Fuel problems
06-07-2010, 01:24 PM
#1
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Fuel problems
Hey there,
I have had my toyota pickup for 10 years, it has been my first and only vehicle. It has the 22RE engine and is a four wheel drive. Unfortunatly it has been on the continual fritz for the past 2 years. I have been patching it together with my limited knowledge in mechanicing but now I need a little advice.
It is no longer getting fuel but i believe everything else is working because when i spray a little starting fluid in it it fires and runs. I had to change out the fuel pump 6 months ago and that was quite a chore. I believe it is the fuel pump again but i would like to be positive. I drug my grandpa out and checked the resistance on the little plug by the battery. The resistance read 104 for the +B. we also crossed +B with FP and i could not hear the fuel pump working in the fuel tank. when it sits for a bit it will start for a few seconds, probably from the pressure in the fuel tank due to rising temps. Is there anything else i can check to verify and also should i drop the tank or should i lift the bed (which i did last time with a borrowed tractor)
I was also wondering if it might be due to the fact that i recently put a new dash cluster in it. it was out of an 85 toyota sr5 with a manual (my truck is also a manual) and it worked great for the two days before my truck quit.
thankyou for your help ~maggi~
I have had my toyota pickup for 10 years, it has been my first and only vehicle. It has the 22RE engine and is a four wheel drive. Unfortunatly it has been on the continual fritz for the past 2 years. I have been patching it together with my limited knowledge in mechanicing but now I need a little advice.
It is no longer getting fuel but i believe everything else is working because when i spray a little starting fluid in it it fires and runs. I had to change out the fuel pump 6 months ago and that was quite a chore. I believe it is the fuel pump again but i would like to be positive. I drug my grandpa out and checked the resistance on the little plug by the battery. The resistance read 104 for the +B. we also crossed +B with FP and i could not hear the fuel pump working in the fuel tank. when it sits for a bit it will start for a few seconds, probably from the pressure in the fuel tank due to rising temps. Is there anything else i can check to verify and also should i drop the tank or should i lift the bed (which i did last time with a borrowed tractor)
I was also wondering if it might be due to the fact that i recently put a new dash cluster in it. it was out of an 85 toyota sr5 with a manual (my truck is also a manual) and it worked great for the two days before my truck quit.
thankyou for your help ~maggi~
06-07-2010, 01:41 PM
#2
Crack the fuel line open at the cold start to see if the fuel pump is working. Reason being that just because the fuel pump is working, doesn't mean the EFI system is operating correctly. I have had many vehicles that the fuel pump was working, but the injectors were not firing due to an EFI component failure.
If no fuel comes spraying out, you then need to determine if the fuel pump itself is bad by jumping the actual pump at the tank. Just run power straight to the pump via a battery or something of that nature.
If it does work, you can move on to the VAFM or the Circuit open relay.
If no fuel comes spraying out, you then need to determine if the fuel pump itself is bad by jumping the actual pump at the tank. Just run power straight to the pump via a battery or something of that nature.
If it does work, you can move on to the VAFM or the Circuit open relay.
06-07-2010, 01:49 PM
#3
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What year is the truck? The dash wouldn't have any effect on the fuel delivery unless you bungled ignition wiring in the process?
I don't know what resistance reading you should be getting from the testing plug......I've never messed with it. But, make sure you're getting voltage across the FP and B terminals. If so, then try starting the truck with the two terminals jumped again. If still no worky pooh, then it's the pump or the wiring. Or, of course, the filter.
I don't know what resistance reading you should be getting from the testing plug......I've never messed with it. But, make sure you're getting voltage across the FP and B terminals. If so, then try starting the truck with the two terminals jumped again. If still no worky pooh, then it's the pump or the wiring. Or, of course, the filter.
06-07-2010, 01:50 PM
#4
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Crack the fuel line open at the cold start to see if the fuel pump is working. Reason being that just because the fuel pump is working, doesn't mean the EFI system is operating correctly. I have had many vehicles that the fuel pump was working, but the injectors were not firing due to an EFI component failure.
If no fuel comes spraying out, you then need to determine if the fuel pump itself is bad by jumping the actual pump at the tank. Just run power straight to the pump via a battery or something of that nature.
If it does work, you can move on to the VAFM or the Circuit open relay.
If no fuel comes spraying out, you then need to determine if the fuel pump itself is bad by jumping the actual pump at the tank. Just run power straight to the pump via a battery or something of that nature.
If it does work, you can move on to the VAFM or the Circuit open relay.
She can't hear the pump running, though.
06-07-2010, 01:53 PM
#5
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BTW, the FP and B terminals bypass the AFM and COR (fuel pump relay), if you didn't know. So, if still no fuel, the could be the pump or wiring. In which case, what CougarCakes said applies. Test at the pump. Uhg. If it does work, AFM or COR.
06-08-2010, 07:48 AM
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well, yesterday evening i jumped the fb and the +b and i could hear the fuel pump working. I started the truck and it ran fine for a minute or so then quit again. there is power going to the little plug i have acess to that sits on the side of the fuel tank. i checked the voltage and it read 11.95 so there is power to the wiring. Just to be sure i went to a salvage yard and pulled a fuel relay out of a 4 cyl manual 22RE, the only thing different was the year (86). But the part number was the same that was printed on it. I installed it in my truck and it started and ran for a bit an then quit. I jumped it again with my hany paperclip and nothing from the fuel pump. So should it pretty much be the pump? I just replaced it 6 months ago! 
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06-08-2010, 08:24 AM
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ok :/
Its an 88 Matthew, poormans version, no AC, powersteering (I added that though), crank windows ect.
Its an 88 Matthew, poormans version, no AC, powersteering (I added that though), crank windows ect.
Last edited by toyota_grrl; 06-08-2010 at 08:27 AM.
06-08-2010, 09:28 AM
#10
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have you checked the fuel pump pressure ? the pump may be leaking in the tank. a friend and i were partners on a s 15 jimmy that acted similar. it turn out the new fuel pump was installed to the fuel line with a rubber fuel line no clamps.it ran fine for several months untill the gas sloshing loosened the connection. it would pump part of the fuel back into the tank every time the pump ran.
06-08-2010, 11:07 AM
#11
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I assumed you're truck was newer, so I mistakenly said that the FP/B terminals bypassed the AFM. Pretty sure it doesn't on older models, just not sure on the years. So, what you might be running into is a problem in the AFM. There's a circuit that completes the ground for the fuel pump relay once the vehicle is running. And, it cuts the ground if the vehicle the stops. You should test that circuit (Fc) with an ohm meter at the AFM terminals. If it appears good there, then check the harness connector for any issues.......like a terminal backing out, or something.
http://personal.utulsa.edu/~nathan-b...33volumeai.pdf
http://www.autoshop101.com/forms/h22.pdf
http://personal.utulsa.edu/~nathan-b...33volumeai.pdf
http://www.autoshop101.com/forms/h22.pdf
06-08-2010, 03:59 PM
#12
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I have an 86 4Runner that I'm restoring, so I have the 86 FSM and wiring diagram manual. I used to have an 89 4Runner and I have the FSM and wiring diagram manual for that too, but I don't have anything for an 88. The FSM's don't give resistance values for the fuel pump circuit, so i did some checking. The resistance of a good fuel pump is about 37 ohms and I'm not entirely sure of what part of the +B circuit you were testing when you measured 104 ohms, but if you were testing from +B of the EFI relay to +B of the Fuel Pump Check Connector, 104 is about right. I just measured an 86 pickup harness between those two points and my ohmmeter read 109 ohms.
The wiring has minimal resistance, but you are measuring through the coil of the Circuit Opening Relay and that is about 109 by itself. (FSM Spec is 88-132 ohms.)
This leads me to believe that your 88 fuel pump circuit is the same wiring configuration as my 86.
On the 89 you have a multiple pin check connector attached to the R/B#2
(Relay/Block or Fuse panel) under the hood on the passengers side. When you jumper Fp and +B on this set up you are taking +B from the main relay directly to +B terminal of the fuel pump which turns the pump on
On the 86 and probably your 88 there is a 2 pin connector over on the drivers side inner fender. The FSM tells you to jumper +B to Fp on the fuel pump check connector, but that is not really what you are doing. If you trace the wiring diagram Fc from the circuit opening relay goes to the Fc terminal of the Air Flow Meter. This is the line side of the fuel pump switch and under a normal start operation this switch closes, power goes to ground and your fuel pump is turned on through the circuit opening relay.
When you jumper +B to Fp on this setup you are actually jumpering +B to Fc after the circuit opening relay and before the air fuel meter. By doing this you are completing the coil circuit of the circuit opening relay, which closes the contact of the circuit opening relay and turns the pump on.
I know this is a drawn out explanation, but I wanted to show you that in a pre 89 vehicle, your problem may be the fuel pump, the wiring in the circuit or the circuit opening relay. You have to rule out each one of these and you have to try to prove if your problem is intermittent or if it is there all the time.
If you were measuring between the points that I mentioned above when you measured the 104 ohms, then that says that the coil circuit of your circuit opening relay is within spec. A relay coil circuit can test to spec, but at the same time the contact in the relay could be burned up.
The easiest way to check this is to get another Circuit opening relay and try it, but you can test yours. It's up under the dash close to the glove compartment, if you remove the glove compartment it's easier to get at. Looking at the base of the relay with the lock at 12 oclock +B is the center terminal(Black wire), Fc is the lower right terminal (Green Wire). Put a ground on Fc and 12vdc on +B, this will complete the coil circuit of the relay and the contacts will close. Take an ohm meter and measure from +B to Fp(Blue wire)which is upper right terminal. If the contacts are good the resistance reading should be very close to zero ohms. With your meter on the resistance setting make sure that you do not go 12v (+B) to ground (Fc) you may blow the fuse in the meter, but 12v (+B) to Fp is ok! If you can keep the ohmmeter leads on the contact terminals, watch the meter scale. Have some one remove the ground and reinstall the ground several times at terminal Fp. The contacts will break, the circuit will open and the meter will read infinity if analog or overload if digital each time the ground is removed. When the ground is re-installed the contacts will make, circuit will be complete and resistance reading should read close to zero each time. If this happens then you are pretty much sure that your circuit opening relay is operating properly each time it is powered up. (Sometimes relays get weak and don't always operate each time they are powered up.) This will rule out an intermittent problem with the relay or a faulty relay.
Next the wiring. Unplug the circuit opening relay and unplug the fuel pump from the connector in the harness at the tank. Measure the resistance from the blue wire of the circuit opening relay to the blue wire of the fuel pump, it should be zero ohms. Next check the ground (white/black) from the connector at the tank to any chassis ground. It should be zero ohms. Plug the circuit opening relay back in, jumper the Fuel pump check connector and turn on the key. Check for voltage from the Fp (blue wire) to the ground wire (white/black) at the tank connector. You should read 12v.
With the meter still connected watch the meter and have someone go along the harness route shaking the harness to see if you have a bad connection or a broken wire in the harness. If you lose the voltage reading during this then you probably have a broken wire somewhere in the harness. If all of the above checks are good, then the wiring is OK to the connector so the next step would be to plug your fuel pump in with the key still on and see if it starts.
If it doesn't then the next test is the fuel pump. As you know fuel pumps can go bad, you already replaced yours, but a fuel pump is an electric motor and electric motors can develop bad segments on the armature. Each time the fuel pump stops there are armature segments directly across from the magnets. If one of these bad segments ends up directly across from one of the magnets, next time the fuel pump is turned on, it may not start. So the fuel pump can have an intermittemt problem as well. The resistance of the fuel pump should be around 37 ohms.
Connect the ohmmeter leads to the fuel pump wires going into the tank, if you don't read somewhere close to this (20-40), but read infinity or overload then your pump probably has a bad segment (an open). Measure from each wire going to fuel pump to a chassis ground with your ohmmeter. If you get a reading and not infinity (analog) or overload (digital) then your pump (Motor) probably has a short.
I know this post is long winded and I'm Sorry for that, but many times when you troubleshoot complex electrical circuits you have to rule out what the problem is not before you discover what the problem actually is.
Hopes this helps! Good Luck
The wiring has minimal resistance, but you are measuring through the coil of the Circuit Opening Relay and that is about 109 by itself. (FSM Spec is 88-132 ohms.)
This leads me to believe that your 88 fuel pump circuit is the same wiring configuration as my 86.
On the 89 you have a multiple pin check connector attached to the R/B#2
(Relay/Block or Fuse panel) under the hood on the passengers side. When you jumper Fp and +B on this set up you are taking +B from the main relay directly to +B terminal of the fuel pump which turns the pump on
On the 86 and probably your 88 there is a 2 pin connector over on the drivers side inner fender. The FSM tells you to jumper +B to Fp on the fuel pump check connector, but that is not really what you are doing. If you trace the wiring diagram Fc from the circuit opening relay goes to the Fc terminal of the Air Flow Meter. This is the line side of the fuel pump switch and under a normal start operation this switch closes, power goes to ground and your fuel pump is turned on through the circuit opening relay.
When you jumper +B to Fp on this setup you are actually jumpering +B to Fc after the circuit opening relay and before the air fuel meter. By doing this you are completing the coil circuit of the circuit opening relay, which closes the contact of the circuit opening relay and turns the pump on.
I know this is a drawn out explanation, but I wanted to show you that in a pre 89 vehicle, your problem may be the fuel pump, the wiring in the circuit or the circuit opening relay. You have to rule out each one of these and you have to try to prove if your problem is intermittent or if it is there all the time.
If you were measuring between the points that I mentioned above when you measured the 104 ohms, then that says that the coil circuit of your circuit opening relay is within spec. A relay coil circuit can test to spec, but at the same time the contact in the relay could be burned up.
The easiest way to check this is to get another Circuit opening relay and try it, but you can test yours. It's up under the dash close to the glove compartment, if you remove the glove compartment it's easier to get at. Looking at the base of the relay with the lock at 12 oclock +B is the center terminal(Black wire), Fc is the lower right terminal (Green Wire). Put a ground on Fc and 12vdc on +B, this will complete the coil circuit of the relay and the contacts will close. Take an ohm meter and measure from +B to Fp(Blue wire)which is upper right terminal. If the contacts are good the resistance reading should be very close to zero ohms. With your meter on the resistance setting make sure that you do not go 12v (+B) to ground (Fc) you may blow the fuse in the meter, but 12v (+B) to Fp is ok! If you can keep the ohmmeter leads on the contact terminals, watch the meter scale. Have some one remove the ground and reinstall the ground several times at terminal Fp. The contacts will break, the circuit will open and the meter will read infinity if analog or overload if digital each time the ground is removed. When the ground is re-installed the contacts will make, circuit will be complete and resistance reading should read close to zero each time. If this happens then you are pretty much sure that your circuit opening relay is operating properly each time it is powered up. (Sometimes relays get weak and don't always operate each time they are powered up.) This will rule out an intermittent problem with the relay or a faulty relay.
Next the wiring. Unplug the circuit opening relay and unplug the fuel pump from the connector in the harness at the tank. Measure the resistance from the blue wire of the circuit opening relay to the blue wire of the fuel pump, it should be zero ohms. Next check the ground (white/black) from the connector at the tank to any chassis ground. It should be zero ohms. Plug the circuit opening relay back in, jumper the Fuel pump check connector and turn on the key. Check for voltage from the Fp (blue wire) to the ground wire (white/black) at the tank connector. You should read 12v.
With the meter still connected watch the meter and have someone go along the harness route shaking the harness to see if you have a bad connection or a broken wire in the harness. If you lose the voltage reading during this then you probably have a broken wire somewhere in the harness. If all of the above checks are good, then the wiring is OK to the connector so the next step would be to plug your fuel pump in with the key still on and see if it starts.
If it doesn't then the next test is the fuel pump. As you know fuel pumps can go bad, you already replaced yours, but a fuel pump is an electric motor and electric motors can develop bad segments on the armature. Each time the fuel pump stops there are armature segments directly across from the magnets. If one of these bad segments ends up directly across from one of the magnets, next time the fuel pump is turned on, it may not start. So the fuel pump can have an intermittemt problem as well. The resistance of the fuel pump should be around 37 ohms.
Connect the ohmmeter leads to the fuel pump wires going into the tank, if you don't read somewhere close to this (20-40), but read infinity or overload then your pump probably has a bad segment (an open). Measure from each wire going to fuel pump to a chassis ground with your ohmmeter. If you get a reading and not infinity (analog) or overload (digital) then your pump (Motor) probably has a short.
I know this post is long winded and I'm Sorry for that, but many times when you troubleshoot complex electrical circuits you have to rule out what the problem is not before you discover what the problem actually is.
Hopes this helps! Good Luck
Last edited by Hadmatt54; 06-09-2010 at 03:41 AM.
06-11-2010, 07:22 AM
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Well first of all let me thankyou for all of your advice, it was very nice of you all to help me out and i really appriciate it! Hadmatt your post was wonderful, i went through the wiring, tested the circuit opening relay and everything was working fine. I didnt know how to use the meter the first time i was checking things or what to test. I do apologize for my lack of mechanic skills, but I'm getting better each time my truck takes a dive. I followed all of your advice and traced things back to the fuel pump. The resistance was good on the plug and the voltage was sufficient. it was consistant each time i turned the key with the +b and fp being jumped. I then started on the plug heading to the tank. the resistance read good, i pluged it in turned on the key and the pump fired, then it started. i turned it off and tried again; nothing. so i checked the resistance again and there was nothing. i wiggled the line, tapped on the tank and tried again nothing. checked the voltage on the plug coming from the front and it was good. checked the resistance to the tank and it registered again, then went away. It was either the wiring to the top of the tank, fuel pump or a ty install on the fuel pump 7 months ago when i put it in, but either way i had to lift the bed. So i grabbed my cousin and my grandpas forklift, lifted it and removed it once more. Everything was sealed and intact on the wiring but no resistance on the top of the tank. So we removed the pump, all the wires were still connected and it sat firmly in its bracket but no resistance on the positive and negative posts.... Took it to kragen, they warranteed the pump and filter. Hooked the pump back up, installed and turned the key on. Music to my ears! pump ran and the pickup fired. just to be sure i drove it around a bit and let it idel for about 15 mins.
Thank you again for all of your help and advice. You saved me from a mechanic bill that would probably be pretty high.
Thank you again for all of your help and advice. You saved me from a mechanic bill that would probably be pretty high.
Last edited by toyota_grrl; 06-11-2010 at 07:24 AM.
06-11-2010, 08:23 AM
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Good ol Kragen parts!! I had a buddy that went through 3 starters in a month. We thought for sure something else was causing them to die. The last time we got one from the junkyard and it's still on there working. All 3 of them from Kragens were crap. Never rule out that just because you just changed a part it's not that again. Glad you got it running and it was a relatively simple fix.
06-11-2010, 08:29 AM
#19
In the future, try to be a little more clear when posting so you don't get advice like mine (which was wrong)
If you can hear the pump running, its not the problem. But sounds like the pump was indeed NOT running.
Glad you got her fixed though.
If you can hear the pump running, its not the problem. But sounds like the pump was indeed NOT running.
Glad you got her fixed though.
