Replacing the fuel filter

[Bitsyncmaster]

The rain finally stopped so I took the car on a test drive with OE ignition ECU. It ran good. Next I plugged in my spare GM ECU. It ran good. Last I removed the two ground wires attached to the metal mounting plate and plugged in the mounted GM ECU and it also ran good.

The OEM harness runs two ground wires into the ignition ECU. They are crimped to one pin in the ignition connector. One of those ground wires goes to a ring terminal and is normally screwed down on the idle ECU mounting screw. Both the OEM and my GM ignition ECUs do run ground to the ignition ECU mounting plate. So it's not good for electrical noise to have two ground connections like that. Ring terminal ground on the lambda ECU also makes a third ground to the metal plate. The lambda ECU has no connection to the metal box it mounts in.

So I remember some owners having problems using the GM ignition modules and I bet those needless grounds were causing problems. You can test just by removing those two black wire ring terminals from the metal plate (let them float).

So my metal mounting plate is grounded at one point by the mounted ignition ECU. The OEM harness runs a ground wire to one connector pin and the pickup ground (shielded wire) goes to another pin but the ECU connects those two signals.

[kings1527]

Funny you mentioned this job. I'm just getting ready to tackle mine for the third or fourth time since becoming an owner and I dread it every time for the reason you mentioned. My latest plan is this: take a flex head 17mm flare nut wrench so I can reach and leverage the top banjo on the filter and not have to mess with the lower portion of the filter at all, aside from spinning a new one on there.

Removal: remove top banjo. Remove bracket. Unscrew filter from elbow. Install in reverse. Of course, making sure to use secondary wrenches when needed to keep torque isolated and not twist anything that doesn't need to be twisted. Looking to do this sooner than later so I'll report back.

https://www.amazon.com/dp/B0014ZYZEC...lig_dp_it&th=1

[Rich]

Also, there?s the DMCH recommended method for fuel filter replacement.

[kings1527]

Also, there?s the DMCH recommended method for fuel filter replacement.

That method works great when the compression fitting actually separates.

[FLUX @88]

How often should the fuel filter be replaced on these cars? I replaced mine almost 2 years ago and roughly put 8k miles on.

[WHO1DMC]

How often should the fuel filter be replaced on these cars? I replaced mine almost 2 years ago and roughly put 8k miles on.

According to dmch 2 years or 15000 miles.
I have about 9 years 11000 miles on mine. But I'm going to put it on my fall to do list.



Dave B.

[Bitsyncmaster]

The rain finally stopped so I took the car on a test drive with OE ignition ECU. It ran good. Next I plugged in my spare GM ECU. It ran good. Last I removed the two ground wires attached to the metal mounting plate and plugged in the mounted GM ECU and it also ran good.

The OEM harness runs two ground wires into the ignition ECU. They are crimped to one pin in the ignition connector. One of those ground wires goes to a ring terminal and is normally screwed down on the idle ECU mounting screw. Both the OEM and my GM ignition ECUs do run ground to the ignition ECU mounting plate. So it's not good for electrical noise to have two ground connections like that. Ring terminal ground on the lambda ECU also makes a third ground to the metal plate. The lambda ECU has no connection to the metal box it mounts in.

So I remember some owners having problems using the GM ignition modules and I bet those needless grounds were causing problems. You can test just by removing those two black wire ring terminals from the metal plate (let them float).

So my metal mounting plate is grounded at one point by the mounted ignition ECU. The OEM harness runs a ground wire to one connector pin and the pickup ground (shielded wire) goes to another pin but the ECU connects those two signals.

Well I knew it to good to be true. The D is back to very bad running on the road. I guess that ground wire change was just due to my problem intermittent and it ran good doing some tests. Car is now staying in the garage till I get EFI.

[FLUX @88]

According to dmch 2 years or 15000 miles.
I have about 9 years 11000 miles on mine. But I'm going to put it on my fall to do list.



Dave B.

thanks for reply

[David T]

Mileage has nothing to do with filter changes for most of us anymore. Originally all of the maintenance schedule was based on using the car regularly and putting roughly 10,000 miles per year on the odometer. If you figure 20 MPG that comes out to about 500 gallons of fuel. A lot of things have changed about fuel. It is a much more filtered product because almost all cars are now fuel injected and therefore much less tolerant of dirt. Also because of the alcohol content more contaminants will dissolve and not get caught by a filter. Time doesn't matter all that much to a filter, a filter only catches what dirt goes through it so if less fuel goes through it, it will stay cleaner longer. There is a filter in the fuel tank too but it catches the larger size particles to protect the pump. The biggest problem is phase separation of the fuel. That happens if you don't use the car and the fuel gets stale. That can happen in as little as 6 months. If you don't use the car the fuel should be drained out of it. If the car sits for an extended period of time with fuel (especially if it has Ethanol in it!) the fuel system should be drained and flushed and all of the filters replaced. As for a time interval to change the filter figure 1,000 miles a year for 10 years and you hit the 500 gallon mark. Using that metric change the filter every 10 years or 10,000 miles. Obviously you can extend that interval, changing that filter is a PITA.

[ssdelorean]

Mileage has nothing to do with filter changes for most of us anymore. Originally all of the maintenance schedule was based on using the car regularly and putting roughly 10,000 miles per year on the odometer. If you figure 20 MPG that comes out to about 500 gallons of fuel. A lot of things have changed about fuel. It is a much more filtered product because almost all cars are now fuel injected and therefore much less tolerant of dirt. Also because of the alcohol content more contaminants will dissolve and not get caught by a filter. Time doesn't matter all that much to a filter, a filter only catches what dirt goes through it so if less fuel goes through it, it will stay cleaner longer. There is a filter in the fuel tank too but it catches the larger size particles to protect the pump. The biggest problem is phase separation of the fuel. That happens if you don't use the car and the fuel gets stale. That can happen in as little as 6 months. If you don't use the car the fuel should be drained out of it. If the car sits for an extended period of time with fuel (especially if it has Ethanol in it!) the fuel system should be drained and flushed and all of the filters replaced. As for a time interval to change the filter figure 1,000 miles a year for 10 years and you hit the 500 gallon mark. Using that metric change the filter every 10 years or 10,000 miles. Obviously you can extend that interval, changing that filter is a PITA.

I'd have to check my records but I haven't changed my fuel filter in at least 10years. Well over due. But I put on between 9k - 13k miles a year. I still get 23-29mpg depending upon how I drive. So I guess it really would depend upon "if" any - and "what kind" of contaminants have gotten into your fuel lines to cause your filter to clog up. Yes, I'm over due. Yes it should be changed. But I would not be too concerned about it. If my car lasted this long, you going over a little bit should not matter much (unless your system was opened at some time changing lines or parts - or received contaminated fuel).

I also need to update my signature as I am up over 250k miles now.