FASS pump and ECM

[farrier]

I have a 1999 ram 2500 and had a FASS pump installed about 7 years ago. I`ve been going through all the threads here trying to figure out if this aftermarket FASS pump is the cause of my ECM failures. I have had starting issues after the pump had been on a few years, codes for CPS especially each time. Finally 4 years ago my ECM is bad. Get a remanufactured one now same issues 3 1/2 years later. Sent ECM off for a rebuild and told it can not be rebuilt because the microprosser is bad. Now having to purchase another and hopegully have found a reputable company. Same codes were thrown before finding ECM is bad. Previous to this ECM going bad I had called FASS and was told to hot wire the FASS into my fuse panel which I did. Started working again. So question is this: Is my ECM going bad because there is some kind of miscommunication in my electrical system because my old lift pump no longer exists? Wires are still dangling and the 2 times we did a cleaning of my engine the water in fuel light came on. I have taken some pictures of the wiring diagrams some of you have posted. I`m worried about installing this rebuilt ECM if something is causing it to go bad with the wiring. I have a great electrical guy working on this but not having to reinvent the wheel here would be awesome!

 

[petersonj]

Really need to have more information regarding exactly how your FASS lift pump is wired.

The OEM lift pump gets its power directly from the ECM. In my opinion this is a poor design as the pump draws a lot of current (about 8 amps or so) through the ECM. The best way to operate the lift pump is with a relay. The ECM will only power the coil portion of the relay (about 150 milliamps) - a much better situation.

When my original VP44 was replaced under warranty (over 280,000 miles ago), the warranty covered re-locating the lift pump. A relayed in-tank lift pump was installed. At 370,000 miles I am still on the original ECM.

- John

 

[farrier]

Thanks for responding John. I had it installed by a diesel mechanic about 7 years ago and I`m not sure how he wired it in but when I called FASS the first time this happened they asked if it was a Dodge. They said I needed to wire directly into the fuse box so as soon as I turn the key on the pump would come on. They said the ECM didn`t recognize the pump. He sent me a diagram on how to rewire it and it involved a cube relay already on the truck on the firewall driver side. I did this myself because I could not find anyone who would know what to do here. So here we are 3 1/2 years later and my ECM is bad again and had been throwing similar codes. The FASS has worked well in terms of keeping my VP44 from being destroyed from all the past lame lift pumps that were put on it. Went from original to the one in the tank and then that one failed so thus the FASS pump. I bought this truck new in 1999 so I know what`s been going on with it since then.

 

[petersonj]

A couple of things.

It sounds like your lift pump is wired to a switched power source. If this is so, there is a risk of a fire should your vehicle be involved in an accident that stopped the engine and caused a fuel leak downstream of the lift pump. With the ignition switch still in the on position, the lift pump would continue pumping fuel. A solution to avoid this risk could be to use an oil pressure switch to control the relay portion of the coil.

Have you heard of the W-T ground wiring modification? It is essentially modifying and improving the ground circuit of the ECM and PCM as well as relocating the alternator charge wire to connect to the passenger side battery. The factory ground wire for the ECM joins a splice with other wires and wanders a bit before reaching a ground connection. This wiring mod can be found on the Mopar1973Man site.

- John

 

[BigPapa]

Went from original to the one in the tank and then that one failed…

I’d like to hear more about the in-tank pump failing.

Ive heard a lot of things, but never heard of a lift pump taking out an ECM. What FASS pump do you have?

 

[SAndreasen]

Thanks for responding John. I had it installed by a diesel mechanic about 7 years ago and I`m not sure how he wired it in but when I called FASS the first time this happened they asked if it was a Dodge. They said I needed to wire directly into the fuse box so as soon as I turn the key on the pump would come on. They said the ECM didn`t recognize the pump. He sent me a diagram on how to rewire it and it involved a cube relay already on the truck on the firewall driver side. I did this myself because I could not find anyone who would know what to do here. So here we are 3 1/2 years later and my ECM is bad again and had been throwing similar codes. The FASS has worked well in terms of keeping my VP44 from being destroyed from all the past lame lift pumps that were put on it. Went from original to the one in the tank and then that one failed so thus the FASS pump. I bought this truck new in 1999 so I know what`s been going on with it since then.

interesting . my 98 has an in tank pump feeding a fass pump in the stock pump location. the in tank pump died several years ago but the fuel pressure stays ok so i’ve never bothered replacing the in tank pump

 

[farrier]

I

I’d like to hear more about the in-tank pump failing.

Ive heard a lot of things, but never heard of a lift pump taking out an ECM. What FASS pump do you have?

 

[farrier]

I think it`s the titanium one

 

[farrier]

interesting . my 98 has an in tank pump feeding a fass pump in the stock pump location. the in tank pump died several years ago but the fuel pressure stays ok so i’ve never bothered replacing the in tank pump

I actually saw that someone had both a FASS and the stock one. I`ve even thought about installing one back into the line to fool the ECM into thinking it`s still there and if it goes out again the FASS will still be working. I also installed a fuel pressure gauge so I know if it fails.

 

[farrier]

I’d like to hear more about the in-tank pump failing.

Ive heard a lot of things, but never heard of a lift pump taking out an ECM. What FASS pump do you have?

I

Titanium series

 

[SAndreasen]

I actually saw that someone had both a FASS and the stock one. I`ve even thought about installing one back into the line to fool the ECM into thinking it`s still there and if it goes out again the FASS will still be working. I also installed a fuel pressure gauge so I know if it fails.

I actually think that system worked pretty good my fuel gauge has never worked quite properly I’ll run out of fuel at 1/8 th of tank looking ate the Genos Catalog there a couple different ones

 

[farrier]

A couple of things.

It sounds like your lift pump is wired to a switched power source. If this is so, there is a risk of a fire should your vehicle be involved in an accident that stopped the engine and caused a fuel leak downstream of the lift pump. With the ignition switch still in the on position, the lift pump would continue pumping fuel. A solution to avoid this risk could be to use an oil pressure switch to control the relay portion of the coil.

Have you heard of the W-T ground wiring modification? It is essentially modifying and improving the ground circuit of the ECM and PCM as well as relocating the alternator charge wire to connect to the passenger side battery. The factory ground wire for the ECM joins a splice with other wires and wanders a bit before reaching a ground connection. This wiring mod can be found on the Mopar1973Man site.

- John

Hi John. I hope snowmaggedon is going to give us a break here now! Hunter has not been able to get out here to look at my truck for a while now. Plan has been to get the ECM pins checked and he needs this special tool to remove them. I`m hoping you might have an idea on where to get one. Part # 6934 terminal removing tool. I looked at Geno`s garage and didn`t find one so thought I`d check with you to see if you had an idea on where to look. Got the part # from my bible of my truck. Manufacturers manuals. Thanks! Denise

 

[petersonj]

I just searched the internet using the part number that you provided. Is this what you are looking for?

- John

 

[Topzide]

I've always used a micro flat tip screwdriver to remove terminals from the connectors. Just need to push tang back to release from housing. The other thing is to use small wire to insert into female connector to test pin out or wire check. I'm all in for having a tool to help in repairs but make do with what I have.

 

[farrier]

I just searched the internet using the part number that you provided. Is this what you are looking for?

- John

View attachment 136661

Yes exactly! I did the same thing and found some and ordered them. Same price and of course shipping is almost the price of the tools! He was out today to take some pictures and the old ECM the check the sizes. He`s out of town next week so will have the truck towed to his place then and we will see how things progress. I`m glad he`s meticulous! Thanks again for the help. Baby steps here hah!

 

[farrier]

I've always used a micro flat tip screwdriver to remove terminals from the connectors. Just need to push tang back to release from housing. The other thing is to use small wire to insert into female connector to test pin out or wire check. I'm all in for having a tool to help in repairs but make do with what I have.

Thanks! All tips and suggestions accepted!