Fuel pump hotwire

[Chris26]

How do I run the pump(s) by jumping the red spade connector???

[Paul Workman]

With the ignition switch OFF, jumper the battery POS directly to the spade of the connector*

Both pumps should run and continue to run as long as the power is applied and the ignition switch remains OFF.

BTW, configuring the VOM to read amperes, you can measure the current draw.

The current draw is the total for both pumps; approx 8-10 amperes total.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/Fuelpumpcurrentcheck004.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/Fuelpumpcurrentcheck004.jpg.html)

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/Fuelpumpcurrentcheck005.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/Fuelpumpcurrentcheck005.jpg.html)

[Chris26]

Thanks!!! ....Did you ground to the frame of just NEG side of batt???

The whole purpose of this is to clear the lines and check the current...

[Paul Workman]

Thanks!!! ....Did you ground to the frame of just NEG side of batt???

The whole purpose of this is to clear the lines and check the current...

Noooooo! Do not connect an ammeter (measuring current) any way but in series with the load.

Connect the VOM (configured to measure amperage) between the positive battery terminal and the fuel pump test (spade) to read current.

[Chris26]

I'm using a VOM don't worry!!!.. Thank-you!!!

[Paul Workman]

I'm using a VOM don't worry!!!.. Thank-you!!!

To quote Alfred E. Newman: "WHAT? ME WORRY????"

Oh, I'm not worried, cuz you ain't usin' my VOM! :p But, when you said...

Thanks!!! ....

Did you ground to the frame of just NEG side of batt???

The whole purpose of this is to clear the lines and check the current...

... from what you wrote, I get the impression you may not be familiar with measuring current with a VOM. Not to put too fine a point on my point, but even in Canada if you connect the VOM (configured to measure current - as seen in the photos above) most meters will only handle 10 amperes. So, if you go probing various places with one probe and grounding the other, [-X you'll blow the fuse (at least).

Note: No offense to you if you're fully aware; but in case you are not, let me say it is a good idea to move the probe from the "A" port on the VOM back to the VOLT - OHM port as soon as you're done measuring current to minimize the chances of forgetting and attempting a voltage measurement. (Ask me how I know!) And, I recommend switching the VOM to "A" before connecting the test leads in series with the load to avoid arching the contacts in the VOM.

:cheers:

[Chris26]

I got a 6.17a reading...

[Paul Workman]

I got a 6.17a reading...

Assuming proper connection/setup, THAT reading appears to be low, i.e., one pump only, or one pump may be faulty, or a bad connection(?).

While monitoring the current, pull the FP1 fuse on the main panel and see what the current is. (Current adds in this case. So, pulling only one fuse and seeing what current remains will tell us what the current draw of each pump is.)

Here is a schematic from a 90 FSM which I hope is similar enough to work on later mo cars too. (Someone may correct me if this isn't accurate beyond the 90 Zs)

Fuse location (1990): one on the main fuse panel, one on the auxiliary panel accessed behind/under the passenger knee panel).

[Chris26]

I got 0.46A with FP1 pulled.

[Paul Workman]

I got 0.46A with FP1 pulled.

Well, that's a problem. It should be in the 4-5A range w/ FP1 pulled (ignition switch in OFF position). So, "ringing out" the circuit and ultimately the fuel pump to find the problem is next. It could be a bad relay or even a connector (ask Jim Voter about his experience w/ pump connectors!).

Present company excepted; BUT! For all that say chit like "It can't be "this or that (part)", because I replace it", especially when dealing with foreign-made parts, one has to VERIFY the replacement part is working. NEVER ASSUME! Just b/c it is "new", doesn't mean it works, OR that it won't fail shortly after it is installed. (Statisticians call it "infant mortality"; the period when a device is most likely to fail is when it is first installed!) Example: One of my new pumps failed right out of the box! Just sayin.....:(

Anywayz... sounds like you're on the right path.

[Chris26]

Thank-you for everything BTW!!!!

Where is the relay located???

I will check connections on the pump assy. In the tank

[Paul Workman]

Thank-you for everything BTW!!!!

Where is the relay located???

I will check connections on the pump assy. In the tank

OK...some legitimate logic here... IF there is (as you indicated) 6+A with both fuses in place, we can assume that both relays (w/ ignition OFF) are not the issue: To have 6+A w/ FP1 and FP2 inserted, the relays are in series, i.e., current in series is common to all circuit components in series.

Next, I would "divide and eliminate": see what you have at the fuel pump connector. Note: Before going further, do NOT expose fuel vapors to the potential of electrical sparks - especially when making voltage measurements with an open fuel tank!! (Course you know that, but you might not be the only one on the internet reading this!)

If it is good there, then check resistance of both pumps, measured between the input power and the ground. Also, inspect both halves of the connector.

[Chris26]

Not worried about fuel vapor and sparks....I live in front of a fire station!!!;)

[Chris26]

These are my two readings...
16.7 ohms
3.1 ohms
Hmmmmmm......

[Chris26]

Ignore those readings they are just an anomaly...
The connectors are corroded due to water that was in the tank.

[Paul Workman]

Ignore those readings they are just an anomaly...
The connectors are corroded due to water that was in the tank.

Good job. Now, when the connector is cleaned up and sealed, is the resistance through the pumps more or less the same? If so, button it up. But, now go back to step (one) and measure current w/ the key off. It should be between 8-10A at the pump prime connector, yes?

[Chris26]

Pumps put out 6.17a under load with gas and 2.70a pumping dry.
they both read about the same...they seem like replacement delco units from 2014.....All contacts were cleaned thoughly ....crud and water at the bottom of the tank....first offer of 7k CDN takes this puppy home( sans water in the tank)..

Got my order in from Jerry's today...

[G8nightman]

Selling the car for 7k?

[Chris26]

In a sarcastic and somewhat sadistic way yes!!!!....I just don't have the resources or time for this project....:mad:

[G8nightman]

Post some pictures of the car..

[Chris26]

Its a 90
arctic white with grey interior (snake skinner)
#1457

Give me a day or so...I'm tired!!!

[geezer]

Chris 26: Where in PQ are you. How far from Ottawa? Don't let the frustration get to you. The 'brotherhood' is here for you!!

[Chris26]

I'm 10 minutes from MTL... One hour from Ottawa...The car's previous owner did

not know what an lt-5 was so go figure.

[Paul Workman]

I got 0.46A with FP1 pulled.

Well, if connections are good now, this reading indicates FP#2 is drawing only 1/10th the current it should be. That is a problem.

Either FP2 is bad, or there is a bad connection somewhere between the battery and FP2. (Refer to the two schematics)

I suggest you "ohm it out". But FIRST(!) I recommend we verify the ground, measured from the pump (input side) BLACK wire terminal to ground, i.e., the frame (or some other good ground location) - just to avoid assuming anything. It should read less than an ohm (I would think - having not actually done this particular test myself). If the ground is OK, then we can proceed with confidence.


With a test lead (alligator clips on each end) ground the pump prime connector (under the hood) and
read resistance between the GREEN-WHITE lead and the BLACK lead on the input (battery) side of the pump connector, and do the same on the GRAY wire. Both should read close to zero to 1 ohm.


Note: This test includes the various wire connections, and resistance of relay FP1, and for FP2 it also includes resistance of relay FP2 as measured on the GREEN-WHITE wire at the fuel pump connector at the tank. If there is a problem with FP2 circuit, resistance would be approx 28 ohms ± (battery voltage/.46A to be precise.)

If the circuit to the pump connector checks out, then connections to FP2 and the fuel pump itself is all that is left. You could swap the pumps and see what the FP1 current draw is when plugged into the FP2 slot (after reconnecting the pump prime connector to the VOM (configured again to read amperes).

If FP1 (now in FP2's position) works as before, then FP2 or its wiring is bad.

[geezer]

Sent you a PM.

[Chris26]

OK

Ground reads about 29ohms...Black input to common ground

green white to ground reads about 1 ohm

tan white to ground reads about 1 ohm

[geezer]

Chris: Did you check your PM's ( private messages)?

[Chris26]

FYI The pump was not under load when tested(connected to injectors and rail).....

[Paul Workman]

FYI The pump was not under load when tested(connected to injectors and rail).....

Just to be sure we're on the same page....

The connector at the fuel pump (for the record) is "C450"

With all circuitry connected normally, AND that includes the fuel lines to the injectors via the fuel rail(s), WITH the battery (pos) is passed through the VOM (configured to measure Amperes) to the FUEL PUMP PRIME CONNECTOR (the red wire/connector near the windshield wiper motor, jutting out of the big wire loom), you should read between 8 and 10 amperes (approx 1/2 of the current to each pump, is how that works).

However, if the current is NOT where it should be, by pulling the FP1 fuse you cut off the current to the FP1 circuit and what is left is the current flowing to FP2 only. Now, if FP2 is normal, under load (pumping fuel) it should read between 4 and 5 amperes.

CHECKING OUT THE HARNESS TO THE FUEL PUMPS:

With C450 disconnected (at the fuel pumps), separating the harness from the fuel pump apparatus, the ignition switch still in the OFF position, and the FUEL PUMP PRIME CONNECTOR no longer connected to anything, and all other connections, etc. in their normal condition/state (i.e., no jumpers or whatever else being present), the VOM configured to read resistance should read zero to 1 ohm or there 'bouts between the GRAY and the DARK GREEN/WHITE (harness) wires (feeding from the battery-side of the C450 connector, NOT the wires leading into the tank).

Again, reading resistance of the ground connection, the resistance measured between the BLACK wire (on the harness side) of the C450 connector and ground (e.g., the frame) should be very close to zero to 1 ohm (i.e., the amount of resistance one reads when the test leads are shorted when measuring ohms).

IF the above is true, i.e., the resistance reading recorded between the GRAY and the DARK GREEN/WHITE (harness) wires was at/near zero, AND the resistance between the BLACK ground wire of C450 of the harness is at/near zero, the harness "ohms out" FOR NOW.

Let's hear what you find/found.

[Chris26]

Thanks again!!! Any tips on how to remove bolts with cracked off heads from the coolant pipes to the injector housing??? I do not have a torch or anything like that. The car was a gift and TBH this is not going the way I planned it out...I'm supposed to be on vacation but instead have a s@#$load of parts on my kitchen table....If i had a garage ...proper resources...cool neighbours ...then I would not be complaining!!!!

[Chris26]

f@#K!!!! I should have never touched those bolts and just left the whole injector assembly together!!!!

[Chris26]

Ok!!! Broken studs removed..

[Paul Workman]

Ok!!! Broken studs removed..

Jerry has some stainless replacements, or you may have a machine Supply outlet nearby where you can also get them.

I put some RTV on the threads to keep water out and to keep them from seizing again. (Common problem after some years.)

[Chris26]

Ok ...the engine has been refreshed and buttoned up....Gas tank was completely cleaned out...Went and put in 20$(12L) of gas and nothing comes out of the lines when I jumper the pump..... The connector is flaky as I get an intermittent reading of 6-13a.....

[Chris26]

Would a clogged fuel filter cause this???....after old fuel and water ran through.

[Paul Workman]

Would a clogged fuel filter cause this???....after old fuel and water ran through.

Well, it would take solids of various sorts to plug the filter. If there was some debris in the bottom of the tank, certainly either the pick-up flilter(s)(attached to each pump) or the inline filter (on the frame rear of the RF wheel well) could become blocked.

As for the different current readings, assuming proper connections, the normal draw is 8-10A, divided between both primary and secondary pumps when both are under load (pumping fuel). (IDK what the current might be if they are not immersed in fuel.)

[Chris26]

ok I blew into the lines at the tank going to the fuel rails....and got a bunch of

crud and water out into my catch bottle ...the lines seem to be unblocked now.

But one problem....the fuel pump will not come on anymore after I try and jump

it. Is there a fusible link somewhere....near the battery area for the pumps???

FP1 fuse checks out fine...F&@k....I have a massive headache and working in

40+ degrees C is NOT FUN!!!!

[Chris26]

I'm getting current to the fuel tank connector.
(blew FP1 fuse in the process.)

[Chris26]

the harness seems to check out.....pulled the pump assy and jumped them directly to the battery and nothing....I think the stress from the clog took them out!!!!