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Fuel pump issues... I hope


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16 replies to this topic

#1 rainman19154

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Posted 27 June 2010 - 09:38 AM

1995 Legacy AWD wagon, automatic trans

First symptom was a morning start up... cranked, started and died. Turned the key and it fired right back up.
Two days later, full tank of gas, sitting in 90+ degree weather after driving for 30 minutes... starts and dies, won't restart. I thought vaguely of vapor lock but had no time to dwell on it. I took the other car and went to my appointment.
Later that day; still won't start.

In the cool of the next morning, it started right up.
Drove it casually for the next day or two.

Yesterday, drove some in the morning and it was fine. Did a quick errand in the heat of the afternoon (90 degrees plus again) and it won't start when I am ready to head home.
Waited over two hours for wrecker. I did disconnect fuel line at filter and determined I'm not getting fuel.
Loosened fuel cap, no change --- not vapor lock (though I didn't really think that was the problem).

When the wrecker arrives, it does start and run to pull out of parking space but then dies and won't restart. Later at home, starts, runs for a few seconds and dies.
This morning, as a test, it starts and seems fine.

I've been to a U Pull it and scored a complete "in the tank" assembly for $5.
I meant to snag the relay also but was so sun baked from wandering thru two yards, I forgot all about it.

Because it's reacting to heat and use, I'm thinking component malfunction. What I can see of the harness and connectors all look good. Nothing burned or loose.

I come back here and post whatever results I get. Any remarks are welcome.

Thx in advance

#2 Legacy777

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Posted 27 June 2010 - 03:26 PM

Sounds like a fuel pump. If the wiring looks ok, I'd probably start there.

#3 nipper

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Posted 27 June 2010 - 09:52 PM

Why does everyone blame the poor innocint fuel pump. Next time it happens remove the gas cap and see if the car starts. If not you need to put a fuel pressure gauge on the system.

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#4 Fairtax4me

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Posted 28 June 2010 - 01:41 AM

Did you try tapping the bottom of the tank with a mallot when it wouldn't start?

Get it warmed up, get it to quit and not start, then check the fuel pump harness for 12v before replacing the pump.



What change will removing the filler cap make? :confused: This isn't an old Ford truck with a mechanical pump. These electric pumps produce ~50psi, I think the tank would implode at 50in Hg. :eek:

#5 rainman19154

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Posted 28 June 2010 - 10:54 AM

I didn't give vapor lock a serious consideration but I know it's in the discussion with older vehicles.
I did loosen the cap but it didn't change anything.

I've put in the jy replacement. It does start and run. I'm gonna wait til the heat of the day and let it run a good while then shut it off. After a few minutes sitting in the heat, I'll then see if it restarts.

Why blame the "poor little fuel pump"?

Because reading here on the forum it pops up often enough to be a suspect.

Because replacing the fuel pump is much much easier than replaciing an ecu... not a common problem but it's in the discussion... let's start with the easier stuff.

Because the car has over 200K.... any mechanical component is well due for suspicion.

Because (as stated earlier) the wiring isn't showing wear, signs of heat at the connectors or any sort of loose fit.

Because it's presenting the symptoms under a defined set of circumstances... loose connections or worn contacts would be more erratic in their symptoms.

Are the ecu or relay off the hook? No... at this point I've taken a calculated shot at it and 'spun the wheel'. Only time will tell if this simple fix has taken care of the problem.

#6 Rooster2

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Posted 28 June 2010 - 11:17 AM

Isn't there a warm or hot start sensor that feeds an imput into the ECU? If so, I would suspect that. A fuel pump that performs fine when cold should still be good.

#7 Olnick

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Posted 28 June 2010 - 11:42 AM

Maybe a long shot, but could it be the coolant temperature sensor? Bad temp info to the ECU can cause poor running/stalling issues.

#8 rainman19154

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Posted 28 June 2010 - 11:48 AM

Isn't there a warm or hot start sensor that feeds an imput into the ECU? If so, I would suspect that. A fuel pump that performs fine when cold should still be good.


I'll plead guilty to shooting for the easy fix but again I'll reference the age of the car and the fact the forums here indicate an ongoing failure rate for these pumps.

Replacing an engine sensor isn't necessarily tough but isolating it as the problem can be dicey.

I'm here to share and learn. If there is something else I should be aware of for a fuel pump not running, I'll heed it.

Searching the forums here have indicated the pump is the most common fix but the relay and ecu are also suspect. Some had harness repairs that fixed them up but they indicated burned or loose connections and I've found none of that.

#9 rainman19154

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Posted 28 June 2010 - 12:01 PM

Maybe a long shot, but could it be the coolant temperature sensor? Bad temp info to the ECU can cause poor running/stalling issues.


At no point does it stall in mid trip. I drive somewhere, shut it off, then find it won't restart when I'm ready to leave.
While waiting for the tow on Saturday, after two hours it did start and then die after just a few seconds but wouldn't restart. It wasn't until it had completely cooled down the next morning that things seemed back to normal.

I'll assess where I am with the jy unit I've installed and take it from there.
I don't want to be 'right. I want it fixed... I'll keep ya'll posted.

#10 nipper

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Posted 28 June 2010 - 12:26 PM

Maybe a long shot, but could it be the coolant temperature sensor? Bad temp info to the ECU can cause poor running/stalling issues.


This was actually my first thought.

All those fuel pump problems were not all fuel pumps.

Vapor lock doesn't exist on fuel injected cars as the fuel is constantly circulating keeping it relativly cool.

There is also the fuel pressure regulator as a possibility


nipper

#11 Olnick

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Posted 28 June 2010 - 01:02 PM

Just trying to think this through with you:

At no point does it stall in mid trip.


That's a good sign. It indicates, as Rooster noted, that the fuel pump is working.

It wasn't until it had completely cooled down the next morning that things seemed back to normal.


That would indicate a temperature related problem somewhere in the system (not just in the fuel pump.) The ECTS--coolant temperature sensor--provides temperature information to the ECU.

ECTSs are known to fail, probably more often than fuel pumps. I drive a '95 Legacy and had to replace mine a while back--was having warm restart issues.

Just some random thoughts to consider!

I do hope the jy pump solves your problem. Good luck and keep us posted.

#12 rainman19154

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Posted 28 June 2010 - 02:01 PM

Just trying to think this through with you:


That would indicate a temperature related problem somewhere in the system (not just in the fuel pump.) The ECTS--coolant temperature sensor--provides temperature information to the ECU.

ECTSs are known to fail, probably more often than fuel pumps. I drive a '95 Legacy and had to replace mine a while back--was having warm restart issues.

Just some random thoughts to consider!

I do hope the jy pump solves your problem. Good luck and keep us posted.


Hey.... good to know. Type "fuel pump" into the search, even limit it to the New Gen forum, and there are lots of hits. Hard to read them all... and ECTS problems would be easily overlooked by that kind of search.
If I get stung by this again, that will be a good one to check. I'll look in my manual now and see what I can find for testing it.

#13 johnceggleston

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Posted 28 June 2010 - 02:06 PM

some one had a thread a feew years ago, his wifes subaru, lego?, would not start when hot. he showed her where to dump a cup of water so it would hit the ects. that way when she got stranded she could get herself home until he found time to fix it. worked like a charm.

the coolant temp sensor is on the water crossover pipe under the intake on the passenger side, accessible from the rear i think.

#14 rainman19154

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Posted 28 June 2010 - 02:51 PM

Thx John! I found the location and removal info in the manual but haven't found test data. I'll do the water trick if I get stuck... it'll serve two purposes: 1) Proof of theory and 2) get me home.

USMB is the bomb! Thx guys!

#15 Legacy777

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Posted 29 June 2010 - 11:46 AM

Just a note regarding the coolant temp sensor. They may test ok with a multimeter but still may not be good.

The sensors are around $20 at the various only subaru dealerships, so most of the time it's usually a good idea to just replace it if there's any doubt it may be bad.

#16 rainman19154

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Posted 27 July 2010 - 03:24 PM

A late followup.
It's been nearly a month since I dropped in that JY Fuel Pump assembly and I've had no more problem.
Thanks for the feedback.

#17 Olnick

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Posted 27 July 2010 - 03:39 PM

That's great news--thanks for the update.




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