DIY - Walbro 255 fuel pump retrofit.

[agent]

I got starvation issues around corners, and off/on ramps without pushing the car hard at all.

The best option for a street driven car is an OEM pump/assembly.

[ncsubowen]

I got starvation issues around corners, and off/on ramps without pushing the car hard at all.

The best option for a street driven car is an OEM pump/assembly.

Given that the OEM in-tank assembly is currently $300+, is there any reason not to do this modification and then also include the inline pump if you're worried about starvation?

[agent]

$300+ seems steep. I seem to recall them being in the $200 neighborhood when I bought mine about eighteen months ago.

[ncsubowen]

$300+ seems steep. I seem to recall them being in the $200 neighborhood when I bought mine about eighteen months ago.

Cheapest I can find on the OEM assembly is FCP Euro @ $278, coupon gets it to $258 but that doesn't address the in-line pump which also needs replaced @ $100+. Would a big pump replacing the transfer pump ruin the in-line if they were both new?

[agent]

I was not aware the pump for early cars was so much more expensive than the one for late cars.

[ncsubowen]

I was not aware the pump for early cars was so much more expensive than the one for late cars.

The problem is that it's not just the pump you're replacing, it's the whole assembly. I'm trying to find a part number that's specific to just the in-tank transfer pump part and then swap that out on the existing assembly, but not having much luck.

That's a huge reason why there's so many people trying to convert to a single pump setup, because that's really $400 in parts before you even touch the car if you stay stock.

[agent]

I can see why you'd want to retrofit it. The $200 I paid was for the entire in-tank assembly (on a late car obviously).

[cWalk3r]

I don't really understand the starvation issue... I put a walbro pump in my very 325i and it sat exactly the same way as the OEM pump. I don't see how it will have starvation issues if it sits the same way.. Maybe I'm just crazy but it doesn't look like it should happen. lol I've been using it for a couple months but haven't driven it hard.

[ncsubowen]

I don't really understand the starvation issue... I put a walbro pump in my very 325i and it sat exactly the same way as the OEM pump. I don't see how it will have starvation issues if it sits the same way.. Maybe I'm just crazy but it doesn't look like it should happen. lol I've been using it for a couple months but haven't driven it hard.

Starvation is for early model cars with a different tank design. Those cars have an in tank transfer pump and an inline fuel pump, so there are some people that have removed the inline pump and retrofitted a walbro (or similar) high pressure pump to the in-tank assembly. Unfortunately, due to the design difference, this causes starvation issues when turning or driving particularly steep hills.

[agent]

I don't really understand the starvation issue... I put a walbro pump in my very 325i and it sat exactly the same way as the OEM pump. I don't see how it will have starvation issues if it sits the same way.

That's the thing - it doesn't sit the same way if these steps are followed:

Modification
[...]
2. Remove the bottom metal shelf that the old pump rested on. Use the pliers to break it off the rod that goes down.

3. Use pliers to bend a small tab for the new pump to rest on, maybe 5mm at most.

4. (Image 6) Install new fuel pump and strap to the rod using the two stainless hose clamps.

Those steps raise the pump (and the sock) at least 5mm higher - probably more like 10mm once the rod is bent - than the OEM assembly. The only sock I was able to source locally which fit the nipple on the Walbro was out of a Mustang kit. It was half the size of the OEM sock, so in my case, that resulted in two things working to induce starvation.

[Regnar75]

just a little note for the early model guys. I converted to a single in tank 255lph pump and here are my quick notes.

-there's a ground going to the old high pressure pump, I grounded it since it seemed like a smart idea. The Hot wire there you will want to cap off and keep protected from shorting out on something.

-feed a high pressure fuel line down from the back seat down the tank towards the exterior fuel pump. you want to run a high pressure line to mitigate risk of bursting the low pressure one. this is VERY easy, i dont understand why people struggle here.

-I bypassed the two fuel pulse whatevers by the exterior pump and just went directly into the hard line, no difference noticed.

-the fuel injector line i used fit on the hard line but not the outlet of the fuel pump housing. a step down hose is needed. or if you're creative and like risks, take the old low pressure hose, and cut off about 5 inches. then feed a piece of the high pressure hose into the low pressure hose piece (about half way) enough that the low pressure hose can go back onto the fuel pump outlet tube and that the high pressure hose butts up against the tube. you should then fit a male to male adapter into the fuel hose going down the tank and into the new double layered hose. you want to use the adapter so when you put a clamp on the double layered hose it can actually clamp the two hoses tighly without collapsing them. clamp all the ends of hoses. Or you can do the smart thing and just get the two sized high pressure hose and avoid this mess.

-the fuel pump i had was very similar to a walbro (i think same size specs) and the early fuel pump housing does not have the bracket holding it on the bottom that you are to trim in the later models. instead if your pump hits the bottom of the tank and you cant bolt the top down, you need to remove (in my case just under an inch) some material from the tube the fuel pump feeds into. I used a hack saw and then a file to dull its edge. the hose that connects the two burst after a short while so use some high pressure hose that wont dissolve when immersed in gasoline. clamp these down tight and make sure your pump isnt sitting on the tank but is close.

-wiring is pretty straight forward I cut soldered and shrink wrapped my new hot wire and grounded the pump to the return tube.

-the whole thing is pretty wobbly since there isnt anything holding it together besides wire and a hose, so use something to keep the unit tight against the drain tube. zipties i wouldnt trust in gas for too long, but using too big of a hose clamp may make fitting the unit back into the tank difficult. use what you've got.

obviously do any cutting, soldering, shrink wrapping with the pump out of the car and preferably in a different room so you dont burn your car down, or yourself. just some notes for us early model guys.


Here's a picture of my fuel pump mounted to the early assembly, I believe it was prior to me cutting a little off the tube that the hose fits onto.
20160111_123724


and here is the Early model in tank fuel pump setup, the larger Diameter hose on the bottom is the feed going into the engine, and the small diameter hose with the bend is the drain going back into the tank. the Early model fuel tanks dont have the drain like the late models.
20160111_103843

[bmw444]

I did this conversion a year or so again on my '86 car with dual pumps using a TRE 255. Once I had pulled out the old pumps I did not like the idea of putting a dodgy joiner from the 8mm fuel hose to the larger inlet on the housing in the tank so I went to the junkyard and got a couple of late model pump/housings and the fuel line which goes over the tank. The late housing just drops in without the hassle of bending/cutting and if the late model junkyard pump works you are home free in any case without shelling out for a new pump. This has been working perfectly for over 12 months now.

[Dkashbmx]

Anyone have ANY suggestions on a fuel pressure regulator!? The DIY write up worked great! No starvation at all HOWEVER, it's pumping so much into the rail. I can smell raw fuel and I suspect the FPR is not holding up. Anyone have any suggestions?

[Regnar75]

Anyone have ANY suggestions on a fuel pressure regulator!? The DIY write up worked great! No starvation at all HOWEVER, it's pumping so much into the rail. I can smell raw fuel and I suspect the FPR is not holding up. Anyone have any suggestions?

I bought an OEM one from Bavauto for like 70$? It's holding up great, I was worried it may wear or break because I have a rrfpr in line with it, but it's going strong.

[NeverEnough02]

Thanks for the early model break down. What sizes did you need for the double sized high pressure fuel line? I am going to do this on my early model soon enough and would like to order ahead of time.

just a little note for the early model guys. I converted to a single in tank 255lph pump and here are my quick notes.

-there's a ground going to the old high pressure pump, I grounded it since it seemed like a smart idea. The Hot wire there you will want to cap off and keep protected from shorting out on something.

-feed a high pressure fuel line down from the back seat down the tank towards the exterior fuel pump. you want to run a high pressure line to mitigate risk of bursting the low pressure one. this is VERY easy, i dont understand why people struggle here.

-I bypassed the two fuel pulse whatevers by the exterior pump and just went directly into the hard line, no difference noticed.

-the fuel injector line i used fit on the hard line but not the outlet of the fuel pump housing. a step down hose is needed. or if you're creative and like risks, take the old low pressure hose, and cut off about 5 inches. then feed a piece of the high pressure hose into the low pressure hose piece (about half way) enough that the low pressure hose can go back onto the fuel pump outlet tube and that the high pressure hose butts up against the tube. you should then fit a male to male adapter into the fuel hose going down the tank and into the new double layered hose. you want to use the adapter so when you put a clamp on the double layered hose it can actually clamp the two hoses tighly without collapsing them. clamp all the ends of hoses. Or you can do the smart thing and just get the two sized high pressure hose and avoid this mess.

-the fuel pump i had was very similar to a walbro (i think same size specs) and the early fuel pump housing does not have the bracket holding it on the bottom that you are to trim in the later models. instead if your pump hits the bottom of the tank and you cant bolt the top down, you need to remove (in my case just under an inch) some material from the tube the fuel pump feeds into. I used a hack saw and then a file to dull its edge. the hose that connects the two burst after a short while so use some high pressure hose that wont dissolve when immersed in gasoline. clamp these down tight and make sure your pump isnt sitting on the tank but is close.

-wiring is pretty straight forward I cut soldered and shrink wrapped my new hot wire and grounded the pump to the return tube.

-the whole thing is pretty wobbly since there isnt anything holding it together besides wire and a hose, so use something to keep the unit tight against the drain tube. zipties i wouldnt trust in gas for too long, but using too big of a hose clamp may make fitting the unit back into the tank difficult. use what you've got.

obviously do any cutting, soldering, shrink wrapping with the pump out of the car and preferably in a different room so you dont burn your car down, or yourself. just some notes for us early model guys.


Here's a picture of my fuel pump mounted to the early assembly, I believe it was prior to me cutting a little off the tube that the hose fits onto.
20160111_123724


and here is the Early model in tank fuel pump setup, the larger Diameter hose on the bottom is the feed going into the engine, and the small diameter hose with the bend is the drain going back into the tank. the Early model fuel tanks dont have the drain like the late models.
20160111_103843