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strange sound testing fuses?.......

Old 09-22-2018, 06:38 AM
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mazzerman
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Default strange sound testing fuses?.......

Hi Guys n Gals
Iv got a really strange crank no start issue.
2005 C6 base no mods
car cut out and wouldnt start again.
Tech II has no relevent codes (only HVAC stuff that i know what it is)
Fuel pressure at the rail was low (less than 50 PSI)
I put a whole new fuel module in but still wouldnt start so went back to basics
Checked all fuses with power probe and found that most fuses made the normal positive and negative tones.
But One line of fuses wihich include the ODD and EVEN injector fuses make a tone i can only explain as like a machine gun....
Now i know thats not normal, so because it is 5 fuses in a line i suspect the fuse box connection underneath the top layer might be the problem but before i start ripping the fuse box apart, has anyone else come across this type of issue with a line of fuses sounding like a machine gun with tester?
Thanks in advance
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Old 09-22-2018, 07:24 AM
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Originally Posted by mazzerman View Post
Hi Guys n Gals
Iv got a really strange crank no start issue.
2005 C6 base no mods
car cut out and wouldnt start again.
Tech II has no relevent codes (only HVAC stuff that i know what it is)
Fuel pressure at the rail was low (less than 50 PSI)
I put a whole new fuel module in but still wouldnt start so went back to basics
Checked all fuses with power probe and found that most fuses made the normal positive and negative tones.
But One line of fuses wihich include the ODD and EVEN injector fuses make a tone i can only explain as like a machine gun....
Now i know thats not normal, so because it is 5 fuses in a line i suspect the fuse box connection underneath the top layer might be the problem but before i start ripping the fuse box apart, has anyone else come across this type of issue with a line of fuses sounding like a machine gun with tester?
Thanks in advance
what fuses were you checking ??...and you were checking injector fuses 1and 2 ??...what Power Probe ??...what mode of the PP were you using...tip voltage ??...I use the Power Probe 4.

Edit: what is the fuel pressure now after changing the module ??...the same ??....you probably should do a voltage drop check on the positive and negative sides of the circuit...you might have a bad ground of feed !!...now I have a C5 and my FP module is on the bottom of the tank..is yours on top where you would have to drop the tank ??...try spraying some brake kleen (a good shot) into an easily accessible vacuum line...now see if it starts...if it starts we know for sure it’s a fuel delivery issue !!

Rob


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Old 09-22-2018, 07:58 AM
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I checked all fuses but is the ones that are arrowed are the problem ones.
The red arrowed fuses are the 20a injector fuses that are making the strange tone as well as the 2 yellow arrow fuses
The power probe is the standard non fancy type i/e no LCD screen, just red and green LED to show positive or ground, usually works a treat. So basically it just tells me that fuses/wires are good/bad with 2 tones, positive and ground.
The noise only happens when ignition is OFF which is not normal.
Its got a brand new fuel pump fitted (yes i had to drop the tank to change it, everything went back in good.
The fuel pressure im testing at fuel rail and with primed pump it reads just under 50PSI and on cranking it is blipping around 59PSI.
I dont really trust my fuel pressure tester though, its a cheap Sealy product and the pressure release is dodgy.
Also i the Racetronix fuel pump hot wire kit fitted so fuel pump is getting max voltage from the generator so i dont thing its a fuel pump issue.


Last edited by mazzerman; 09-22-2018 at 08:23 AM.
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Old 09-22-2018, 08:26 AM
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Ok, let’s get the fuel pressure issue taken care of maybe with a new pressure gauge...pressure for my ‘01 is 55-62 primed. No, with key off there should be nothing at the injector fuses..,was it showing power or a ground ??...like I said give it a shot of brake kleen and see if it runs. Do you have any movement of the tach when you try to start it ??...you can read RPM off the Tech 2...if no you might have a bad crank sensor. I helped someone a while back..no tach movement during crank and he found the crank wires burned up. With accurate pressure gauge if pressure is still below minimum check power and grounds. With new pump you should be running at the higher end of the spec !!...and check for spark while cranking...that’s all you need to start...fuel, air, spark !!

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Old 09-22-2018, 11:16 AM
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Gonna try a different gauge and fully charged good battery tomorrow, then ill start checking connections from tank.
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Old 09-22-2018, 12:11 PM
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Like I had said try the brake kleen first...if it starts or try’s to start all you have to concentrate on is fuel delivery issue...don’t know if you own a DVOM but you can try too see AMP draw of the pump...a DVOM usually has about a 10 Amp max before it blows a fuse...you can turn pump on with Tech 2 and hook up DVOM across load side of pump relay...should be pins 30 and 87...if low start looking for resistance (bad ground) somewhere in the circuit...my ‘01 draws about 5.5 AMPS at 3500 RPM...new pump probably is s a little higher...mfg. usually doesn’t current draw numbers in FSM. Just need to get in the right “funnel” to diagnose !!

Rob


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Old 09-22-2018, 01:09 PM
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Iím ďassumingĒ the fuel filter had been changed along with the fuel pump ??
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Old 09-22-2018, 01:25 PM
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Originally Posted by rwobs777 View Post
Iím ďassumingĒ the fuel filter had been changed along with the fuel pump ??
Yes the complete module was changed.
When you say put the DVOM across the load side, do you mean remove relay one probe in lead in 30 the in 87?
You mention Amps so does the DVOM need to be in the 20 amp input of the DVOM rather than the normal V/OHMs etc?
and set the dial to 20 AMP? then turn on the pump with TechII and check reading? Am i correct in my thinking there?
Also i am presuming the pins 30 and 87 will be the ones i used to jump the relay when i was emptying the tank. Or do you have a pin out of the relay terminals?
There is a pinout on the relay but i dont know if thats even the right way round as its not clear which way round it goes although i think its correct as the fuel pump primes when i put into start mode.
Cant get hold of brake cleaner until Monday i have air flow sensor cleaner and also Throttle body cleaner but no brake cleaner so cant test that.
Also when i get some what port can i blast it into? i cant do it through the front of the throttle body as i dont have anyone that can open the throttle for me from inside the car
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Old 09-22-2018, 01:43 PM
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Just thinking about it, i dont think there is much point testing the FPR in the fusebox as i have the Racetronix hotwire kit fitted which i believe gets its power direct from the generator and has its own relay so dont think it uses the fusebox relay.....
Just a thought.
But maybe i can do some tests at the connector that comes from the Fuel pump and plugs into the hotwire harness to make sure its getting good voltage from the generator.
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Old 09-22-2018, 02:00 PM
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I misspoke about turning on the pump with the Tech 2...you just have to jump pins 30 and 87 at the relay...that will make the pump run !!...if you look at the bottom of the relay it will tell you the pin out...just remember it’s backward looking at it...not familiar with your DVOM but what ever setting is for amps 10 or 20 amps...not sure how your set up works with the Racetronix wiring...I use a “mini amp clamp” that I clip around the power wire to read AMPS...real easy to use and it’s accurate too...I compared the number to my scope and it was right on..they are pretty cheap and you don’t have to fiddle around with disconnecting wires...you can find them on Amazon !!.,,change that filter if you haven’t..,that might be your problem !’

Last edited by rwobs777; 09-22-2018 at 02:01 PM.
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Old 09-22-2018, 02:10 PM
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Originally Posted by rwobs777 View Post
I misspoke about turning on the pump with the Tech 2...you just have to jump pins 30 and 87 at the relay...that will make the pump run !!...if you look at the bottom of the relay it will tell you the pin out...just remember itís backward looking at it...not familiar with your DVOM but what ever setting is for amps 10 or 20 amps...not sure how your set up works with the Racetronix wiring...I use a ďmini amp clampĒ that I clip around the power wire to read AMPS...real easy to use and itís accurate too...I compared the number to my scope and it was right on..they are pretty cheap and you donít have to fiddle around with disconnecting wires...you can find them on Amazon !!.,,change that filter if you havenít..,that might be your problem !í
I have a 65amp mini amp clamp and USB automotive scope so can use them to check the amps as you have said....which power lead do you put it round for the reading? down near the pump itself?
Filter is changed, i changed the whole entire unit.......this one with filter built in at the top
Fuel pump module
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Old 09-22-2018, 03:29 PM
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Wow !!...you have an amp clamp AND a scope !!...I have a 2 channel Picoscope..,best diagnostic tool I own !!...just hook it around the feed wire to the pump that is most accessible !!...I remove the fuel pump fuse and insert a fused jumper loop and clamp the amp clamp around the jumper wire..,easy !!
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Old 09-22-2018, 05:28 PM
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Originally Posted by mazzerman View Post
Yes the complete module was changed.
When you say put the DVOM across the load side, do you mean remove relay one probe in lead in 30 the in 87?
You mention Amps so does the DVOM need to be in the 20 amp input of the DVOM rather than the normal V/OHMs etc?
and set the dial to 20 AMP? then turn on the pump with TechII and check reading? Am i correct in my thinking there?
Also i am presuming the pins 30 and 87 will be the ones i used to jump the relay when i was emptying the tank. Or do you have a pin out of the relay terminals?
There is a pinout on the relay but i dont know if thats even the right way round as its not clear which way round it goes although i think its correct as the fuel pump primes when i put into start mode.
Cant get hold of brake cleaner until Monday i have air flow sensor cleaner and also Throttle body cleaner but no brake cleaner so cant test that.
Also when i get some what port can i blast it into? i cant do it through the front of the throttle body as i dont have anyone that can open the throttle for me from inside the car
The fuel filter Iím taking about is the external fuel filter on the frame rail..my filter/ pressure regulator sits on the left frame rail just forward and above the left rear tire...you can use the other cleaners you mentioned...I use propane with a hose on the end..,you can disconnect the brake booster hose or the PCV hose...you donít need someone else to check..just give it a good shot and jump back in the car and try to start it. If the filter is clogged youíll have a low pressure at the fuel rail !!
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Old 09-22-2018, 07:01 PM
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mine is a 2005 C6, there is no external fuel filter it is built into the fuel pump module
I have a fused loop, i can do that (loop it through the fuel pump fuse and test on the scope.
yeah my scope is quite cool as i have a coil on plug paddle as well so can get a great secondary ignition waveform.
yep i have propane as well so will try that into the brake booster hose.
Thanks for the advice, i'll let you know how i get on.
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Old 09-22-2018, 08:02 PM
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No filter huh ??...that stinks !!...like I said my average current was 5.5 AMPS...we are probably .0001 percent of Corvette owners that have a scope...I upgraded from the Snap On Vantage Pro to the Picoscope and there is NO comparison...I have been getting a bunch of waveforms for my own library for my car...MAF, Cam/Crank, fuel pump, and a few others. I mounted a 27 inch monitor to my toolbox lid and it’s great seeing the Pico on that... yes, the paddle probe works great on the coils for secondary..,I’ll send you a link to 2 great videos of ignition testing and misfires...really good...ok try the propane and we will see if we can at least get it started...if not might have to go another direction !!


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Old 09-22-2018, 08:12 PM
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Yeah i dont think most owners know how when used correctly how good the scope is for diagnosis. The DVOM i have is an automotive one as well automotive digital engine analyser
cool i will try you suggestions tomorrow, it's 02.11am here so need some sleep but gonna get stuck into it in the morning.
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Old 09-22-2018, 08:25 PM
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Cool !!...yeah, I see you’re in Spain...I use an Autel MS906 as my scan tool...it’s bi-directional and really helps in diagnostics...and the Vantage Pro is a fair scope and a good graphing meter and component tester... the first thing I’ll ask someone with a problem...do you have a scan tool ??...without that and some basic diagnostic and electrical knowledge you’ll be just changing parts !!...have a great night !!

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Old 09-22-2018, 11:48 PM
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If your car is completely stock why in the world would you install the Racetronix fuel harness?
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Old 09-23-2018, 04:42 AM
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Originally Posted by saplumr View Post
If your car is completely stock why in the world would you install the Racetronix fuel harness?
The reason was because i was having a lean misfire problem and one of the suggestions i read on the forums is that sometimes the fuel pump doesnt get enough voltage from the OEM set up so to eliminate the issue i installed the hotwire kit so that the fuel pump would get the max voltage it would need. Thats the only reason.
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Old 09-23-2018, 08:24 AM
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ok, i put a spark tester on and have a no spark situation, battery went low with all the testing iv been doing so is now on charger so next step when battery is charged is test for RPM signal on TechII then if thats ok i'll start checking for power and ground at the coils.
Already tested all fuses including under the passenger floorboard, but i'm suspicious of the block connectors under the fuses/relays as iv heard they can be a problem.
Any more ideas folks?
BTW there are no DTC's showing on TechII.

Last edited by mazzerman; 09-23-2018 at 08:24 AM.
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