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1991 geo tracker doesn't usually start in colder weather.
06-15-2018, 08:38 PM
Post: #21
RE: 1991 geo tracker doesn't usually start in colder weather.
sure
the pump only needs 2 things,
1: 2 wires there with power. 12vdc, power to the pump.
2: and fuel.

get ready for fuel to shoot out the , fuel, port on top of the fuel rack. it sure will disconnected, lots and lots of fuel , even in 3 short seconds.

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06-15-2018, 10:19 PM
Post: #22
RE: 1991 geo tracker doesn't usually start in colder weather.
your ideas are very good and valid (testing is always a good idea, short of not causing a fire,)
I too never just throw cars together, I test them first. (when ever possible) Electrics tops my list of when to do this.

in fact, I even have dummy load resistors to test the wiring (after each connector was inspected first for damage, end to end)
we did this is a factory too. (QA) (load testing harnesses)

The dummy load is 3 ohm 50 watt resistor, (special ordered, from Mouser.com)
or one grab any spare head lamp and use that, it uses the same current flow. (very close to the actual pump)

we connect it and key on and see the lamp glows at full brightness, and with a voltmeter we will see about 11.5v (battery is 12.5v) so this is the normal voltage drop seen on cheap weak suzuki wiring. (again the 3second run time is 100% ECU created, the ECU runs a clock timer to do that )

The other ways is use the actual pump, that lets me see the voltage is correct and the pump actual works, (even test a new pump, do not buy cheap A$$ 15 buck pumps from china. (fail U will)
you can in fact bench test a pump
or tank on the ground the pump.
and sure even with tank mounted (and yours failed ,before now.)
We can also scope a pump, running, to see if the commutators is going bad, we have youtube videos of this, (this finds bad pumps before the fully fail)


https://www.youtube.com/watch?v=_HT3j82SCnw


There is no way , you want to ever buy a cheap pump, after all that hard nasty wet ,risky work.
Benzine in the fuel, is a cancer causing agent, (no BS , nasty) Best is to work car out doors, with lots of fresh air and a fire extinguisher handy, even a blanket)
If you do not know the good names, ask. Carter, ACdelco, BECK, BOSCH (yah German) and more. not "SOM Ting Wong" or any of 100 other names, no body here can pronounce.(or research)

I recommend watching Scotty's youtube videos. on topic too.


Most of the advice and vidoe's, you see examples of modern cars 10 years or newer.
your car is not that car , (hint more bad to be seen)
your car will have bad wiring (this means connectors too. they are part of all wiring)

when testing a real pump
be real sure the polarity is correct. some pumps have diode protectors inside and will turn on when reversed, and then the wires burn up connected wrong, (or fuse blows )
not all have this but just do not run the pump backwards, ok? only wire it PLUS TO PLUS. testing or otherwise.

the tests will fail if I saw 8v at the pump
do you see why?


the pump in the video failed a simple continuity test, the test showed the brushes are not touching the motors commutator ring.
but was in fact, the connector inside not mated correctly
The pump can also be bad, and fail that, 3 to 10 ohms is par, , but infinity is a dead open pump, no DC brush motor shows infinity ohms connected to a DMM
that video is one of the best there
he even says, do no use water, (correct, after would you like rust on the steel check balls inside later? no)
in injector shop, we have fire proof test fuel to test pumps or injectors and zero risk of fire.

the black wire is ground. simple as can be.
omg his first test showed a leak. (rust happens, new rack time?)

if he was really savvy? he;'d use the fuel pressure gauge and do the SHUNT test on that hose,(tightly clampled) and see 50PSI.
if it reads lower way lower, then check voltage
if voltage is too low the pump runs slower, so fix the bad wiring now.

that is all you can do on the ground (tank)
1: voltage checks'
2: pump heard to run.
3: pump flow seen in to bucket.
4: shut test passes
5: 3 seconds test, passes, using car wires not jumper hot wires, and voltage near 11.5v pump runs for 3 seconds
6: no leaks.
7: fix the dead fuel gage sender too, while there>?

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06-15-2018, 10:27 PM (This post was last modified: 06-16-2018 12:30 AM by fixkick.)
Post: #23
RE: 1991 geo tracker doesn't usually start in colder weather.
the polarity is easy
the pin that goes to pink is Plus
easy to see that. and that may go to rack wiring that is RED.
keep and open mind the rack there can be non suzuki rack and have any color wires in and on the rack.
use the main harness colors as the guide, those are stock. and unchanged.

if done right , no need to repeat 4 hours lost out and back in.
keep in mind pumps have many failure modes.

all leaks bad.
lost of 12 DC power, bad.
bearings bad.
commutator bad
brushes bad.
impeller bad. seals on Impeller bad makes it useless.
hoses inside cracked , leaking where no one can see.
the motor can be bad other ways, (wires in it failed)
The SOCK can be packed. (or fell off, and pump sucks AIR with lower fuel levels.
The check ball jammed. (this magic ball keeps the fuel line changed up under pressure)
end short list.
a pump can in fact be intermittent for lots of reasons. (both by vibration or thermal expansion or contraction of materials)
I had jeep that sucked air,(pump) any time left turns fast, and 1/4tank of fuel. (or less) and a huge racket from back aft.

by bad design it did that. (tank lacked proper baffles) Jeeps first 4L (i6)did that. all did then.
But dang, ran for 250,000 miles , no failures. (related)

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06-16-2018, 12:26 AM
Post: #24
RE: 1991 geo tracker doesn't usually start in colder weather.
Fuel pumps seem simple at first.
but are not. ( many failure modes, and stated above by me)
what is simple is that it runs on 12vdc, it will run all day on 12vdc, just like the blower in the cab will.
The pump however , is fuel cooled, and fuel lubricated, and is not a water pump. (in fact most pumps do not like running dry ever, as s general rule)
The pump if connected to say a 12vdc battery directly will wreck the impeller, un less you keep its (sock) submerged in FUEL.


the 3 seconds is inside the ECU , and NO WHERE ELSE.
you can in fact
bench test any pump (ask how)
or tank on the floor, with a portable battery 12vdc or you can use the stock harness and see and hear the pump work for 3 second each key on.
the pump is just an electric motor , that runs a fuel impeller pump device. all in one.

3 second rules of for CRASH SAFETY,.
and is LAW. (DOT laws) (if a driver hits a tree , do you want the pump running and causes a huge fuel fire, killing every one there, for sure in car or near, or even the fireman? no)
understanding purposes makes the why more easy to understand and remember , ok?

the pump can be tested , 3 ways,
on the car tests
tank on ground
pump on bench
3 ways.
it's just DC motor, (but the impeller must not be damaged testing it)

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