Novak Conversions Jeep Wrangler YJ shifters

Weber carb plays up after long steady drive

jpjeep26uk

jpjeep26uk

YJ Enthusiast
Joined
Nov 12, 2022
Messages
324
Location
UK
Hi all.
I had my EFi taken out of my 1989 2.5 4cyl and a Weber lookalike Carb put it.
After about two months of fiddling around and tweaking to what I thought was perfection I now have this problem...
I drive 110 miles at approx 60mph for about 2.5 hours. Drives beautifully, better than ever.
But when I eventually pull off the motorway and end the journey on quieter lanes she immediately wants to stall. To get the last 6 miles to the hotel I have to bump start her as I slow down or she stalls or I have to crank her up every single time I come to a stop because she dies.
Parked her oveenight at the hotel and ahe fired up and was back to normal.
Next day drive 120 miles home at approx 60mph and rhe exact same thing, stall stall stall.
I figured I'd come close to running out of petrol so I filled her up and took her for a gallop.
Nope, she won't even stay on now unless I keep the gas coming.
Here's the set up:
Filter is on the rear drivers side on the chassis arch, one pipe in, one out, sits at a about a 40 degree angle and is mounted the right way for flow.
Electric fuel pump is mounted down on the chassis directly below rhe carb which is where the old EFI sat.
Just under the carb is the fuel pressure regulator set at 3.5psi.
The pump was originally installed where the air housing was but I went through two pumps in a
month before someone told me it was asking too much of the pump to move fuel up from the chassis line then around a loop of 1 meter into the FPR and then into the carb.

Can any one tell me why she drove brilliantly for 250 mileage at cracking speed and now she's gotten home she won't stay on without constant gas and whe she does drive she feels 'retarded' inconsistent and actually quote rough until I demand 50-60 mph out of her.
Sorry for long message but I spent $2300 on the carb swap and new brake lines and I thought my troubles were over hahahaha.
Thanks everyone.
( also if anyone knows how to properly set a weber clone up I'd appreciate some guidance)
 
jpjeep26uk said:
Hi all.
I had my EFi taken out of my 1989 2.5 4cyl and a Weber lookalike Carb put it.
After about two months of fiddling around and tweaking to what I thought was perfection I now have this problem...
I drive 110 miles at approx 60mph for about 2.5 hours. Drives beautifully, better than ever.
But when I eventually pull off the motorway and end the journey on quieter lanes she immediately wants to stall. To get the last 6 miles to the hotel I have to bump start her as I slow down or she stalls or I have to crank her up every single time I come to a stop because she dies.
Parked her oveenight at the hotel and ahe fired up and was back to normal.
Next day drive 120 miles home at approx 60mph and rhe exact same thing, stall stall stall.
I figured I'd come close to running out of petrol so I filled her up and took her for a gallop.
Nope, she won't even stay on now unless I keep the gas coming.
Here's the set up:
Filter is on the rear drivers side on the chassis arch, one pipe in, one out, sits at a about a 40 degree angle and is mounted the right way for flow.
Electric fuel pump is mounted down on the chassis directly below rhe carb which is where the old EFI sat.
Just under the carb is the fuel pressure regulator set at 3.5psi.
The pump was originally installed where the air housing was but I went through two pumps in a
month before someone told me it was asking too much of the pump to move fuel up from the chassis line then around a loop of 1 meter into the FPR and then into the carb.

Can any one tell me why she drove brilliantly for 250 mileage at cracking speed and now she's gotten home she won't stay on without constant gas and whe she does drive she feels 'retarded' inconsistent and actually quote rough until I demand 50-60 mph out of her.
Sorry for long message but I spent $2300 on the carb swap and new brake lines and I thought my troubles were over hahahaha.
Thanks everyone.
( also if anyone knows how to properly set a weber clone up I'd appreciate some guidance)
Click to expand...

Just to add we are having an unusually hot summer over here with temps regularly up in the late 20s which is phenomenal for our island! Does ambient heat play a factor? I've put heat shielding around my fuel line as it comes to the pump and up to the carb and have a directional custom made air pipe aimed at the pump to keep everything as cool as possible. THANKS!!!!
 
jpjeep26uk said:
Hi all.
I had my EFi taken out of my 1989 2.5 4cyl and a Weber lookalike Carb put it.
After about two months of fiddling around and tweaking to what I thought was perfection I now have this problem...
I drive 110 miles at approx 60mph for about 2.5 hours. Drives beautifully, better than ever.
But when I eventually pull off the motorway and end the journey on quieter lanes she immediately wants to stall. To get the last 6 miles to the hotel I have to bump start her as I slow down or she stalls or I have to crank her up every single time I come to a stop because she dies.
Parked her oveenight at the hotel and ahe fired up and was back to normal.
Next day drive 120 miles home at approx 60mph and rhe exact same thing, stall stall stall.
I figured I'd come close to running out of petrol so I filled her up and took her for a gallop.
Nope, she won't even stay on now unless I keep the gas coming.
Here's the set up:
Filter is on the rear drivers side on the chassis arch, one pipe in, one out, sits at a about a 40 degree angle and is mounted the right way for flow.
Electric fuel pump is mounted down on the chassis directly below rhe carb which is where the old EFI sat.
Just under the carb is the fuel pressure regulator set at 3.5psi.
The pump was originally installed where the air housing was but I went through two pumps in a
month before someone told me it was asking too much of the pump to move fuel up from the chassis line then around a loop of 1 meter into the FPR and then into the carb.

Can any one tell me why she drove brilliantly for 250 mileage at cracking speed and now she's gotten home she won't stay on without constant gas and whe she does drive she feels 'retarded' inconsistent and actually quote rough until I demand 50-60 mph out of her.
Sorry for long message but I spent $2300 on the carb swap and new brake lines and I thought my troubles were over hahahaha.
Thanks everyone.
( also if anyone knows how to properly set a weber clone up I'd appreciate some guidance)
Click to expand...

Since you've mentioned that the car drives well initially but then stalls after changing speed, it could indicate that your fuel pump isn't supplying enough fuel under certain conditions. Given that your setup is using an electric pump positioned below the carb, it should ideally create enough pressure, but if the pump is struggling or if there's a blockage in the lines, it could lead to stalling after a steady drive.

One common problem when switching from EFI to a carb is vapor lock, especially if the fuel lines are close to heat sources. After a long drive, fuel could be heating up and vaporizing before it reaches the carb. Make sure your fuel lines are insulated or routed away from heat sources.

It's also possible that the carb needs fine-tuning. Check the float level; if it's set too low, it won't allow enough fuel into the bowl, leading to stalls. Adjusting the idle mixture screw may also help if the engine is running rich or lean. Given that it's a Weber clone, make sure to refer to the specific tuning guidelines for your model.

Make sure there aren’t any air leaks between the carb and the intake manifold. An air leak can cause the engine to stall when coming to a stop.

Double-check the fuel filter and lines for any obstructions. A clogged filter or kinked line could severely restrict fuel flow.

Since you had issues with the original placement of the pump, ensure that it is functioning correctly and providing consistent pressure while the engine is running. It may be worth checking the specifications of your pump against the requirements of the Weber.

As for setting up a Weber clone, a good starting point is to ensure that the float height is accurate, verify that the main jet and idle jet sizes are appropriate for your application, and adjust the idle speed screw until you achieve a smooth idle.

Hopefully, this gives you some directions to explore. Let us know how it goes, and good luck!
 
Chris said:
Since you've mentioned that the car drives well initially but then stalls after changing speed, it could indicate that your fuel pump isn't supplying enough fuel under certain conditions. Given that your setup is using an electric pump positioned below the carb, it should ideally create enough pressure, but if the pump is struggling or if there's a blockage in the lines, it could lead to stalling after a steady drive.

One common problem when switching from EFI to a carb is vapor lock, especially if the fuel lines are close to heat sources. After a long drive, fuel could be heating up and vaporizing before it reaches the carb. Make sure your fuel lines are insulated or routed away from heat sources.

It's also possible that the carb needs fine-tuning. Check the float level; if it's set too low, it won't allow enough fuel into the bowl, leading to stalls. Adjusting the idle mixture screw may also help if the engine is running rich or lean. Given that it's a Weber clone, make sure to refer to the specific tuning guidelines for your model.

Make sure there aren’t any air leaks between the carb and the intake manifold. An air leak can cause the engine to stall when coming to a stop.

Double-check the fuel filter and lines for any obstructions. A clogged filter or kinked line could severely restrict fuel flow.

Since you had issues with the original placement of the pump, ensure that it is functioning correctly and providing consistent pressure while the engine is running. It may be worth checking the specifications of your pump against the requirements of the Weber.

As for setting up a Weber clone, a good starting point is to ensure that the float height is accurate, verify that the main jet and idle jet sizes are appropriate for your application, and adjust the idle speed screw until you achieve a smooth idle.

Hopefully, this gives you some directions to explore. Let us know how it goes, and good luck!
Click to expand...
@Chris Wow that's a helpful reply with a tonne of stuff to check over.
I'll have to do my homework on what a float bowl is haha and how to figure out the Jets etc and then I'll start rooting around and see what can be done. Great stuff and thanks for the guidance and I'll post my progress.
(I didn't put or choose the clone carb, the shop fixing it did that to keep the overall price low for me so should I replace it with a 'real' Weber? or are they pretty much the same deal? Apologies for my ignorance)
 
Hi all.
Got round to work on the fixes and spotted this brown stain in the carb. Never seen it before. Put my finger underneath and it was slightly wet and is definitely petrol.
Do I tighten that bolt up? Is it leaking from above and down to that bolt because there is similar brown residue in the assembly too?
What could that be caused by?

Pump is set to 3.5psi as recommended and there is fuel in the pipe hitting the carb opposite the dirty bolt?
20250813_184625.jpg


17551073996427346116047505111896.jpg
 
Also, with the choke on fully, this is as far shut as my plates go. Is that right as I thought they should be almost totally closed when the manual choke is engaged??
20250813_185511.jpg
 
Up date. Fiddled with the low idle and high idle and the mixture screw and for now she is running steady and stays on when I fire her up.
Not totally sure what I did , started from scratch and just tuned screws around until she ran smoothly.
I need a lesson in carb tuning.
I think the screw attached is the high idle.....

20250813_194502.jpg
 
jpjeep26uk said:
Also, with the choke on fully, this is as far shut as my plates go. Is that right as I thought they should be almost totally closed when the manual choke is engaged??
View attachment 124172
Click to expand...

That choke looks about right. But the stalling problem after driving for hours at speed doesn’t sound like a problem with too little choke. The first place that I would start is adjusting the idle speed up a little. That may make it idle faster than you want when cooler but possibly not stall when hot. And yes a real Weber carb would have been a safer choice. You are not really sure what you are getting with a clone.
 
ytradio said:
That choke looks about right. But the stalling problem after driving for hours at speed doesn’t sound like a problem with too little choke. The first place that I would start is adjusting the idle speed up a little. That may make it idle faster than you want when cooler but possibly not stall when hot. And yes a real Weber carb would have been a safer choice. You are not really sure what you are getting with a clone.
Click to expand...

Hi YTradio, ill probably start looking into a genuine weber carb soon. I can't seem to find a picture or advice on my particular clone version. Apparently it's from a VW camper van website as they work on YJs with a slight mod to make them fit direct to the intake.
I did what you and other have suggested and yep, raised the idle speed higher and she runs but I feel she's over running at 1200 rpm at lights and stops etc.
ytradio said:
That choke looks about right. But the stalling problem after driving for hours at speed doesn’t sound like a problem with too little choke. The first place that I would start is adjusting the idle speed up a little. That may make it idle faster than you want when cooler but possibly not stall when hot. And yes a real Weber carb would have been a safer choice. You are not really sure what you are getting with a clone.
Click to expand...

Hi, I did that adjustment and yip, that fixed it. I baselines the mixture then adjusted the idle and its now idling at 1200 revs. A lot higher than usual but at oesst she starts, stays on and doesn't stall at every stop sign. I'll buy that for a dollar.!
 
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