In-tank Fuel Pump Modification

[harrypalmer]

It would be most helpful if glowell222 could actually name the brand and or reference of said submersible hose for anyone's interest.

BTW and FWIW, had previously commented having some sort of hiccups with my own pump mod, but I was wrong as it is only susceptible when the fuel gets too warm (very particular to my car). Will be installing a fuel cooler next week and report.

[Shawn D.]

It would be most helpful if glowell222 could actually name the brand and or reference of said submersible hose for anyone's interest.

It's not hard to find, just search the interwebs for "submersible fuel hose." I recently got some from Summit Racing.

[glowell222]

It would be most helpful if glowell222 could actually name the brand and or reference of said submersible hose for anyone's interest.

It's not hard to find, just search the interwebs for "submersible fuel hose." I recently got some from Summit Racing.

This is exactly what I did (Summit Racing), and I had to buy several different diameters to work out which one was best. Of course, I don't recall which one I ended up using, so double-useless on my part-apologies for that.

[harrypalmer]

BTW and FWIW, had previously commented having some sort of hiccups with my own pump mod, but I was wrong as it is only susceptible when the fuel gets too warm (very particular to my car). Will be installing a fuel cooler next week and report.

A year later, have installed a E28 specific fuel cooler. It does greatly improve the engine's drive ability in traffic. However, the fuel starvation is present when pulling hard (4,500 to 6,500 rpm via a D'sylva chip) which is the way I mostly drive. Anyway, I am going to take the intank fuel pump out and get a dedicated submersible fuel hose like Davintosh suggested earlier. And report back again.

Does anyone out there, have experienced fuel starvation with this fuel mod?

[1st 5er]

BTW and FWIW, had previously commented having some sort of hiccups with my own pump mod, but I was wrong as it is only susceptible when the fuel gets too warm (very particular to my car). Will be installing a fuel cooler next week and report.

A year later, have installed a E28 specific fuel cooler. It does greatly improve the engine's drive ability in traffic. However, the fuel starvation is present when pulling hard (4,500 to 6,500 rpm via a D'sylva chip) which is the way I mostly drive. Anyway, I am going to take the intank fuel pump out and get a dedicated submersible fuel hose like Davintosh suggested earlier. And report back again.

Does anyone out there, have experienced fuel starvation with this fuel mod?

My only delivery issue has been when tank is extremely low on fuel, ~ 1/8 tank, and under hard cornering.
Submersible high pressure hose is a must.
Somebody out there knows the rating numbers,
or they may be listed earlier in this thread.

[gwb72tii]

Ask Charlie what he did with Vlad

[harrypalmer]

My only delivery issue has been when tank is extremely low on fuel, ~ 1/8 tank, and under hard cornering.
Submersible high pressure hose is a must.
Somebody out there knows the rating numbers,
or they may be listed earlier in this thread.

When you say 1/8 tank, how much fuel would you say is that in gallons?
In my case I feel fuel starvation occurs when there are roughly 4 gallons left in the tank (if I don't accelerate hard I won't notice it at all) but as mentioned earlier I usually drive hard, which makes the fuel range obsolete, or about 150 miles.

BTW my fuel pressure last time I measured (two different fuel regulators) read fine. Should I try larger fuel injectors at this point?
Any suggestions welcomed.

[harrypalmer]

Ask Charlie what he did with Vlad

I will. Thank you.

[tig]

Ask Charlie what he did with Vlad

I will. Thank you.

Like I remember. I'm regularly doing mye28.com searches on topics, finding threads with great writeups on how to do things, and then discovering that I'm reading something *I* wrote. ADHD FTW!

[1st 5er]

My only delivery issue has been when tank is extremely low on fuel, ~ 1/8 tank, and under hard cornering.
Submersible high pressure hose is a must.
Somebody out there knows the rating numbers,
or they may be listed earlier in this thread.

When you say 1/8 tank, how much fuel would you say is that in gallons?
In my case I feel fuel starvation occurs when there are roughly 4 gallons left in the tank (if I don't accelerate hard I won't notice it at all) but as mentioned earlier I usually drive hard, which makes the fuel range obsolete, or about 150 miles.

BTW my fuel pressure last time I measured (two different fuel regulators) read fine. Should I try larger fuel injectors at this point?
Any suggestions welcomed.

~ 2 gallons.
Typically would be just about the time the light would come one. It had only happened on a hand full of occasions, as I don't normally let the tank get that low. It's usually refilled around 1/4 tank or better.

I have no fuel pressure or injector recommendations.

[harrypalmer]

Ask Charlie what he did with Vlad

I will. Thank you.

Like I remember. I'm regularly doing mye28.com searches on topics, finding threads with great writeups on how to do things, and then discovering that I'm reading something *I* wrote. ADHD FTW!

LOL. Spot on!

[harrypalmer]

My only delivery issue has been when tank is extremely low on fuel, ~ 1/8 tank, and under hard cornering.
Submersible high pressure hose is a must.
Somebody out there knows the rating numbers,
or they may be listed earlier in this thread.

When you say 1/8 tank, how much fuel would you say is that in gallons?
In my case I feel fuel starvation occurs when there are roughly 4 gallons left in the tank (if I don't accelerate hard I won't notice it at all) but as mentioned earlier I usually drive hard, which makes the fuel range obsolete, or about 150 miles.

BTW my fuel pressure last time I measured (two different fuel regulators) read fine. Should I try larger fuel injectors at this point?
Any suggestions welcomed.

~ 2 gallons.
Typically would be just about the time the light would come one. It had only happened on a hand full of occasions, as I don't normally let the tank get that low. It's usually refilled around 1/4 tank or better.

I have no fuel pressure or injector recommendations.

5er, Thank you for your answers. I'll keep re-reading this whole thread and make adjustments. Maybe my Tre 255 is defective? Willing to replace it or get the Walbro. I'll keep you all informed.

[1st 5er]

My only delivery issue has been when tank is extremely low on fuel, ~ 1/8 tank, and under hard cornering.
Submersible high pressure hose is a must.
Somebody out there knows the rating numbers,
or they may be listed earlier in this thread.

When you say 1/8 tank, how much fuel would you say is that in gallons?
In my case I feel fuel starvation occurs when there are roughly 4 gallons left in the tank (if I don't accelerate hard I won't notice it at all) but as mentioned earlier I usually drive hard, which makes the fuel range obsolete, or about 150 miles.

BTW my fuel pressure last time I measured (two different fuel regulators) read fine. Should I try larger fuel injectors at this point?
Any suggestions welcomed.

~ 2 gallons.
Typically would be just about the time the light would come one. It had only happened on a hand full of occasions, as I don't normally let the tank get that low. It's usually refilled around 1/4 tank or better.

I have no fuel pressure or injector recommendations.

5er, Thank you for your answers. I'll keep re-reading this whole thread and make adjustments. Maybe my Tre 255 is defective? Willing to replace it or get the Walbro. I'll keep you all informed.

Been running Tre since the beginning of this thread w/o one failure.

[harrypalmer]

Been running Tre since the beginning of this thread w/o one failure.

1st 5er, I think you are right. The TRE should not to be blamed. I'm thinking perhaps one of the fuel lines is being squeezed or jammed a bit between the tank and the car's body? In any case, going to disassemble and report back. Thank you!

[BDKawey]

Spoke with someone from tre performce. they confirmed I am safe to simply install the tre in the tank and leave the in line pump in place and will be perfectly safe.

currently experiencing 1/4 hesitation and I want to retain the safety of having the in line pump with another pump supporting it. I have a barb reducer on the way as well to throw in the glove box if theres ever a problem with the in line pump. doing this because a) lazy. b) reliability of 2 pumps.

just wanted to pass along that information. flame me if you'd like since its not what most people have been doing.

[1st 5er]

I wasn't aware the inline pump would allow that much free flow.

But, hey, it if works...

Looking toward to hearing your actual results.
I carry a spare hanger with Tre pump attached, extra hose, etc., in any car I drive that hasn't been swapped. If your work around works it'll save crawling under the car on the side of the highway when it's 110° outside.

[Ju@n]

Spoke with someone from tre performce. they confirmed I am safe to simply install the tre in the tank and leave the in line pump in place and will be perfectly safe.

currently experiencing 1/4 hesitation and I want to retain the safety of having the in line pump with another pump supporting it. I have a barb reducer on the way as well to throw in the glove box if theres ever a problem with the in line pump. doing this because a) lazy. b) reliability of 2 pumps.

just wanted to pass along that information. flame me if you'd like since its not what most people have been doing.

I haven't removed it, but it was working last time I checked, so not sure it's the same scenario as yours

[BDKawey]

Spoke with someone from tre performce. they confirmed I am safe to simply install the tre in the tank and leave the in line pump in place and will be perfectly safe.

currently experiencing 1/4 hesitation and I want to retain the safety of having the in line pump with another pump supporting it. I have a barb reducer on the way as well to throw in the glove box if theres ever a problem with the in line pump. doing this because a) lazy. b) reliability of 2 pumps.

just wanted to pass along that information. flame me if you'd like since its not what most people have been doing.

I haven't removed it, but it was working last time I checked, so not sure it's the same scenario as yours

mine is functioning. if it werent i would certainly remove it because it very well may restrict flow if it did crap out. suppose thats the only argument to removing it.

years ago on this thread I asked about leaving it in place and was advised to remove it because the tre/walbro may not like to pump through it. so just wanted to circle back and say its perfectly safe per the manufacturer

[Ju@n]

Ah! then we are on the same boat

[BDKawey]

Dang I ordered it monday at lunch and it came today, costa mesa to columbus in 2.5 days. The first and only email i got said that it was pending review from sales staff.

[1st 5er]

Ah! then we are on the same boat

Based on your signature, we drive the same car.

[Ju@n]

Ah! then we are on the same boat

Based on your signature, we drive the same car.

car/boat/aircraft carrier

[onesidedsquare]

Just did this mod with the Tru pump,
AND IT IS GREAT, totally worth it, some troubleshooting notes

Don't use the worm clamps, nearly each one leaked, get the right fuel clamps the first time
Don't test the pump out side the tank, as its not grounded and will burn thru a few fuses while you figure it out
I used a smaller hose to go inside the bigger hose at the pump and the filter and it works just fine
Don't connect the inline fuel pump wires (am idiot) as it will burn thru a few fuses while you figure it out, just tape them off

[1st 5er]

Just did this mod with the Tru pump,
AND IT IS GREAT, totally worth it, some troubleshooting notes

... will burn thru a few fuses while you figure it out.
... will burn thru a few fuses while you figure it out,

I like your attitude.

[EE TWO EIGHT]

Is the stepped hose that goes between the pump and in tank assembly still available new? Part number if available or a link to where I can order one?

[1st 5er]

Is the stepped hose that goes between the pump and in tank assembly still available new? Part number if available or a link to where I can order one?

Not sure, but all the OE stepped pieces I've seen are rubber and not designed for high pressure application.

[harrypalmer]

BTW and FWIW, had previously commented having some sort of hiccups with my own pump mod, but I was wrong as it is only susceptible when the fuel gets too warm (very particular to my car). Will be installing a fuel cooler next week and report.

A year later, have installed a E28 specific fuel cooler. It does greatly improve the engine's drive ability in traffic. However, the fuel starvation is present when pulling hard (4,500 to 6,500 rpm via a D'sylva chip) which is the way I mostly drive. Anyway, I am going to take the intank fuel pump out and get a dedicated submersible fuel hose like Davintosh suggested earlier. And report back again.

Does anyone out there, have experienced fuel starvation with this fuel mod?

As a follow up I am glad to report that I've found my in-tank TRE-340 pump mod came totally loose from the pump hanger so obviously that was the fuel starvation cause and symptom.

However, since I was prepared to war, not knowing what to expect; I re-tightened it to the hanger, and then proceed to (unmod) my mod and reinstalled a fresh 8X13 hose to a main Quantum High-Flow Pump 603 (underneath). Ended up not using a submersible hose previously purchased as I kept the halved rubber reducer from the original Bosch pump instead for the in-tank pump.

So, contrary to advice I truly respect and mostly do follow, it seems the two high-flow pump setup is getting along fine, even in the heat of mid September. Car has been running fantastic ever since with no fuel starvation or hesitation. I'll report back further more if the need arises.

[davintosh]

Is the stepped hose that goes between the pump and in tank assembly still available new? Part number if available or a link to where I can order one?

Just eliminate the need for it by using the small pipe on the tank assembly for the pump output. I've done that on two cars now, and it works fine. Very easy modification, and allows you to use the connector hose that comes with the pump.

This is the one I did several years ago for my 528e:



And this is the one I did last year for my M535i:

[ericboston]

Hi gang - thanks to you all, including you, cek and davintosh, for all your insights and banter around this subject. I just finally finished my conversion using all the excellent documentation and hard knocks. So - sorry to bump this up, but I wanted to provide my thanks. And maybe just a little insight for those of you who, like me, might lack some of the smarts these other people have:

1. the main power wires to the pumps and what to do with them. Every post says to just seal them up and put them away. Welp, my 1985 535i has what looks like two power lines and a ground wire going to the main pump. After straight up cutting off the eyelets, and sealing them off (and attempting to sell the old pump as cek said) and then the new groovy pump didn't work...well, this led to a lot of head scratching and confused looks...and then a lot of diagnosis. I finally figured out that the two power lines at the main pump actually have to be connected. Although the pumps are wired in parallel, the main line from the fuse box hits the main pump AND splits to the aux pump. So when you do "tie them off", make sure to solder the apparently two power wires (green/purple in my case) together and seal them up. and cap off that ground like everyone says as well. Don't connect that to anything.

2. the tricky hose-in-hose line reducer for me, at the fuel filter, didn't work. Leaked like crazy. So I'm doing the barbed reducer from the big line to the small line into the fuel filter to fix that weak point.

There you have it, FWIW. Again - thanks to you all for this great discussion. It's been an awesome resource I have read through over and over again just to make sure I got it right. Seems to be working great now! I'm a recent graduate to the E28, but not new to BMW, and I'm really excited to jump in and do some of these restomods to make it a great machine again.

[Galahad]

1. the main power wires to the pumps and what to do with them. Every post says to just seal them up and put them away. Welp, my 1985 535i has what looks like two power lines and a ground wire going to the main pump. After straight up cutting off the eyelets, and sealing them off (and attempting to sell the old pump as cek said) and then the new groovy pump didn't work...well, this led to a lot of head scratching and confused looks...and then a lot of diagnosis. I finally figured out that the two power lines at the main pump actually have to be connected. Although the pumps are wired in parallel, the main line from the fuse box hits the main pump AND splits to the aux pump. So when you do "tie them off", make sure to solder the apparently two power wires (green/purple in my case) together and seal them up. and cap off that ground like everyone says as well. Don't connect that to anything.

For anyone reading in the future, an alternative to this is not cutting off the eyelets. I used heat shrink to cover mine so they didn't short to anything