would you know how to check if fuel pump is failing aside from using the pressure gauge? i dont think i know someone who has it here. 
thanks!
thanks!
how to diagnose a bad fuel pump?
nyagi
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1,106 Posts
Fuel pumps tend to work 100% fine, or not at all.
99.95% of fuel pumps work great right up to the point they dont work at all, just like lightbulbs.
Brett
99.95% of fuel pumps work great right up to the point they dont work at all, just like lightbulbs.
Brett
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6 Posts
I agree with a minor mentionable catch; typically pumps that are actively failing make a whining noise so although it works "100%" at that time its telling you that it won't be for long. Hope that helps (HTH).brett gazdzinski said:
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876 Posts
the only other thing that you can check is the pump resistance. It will not tell you a whole lot other than spec range if it not it needs to be replaced, if it is then you need to get a pressure gauge on it.
Its on the 7th and 8th posts down with proper pressure testing procedures
http://rav4world.com/forums/viewtopic.php?t=20926&highlight=fuel+pump+resistence+resistance
Fuel pump pin out is on the 5th post down
http://rav4world.com/forums/viewtopic.php?t=24030&postdays=0&postorder=asc&&start=30
Its on the 7th and 8th posts down with proper pressure testing procedures
http://rav4world.com/forums/viewtopic.php?t=20926&highlight=fuel+pump+resistence+resistance
Fuel pump pin out is on the 5th post down
http://rav4world.com/forums/viewtopic.php?t=24030&postdays=0&postorder=asc&&start=30
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89 Posts
i'm getting misfires/hesitations when i step on the accelerator quickly. sometimes, when doing uphill, i tend to lose power. a mechanic told me that the fuel pump might be failing.hd72m said:
i'm trying to diagnose my long time problem.. i'm now down to two parts:
a. the spark plug chords
b. fuel pump
buying a replacement part is a big risk, thus, i want to isolate which path should i go first. $120 is a big amount here in the Philippines.
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1,106 Posts
My guess would be the throttle position sensor, or the map sensor.
maybe check the connections to those sensors, or test them before springing for a fuel pump.
Save the old fuel pump, its likely good for another 150,000 miles.
Brett
maybe check the connections to those sensors, or test them before springing for a fuel pump.
Save the old fuel pump, its likely good for another 150,000 miles.
Brett
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94 Posts
nyagi said:i'm getting misfires/hesitations when i step on the accelerator quickly. sometimes, when doing uphill, i tend to lose power. a mechanic told me that the fuel pump might be failing.hd72m said:
i'm trying to diagnose my long time problem.. i'm now down to two parts:
a. the spark plug chords
b. fuel pump
buying a replacement part is a big risk, thus, i want to isolate which path should i go first. $120 is a big amount here in the Philippines.
Hi Nyagi, aren't you on the gruporav4 too? Anyway, have you tried having your ICV and injectors cleaned? Had the same problem before but the culprit was poor valve clearance and installation. I don't think changing your high-tension wires would do the trick though.
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89 Posts
hi brett..
won't these two devices bring a CEL signal if not working properly? if not, then how do i diagnose them? sorry for the question, i'm still waiting for my hayne's to arrive.
@rohn..
yep.. same nyagi from gruporav4. with regards to valve clearance.. arent our valves self adjusting? if not, where can i have them diagnose and fix?
won't these two devices bring a CEL signal if not working properly? if not, then how do i diagnose them? sorry for the question, i'm still waiting for my hayne's to arrive.
@rohn..
yep.. same nyagi from gruporav4.
with regards to valve clearance.. arent our valves self adjusting? if not, where can i have them diagnose and fix?
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1,106 Posts
You may or may not get a fualt code with some problems, on some sensors.
When you step on the gas, the ecu uses the throttle position sensor, and maybe the map sensor to adjust the mixture quickly, without the correct signals, the ecu wont know to enrich the mixture for the large throttle opening.
The tps you measure the resistance of the sensor as you move the throttle, or use a scanguage.
Brett
When you step on the gas, the ecu uses the throttle position sensor, and maybe the map sensor to adjust the mixture quickly, without the correct signals, the ecu wont know to enrich the mixture for the large throttle opening.
The tps you measure the resistance of the sensor as you move the throttle, or use a scanguage.
Brett
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876 Posts
Did you do the fuel filter yet? I would try that first before chasing sensors
Hows the air filter?
Hows the air filter?
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1,106 Posts
Not off hand, but the tps should change resistance smoothly as you slowly open the throttle, with no jumps.
Maybe just reseat the connectors as a first step.
The fuel filter is big, and I dont know if Toyota even recomends replacing it...
I did mine at 100,000 miles just in case, but lack of fuel flow would give you a fine idle, worse cold engine performance, and serious problems at high power outputs where you need lots of fuel.
Ignition stuff could also cause the issues you have, plugs, wires, cap and rotor (if you have them).
You wont notice misfires much at higher rpm's, even though they might be there.
Brett
Maybe just reseat the connectors as a first step.
The fuel filter is big, and I dont know if Toyota even recomends replacing it...
I did mine at 100,000 miles just in case, but lack of fuel flow would give you a fine idle, worse cold engine performance, and serious problems at high power outputs where you need lots of fuel.
Ignition stuff could also cause the issues you have, plugs, wires, cap and rotor (if you have them).
You wont notice misfires much at higher rpm's, even though they might be there.
Brett
nyagi said:thanks brett. would you know how much resistance i should get to know if the map sensor and TPS sensor is about to fail or not?
a scangauge is out of the question.
thanks!
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94 Posts
Well, they aren't really self adjusting, it's just that they no longer require (constant) valve clearance adjustments like old engines do. Since your rav got flooded and all, it's not far off that water might have made its way up your engine, which may have also caused undue friction and overheating of the internal components such as valves, cylinders, pistons, etc. This may result in cracking and loss of power. But hopefully it's just the valve clearance. But still, it's just an idea since i've had the same loss of power. Just another area you might consider sir.nyagi said:hi brett..
won't these two devices bring a CEL signal if not working properly? if not, then how do i diagnose them? sorry for the question, i'm still waiting for my hayne's to arrive.
@rohn..
yep.. same nyagi from gruporav4.
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170 Posts
Same problem here i replaced almost everything but still the same
and just happend when im go to different places in less than an hour. you know when u pull over somewhere then half hour later u start the engine and go to another place then start loosing power and misfiring and behaving like crap for five mins the the idling becomes terribles and few minutes later everything comes back to normal. its crazy
and just happend when im go to different places in less than an hour. you know when u pull over somewhere then half hour later u start the engine and go to another place then start loosing power and misfiring and behaving like crap for five mins the the idling becomes terribles and few minutes later everything comes back to normal. its crazy
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