Fuel system for a custom buggy

[rcx132]

Hi. Would anyone who's done a custom fuel system on a kit car or buggy share how they did it?

My buggy will be running a 1.6L EFI engine. The fuel intake on the engine looks like a AN connection and the fuel return from the engine is just a barbed metal pipe. The fuel tank I've ordered has 10AN connectors. I also have several metres of 8mm plastic poly fuel line left over from a previous project which I was hoping to reuse. The generic fuel cell/tank I've ordered has 10AN outlets.

I've done a bit of Googling, and the Bosch 044 type external fuel pump is the most common I've found on custom builds. It's an external / inline pump which is great as I don't think my tank can take an in-tank pump. Does anyone have experience with this type of pump and is it what I should be using ?

There don't appear to be any AN to compression or AN to poly tube fittings available, these AN connectors seem to be designed to be used with rubber hose or aluminium hard line. I also don't get why the 10AN fittings go to 5/8 aluminium hard line. Who runs 5/8" / 15mm fuel lines?

 

[ajlelectronics]

You use Cohline 2240 flexibles or equivalent to bridge between the rigid hose and the fittings.

 

[slim_boy_fat]

Who runs 5/8" / 15mm fuel lines?

I'm guessing, but those running large engines with high pressure/volume fuel demands?

 

[jsf55]

You need 10AN to 6AN reducer and stick with 10mm or 3/8 fuel line, which is still overkill for a 1.6 efi

 

[rcx132]

I'm guessing, but those running large engines with high pressure/volume fuel demands?

Actually that makes sense... these kit car tanks are often listed as being suitable for drag racing, which explains the outlet size.

 

[Haz87]

An 044 is overkill for a 1.6.
A 941 will be more than enough (same design) even for a tuned 1600. Just watch out for cavitation - genuine* pumps are resilient, but this is the one thing that ends up killing them.

*I specify genuine as there are sooooo many fakes of these pumps floating about (all bosch external, not just 941/044) and they are pretty impressive/difficult to detect!

 

[rcx132]

You need 10AN to 6AN reducer and stick with 10mm or 3/8 fuel line, which is still overkill for a 1.6 efi

Thanks. 6AN goes to ~10mm lines, 4AN goes to ~6mm lines, 5AN goes to 8mm, which is what I want, but 5AN only exists on paper, no one sells them.

 

[rcx132]

An 044 is overkill for a 1.6.
A 941 will be more than enough (same design) even for a tuned 1600. Just watch out for cavitation - genuine* pumps are resilient, but this is the one thing that ends up killing them.

*I specify genuine as there are sooooo many fakes of these pumps floating about (all bosch external, not just 941/044) and they are pretty impressive/difficult to detect!

Thank you. Is this the 941 pump?
Apparently used on Escorts?

 

[8ob]

None of these of these efi pumps like gulping air, built a tank for a mates off roader with a weighted flexible pickup hose/pipe. That kept the pickup in the wet stuff no matter where he went.

Bob

 

[ajlelectronics]

I have found that a smear of silicone grease will allow 2240 to fit onto a 10mm stub. I had to do that for the stainless tank I have just fitted. Getting it back off might be an issue, but hopefully the Cohline will not need replacing in the future. Otherwise a 12 to 8mm brass barb reducer would be a solution. You will also need a post pump filter, I use a KL470 which is 8mm in and out.

 

[Neilj]

Keep the suction side of the pump at full bore, if your tank is AN10 and you go for a 044/941 style pump (probably 15-16mm hose connection) then use 16mm / 5.8" hose. The pumps don't like restrictions upstream and they cavitate as mentioned earlier, leading to a noisy pump and a short life. After the pump can be any size you want, 8mm is pretty common.

 

[rcx132]

Does anyone know the fitting sizes on the 941 pump? I want to pre order to fit the system over Christmas if that's possible with these Royal Snail strikes.

The fitting on the engine is now identified as an M14x1.5 with 45° flare.

 

[minimutly]

The problem with in line pumps is getting a suitable strainer before the pump. The in tank with its own strainer is a neat solution. Running without a strainer is just asking for the pump to jam. This is the main issue to get right, then the correct pressurised hose and fittings, an adjustable regulator is a good idea.

 

[rcx132]

You will also need a post pump filter, I use a KL470 which is 8mm in and out.

Would that be on a non EFI engine though? I think EFI engines need high pressure lines so a filter with barbs wouldn't cut it.

The problem with in line pumps is getting a suitable strainer before the pump.

Ok it's starting to look like I won't get this done over Christmas, I need to wait for the tank to arrive to check if it has an in built strainer, wait for the pump to arrive and measure the fittings etc.

 

[ajlelectronics]

Would that be on a non EFI engine though? I think EFI engines need high pressure lines so a filter with barbs wouldn't cut it.

It would be fine and typical fitment. Even 8mm nylon pushed inside 2240 and correctly clipped is more than adequate against injection pressure. You will note that factory EFi pumps have an 8mm barb output. The
rover V8 EFi pump I am using doesn't even feature barbs.

 

[8ob]

Does anyone know the fitting sizes on the 941 pump? I want to pre order to fit the system over Christmas if that's possible with these Royal Snail strikes.

The fitting on the engine is now identified as an M14x1.5 with 45° flare.

The ones I have here are 18mmx1.5 thread on the inlet and 12mmx1.5 on the outlet.

Bob

 

[PhillipM]

I use an 044 but I'd think for a little 1.6 it might flow so much fuel around it's just going to overheat your fuel and lead to boiling, they're good for 500-600bhp generally.

 

[PhillipM]

Oh and the 044's have a fuel strainer built into the intake - it's a little thimble basket - then you want a proper filter afterwards.
I run a filter before the pump, just because of all the dirt that can get in a tank refuelling in comp, but that can cause cavitation if you're not careful.

 

[rcx132]

For posterity, from what I can see, the "941" fuel pump full code is Bosch 0580254941. Used mainly on Fords eg XR3i.

 

[minimutly]

Oh and the 044's have a fuel strainer built into the intake - it's a little thimble basket - then you want a proper filter afterwards.
I run a filter before the pump, just because of all the dirt that can get in a tank refuelling in comp, but that can cause cavitation if you're not careful.

Indeed, as I said - the most important thing is this strainer - a tiny spec of grit will stop the pump dead. Any production efi filter after the pump would be fine.