NickL

The fuel pump on my 93 Pickup just died. Confirmed 12volts is getting to it, but it won't run. Wired it directly to a battery, same deal. I'm going to replace it this weekend, but in the meantime I'm trying to figure out what killed it so I don't have to go through this expensive ordeal again.

The previous owner was having problems getting the motor to run due to inadequate fuel delivery so he put in a brand new OEM pump. That was less than a year and a half ago and it already went bad. What would cause that? A gunked up tank? Bad wiring? Running out of gas? Bad luck?

Basically, What should I check for or replace when I swap out the pump so this doesn't happen again?

85toy4runner

one thing I read if you run low fuel all the time , the fuel pump over heats and after time can damage it, I dont know if thats correct or not.

wyoming9

iTrader: (1)

Heat !! will kill any electrical device after time.

Hard to believe and understand but the pump running submerged in gas helps keep it cool.

I knew a farmer always drove around between 1/8 and empty got about 3 months per new pump . Was convinced the new pumps were just junk. Bought the truck when the last pump quit .

25,000 miles later still the used pump I put in. Tried to tell him he just would not listen.

Then dirty gas does not help either if the sock gets full of dirt always drawing through the crud is hard on the pump.

I always fill my tank when it gets around 1/2 tank other then sending unit issues I never had a pump fail yet in 10 plus years of Toyota 4X4 vehicles.

Gevo

had a chevy suburban while back and dealer said same thing after taking it in for warranty repair of fuel pump. Overheats "sometimes' if running constant low fuel... I found it hard to buy though, you'd figure that the designers woulda thought of that and compensated somehow..

maybe thats why my audi bugs me about low fuel with 6 gallons still in the tank.(nearly 1/3 full!)

1993 4x4

Knock on wood but my 93 pickup still has the original fuel pump. My Chevy 2500 van on the other has has gone through like 3 in 10 years. Go figure. I wonder the same thing.

SoCal4Running

My 86 4Runner still has its original too.


Just turned over 352,000 miles!

stanprophet

Well like others have said heat is a killer. So running it for long periods of time below 1/4 tank will keep the pump mostly above the fuel line, and not cool it very well. Also age, or run time will also cause a pump to just wear out. Most pumps to wear out. Just like any motor there are brushes and commutators that wear out in them.

Here is some things that will blow your mind.
Average Fuel pump RPM = 6000 rpm's (Mid range on a good pump)
Rough average MPH = 45
Mileage 372,000
Hours on fuel pump=8266.67
Minutes on fuel pump= 496,000
Revolutions on pump=2,976,000,000

This does not take into account the idle time on the vehicle. It is a rough estimate, give or take a million or so revolutions ha ha!

Now GM's have a different problem. The wiring connector that goes to the pump was not designed to handle the current that is drawn by the pump. So over time the pump overheats the connectors causing them to arch and burns the wiring and the pump up.

Here is a picture that will make you think!


This vehicle would shut off when making a hard left turn below half a tank. The wiring overheated and the positive and ground were shorting together inside the tank!

Here is a waveform of a worn out fuel pump. You are looking at the current draw of the pump on an Oscilloscope. Each little hump is a commutator in the pump as it begins to hit the brushes.


The erratic spikes show how the commutators are worn out.

Here is a good one.

Terrys87

iTrader: (1)

I fill up at the 14th mark to keep the pump cool as mentioned. Also the return line can get clogged on these putting the pump under a lot of pressure. I have seen the "J" Lines get clogged and clogs in the line itself. Here is some info that may help>>> https://www.yotatech.com/forums/f199.../#post51633022 To clear the line, I have used Marvel Mystery oil and using a small funnel off of a gear oil bottle slowly filled the line and keep working it with an air hose. It has taken me a couple of days soaking the line.

Gevo

Well, I had planned to be draining and cleaning my tank... here is more reason to do so.. I'm pretty sure in its 216k miles life before I got it it has not been done.

The old fuel pump I took out was pretty bad, flow was restricted quite a bit and it was dated 2010.

cheers to 1/4 tank or higher and clean fuel lol

osv

great thread.

fuel pumps are cooled down by the fuel running through them, although it sure makes sense to keep 'em submerged.

if crap in the tank clogs it, or the filter sock, the cooling will be limited.

NickL

So it looks like you guys were right about heat being the culprit. I pulled the pump today and everything seemed to look good from the outside. The gas I drained was clear, the filter sock still had a lot of white showing, the electrical connections look good, and none of the lines were blocked. I'll swap out the pump and keep the tank above 1/4 full from now on.

As far as pumps, which brand do you recommend? I thought I read that DENSO makes the OEM pump, but I'd have to order it online because the local parts stores only carry Delphi, Airtex, etc. The dealerships want $320 for the OEM one, though it looks like I could buy one online for $220. Is the OEM pump worth the extra $$$, or should I stick with an aftermarket brand? I just don't want to have to deal with my truck dying on me again.

osv

$120 for the denso pump, at sparkplugs.com? check that part number.

http://www.sparkplugs.com/product.aspx?zpid=13597