75’ RHD FJ45 carb swap question

[jestlurnin]

Full disclosure…I’m being lazy. Half a** search done just now.

The question: Can anyone see why my city racer carb would not be a direct bolt on replacement for the OE aisin carb on my New Zealand 75’ FJ45?

Getting the current carb off won’t take much effort but I’m not 100% sure it’s a direct swap and want to be prepared. All the plumbing looks the same.

 

[Pighead]

The linkage looks similar at least, the phenolic (?) spacer looks thicker on your OEM though. Check overall height of both?

 

[jestlurnin]

Upon further inspection I think you are right @Pighead, looks significantly different rough to get a tape on it. I also noticed that the original carb has the return fuel line, the city racer one does not. I’d have to do some digging to figure out how to make that work.

Honestly the plan is to ship this baby off to one of the esteemed rebuilders but was hoping to get by with the city racer one while that’s getting done.

 

[Wayneraintree]

any pics of the whole rig? wondering if it has a full styleside bed or flat bed? I have an 84' BJ45 from NZ that was assembled in NZ so I am always curious.

 

[jestlurnin]

Hauling precious cargo here…

 

[Wayneraintree]

That is quite the beauty! Interesting tailgate as well.

 

[jestlurnin]

Ok everyone finally had some wrenching time today so I’m back to the city racer carb on my 45. @Pighead we were both wrong the spacer is correct and the city racer carb is secured and ready to roll.

New problem…the city racer carb does not have a fuel return port like my OEM carb does. This 75’ 45 originally came with a 2F according to the data plate. I believe it was @65swb45 that mentioned in a thread I found that the return line is only to help with vapor lock and capping it is fine.

Can someone explain the fuel return line from the carbs purpose? @Spike Strip @Pin_Head

I have done a ton of thread reading on the importance of the return line from the carb. Most say just to cap it and if it runs then run it. I have no problem doing that but im also trying to think of potential issues this might cause.

Appreciate everyone’s 2 cents

 

[Pighead]

@Pighead we were both wrong

Not for the first time I'm sure.

I like the fuel return line. I know that many people simply do without and see no difference. I "think" that it may add a little positive pressure to my fuel tank that may help with fuel delivery too. In your case, I might think about switching to a later 2F fuel pump (with spacer) that has the fuel return line takeoff built in.

 

[pb4ugo]

I prefer to run a return line. As mentioned, a return line can help eliminate vapor locks. The reason there could be a vapor lock is because the fuel in the line is at a dead end and will only flow when the float allows it, so the fuel is in the line for some time.
The fuel becomes heated from the ambient engine temps, then enters the carb that's sitting on a hot engine. Boiling fuel creates a vapor lock. If you think about it, Toyota uses a phenolic spacer under the carb, i think later models had heat shields, return lines and a cooling fan. The return line allows fuel to flow more quickly thru the supply line, then unused fuel goes back to the tank where it is cooled by the gas in the tank. I think the cooler fuel helps cool the pump, especially electric pumps in hopes to extend their life. Cooler fuel makes more power. Racers use cool cans filled with ice to cool the fuel b4 it goes into the carb.

 

[mattressking]

You were better off rebuilding stock carb. Fuji rep is ok....hopefully you get some miles before you sort some internal issues out.

Cap/remove return line or swap to late model Fuel Pump and adapt the fuel pipe as return is eliminated from pump to carb portion. Return shifts to fuel pump to tank.

 

[jestlurnin]

Plan is to have OE carb rebuilt but last time I sent one to the gurus it took almost 4 months to get it back. This is the stop gap. Really want to put some miles on this rig starting yesterday. Rebuilding a carb is not something I’m willing to try. Yet…..

 

[Pighead]

If the plan is to eventually install your original carb, then just cap off the return line and run it.
You really should rebuild your own carb. It's a golden opportunity to save both time and money. It'll make you a better owner.
It's not that hard. There's books and videos and 'Mud and it's not our first time.

 

[kiwipip]

Plan is to have OE carb rebuilt but last time I sent one to the gurus it took almost 4 months to get it back. This is the stop gap. Really want to put some miles on this rig starting yesterday. Rebuilding a carb is not something I’m willing to try. Yet…..

I’m based in Auckland and went down the new carb route then would have to change to the later fuel pump with the extra return line etc. I ended getting the existing one rebuild turn around was 1 week so was a happy chappy

 

[Pin_Head]

Can someone explain the fuel return line from the carbs purpose? @Spike Strip @Pin_Head

In addition to cooling the fuel at the inlet as many people have mentioned, the return has a restriction that may also serve to clip the pressure spike from the pulsatile flow of the pump. I’m not sure what this might help. Neither function seems compelling, which is probably why they run so well without a fuel return. If you really want the original 75 return for any reason, let me know and I may be able to help you out.

 

[charliemeyer007]

Simple carb, KISS - not much to go wrong or to work on. You want the best fuel mix for any condition then computerized fuel injection with sensors and brain boxes - plenty of stuff to go wrong, good luck working on it.

 

[jestlurnin]

So was able to finish up the work around to get the 45 going again today. @Pighead was correct for the final fix once everything arrives from @ToyotaMatt is the later style fuel pump with the return line coming straight out of the body of the pump and back to the tank coupled with the insulator block or spacer or whatever it’s called.

As usual Matt went above and beyond helping me solve a problem on my odd ball rig. Matching the appropriate fuel pump to the appropriate carb. Or at least the carb the Fuji was modeled after. I plan on utilizing some cut up hard fuel line I already have from some cruiser I can’t remember from the Fuji carb; coupled with soft line back to the new later style fuel pump. For now the bolt + clamp seems to be working well. Got the 45 tuned up and she running great. Pulling 21mm and idling nicely at 690RPM’s

I don’t have enough brain power to rebuild a carb right now. But it is on the bucket list.