Will a '79+ fuel pump work on a '78 FJ40? Having issues with my FJ40 running right. (1 Viewer)

[405]

Hi All,

Trying to get my newly purchased 1978 FJ40 to run right. Bought it about a month ago and it ran well, but now I think it is having a fuel starvation issue. I'm going to start with the fuel pump and filter. I was about to order a fuel pump but I noticed the one on my truck looks like the 79 and later style. It looks like someone cut the fuel hard line that goes to the carb and replaced it with rubber line. So I don't think the '78 style pump will work for me as I don't have the hard line and fitting that would thread into the 78 pump. Can I use the 79+ style fuel pump without issue? Looks like that is what is on there now, or a generic version. (see pictures)

Also, should the R on the fuel pump be going to the carb? That is how mine is and I thought R was for Return which should go back to the fuel tank? (See picture).

My truck just recently has started running poorly. It sputters under load when cold and between gear changes. Under throttle it will run rough before evening out and becoming smoother. Sometimes back firing through the carb. The symptoms are much worse when cold. While I think it is a fuel problem, it may be a voltage issue too as I've noticed my Amp meter on the cluster jumps around all over the place. The truck starts right up and idles well. The motor revs freely in neutral. It is a Columbian model if that matters. Any ideas?

 

[3_puppies]

first off, any of the fuel pumps will work on any F or 2F block, from the early 60's thru `1987 in the US
if the pump has 2 lines it does not require a spacer
if the pump has 3 lines like the above pic it requires a spacer

in your first pic
line at 12 oclock is the return
line at 3 oclock is the carb feed
line at 7 oclock is the feed from the tank

 

[405]

first off, any of the fuel pumps will work on any F or 2F block, from the early 60's thru `1987 in the US
if the pump has 2 lines it does not require a spacer
if the pump has 3 lines like the above pic it requires a spacer

in your first pic
line at 12 oclock is the return
line at 3 oclock is the carb feed
line at 7 oclock is the feed from the tank

Thanks for the info. I will go ahead and order the '79+ pump with the spacer.

Based on your info above, it appears that my fuel lines are not correctly installed on the pump . On my fuel pump in the picture, the return line and the carb feed are switched. I have my carb being fed from the 12 oclock port and the return is at 3 oclock port. I will switch the 2 and see what happens.. Maybe this will solve my problem? But the truck has ran this way without issue since I bought it a month ago until recently.

 

[Goldbug]

I don't know if a new fuel pump will solve your problem. You may want to reach out to @red66toy who runs The Cruiser Cult and is a bit of a fuel pump maestro. Of course I'm as guilty as anyone of throwing OEM parts at a problem.

If you haven't already, check the sight glass in the carb to see if it's getting fuel. Your carb should have one.

 

[red66toy]

Hopefully this is helpful. Sounds like you have the lines backwards.

 

[3_puppies]

a 78 carb would have had the return off the carb
in late 79 it was changed to return from the fuel pump.

an easy way to check is to see how much fuel is coming out of both fuel lines when the engine is turned over

 

[405]

I don't know if a new fuel pump will solve your problem. You may want to reach out to @red66toy who runs The Cruiser Cult and is a bit of a fuel pump maestro. Of course I'm as guilty as anyone of throwing OEM parts at a problem.

If you haven't already, check the sight glass in the carb to see if it's getting fuel. Your carb should have one.

Thanks. I will take a look at that. Should the sight glass only have fuel visible if the truck is running?

Hopefully this is helpful. Sounds like you have the lines backwards.

Thanks, it is. I switched the lines and it is now correct. The outlet is now feeding the carb instead of the return.

After switching the lines it runs a little better, but not great. Still dealing with the problems as I was in post 1. I have noticed that in 2nd gear there is no power. The revs build but I don't go any faster.

I have booked an appointment with a local mechanic next week. They are going to service the carb and see if there is something in there. My mechnaic seems to think it could be the accelerator pump

a 78 carb would have had the return off the carb
in late 79 it was changed to return from the fuel pump.

an easy way to check is to see how much fuel is coming out of both fuel lines when the engine is turned over

Do you know if that would be true of a Columbian model? I only see 1 fuel line from my carb and that is the feed from the pump.