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fuel pump problem again and again

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Old 08-13-2017, 11:22 AM   #1
captainyellowbeard
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Default fuel pump problem again and again

replaced fuel pump four times. the last time I replaced fuel regulator and pig tail also pump and wiring. fourth start up fuel pump out again. cleaned tank out replaced in line fuel filter and sock on pump as well. Can not case down repeated fail of fuel pump. Any help out there,
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Old 08-13-2017, 04:05 PM   #2
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Are you sure that it is the pump itself that is failing? Could be a bad F/P relay that is not always powering up the pump. If you have one of the failed pumps, try to run it on a bench; apply 12v and see if it runs.

What brand of fuel pump are you buying? I would go with a GM OEM version or AC Delco Professional Grade. No way would I even consider stuff like Dorman or Standard Products or any of the so-called "white box" parts like those sold thru the chain parts stores.
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Old 08-13-2017, 04:17 PM   #3
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4 pumps going bad in the same vehicle doesn't seem right. There has to be something else going on here. Whether it's the installation procedure, some other part affecting it or what - no idea.

About the only comment I can made is the same thing referenced whether in a Vette or some other brand/model of vehicle. Are you consistently running the tank dry or low on fuel? the gas acts as a coolant for the pump and it can overheat if consistently/exposed to air. Just a thought.
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Old 08-13-2017, 06:22 PM   #4
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Hey Captain,

Please give us a little info on your car; year, type of engine and anything else you did to your engine. This info can help us!
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Old 08-13-2017, 11:39 PM   #5
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Default fuel pump c4 corvette delco replacement

where is the regulator mentined replaced one on fire wall and pig tail with it as well.
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Old 08-15-2017, 12:18 AM   #6
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Quote:
Originally Posted by hcbph View Post
Are you consistently running the tank dry or low on fuel? the gas acts as a coolant for the pump and it can overheat if consistently/exposed to air. Just a thought.
That part is total BS. If it was making that much heat, you'd vaporize your fuel all day long. Also Tom400CFI has proven an old used pump can run for 45 minutes without coolant. If it were to generate heat, and it does, it is going to be slight, You wouldn't want a hot rock in the tank, would you? That is the grandma of old wives tail
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Old 08-15-2017, 12:19 AM   #7
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How did you determine the fuel pumps were bad? Source of the pump?
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Old 08-15-2017, 06:07 AM   #8
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Quote:
Originally Posted by aklim View Post
That part is total BS. If it was making that much heat, you'd vaporize your fuel all day long. Also Tom400CFI has proven an old used pump can run for 45 minutes without coolant. If it were to generate heat, and it does, it is going to be slight, You wouldn't want a hot rock in the tank, would you? That is the grandma of old wives tail
Believe it or not, your choice. If it was poppycock, why would the manufacturers say to not do it? I know at least 3 people including my kid that consistently ran the tank very low and had premature fuel pump failures. It didn't happen immediately but it did happen prior to expected life expendency.

To me it's no different than if you run an engine with low coolant or airlocked. It's designed to have heat removed through the mechanisms designed to do it, take away that coolant methodology and eventually something is going to give up the ghost.
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Old 08-15-2017, 06:21 AM   #9
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Quote:
Originally Posted by hcbph View Post
Believe it or not, your choice. If it was poppycock, why would the manufacturers say to not do it? I know at least 3 people including my kid that consistently ran the tank very low and had premature fuel pump failures. It didn't happen immediately but it did happen prior to expected life expendency.

To me it's no different than if you run an engine with low coolant or airlocked. It's designed to have heat removed through the mechanisms designed to do it, take away that coolant methodology and eventually something is going to give up the ghost.
Look at Tom400CFI. He ran a video over 30 minutes. Power to dry pump before it quit at 45 minutes, IIRC. I have been running tanks to empty since 90. When there is no fuel, power to the pump stops.

Your theory will have the pump become a mini immersion heater in the tank. How much fuel would you lose? If you are talking cooling, it is done by the fuel in the tank or you will evaporate the fuel. Going through the pump, sure. As long as fuel flows there will be cooling. When it stops your pump stops
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Old 08-15-2017, 07:39 PM   #10
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I had an intermittent FP failure even after replacing all of the wiring. The problem turned out to be the bulkhead connector where the wiring goes into the tank. Original fuel pump wiring does not like ethanol. I replaced my filler neck/fuel sender with a stainless steel unit.
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Old 08-15-2017, 08:34 PM   #11
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Quote:
Originally Posted by captainyellowbeard View Post
replaced fuel pump four times. the last time I replaced fuel regulator and pig tail also pump and wiring. fourth start up fuel pump out again. cleaned tank out replaced in line fuel filter and sock on pump as well. Can not case down repeated fail of fuel pump. Any help out there,
..... Check your fuel line from tank to engine ... look for kinks , dents , anything unusual ... you might consider letting someone else put in #5 .....
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Old 08-15-2017, 09:58 PM   #12
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Default Fuel pump out

IN my 1998 Chevy Tahoe a few years ago, The fuel gauge sending unit went bad. I ran it out of gas twice in about a months time.
2 weeks later... fuel pump went out.
Might be folklore... But if anyone at my house gets caught with less then 1/4 tank of gas...
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Old 08-16-2017, 12:08 AM   #13
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Quote:
Originally Posted by Gene D View Post
IN my 1998 Chevy Tahoe a few years ago, The fuel gauge sending unit went bad. I ran it out of gas twice in about a months time.
2 weeks later... fuel pump went out.
Might be folklore... But if anyone at my house gets caught with less then 1/4 tank of gas...
I have run out of gas way more than that. I have only replaced the pump because I wanted a better one. So I'm betting it is folklore or you should buy stocks in fuel pumps since I am always running past empty mark and sometimes get caught.
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Old 08-16-2017, 11:35 AM   #14
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Quote:
Originally Posted by Gene D View Post
II ran it out of gas twice in about a months time. 2 weeks later... fuel pump went out.Might be folklore... But
Gasoline is a lubricant for the pump and may serve as a heat transfer agent as well; i.e. coolant.

In many aircraft, the fluids that run through variuous pumps do the above and there are certification standards that require minimum fluid levels in such tanks, to keep all within temperture limits. Some newer Boeings, particularly long range types, employ fuel tank heat exhangers to cool the hydraulic fluid used to operate flight controls while keeping the fuel above minimum temperatures during extended high altitude, very zub-freezing, conditions.

With the well-known low fuel indication problems with C4s, drivers are wise to start looking at refills around 1/2 tank, unless a fix was accomplished and the low fuel levels are accurate; then perhaps 1/4 tank.

Last edited by whalepirot; 08-16-2017 at 11:41 AM.
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Old 08-16-2017, 01:14 PM   #15
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Quote:
Originally Posted by whalepirot View Post
Gasoline is a lubricant for the pump and may serve as a heat transfer agent as well; i.e. coolant.

In many aircraft, the fluids that run through variuous pumps do the above and there are certification standards that require minimum fluid levels in such tanks, to keep all within temperture limits. Some newer Boeings, particularly long range types, employ fuel tank heat exhangers to cool the hydraulic fluid used to operate flight controls while keeping the fuel above minimum temperatures during extended high altitude, very zub-freezing, conditions.

With the well-known low fuel indication problems with C4s, drivers are wise to start looking at refills around 1/2 tank, unless a fix was accomplished and the low fuel levels are accurate; then perhaps 1/4 tank.
I don't drive my car in those altitudes so it is a non-issue. If the coolant and lubrication were that critical, how do you explain that Tom400CFI could run a dry pump for over 10 mins with no fuel? That is an extreme condition that cannot be achieved in your car since if you have no fluid going through the pump, the car dies in less than a minute. Engine dies, no power to cycle the pump?

https://www.corvetteforum.com/forums...post1590728908

According to his comments, it never got to over 100
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Old 08-18-2017, 09:30 PM   #16
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Yikes - 4 Fuel Pump failures.... something is clearly not right !!!

First off I would check fuel lines for restriction. I'd probably start by blowing them out with compressed air and having someone check to verify that lots of air is flowing through the lines (remember to check the return line as well).

Wherever you are getting your fuel pumps from - I'd go with a different brand for Number 5. Both Racetronix and Walbro make High Performance fuel pumps that fit the C4 - maybe give one of them a try.... I would also check current draw of pump number 5 after you install it (you should be able to get current draw from oil pressure switch connector).
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Old 08-18-2017, 10:33 PM   #17
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(you should be able to get current draw from oil pressure switch connector).
From the oil pressure switch?
I would think you would need to get draw readings from the relay base terminals?
Bridge the terminals with relay removed, thus bypassing the relay and putting an amp meter in the jumper?
I have lots to learn.
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Old 08-19-2017, 08:50 AM   #18
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Not sure of OP's vehicle year - but I know on the LT1/LT4 cars the power to run the Electric Fuel Pump is routed through the oil pressure switch. Yes there is a fuel pump relay - and it's sole job is to run the pump when the key is first turned on, or when the engine is cranking - the rest of the time the power to run the pump comes from the oil pressure switch... If the engine dies - the oil pressure drops to zero and the fuel pump is shut off.

Now - as far as getting to the relay - again on the LT1/LT4 cars it's tucked up under the pass side dashboard face. For the most part - you're working by feel... Not a whole bunch of fun!!! While the oil pressure switch is also annoying to get to - IMO - it's not as bad to get to as the fuel pump relay.
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Old 08-19-2017, 09:00 AM   #19
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Quote:
Originally Posted by Purple92 View Post
Not sure of OP's vehicle year - but I know on the LT1/LT4 cars the power to run the Electric Fuel Pump is routed through the oil pressure switch. Yes there is a fuel pump relay - and it's sole job is to run the pump when the key is first turned on, or when the engine is cranking - the rest of the time the power to run the pump comes from the oil pressure switch... If the engine dies - the oil pressure drops to zero and the fuel pump is shut off.

Now - as far as getting to the relay - again on the LT1/LT4 cars it's tucked up under the pass side dashboard face. For the most part - you're working by feel... Not a whole bunch of fun!!! While the oil pressure switch is also annoying to get to - IMO - it's not as bad to get to as the fuel pump relay.
IDK if they changed in 92 and up. Have you ever tried running the car and then disconnect the oil pressure sensor? I did with my L98 and it keeps going and they are a backup. I'm curious if they changed it in the 92 and up.
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Old 08-19-2017, 09:15 AM   #20
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Quote:
Originally Posted by Purple92 View Post
.. the rest of the time the power to run the pump comes from the oil pressure switch...
If the engine dies - the oil pressure drops to zero and the fuel pump is shut off.
That has been discussed many times on the forums, and it just isn't true.

https://www.corvetteforum.com/forums...t-failing.html
https://www.corvetteforum.com/forums...fuel-pump.html
https://www.corvetteforum.com/forums...right-lt1.html

Quote:
Originally Posted by aklim View Post
IDK if they changed in 92 and up. Have you ever tried running the car and then disconnect the oil pressure sensor? I did with my L98 and it keeps going and they are a backup. I'm curious if they changed it in the 92 and up.
I don't believe they operate any differently on the LT1/LT4 cars.

I am not a mechanic, and have no first hand experience.
But over the years this has been brought up many times.

Last edited by RollaMo-LT4; 08-19-2017 at 12:13 PM.
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