure when the pump is running, and it changes as described in the manual when the pressure regulator vacuum is changed, you want to run the "clamp test" on the return line if you don't have very high pressure readings or it drops to zero as soon or very shortly after the pump jumper is removed... You have a fuel pump failure, there is a check valve in the pump and this will stick open if the prefilter is trashed allowing debris thru another side effect of that is lower fuel pressure/volume..
01-16-2019, 07:46 AM
#36
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Thread Starter
Checked dizzy, primary and secondary coil resistance. Everything checked out fine. One thing that was questionable was the air gap between the rotor and pickup coil projection. The thicker part of the allowance didn’t fit? Also had some scum inside dizzy cap? Trying to post a pic but I haven’t in forever that I forget how to. Okay got pic to post. Have no idea how haha. Anyway im letting my truck run currently for a while and going to duplicate issue then check resistances again.
UPDATE!!.... I duplicated the issue and retested the distributor pickup coil. I’m getting no resistance between NE and G-. I have to readjust probes and I get a split sec of resistance and the goes to open circuit. Other test points are solid. And I didn’t get this under cold conditions. Haha so what exactly does this mean? No spark? Tested the primary and secondary again and they were fine. Again my meter isn’t good enough to go so low for the primary but it’s reading resistance. Manuel says to get a new dizzy of this occurs. Should I go that route? Who sells a Denso dizzy?
Update again. I keep going out checking resistance between NE and G- every 10 minutes or so. Every time I get a resistance reading that last a little longer than the last time. It will hold a reading for about 3 seconds right now before going to infinite. Seems like its cooling and working it’s a way to a normal state.
Last edited by bensyota; 01-16-2019 at 10:02 AM.
01-17-2019, 08:50 AM
#37
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Thread Starter
Installed permanent fuel pressure gauge! Works great! Has anybody ran into the problem of the original crush washers that come with banjo fitting are too big and spray fuel everywhere!!! Ughhhh just used original for now. Not leaking anywhere. Fuel pressure is fine. I love this mod. Getting ready to go pick up new dizzy and see if it is the solution to my problem. Fingers crossed🤞🏼Untitled 1https://drive.google.com/file/d/1Y9U3gmYktDtEIr-wfjG0lgXkKMbLyIfx/view?usp=
update: still have the same problem. Check resistance between the two terminals on the good dizzy and it’s foing the same thing. It must just be normal? I fired it with ether. It started and ran. At first it was running with fuel pressure around 24 psi. Then it made its way to about 31psi. When I shut the truck off it jumps to almost 40 and sits there. Why would it jump when the truck is shut off
update: still have the same problem. Check resistance between the two terminals on the good dizzy and it’s foing the same thing. It must just be normal? I fired it with ether. It started and ran. At first it was running with fuel pressure around 24 psi. Then it made its way to about 31psi. When I shut the truck off it jumps to almost 40 and sits there. Why would it jump when the truck is shut off
Last edited by bensyota; 01-17-2019 at 08:42 PM.
01-19-2019, 11:08 AM
#38
Installed permanent fuel pressure gauge! Works great! Has anybody ran into the problem of the original crush washers that come with banjo fitting are too big and spray fuel everywhere!!! Ughhhh just used original for now. Not leaking anywhere. Fuel pressure is fine. I love this mod. Getting ready to go pick up new dizzy and see if it is the solution to my problem. Fingers crossed🤞🏼Untitled 1https://drive.google.com/file/d/1Y9U3gmYktDtEIr-wfjG0lgXkKMbLyIfx/view?usp=
update: still have the same problem. Check resistance between the two terminals on the good dizzy and it’s foing the same thing. It must just be normal? I fired it with ether. It started and ran. At first it was running with fuel pressure around 24 psi. Then it made its way to about 31psi. When I shut the truck off it jumps to almost 40 and sits there. Why would it jump when the truck is shut off
update: still have the same problem. Check resistance between the two terminals on the good dizzy and it’s foing the same thing. It must just be normal? I fired it with ether. It started and ran. At first it was running with fuel pressure around 24 psi. Then it made its way to about 31psi. When I shut the truck off it jumps to almost 40 and sits there. Why would it jump when the truck is shut off
The injectors stopped firing, and vacuum was removed from the fuel pressure regulator. Mostly the last part if everything is working correctly the injectors firing should only cause a small oscillation which is what the damper was intended to handle..
Pretty sure 24 is way below spec, does it do this consistently, does it only happens when cranking or can you replicate it with manually turning in the fuel pump via the diagnostics port. This could be a bad pump, gunk in the tank line or filter, or just a byproduct of cranking vacuum applied to the fuel pressure regulator.
Did you do the volume test on the fuel pump? (Pull return line, plump return into a large soda pop bottle, run the pump for sixty seconds, mark the bottle with a marker, dispose of fuel, fill bottle to line from a measuring cup or graduated cylinder)
You should have about 500cc/ml a minute.
Did you check the FPU (fuel pressure up) system? This is intended to give more fuel pressure on hot/warm starts. It functions by disconnecting the regulator from the vacuum. (Follow the vacuum line on the regulator and it will lead to a vacuum switch, this is the FPU-VSV, disconnect it's electrical determine if the ECU is commanding it to switch when the engine is in the hot start condition.. Engine warmed up, key off, volt meter to each side of this connector. When you set the key to START, you should see battery voltage on the meter. ) There is also a thermal switch in this system, we can cover that later if needed cause I don't want to go dig out the specs and diagrams right now.
Check the "health" of the fuel pump, does it supply adequate pressure in a timely manner? (Get a pair of flat jaw vice grips cover the jaws with sections of hose, they actually make a smooth jawed tool for this, and clamp off the return line from the regulator, now momentarily power on the fuel pump at the diagnostics port and note the system pressure. I do not recall the spec when the fuel pumps internal bypass opens, but it is substantially higher than the mid thirties listed as the fuel pressure spec from the FSM.)
01-20-2019, 05:24 PM
#40
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Thread Starter
Okay I was on vacation all week and was able to mess around with it. I will run these tests next weekend for sure. Thank you again.
After cleaning dizzy contacts and temps being in the teens, I actually couldn’t duplicate the problem again recently. I’ll wait for a warmer day and try again.
i did pull vac line to vsv when issue occurred and it didn’t make a difference. I was going to pull csi and see if it activated under warm start and also check time switch for it.
After cleaning dizzy contacts and temps being in the teens, I actually couldn’t duplicate the problem again recently. I’ll wait for a warmer day and try again.
i did pull vac line to vsv when issue occurred and it didn’t make a difference. I was going to pull csi and see if it activated under warm start and also check time switch for it.
Last edited by bensyota; 01-21-2019 at 03:44 AM.
