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klapa
09-21-2010, 02:44 AM
Well - I was confused about this - and most of this confusion was because I did not do my proper "homework" - plus I was looking at Haynes manual electrical diagrams - instead of really investigating the BGB here.

Still - in some "wimpish" defense of my actions I must say that the electrical diagrams for the Alltrac on the BGB leave at least a little to be desired.

My "confusion" began based on the premise that all Celica's (at least fifth gens) have this "fuel pump relay". My confusion on this point was partly fueled by what seemed to be conflicting information in diagrams - but also due to the fact that I have had "on and off" performance of my Alltrac fuel pump which at some times required arbitrarily jumpering the fuel pump "on" at the diag connector.

i was ALSO confused by the fact that I have four 5th gen Celica's - and I was comparing notes between them.

I will not seem to be an "expert" here - as obviously I am "anything but" - yet these are my conclusions:

First - I thought I DID NOT have a fuel pump relay - because at a casual glance in my relay/fuse box on the passenger side of the engine I did not see one in the allotted space. Yet "casual" would be the "watch-word" here - as I was looking for a "normal" relay - not for what I actually have - which is a relay without the cover which has been "hacked" into this car's harness:

http://www.nashdom.com/Alltrac/FuelPumpRelay%28640%20x%20480%29.jpg

So - working "backwards" here - I did find on both my GT and GT-S that neither had such relay. The GT has a two-pin connector in this position - the GT-S has a four pin connector with only two pins populated.

In both cases - neither is fitted with a separate relay for the fuel pump.

In fact - looking closely at the BGB instead of the "Haynes manual" - neither DOES have that relay fitted. It is difficult because the BGB does not really have emphatic information about the Alltrac in the wiring diagrams - yet if one looks at the "block diagram" in the EFI section one may get the idea.

For the GT and the GT-S (5SFE cars) it seems that only the "circuit opening relay" is used to control the fuel pump. Yet for the Alltrac - there IS a separate fuel pump relay in series with the "circuit opening relay" which ostensibly - possibly - has a resistor in series with the coil - and also possible has a parallel path from the ECM to the relay coil either through the resistor or directly to the coil.

Aside fom all of the above "conjecture" I wondered why I have such a "rube" setup on my car - and also why did the main fuse/relay box on the driver side have Japanese writing on it while the relay/fuse box on the passenger side (which is really f*cked up) does not?

Maybe my answer IS what I found when I searched around today for "JDM harnesses". Of course - nobody sells just the harness - they only sell the harness with the engine.

Yet looking closely at all those engines and harnesses I noticed that actually - they ONLY include the driver side engine harness with the engine - never the passenger side (where all this other stuff like "fuel pump relays" are).

So I think whoever did this swap had to "hack" whatever fuse box they had - and in this case it probably did not support the fuel pump relay - which seems to be Alltrac specific.

As it is - my GT-S has a four pin connector there where that relay should reside - while the GT has only a two-pin connector with a jumper installed. The relay I have "lurking" in the bottom of that fuse box on the Alltrac now has four pins.

Thus I might "re-pin" the GT-S fuse box and use that "in a pinch" - yet at this point I am in no "itching hurry" to hack up the GT-S parts car - I'd like to get it running so I can put it in it's "final resting place" to be stripped.

ChrisD
09-21-2010, 04:55 PM
So...what's the question?

From memory, the fuel pump relay is not in the fuse box. It is a standalone relay, probably located somewhere near where the FP resistor pack sits. Or maybe on the firewall. Or maybe that's just the 165. I can't remember. I always eliminate it anyway.

In any case, I'm a proponent of eliminating the relay and resistor from the circuit in their entirety.

I'm a bit confused what you mean with "drivers side" and "passenger side" harnesses. There is the engine harness (engine control functions, connects ECU to engine and to fuse box), the engine room harness (goes around the engine bay on the exterior of the engine "room", and many harnesses on the interior of the car.

Also, moving to Forced Induction as this is a swap/3SGTE specific issue.

---------- Post added at 09:55 AM ---------- Previous post was at 09:50 AM ----------

Found this pic in one of your other threads:

http://www.nashdom.com/Alltrac/FunnyStuff2%28640%20x%20480%29.jpg

That is your fuel pump resistor pack. Basically, the FP relay will send the power through the resistor before getting to the pump, except when needed, it will bypass the resistor and send full voltage to the pump.

I'm not a fan of this setup, and I personally just like running full voltage to the pump at all times.

klapa
09-21-2010, 09:41 PM
So...what's the question?

From memory, the fuel pump relay is not in the fuse box. It is a standalone relay, probably located somewhere near where the FP resistor pack sits. Or maybe on the firewall. Or maybe that's just the 165. I can't remember. I always eliminate it anyway.

In any case, I'm a proponent of eliminating the relay and resistor from the circuit in their entirety.



Well - no "questions" there actually - just answering my own questions I had in my other thread as to what I found on my car after digging into it a little bit. I had a good reason - I couldn't start my car and investigating found numerous problems with grounds.

During that process I needed to install an "external" starter relay - which is still in - but also found that the car would not start unless I jumpered the fuel pump at the diag connector.

After finding the worst (I hope) of the grounding problems I found that "magically" the car ran without the jumper wire. So I wanted to know why. That's when I dug into the "fuel pump relay thing".

To be truthful - this car scares me - because I don't yet understand how it works - but I need to keep it running well enough to move it around - else the "neighborhood police" will be on my back.

When I came up - dinosaurs roamed the earth, and cars had a radiator, four hoses, and an engine. Due to traffic - brakes were "optional" in those days.

While I'm an engineer - I don't know shit from shinola about engine control systems - thus I thought the relay was a necessity. If I can just forget about it and simply provide power to the fuel pump when ignition is on - that'll work for me!

I once had your website in my links (a great resource!) but as my laptop died and got wiped out I don't have that anymore.




I'm a bit confused what you mean with "drivers side" and "passenger side" harnesses. There is the engine harness (engine control functions, connects ECU to engine and to fuse box), the engine room harness (goes around the engine bay on the exterior of the engine "room", and many harnesses on the interior of the car.



While you certainly have more experience than me - I would beg to differ on this issue - based on my research and my experience with my own cars.

I have all 5th gen cars - '91 AllTrac ST185, '92 GT ST184, '93 GT-S ST184 (parts car), and finally '92 STX (the car that actually starts up and hauls my ass to work everyday). If It matters - the DOM for all of these cars is early August to September of the year model.

I looked around for engine "engine harnesses" for my ST185 - and there were plenty advertised - always along with an engine. I also looked around for "engine harnesses" for my ST184 and also found plenty - many separate - on eBay - with good photos.

In ALL cases - the "engine harness" IS that harness that connects the ECM to the engine bay - and that is a separate harness that comes out of the firewall on the passenger side and then travels along the driver side of the car.

Yet there were also many other passenger side "engine harnesses" available - separately. These exit the firewall at nearly the same location but travel along the passenger side and have the fuse/relay box that includes the A/C fan relays 2 and 3, cooling fan relay 1, and - YES - that "mythical" fuel pump relay! The photos for JDM engines were revealing - and the eBay offerings for ST184 harnesses were the "icing on the cake".

So - to be "succinct" - while I know nothing about an ST165 and only a little about an ST185 I would go "out on a limb" here to state that there ARE two distinct and different harnesses in the engine bay of a 5th gen - and that would apply to both ST185 and ST184 - and that the "passenger side" harness houses the fuel pump relay - which seems to be only installed on an ST185.

Also, moving to Forced Induction as this is a swap/3SGTE specific issue.

---------- Post added at 09:55 AM ---------- Previous post was at 09:50 AM ----------

Found this pic in one of your other threads:




http://www.nashdom.com/Alltrac/FunnyStuff2%28640%20x%20480%29.jpg

That is your fuel pump resistor pack. Basically, the FP relay will send the power through the resistor before getting to the pump, except when needed, it will bypass the resistor and send full voltage to the pump.

I'm not a fan of this setup, and I personally just like running full voltage to the pump at all times.

Sounds good to me - as I indicated I am new to these cars and really am apprehensive to change "fuel things" - due to the safety aspect of it all - I was thinking maybe the ECM needed to control the pump for some reason - maybe it was just for my "Toyota Security System" - :).

So If I can just diump all that stuff and provide a good feed to the fuel pump - bypassing my own existing "feature relay" - that'll work for me.

joe's gt
09-22-2010, 07:01 AM
yup klapa, almost everyone who does the swap just has supplies the fuel pump with a constant full voltage. I have done that, and have had absolutely zero problems with my walbro for 5 years. So you should be fine just eliminating the relay/resistor entirely.

ChrisD
09-22-2010, 05:37 PM
hehe, well, I think you already know more than most, so you're well on your way. Once you figure a few of the things out these engines aren't all that complex.

It could very well be that the FP Relay is on a separate harness. I think the "passenger harness" that you are referring to is what Toyota refers to as the "engine room" harness. This travels around the outside of the engine bay and passes into the engine bay for various things. There are a bunch of connections to the engine room harness that pass through the firewall. The fuse box is a good example of this, where about half of the wires go to the engine harness, and half go to the engine room harness on the outside of the engine bay (hides underneath the fenders).

But in all cases, the engine room harness stays on the outside of the engine bay. (this I can guarantee)

Here is the Toyota description on the wiring routing and harnesses: http://bgbonline.celicatech.com/90ewd/Electrical%20Wiring%20Routing.pdf