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Old 07-27-2010, 12:08 PM   #1
Hondaeat-r
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Default '02 Wagon Hard Starting, HOT Fuel Pump Relay !!

OK,

So the past few days my car ('02 wrx) does not like to start when the engine is "cold". Don't confuse this with weather, I'm talking engine temp here. First start of the day is tough. Probably 5 -7 cranks to get it going. It then stumbles to life, and after a minute is idling / running fine.

I drive for 20 minutes, I'll turn the car off, run in to a store (hypothetical) and be back out in 10 minutes, and the car starts fine then, maybe a bit slow compared to past cars, but waaaayyyy better than the first start of the day. Then, I'll get to work (it's 80F outside) the car will sit for 8 hours, and when I go back out to start it...it's back to being tough to start. I don't get it.



Maybe I have a clogged fuel filter, or the fuel pressure regulator is malfunctioning in someway ?

Battery tests good in all categories.


Also, the car idles a bit rough initially, after the rough start-up, eventually smoothing out. BUT overall, it's a very "shakey" motor at idle...anyone else ?



I have a decent tune-up coming up this week: Plugs, Air filter, Fuel Filter, PCV, oil change...etc Maybe a few of those will help, but I doubt solve the problem. Was also considering doing Seafoam or something of that nature, because the previous / original owner was a woman who probably never saw 3500 RPM's....
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Old 07-27-2010, 12:09 PM   #2
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OK, I looked at the fuel pump relay yesterday, and it was HOT to the touch. I can touch it, but it's very very hot when compared to the main relay next to it....

Also, two of the four copper male pins on the fuel pump relay were not "scorched" but definitely a very different shade of copper......


UPDATE: Looked again today, the relay itself has 4 ( i think) male spade connectors inside it, 2 of which are a much different copper color than the other two. Also, looking at the plug that mates with the relay, I noticed that two of the female spades in the plug were silver looking, and two were normal copper color..... I think it's safe to assume that Subaru didn't use two different material spades, and it's also safe to assume that the discolored connections on the relay and plug match up to each other. I now need to know what those two connections go to exactly (load, ground, hot, etc.. ?)

I'm going to pull the pump when I get home today, and look at the pumps connectors to see if it shows the same signs on the connector(s).

Can someone looks at their fuel pump relay and tell me A) Is it hot to the touch and B) Are your spade connectors different colors (or shades).

Last edited by Hondaeat-r; 07-27-2010 at 12:22 PM.
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Old 07-27-2010, 01:19 PM   #3
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sounds to me like you may be losing the prime of your fuel systems. Try cycling the key several times before trying to start it. If it does start you may have a leaking injecter which could also cause the rough idle after start up. If its been going on for a wile now you may also be able to smell gas in your oil. Also, some cars have check vavles in the pump sending unit. Not sure if subaru does or not. hope it helps
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Old 07-27-2010, 01:25 PM   #4
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One set of terminals on the relay will be the coil. The coil is energized from a normally-open contact on the main relay (brown relay next to fuel pump relay). The other set of terminals on the fuel pump relay is the normally-open contact that delivers power to the fuel pump controller.

My guess is your fuel pump may be on it's last leg, or have a shorted motor coil. It could also be, as you mentioned, a clogged fuel system forcing the pump to work much harder than normal.

The relay should not be getting very hot. All relays drop some voltage, but very little energy should be given off as heat.
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Old 07-27-2010, 01:30 PM   #5
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I'll try the multiple prime suggestion. None of this explains why that relay is so hot... I need someone to check theirs to see if it's hot as well.

I think I eliminated the leaky injector possibility by: With the car running, I pulled the fuel pump connector from the relay to starve the car of fuel 'till it stalled. Then i cranked it 5 more seconds. I waited 3 hours, went back out and re-connected the fuel pump relay, and tried to start.... I had the same hard start as before. I drained all the residual fuel in the lines, so if it was a leaky injector, the car would've started up fast. I hear ya though, this my first suspicion.


I have some pictures of the different colored spade connectors inside the fuel pump relay. Will post in a minute. The difference in color suggests to me that that two larger wires that connect to these leads, are putting out some heat...
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Old 07-27-2010, 01:43 PM   #6
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Quote:
Originally Posted by Hondaeat-r View Post
None of this explains why that relay is so hot...
If the fuel pump is pulling excessive current...yes...it will be hotter than normal. I listed out some possibilities for you.
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Old 07-27-2010, 01:50 PM   #7
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Quote:
Originally Posted by Haelan View Post
One set of terminals on the relay will be the coil. The coil is energized from a normally-open contact on the main relay (brown relay next to fuel pump relay). The other set of terminals on the fuel pump relay is the normally-open contact that delivers power to the fuel pump controller.

My guess is your fuel pump may be on it's last leg, or have a shorted motor coil. It could also be, as you mentioned, a clogged fuel system forcing the pump to work much harder than normal.

The relay should not be getting very hot. All relays drop some voltage, but very little energy should be given off as heat.

Thanks for that. I'll be pulling the pump tonight to look, but not sure how to actually test it....looking is useful, but limited. I have DMM, but no portable power supply.

Here is a pic of the relay. Notice the discolored connectors on the left. Those connectors correspond to the larger 2 of 4 wires on the circuit....is this indicative of overheating ? And if so, what do the larger 2 of 4 wires correspond to, as maybe I can narrow this down even more. Thanks a lot guys.





Last edited by Hondaeat-r; 07-27-2010 at 01:56 PM.
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Old 07-27-2010, 01:58 PM   #8
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A reddish tint to the copper would indicate lots of heat.
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Old 07-27-2010, 03:49 PM   #9
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Bump for a schematic... top left is the fuel pump relay, below it is the fuel pump controller.



Last edited by Hondaeat-r; 07-27-2010 at 03:55 PM.
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Old 07-27-2010, 04:50 PM   #10
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Grab your multimeter and test the terminals. The one that reads 'open' or 'infinite' will be the normally-open contact going to the fuel pump controller. The other set should be the relay coil and have some low resistance...my guess is 40 ohms to 350 ohms or very near.

That's the easiest way to figure out which is which.
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Old 07-27-2010, 05:13 PM   #11
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The "normal" colored spades are for the relay coil, the ones that are "hot" looking, 1 goes to the fuel pump controller, and the other goes to "E/G TB-03" (main relay ?).


I appreciate the help, but I'm not an electrician so, if you have the time, it'd be awesome if you could expand on your instructions....

"Test the terminal" = What ? One DMM probe on a terminal and the other probe on chassis ground ? Or testing two terminals at once?
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Old 07-27-2010, 05:20 PM   #12
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http://www.northursalia.com/modifica...Electrical.pdf

I had that wrong above. The fuel pump relay coil is pulled in by the ignition. The contact is then closed and power is delivered to the fuel pump controller.
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Old 07-27-2010, 05:43 PM   #13
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Quote:
Originally Posted by Hondaeat-r View Post
I appreciate the help, but I'm not an electrician so, if you have the time, it'd be awesome if you could expand on your instructions....

"Test the terminal" = What ? One DMM probe on a terminal and the other probe on chassis ground ? Or testing two terminals at once?
It was to help you determine which sets of terminals are which. It sounds like you have that figured out now though, but yes you would test the terminals as pairs using both of the meter's leads checking for resistance.

It's good you figured it out, but the basic problem is still there. If you're not comfortable testing the fuel pump when you remove it, you may want to put a fuel pressure tester in series with the fuel line after the fuel filter and check the pressure.

Should help you narrow it down further.
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Old 07-27-2010, 06:26 PM   #14
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I don't have a power source to test the pump, other than the car battery. Thanks again for the help.

I can hear the fuel pump prime, so maybe it's just "on it's way out" or their is some other electrical issue in-line, because I've never had the car stall on me, and it always starts. The trouble is: It takes way too many cycles of the motor to start, and that relay being so damn hot.

Geez, I hate this crap, right after I buy a car, haha.
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Old 07-27-2010, 06:35 PM   #15
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Quote:
Originally Posted by Hondaeat-r View Post
I don't have a power source to test the pump, other than the car battery. Thanks again for the help.

I can hear the fuel pump prime, so maybe it's just "on it's way out" or their is some other electrical issue in-line, because I've never had the car stall on me, and it always starts. The trouble is: It takes way too many cycles of the motor to start, and that relay being so damn hot.

Geez, I hate this crap, right after I buy a car, haha.
I use an old Linksys router AC adapter than outputs 12VDC to test these kinds of things. I imagine the pump would take no more than 1 amp for it's size.

You could prime the pump several times in a row to build up the pressure. If it starts up using that method then you're losing fuel pressure while the vehicle is sitting. The system should keep the pressure between the FPR and the fuel pump. If not--one of them is relieving the pressure and allowing fuel to flow back to the tank.
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Old 07-27-2010, 10:31 PM   #16
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Well, I disconnected the fuel pump relay to run the car out of fuel, and the car ran for like a solid 2-3 minutes w/out the pump on.....odd, right ? Then I cranked it more to get rid of any residual fuel. Changed the fuel filter (air filter too) and even though I depressurized, I got blasted in the EYE with fuel...awesome. Any way, I pulled the fuel pump and inspected the inside of all plugs / connectors, terminals and their respective housings. No damage found, so I threw some dielectric grease on 'em, and put the pump assembly back in the tank.

Somebody told me to look for burn spots on the tank cover near the plug housing mounted to it. There was no scorching seen, but some discoloration of the steel tank cover. Not sure if it's normal or not, but I'm being cautious. Here are the pics.





I'll see if the car starts better tomorrow, but after doing the fuel filter, the car started a bit better, even having to fill the new filter. Not sure if this areal improvement, or just seeming that way because I depressurized the fuel system, and if there was a leaky injector before causing the issue, then w/ the pressure relieved the problem wouldn't be present. Like I said, I'll see tomorrow morning.... I'll likely buy a relay too just for kicks. Thanks for the help.


Quick EDIT: Just saw this http://shop.advanceautoparts.com/web..._926429180___#

It seems that the color of my terminals in the fuel pump relay aren't abnormal in color, as this brand new one in the link shows the same thing... Ok, I'm still going to buy a new one, haha.

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Old 07-28-2010, 01:18 AM   #17
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Sub'd
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Old 07-28-2010, 08:41 AM   #18
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first of all, the pump draws a hell of a lot more than 1a

second, are there any other mods on the car?

third, can you get access to someone with a obd2 cable so that you can datalog some parameters.

every hard start issue i've ever dealt with has been fuel related. if the trims are out of whack then the first thing to show the issue is the cold start, because for a few moments after start there ARE NO fuel trims applied. the excessive trims are a symptom, not the problem itself. the problem may be charge air leak, faulty maf sensor, faulty front o2 sensor, failing pressure regulator, failing fuel pump, or exhaust leak, among others.
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Old 07-28-2010, 09:49 AM   #19
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first of all, the pump draws a hell of a lot more than 1a

second, are there any other mods on the car?

third, can you get access to someone with a obd2 cable so that you can datalog some parameters.

every hard start issue i've ever dealt with has been fuel related. if the trims are out of whack then the first thing to show the issue is the cold start, because for a few moments after start there ARE NO fuel trims applied. the excessive trims are a symptom, not the problem itself. the problem may be charge air leak, faulty maf sensor, faulty front o2 sensor, failing pressure regulator, failing fuel pump, or exhaust leak, among others.
Yeah I was off on the pump rating. Looks like a Walbro can pull somewhere around 17A @ 100 PSI.
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Old 07-28-2010, 09:51 AM   #20
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- No mods.....ever.

- An ODII "cable", or scanner ? Which do you mean ? There may be some local guys.

- I have no CEL's, and will check for dormant codes today, but no CEL. Front O2 is less than 8 months old, and OEM. The fuel pump sounds as it should, and primes when the key is on "start". I'll look at the FPR as soon as I find it, hahah.

- After just changing the fuel and air filter yesterday, the car started much faster this morning. We'll see how things go for the next couple of days. I may have a small exhaust leak, but nothing really serious. I need to find a cheap wideband somewhere, so I can have a better idea of whats going on.

- Also, there is no real indicator that the trims are excessive (rich), as they could very well be lean. Like I said, I need a wide band to get some feel for the AFR's. Does the nice ScanData tool show fuel trim / pressure, etc.. ?

Thanks to all who are trying to help.
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Old 07-28-2010, 09:59 AM   #21
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Quote:
Originally Posted by Hondaeat-r View Post
- No mods.....ever.

- An ODII "cable", or scanner ? Which do you mean ? There may be some local guys.hehegeheheh

- I have no CEL's, and will check for dormant codes today, but no CEL. Front O2 is less than 8 months old, and OEM. The fuel pump sounds as it should, and primes when the key is on "start". I'll look at the FPR as soon as I find it, hahah.

- After just changing the fuel and air filter yesterday, the car started much faster this morning. We'll see how things go for the next couple of days. I may have a small exhaust leak, but nothing really serious. I need to find a cheap wideband somewhere, so I can have a better idea of whats going on.

- Also, there is no real indicator that the trims are excessive (rich), as they could very well be lean. Like I said, I need a wide band to get some feel for the AFR's. Does the nice ScanData tool show fuel trim / pressure, etc.. ?

Thanks to all who are trying to help.
He's talking about a Tactrix cable. You can then log parameters from the ECU with a laptop.

FPR is located by the stock airbox...underneath the after-MAF hose. It will have two bolts connecting it to the fuel rail. It should have a small vacuum hose connected to it. Check this hose...it gets hard and brittle and falls off the nipple. It can cause fueling issues.
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Old 07-28-2010, 02:08 PM   #22
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He's talking about a Tactrix cable. You can then log parameters from the ECU with a laptop.

FPR is located by the stock airbox...underneath the after-MAF hose. It will have two bolts connecting it to the fuel rail. It should have a small vacuum hose connected to it. Check this hose...it gets hard and brittle and falls off the nipple. It can cause fueling issues.
Ok, I got ya. What software do I need to correspond with it ? Thanks a lot man.

I'll also look at the FPR tonight, see what's up.
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Old 07-28-2010, 10:10 PM   #23
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Well, I bought a new fuel pump relay, and that one got really hot quickly too. Whats next ? Fuel pump ?
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Old 07-29-2010, 12:55 AM   #24
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Well, I bought a new fuel pump relay, and that one got really hot quickly too. Whats next ? Fuel pump ?
It'd really be better if you tested the fuel pressure beforehand. I don't like to see people spending money on replacement parts they may not necessarily need.
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Old 07-29-2010, 08:03 AM   #25
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I don't like to do that either. Now I need to buy a fuel pressure gauge, and find how the hell you hook it up.

I'd really like it if somebody would look at their relay to see if there's is getting hot as well.... :0) Hint Hint, haha. I doubt others peoples are, but it's good to be able to compare to others.

EDIT: Wouldn't I want to test it after the FPR ? I should test that too.

Last edited by Hondaeat-r; 07-29-2010 at 08:13 AM.
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