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Discussion Starter · #1 ·
SORRY for the long thread I’m trying to explain everything and cover all my bases but PLEASE all help with these problems would be amazing. Thank you in advance for those of you reading this and giving suggestions. Much Appreciated!

For starters I have replaced my fuel pump 5 times in the years of owning my bronco (almost 8 years). I’m am not sure if I have two problems going on now or not but now I have an external pump on my truck and I’m still having problems with it. The pump I have is rated for 57gph and the correct fuel pressure. I installed a fuel pressure gauge at the Schrader valve whenever I done the external pump and my fuel pressure is 45 KEOF and 35 KEOR.
The problem I was having is my fuel pumps keptburning up. The last fuel pump I’ve installed in the tank (before going external) was having an issue I’m about to explain in a second. This is why I decided to external and install my own wiring harness with a relay to hopefully fix the issue but the problem is still there and now my external fuel pumps continue to burn up with in a day.(I’ve tried 2 jegs, 1 msd, and now have a car quest that has left me stranded but cools off to start up again.)
My setup now is an external pump, new rubber fuel injection lines, and I left the existing pump harness inside the tank and removed the fuel pump. Then added an extension ss tubing with a Submersible rated fuel house as a coupling. The fuel runs to a stock filter before the pump. The fuel pump is mounted on the frame and is installed at the correct angle for vapor locking and is is about directly crossed from the middle of the gas tank for the proper height so gravity does most of the work.

Now aside from the issue with my fuel pumps burning up. This issue boggles my head. When I go to start my truck after letting it sit for a period of time (usually over night while sleeping) I will have to let the truck do what I call “priming” before starting it. I will turn the key on engine off and have to let the truck sit there for almost 5 minutes before starting. Once I hear a click in the throttle body. Then click in the power distribution box where my relays are located.( I held my finger on all the relays and number 2 clicked, which is the fuel pump relay). Then finally you will hear another click at the throttle body again, and finally I can start my truck. Once my truck is started I can drive around all day turning my vehicle on and off and have no issues until I let it sit for an extended period of time.
I have replaced several parts in the time period of owning the truck. Some of which that I figured might cause the problem is the ECU, IAC, map sensor, ICM, TPS, fuel pressure regulator, and I’m sure plenty others. I will add this that I had this issue of what I call “priming” before I swapped my setup to external.
If anyone has any clue as to what may be the cause of this issue I’m all ears please. And as far as the fuel pumps burning up I would like to know if going external was a good decision or should I swap back to in-tank and bite the bullet for a complete Ford motorcraft harness and pump.

Thanks to all!
 

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Do you run your fuel low all the time or go down rough roads. Also what about you fuel filters? Regular maintenance?


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First off, the reason that pretty much 100% of OEMs use intank pumps is because they simply tend to work better and last longer that way.
Not to give you a hard time or anything, but I can see simply replacing the pump once, but after the SECOND time your fuel pump burned out, you probably should have stopped and tried to figure out why it was happening rather than continuing to go to greater and greater expense and modification. Obviously some people go years and years, decades even without this issue (I have maint. records on my '95 back to 2006, and the pump hadn't been replaced in that time period, so I going on 13 years).
A pump is going to burn up for basically one of two reasons:
a. It is drawing too much current due to a wiring inadequacy (including a bad ground).
b. It is having to suck too hard because of a venting problem in the tank.

a. Is reasonably easy to figure out, assuming you are systematic about it and have a wiring diagram.
b. Might require you to drop the tank and check the vapor lines coming out the top and running forward to the charcoal canister on the frame under the battery. As the pump is sucking fuel out of the tank, air has to come in to replace it. Since venting fume out the fill neck is bad business, the fumes get vented through the charcoal canister AND the same lines let fresh air into the tank.
 

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1996 Bronco XLT 5.8L automatic
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Just a thought here, someone correct me if I'm wrong. I know you replaced the regulator at some point, but if the regulator was faulty and constantly allowing a large flow back to the tank, this could make the pump run at high or max output all of the time. I think a simple test would be to disconnect the return line at the regulator and run a hose into a container to see if fuel is flowing back when it shouldn't be.
 

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Just a thought here, someone correct me if I'm wrong. I know you replaced the regulator at some point, but if the regulator was faulty and constantly allowing a large flow back to the tank, this could make the pump run at high or max output all of the time. I think a simple test would be to disconnect the return line at the regulator and run a hose into a container to see if fuel is flowing back when it shouldn't be.
That would actually put LESS strain on the pump, because the regulator is "pushing back" against the flow, so if the regulator was wide open, there would be less resistance to flow.
 

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1996 Bronco XLT 5.8L automatic
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That would actually put LESS strain on the pump, because the regulator is "pushing back" against the flow, so if the regulator was wide open, there would be less resistance to flow.
Agreed, for a blocking regulator, but I was talking about a return style regulator which reduces pressure by allowing flow back to the gas tank. I should have stated that up front.
 

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Discussion Starter · #8 ·
Do you run your fuel low all the time or go down rough roads. Also what about you fuel filters? Regular maintenance?

Fuel filters get changed on a regular basis


Sent from my iPhone using Tapatalk
First off, the reason that pretty much 100% of OEMs use intank pumps is because they simply tend to work better and last longer that way.
Not to give you a hard time or anything, but I can see simply replacing the pump once, but after the SECOND time your fuel pump burned out, you probably should have stopped and tried to figure out why it was happening rather than continuing to go to greater and greater expense and modification. Obviously some people go years and years, decades even without this issue (I have maint. records on my '95 back to 2006, and the pump hadn't been replaced in that time period, so I going on 13 years).
A pump is going to burn up for basically one of two reasons:
a. It is drawing too much current due to a wiring inadequacy (including a bad ground).
b. It is having to suck too hard because of a venting problem in the tank.

a. Is reasonably easy to figure out, assuming you are systematic about it and have a wiring diagram.
b. Might require you to drop the tank and check the vapor lines coming out the top and running forward to the charcoal canister on the frame under the battery. As the pump is sucking fuel out of the tank, air has to come in to replace it. Since venting fume out the fill neck is bad business, the fumes get vented through the charcoal canister AND the same lines let fresh air into the tank.
Don’t worry about give me a hard time I’ll take any information I can get even if that means I was being stupid😂 I just got to get this problem fixed. I’m definitely gonna look into the charcoal canister and see if I have a good flow or not. Thanks. What about The other issue I have going on where it takes five minutes for something to warm up and then I can start my truck. Any thoughts on that?
 

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Discussion Starter · #9 ·
I’ve done a test on the fuel pressure regulator and there was no fuel in the lines . my fuel pressure is great for factory specs. Thanks for the info and suggesting!
 

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Discussion Starter · #11 ·
Does anybody have any thoughts on to why it may take five minutes or so before I can start my vehicle.
 

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Charlie don't surf..
'92 Ford Bronco XLT
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Does anybody have any thoughts on to why it may take five minutes or so before I can start my vehicle.
no, it should not take 5 minutes to start your Bronco..I'm running an aftermarket adjustable FPR that will leak down when my Bronco has been sitting for a period of time..this requires me to "prime" the rail by cycling the key off and on a couple of times..if I don't do this it fails to start on the first crank..my opinion, I think you need to go back to the factory in tank setup..like @Rspasoje mentioned they just work better.
 

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1986 Eddie Bauer 5.0EFI AOD Full length headers Y pipe into single 3" Magnaflow 3" factory exit
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I believe there a check valve that would keep pressure in the line when the vehicle is off. If that check valve is bad, the pump may lose its prime. In theory, the in tank pump is the lift pump, I brings fuel to the high pressure pump. Then the high pressure pump goes feeds the injectors, this should remain pressurized when the vehicle is off or slowly bleed down. Not sure what controls how it feeds back to the tank, but It sounds like yours is letting it flow right thru, back to the tank.

What does your fuel pressure guage read at your Schrader valve once you turn off the key?
 

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Discussion Starter · #14 ·
I believe there a check valve that would keep pressure in the line when the vehicle is off. If that check valve is bad, the pump may lose its prime. In theory, the in tank pump is the lift pump, I brings fuel to the high pressure pump. Then the high pressure pump goes feeds the injectors, this should remain pressurized when the vehicle is off or slowly bleed down. Not sure what controls how it feeds back to the tank, but It sounds like yours is letting it flow right thru, back to the tank.

What does your fuel pressure guage read at your Schrader valve once you turn off the key?
Whenever I turn the key off it’s between 30 to 35 psi. But here’s the thing I pulled a fuse on my fuel pump disconnecting my fuel pump and let it sit for five minutes without the fuel pump running and I hear some Electronic parts clicking on and off. Then I put the fuse back in my fuel pump turning my fuel pump back on and then my truck starts up. So either way My fuel system isn’t affecting my five minute start a problem I believe it’s something electronically but I don’t know what electronic parts could make something like that happen. Any thoughts?
 

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Discussion Starter · #15 ·
no, it should not take 5 minutes to start your Bronco..I'm running an aftermarket adjustable FPR that will leak down when my Bronco has been sitting for a period of time..this requires me to "prime" the rail by cycling the key off and on a couple of times..if I don't do this it fails to start on the first crank..my opinion, I think you need to go back to the factory in tank setup..like @Rspasoje mentioned they just work better.
I believe that’s my thoughts on it to it’s just going back to factory. Whenever I do my five minute start up in the morning I disconnect my fuel pump from the fuse and wait five minutes and then put the fuse back in and started up and it runs it doesn’t matter whether the fuel pump is running or not it still takes five minutes.Telling me that fuel has no relation to what’s happening my theory is it something Electronic, But what exactly I’m not sure. Any thoughts?
 

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Charlie don't surf..
'92 Ford Bronco XLT
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I agree with @Rspasoje, you probably have an electrical issue if you're burning up pumps like that..in the morning when the engine is cold and you turn the KOEO, do you hear the pump prime?

Something else you might want to check would be your ignition switch..They can cause some weird starting problems.
 

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1996 Bronco XLT 5.8L automatic
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I believe that’s my thoughts on it to it’s just going back to factory. Whenever I do my five minute start up in the morning I disconnect my fuel pump from the fuse and wait five minutes and then put the fuse back in and started up and it runs it doesn’t matter whether the fuel pump is running or not it still takes five minutes.Telling me that fuel has no relation to what’s happening my theory is it something Electronic, But what exactly I’m not sure. Any thoughts?
Regarding the 5 minute priming. To assess if it might be some electronic component(s) or an intermittent connection that need to warm up before working properly, you could go out in the AM and before turning the key, warm up the suspect component with a blow dryer, then see if the 5 minutes get shorter or goes away. If it does change, you have more reason to suspect it. You could start with the PCM, and if that doesn't change things, try other areas of wiring connections (like around the pump relay). You can also use freeze spray to cool things down as well (but have to be very careful to not damage good components with the temperature change shock).

Regarding the pump burning up, maybe the following will show something unexpected that might help. If you could insert an ammeter in the positive wire feeding the pump, and measure the voltage drop across the pump terminals**, that will tell you how much power it is actually using (voltage X current). Then compare that to what the pump says it should draw.

** The reason to measure voltage at the pump terminals, not elsewhere (like at the pump relay), is that non-trivial voltage drops can occur anywhere along the circuit (poor wiring, poor connections or grounds, bad relay contacts), so to know what's actually going on in the pump, you need to see the voltage right at the pump terminals.
 

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My mind keeps going back to electrical, like a bad ground, or the voltage not being correct at the pump, or possibly at the coil, I would get a meter & start checking things to see what voltage you have at these items verses what the are supposed to be. Basicly what MPZ just said above.

I only bring up the coil voltage because I have seen problems when the coil is not fed a full 12 volts. Wires/connections corrode, sending less than 12 volts & crazy things happen when fed low current.

Then the battery grounds in broncos are notorious for being bad. I got my truck for a steal cuz it had all sorts of crazy issues, it had a completely corroded battery ground & once I replaced it, I haven't had any issies since electrically. Its kind of grasping at straws, but its definitely something cheap to replace ($12 @ Orileys) that certainly won't be a bad idea. Battery ground, to frame, to block connection.
 

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Discussion Starter · #19 ·
My mind keeps going back to electrical, like a bad ground, or the voltage not being correct at the pump, or possibly at the coil, I would get a meter & start checking things to see what voltage you have at these items verses what the are supposed to be. Basicly what MPZ just said above.

I only bring up the coil voltage because I have seen problems when the coil is not fed a full 12 volts. Wires/connections corrode, sending less than 12 volts & crazy things happen when fed low current.

Then the battery grounds in broncos are notorious for being bad. I got my truck for a steal cuz it had all sorts of crazy issues, it had a completely corroded battery ground & once I replaced it, I haven't had any issies since electrically. Its kind of grasping at straws, but its definitely something cheap to replace ($12 @ Orileys) that certainly won't be a bad idea. Battery ground, to frame, to block connection.
I checked over my grounds and they seem fine. I had an MSD ignition coil on there and I’ve heard they’re not that great so I swap back to stock. I will do some voltage tests on my ignition system later this evening and start there. Thanks
 

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Discussion Starter · #20 ·
Regarding the 5 minute priming. To assess if it might be some electronic component(s) or an intermittent connection that need to warm up before working properly, you could go out in the AM and before turning the key, warm up the suspect component with a blow dryer, then see if the 5 minutes get shorter or goes away. If it does change, you have more reason to suspect it. You could start with the PCM, and if that doesn't change things, try other areas of wiring connections (like around the pump relay). You can also use freeze spray to cool things down as well (but have to be very careful to not damage good components with the temperature change shock).

Regarding the pump burning up, maybe the following will show something unexpected that might help. If you could insert an ammeter in the positive wire feeding the pump, and measure the voltage drop across the pump terminals**, that will tell you how much power it is actually using (voltage X current). Then compare that to what the pump says it should draw.

** The reason to measure voltage at the pump terminals, not elsewhere (like at the pump relay), is that non-trivial voltage drops can occur anywhere along the circuit (poor wiring, poor connections or grounds, bad relay contacts), so to know what's actually going on in the pump, you need to see the voltage right at the pump terminals.
My pump is using 12 V when I tested it last.
So I’m getting a good solid connection and I cleaned up the grounds.
 
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