fuel pump problems on classic
 

Hi all

I'm having intermittent problems with my fuel pump. I have a MY98 ver4 GF8 STi, no mods, running an ESL ecu still using the factory tune.

I have a Deatchwerks dw200(usa company) and it is 3 years old. I remember the pump not working once, appx 2 years ago, all i did was bang on the fuel tank, while my wife cranked the car and it worked. Every since then it was fine. Past few days, I noticed the pump would not prime and car would not start up. So what I did was pulled the connections and sprayed some contact cleaner I got from a local auto store. This seemed to work as it started but the car died again within 20 seconds. So I pulled the connection apart and plugged it back in. This seem to do the trick, so I let it idle for 10mins. Now this morning same thing, would not prime, I'd have to disconnect the harness and re connect it to work. Each time it would run for up to 30seconds and die. This happened 4 times and finally after the 4th time the car stayed on and I managed to drive home from the grocery store.

I'm not sure if its the fuel pump, or is it the connection as the pump is not getting enough voltage? I tested the harness with a multimeter and Im getting 11.5-12vs for 2 seconds when it primes. I also checked the relay and I'm getting the same voltage. Could it be clogged? To be quite frank this started after adding fuel cleaner and a full tank. Could this have caused a fuel pump to die?? Since the car is so old could it be the wires not supplying a constant 12 voltage all the time?

https://cimg5.ibsrv.net/gimg/www.sco...e9bbc1777f.jpg
(Pic above is an old picture, I depinned and replaced this connector because of the melted plastic. Anyone know how that happened??

I've had this fault.
If you look your block has melted on 2 pins,looks like it's been shorting out due to bad connection or bad pump.
This killed my pump,was intermittent like yours then packed in.
I managed to get hold of a new connector but did consider soldering the pins to the top block as some do,was suggested I do that but I did manage to get a 2nd hand connector.

If I am remembering correctly, there is a second connector under the seat in front of the fuel pump location which is prone to burning out. Worth checking that

thanks I will check this out, I remember checking this part when I first got the car and it was clean and nothing melted... But that was almost 4 years ago.

This would be my 2nd time replacing this connector. I have 2 more spares I found at the wrecking yard. So it's caused by bad pump, or bad connection... Is it possible to depin and repin both sides with a newer connector? I'm looking at the top of the fuel pump and it seems like I'd have to break that male part to expose the wires.

Soldering is also a last option I could do.

Any problem with the 2nd hand connector? Is there some sort of grease or lube that I could use to improve the connection?

Mine was ok after I replaced the connector and fuel pump.
Darrell at scoobyworx told me if a pump is faulty it can cause the wires to overheat which then melts the connector.
I also gave mine a good squirt of wd40 (Well the German equivalent).

That's what I'm afraid of, I dont want to change my connector if it will happen again. Is there a way to test if a pump is faulty? I'll have to call the manufacturer and see if they have diy testing tutorials and what to look for.

For the wd40, you sprayed it into the inlet?

Not sure what is needed to bench test a fuel pump tbh.
The wd40 contact cleaner I sprayed direct into the electric connectors,we have some German stuff at work which is equivalent.

Oh ok yeah I used a north american equivalent. I noticed there is grease on the female connection. I don't remember putting any kind of conductive grease when I installed the pump.....

Edit: called my friend who helped me install it, he said he put some dielectric grease in.......

are there any fuses associated with the fuel pump? I tried looking under the hood but the fuse box is in japanese.

The fuel pump relay is protected by a fuse (number 11 on a MY99 car) - but no fuse directly in line with the pump

Probably also worth mentioning that the feed from ECU to the relay, or from relay to pump, will likely be going through any immobiliser fitted to the car, which might be starting to show its age now (assuming one is fitted, and has been there the entire life of the car).

Yep - The immobiliser is a well known weakness - The one on my own car failed.....

Thank you guys!

I checked the fuse and the 11 is fine. I dont know if mine is equipped with one.... Im assuming its a black box near the ecu? Ill have to check the wires from the ecu to the relay. Is this something that was equipped from the factory? I dont have the oem key, its just a regular metal key. A friend of mine has a 00 type r, and his oem key has a keyless entry button built in. I know the new immobilisers you need a special key fob near to operate the car.

You very likely don't have an immobilizer then (or if you do, it's been completely disabled and bypassed somehow). Over here in Europe, auto manufacturers were legally obliged to fit them on all cars starting around 1995, but the same probably wasn't true your side of the pond.

Well this is a Japanese spec sti, never heard of the JDM models having it.

I measured the voltage and ohms per Subaru manual on the relay, and the harness. I'm getting proper voltage.

I may just hardwire the pump directly to the relay and see if I still have issues. I just need to source the the proper OEM female pins and maybe up the size of the wire to a 16awg.

hey guys

Does anyone know what this 2 pin wire powers? Its splices from the rear harness under the rear seat.

https://cimg4.ibsrv.net/gimg/www.sco...5bea4aad1d.jpg

Also does the UK classic come with this resistor for the pump? I noticed the ground wire looks beat up, the plastic insulator is melted, and the wires near the ring terminal are black. Could this have caused my OEM pump to fail?

https://cimg4.ibsrv.net/gimg/www.sco...c5e73cc20a.jpg
https://cimg8.ibsrv.net/gimg/www.sco...a237cedeec.jpg

Whatever that wiring assembly is with the resistor, it's obviously not factory, and I know from fitting an upgraded pump to my UK classic that there was nothing like that there.

Best guess, it's the remnants of remote fuel cut-off switch that someone added to the car earlier in its life as basic form of security device, or something along those lines.

The two-pin thing - isn't that just feed to/from the fuel gauge sender?

Thanks for all the help guys. I just used new 16awg wiring from the harness under the rear seat to the fuel pump connector. So far it's been running like a dream.