Fuel Pump Relay Cleaning (2 Viewers)

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Mudders
This thread will walk you through the procedure for removing, opening and cleaning the contacts on the Fuel Pump Relay on the 80 truck.

After reading thru RT issues in chasing down some hard starting, I decided that after 145k, it was time to clean the contacts on the Fuel Pump Relay, in an attempt to chase a slight miss on my 94. The result was better startup, and better acceleration. It's not dramatic, but certainly a worthwhile and *free* PM, assuming you don't break anything. If you do, I believe the relay runs about 80USD

LOCATION
The Fuel Pump Relay (FPR) is located on the driver side of the car, just forward of the fuel pump resistor. It's attached to the fender, and the body of the relay is inside the fender itself.

Here are the pics of the location. It is held onto the fender using a 12mm head self tapping screw.

Next up... Surgery.

Scott Justusson
LOCATION.jpg
LOCATION2.jpg
SIDEVW.jpg
 
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FUEL PUMP RELAY CLEANING - Continued

Once removed, you will need to separate the top from the bottom. To do this, you turn the relay bottom side up, insert 2 screwdrivers 90 degrees apart and spread the 4 tabs out while pulling on the top box. It's a bit tricky, and you can see from my photo that one of the tabs popped (brittle from age). Not a big deal as long as the oring will still seal against the box when you open it up. The trick is to pull apart the 2 pieces while just getting the tabs to clear the bottom board. Do note there is a key and socket to orient the 2 pieces of the relay. This means the relay top can only go in 1 way to the bottom board.

The relay works as follows: When not powered from the ECU (idle), the fuel pump power travels thru the Fuel Pump Resistor. When powered, the wire wound magnet gets power, closes the contacts (points type) and 12 volts is fed directly to the downstream side of the Fuel Pump Resistor. The problem with points type switches, is that they get pitted.

In picture 2, you can see where I inserted fine sand paper into the gap in the points and cleaned the contact pucks. RT used a matchbook striker which is a great idea. It's key NOT to bend the contacts in any way, or there is a good chance the relay will no longer work (outside the field of the magnet). You need to clean the bottom contact puck *and* the top contact puck.

Once done, orient the key in the top cover to the slot in the bottom board, and press together until the 4 tabs clip over the bottom board. Make sure the oring is not deformed, missing or cracked. If so, you will need to use RTV or some sealant against moisture.

Plug relay back in, and install relay to the fender. Done. I also like to reset the fuel by pulling the EFI fuse, but it's not really necessary.

On my 94 the results of this cleaning was noticeable, the truck was much smoother under acceleration, and exhaust was quieter. On the 93 these pics are from, the cleaning resulted in easier starting, and smoother acceleration.

HTH

Scott Justusson
94 FZJ 80 Supercharged
Chicago
SPLIT.jpg
CLEAN.jpg
 
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Cool thread, I'm wondering whether having a spare FPR perhaps from a pick and pull yard would be a good idea; that little bugger looks hard to rig for repair on the trail? Thanks for the thread again! :cheers:
 
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Cool thread, I'm wondering whether having a spare FPR perhaps from a pick and pull yard would be a good idea; that little bugger looks hard to rig for repair on the trail? Thanks for the thread again! :cheers:

An excellent spare to have around. A bypass harness will work in a pinch, but you wil be massively rich at idle.

SJ
 
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Good writeup!


Just curious, If the FPR is working, then the pump is getting voltage, so how does cleaning it make your idle any smoother? I am not an expert, but it seems like idle is a function of the VAF/MAF, air filter, fuel filter, fuel pressure regulator, and most importantly, injectors. I am all for cleaning the relay, but I don't see how cleaning an already operating relay can affect the truck in the way you described...

please enlighten me.
 
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Good writeup!


Just curious, If the FPR is working, then the pump is getting voltage, so how does cleaning it make your idle any smoother? I am not an expert, but it seems like idle is a function of the VAF/MAF, air filter, fuel filter, fuel pressure regulator, and most importantly, injectors. I am all for cleaning the relay, but I don't see how cleaning an already operating relay can affect the truck in the way you described...

please enlighten me.

The idle hasn't changed, startup did, but I'm convinced the ECU triggers full 12v on startup.

The benefits are the same as cleaning points on window switches, ignition switches, or ignition points. Over time the points get pitted from electrical arcing. Cleaning them reduces the resistance of the pitted contacts.

Those of us that remember the old points ignition know that cleaning and regap did wonders.

SJ
 

re_guderian

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...but you wil be massively rich at idle.

SJ

Shouldn't the fuel pressure regulator take care of this? I have an intermittent open in my harness to my fuel pump resistor so I have had to bypass that to run (fuel pump runs at 12v constantly). You are right, the ECU sends 12v to the pump at start up, and immediately swtiches to lower voltage.
 
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How much abrasion does it take to clean them? Just a light rubbing back and forth does the trick?
 
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The idle hasn't changed, startup did, but I'm convinced the ECU triggers full 12v on startup.

The benefits are the same as cleaning points on window switches, ignition switches, or ignition points. Over time the points get pitted from electrical arcing. Cleaning them reduces the resistance of the pitted contacts.

Those of us that remember the old points ignition know that cleaning and regap did wonders.

SJ

Still doesn't answer my question, you said that your truck is smoother under acceleration....

Those of you that were around when points ignition systems were in production are not the only ones who know how they work.......

Maybe I have no clue, but I thought that the 69 and 76 FJ-55s had points, and could somebody tell me if early 60s ford fairlanes, mercury comets and Mercury meteors had points?:rolleyes:
 
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Still doesn't answer my question, you said that your truck is smoother under acceleration....

Those of you that were around when points ignition systems were in production are not the only ones who know how they work.......

Maybe I have no clue, but I thought that the 69 and 76 FJ-55s had points, and could somebody tell me if early 60s ford fairlanes, mercury comets and Mercury meteors had points?:rolleyes:

I just don't like to post date myself or others... Here's what I figure happens... Over time, points get pitted, and arcing of the contacts and carbonizing of the contacts makes for some resistance under closing. This will vary depending on how the points close, age and frequency. Every time you take your foot off the gas, that relay opens, every time you put your foot on the gas, that relay closes. That's a lot of duty cycle.

Clean up the pitting, there is more consistent voltage/amperage going to the fuel pump, and the result is more consistent pump pressure and flow.

In the turbo audis, I actually run a second relay a 18in from the pump, activated by the first relay (rollover safety shutoff stays intact). I have designed how to do that mod to the 80, but haven't added the project to my list quite yet, that pesky resistor makes things a bit more involved (or I'm lazy, my truck runs great). I have high confidence that increasing wire size and decreasing it's length will have benefits in the 80's as well, especially with force induction.

In the meantime, optimize what you have, clean the existing relay.

HTH

SJ
 
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Shouldn't the fuel pressure regulator take care of this? I have an intermittent open in my harness to my fuel pump resistor so I have had to bypass that to run (fuel pump runs at 12v constantly).

I don't think the fuel pressure regulator can handle this well. I suspect that at idle with the large injectors in the 80, at full 12 volts a lot of fuel is sent back to the tank, maybe enough to cause backpressure if conditions are right. When I ran the calculations and confirmed the size of the injectors on the 80, the resistor makes a lot of sense.

You are right, the ECU sends 12v to the pump at start up, and immediately swtiches to lower voltage.

Thanks for confirming that. I figured it would since a good shot of rich fuel makes for better startup.

How much abrasion does it take to clean them? Just a light rubbing back and forth does the trick?

Tough one to answer, depends on how bad the pitting is. You can put under a light and magnafier to see how pitted the contact pucks are. Probably 1 minute of light sawing for each puck is plenty. More if the contacts are really pitted. Do this with almost no pressure, or you will bend the lower puck.

I suspect this is a one or two time fix, then a replacement is dictated. I might suggest a clean up, save for a new one, and use the cleaned one as a trail spare.

SJ
 
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landtank

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nice write up, similar to the one I did years ago.

The proper tool for cleaning contacts is called a bernishing tool. Sand paper is really too rough for the silver contacts.

In a pinch an unused striker from a book of matches is a good substitute for the tool.
 
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nice write up, similar to the one I did years ago.

The proper tool for cleaning contacts is called a bernishing tool. Sand paper is really too rough for the silver contacts.

In a pinch an unused striker from a book of matches is a good substitute for the tool.

Depends on the amount of pitting Rick. The one on the 93 was in bad shape, so it couldn't get 'worse'. This procedure won't last as long as a new Relay, but can certainly make a crappy one better for the near future, even if you take all the silver off. I suggest if using the striker, to pull as much of the paper backing off of it and folding it in half so you do the upper and lower pucks at the same time. It's not easy to sneak in there with anything that holds it's shape.

ST

SJ
 

Romer

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I forgot about that write-up. To be complete, here it is

Well I've had similar running issues like yourself but it happened after a period of time once the truck was ran for an hour or so. That was until this morning, when it behaved just as yours. The relay was mentioned on my thread but when I went out to check my truck I couldn't find it as it's in the fender and I just replaced the EFI main replay for like 8.00.



Well I got out the manual and did find it today and checked the contacts and they did look dirty. I priced out a new relay locally at @ $100.00 so cleaning it would be a cheaper option.



The proper way of cleaning a relay is with a burnishing tool. This is like a ultra fine very thin file specifically for relay contacts. Good luck finding one, I did and it was an hour away. So plan B, (not -B-), is to use an old trick I was taughtback when I first started in field service.



What you need to find is a new match book. Cut the strike area out of the book and you have a very good substitute foe a burnishing tool. You slide the striker in between the contacts and the in a filing motion clean the contacts. DO NOT add any addition force to pinch the contacts closer!!! Once done on one contact flip and rotate the striker to clean the other contact in a clean area of the striker.



Attached is pics of the striker installed in the relay and the used end of the strker as what came off.

attachment.php

attachment.php
 
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It very :cool: that Toyota didn't seal the relays with epoxy like most do, allowing them to be messed with. Not sure what it's made from, but the contact material is some very hard stuff, also if new ones are examined closely, they are dome shaped and highly polished. This is to make a clean, small closing, opening contact arc/spark. If they are sanded the contact point is flattened and scratched this causes the arc to grow greatly in size and heat produced. Also the reason that the burnishing tool tool that Rick mentioned is used is due to the makeup of the abrasive in it. A lot of oxides in common sandpaper will become embed in the contact surfaces and with the heat, arc, change the metallurgy of the points, greatly reducing their life. Aluminum oxide is one of the most common sandpaper components and is one of the worst offenders.

Will cleaning them work, yes. My A/C fan became intermittent just before CM07, cleaned up the contacts on the heater relay and good to go. IMHO it's a great trick for noncritical components and emergency get me home fixes on critical ones. I wouldn't do it as "PM" on something that can leave me stranded in the middle of Lockhart, like a pump relay, I would clean it up, then order, install a new one and put the "cleaned" one in the spares box. Anyone that has worked on an old points system will tell you that cleaned points will have nowhere close to the life of new ones and are much more likely to fail.

I haven't measured the voltage drop across one on an 80, that would be helpful data to have? New, cleaned and a measurement when the pump performance is affected.
 

re_guderian

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The idle hasn't changed, startup did, but I'm convinced the ECU triggers full 12v on startup.

The benefits are the same as cleaning points on window switches, ignition switches, or ignition points. Over time the points get pitted from electrical arcing. Cleaning them reduces the resistance of the pitted contacts.

Those of us that remember the old points ignition know that cleaning and regap did wonders.

SJ

I am still struggling with the logic of this. As one who has gone through this circuit ad nauseum, unless it's corroded to the point of reducing the voltage to the fuel pump during high load situations so much so that it is causing fuel starvation in front of the pressure regulator, I'm not sure how this would help. And wouldn't that cause noticable stumbling? Or large changes to both the short term fuel trim and/or long term fuel trim under load (because of a lean condition)? IIRC, at idle through the resistor circuit, it should be ~9 volts or so. Scott, you are running a SC, no? Do you still have the OEM pump? That might make a difference...
 
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...

Will cleaning them work, yes. My A/C fan became intermittent just before CM07, cleaned up the contacts on the heater relay and good to go. IMHO it's a great trick for noncritical components and emergency get me home fixes on critical ones. I wouldn't do it as "PM" on something that can leave me stranded in the middle of Lockhart, like a pump relay, I would clean it up, then order, install a new one and put the "cleaned" one in the spares box. Anyone that has worked on an old points system will tell you that cleaned points will have nowhere close to the life of new ones and are much more likely to fail.

I haven't measured the voltage drop across one on an 80, that would be helpful data to have? New, cleaned and a measurement when the pump performance is affected.

Already posted most of this. However, I'll give big trail tip number 2. For a simple field repair of a failed fuel pump relay, you only need to jumper the connector going to the fuel pump resistor. This will allow 12 volts to bypass the failed relay and go directly to the pump. I'm convinced Toyota has this procedure in some military manual.

That relay could catch on fire, and you will still have a hard connection between the resistor bypass in the relay plug. In my field kit, I'd make me up a connector that plugs into the resistor bypass connnector. When the relay fails, unplug the resistor circuit and pop in the jumper connector until you are done wheeling for the day.

Yes you can get that plug, I ordered it already.

ST
 
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I am still struggling with the logic of this. As one who has gone through this circuit ad nauseum, unless it's corroded to the point of reducing the voltage to the fuel pump during high load situations so much so that it is causing fuel starvation in front of the pressure regulator, I'm not sure how this would help. And wouldn't that cause noticable stumbling? Or large changes to both the short term fuel trim and/or long term fuel trim under load (because of a lean condition)? IIRC, at idle through the resistor circuit, it should be ~9 volts or so. Scott, you are running a SC, no? Do you still have the OEM pump? That might make a difference...

Ck the contacts for pitting, all relays have a service life, and failures are usually contact related. To ck the efficiency of your relay, I suppose you could unplug and jummper the resistor and see if off idle driving gets better.

ST
 
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what is the toyota part number for the FPR? just in case i do end up needing to replace it rather than clean it?
 

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